WO2023137339A1 - Screening the degradation of polymer microparticles on a chip - Google Patents

Abstract

The present disclosure provides methods, systems, and devices for enzymatic degradation of at least one polymeric microparticle, optionally coupled with real-time analysis (visualization and quantification) of the degradation process, e.g., using a microfluidic chip. The change in transparency, porosity, smoothness, brightness, and/or particle size of the polymeric microparticles may be observed, analyzed, and/or quantified as indicators of enzymatic degradation.

Description

SCREENING THE DEGRADATION OF POLYMER MICROPARTICLES ON A CHIP CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims priority to U.S. Provisional Patent Application Serial No. 63/298,501 filed on January 11, 2022, the contents of which is incorporated herein by reference in its entirety. FIELD OF TECHNOLOGY [0002] The disclosure provides devices, systems, and methods for visualizing and quantifying the degradation of polymeric microparticles, e.g., using a microfluidic chip. BACKGROUND OF THE DISCLOSURE [0003] Petroleum-based plastics are one of the most consumed materials with a historically high production rate, for example 380 million tons per year in 2015. However, the limitations of petroleum resources, environmental concerns associated with using such materials, and legislative pressure prompted the development of environmentally-friendly substitutions, such as biodegradable polyesters in the 1980s. Aromatic polyesters have been well-known for their lower biodegradability rate compared with aliphatic polyesters. Alternatively, aliphatic polyesters suffer from high rigidity and lower elongation at break, limiting their applications. [0004] To address these issues, various biodegradable polymeric materials such as polyesters and polyurethanes have been developed. For example, Poly (1,4-butylene adipate-co- terephthalate) (PBAT) was developed by BASF. PBAT is a linear random co-polyester of 1,4 butanediol and adipic acid dimers (BA) as flexible (soft) units, along with crystalline terephthalic acid and 1,4 butanediol dimers (BT) as rigid (hard) units. The copolymerization of BA and BT units provides biodegradability, flexibility, longer elongation at break, hydrophilicity, and better processability. PBAT is considered as a fully compostable polyester and its microbial degradation has been extensively studied. Further, PBAT hydrolysis and degradation by erosion has been reported and it has been confirmed that the aliphatic region in PBAT is most susceptible to degradation. Moreover, it has also been reported that anaerobic sludge changes the crystallinity of PBAT during degradation. [0005] To ensure degradation of water-insoluble polymers, microorganisms secrete extracellular enzymes to catalytically hydrolyze the ester bonds to provide water-soluble intermediates. Once the polymers are broken down into smaller water-soluble intermediates, microorganisms uptake the intermediates and metabolize them to CO₂ to complete the degradation. The enzymatic hydrolysis step is considered the rate-controlling step in biodegradation and, consequently, enzymatic degradation of biodegradable polymers has been the subject of numerous studies. Several studies have focused on finding various types of enzymes, isolated from different microorganisms, that can perform polyester degradations. Field test methods, such as soil burial and composting, simulate environmental degradation conditions and are deeply informative of polymeric degradation, but they are time-consuming and have a limited scope of analysis as the degradation rate also depends on the physiochemical and morphological properties of polymers and the inoculum being used. [0006] To broaden the application of biodegradable polyesters, a time-resolved degradation profile in a predefined environment is required. Currently, degradation analyses for bulk samples are time-consuming and require multiple tests of similar samples at different time intervals, making them unable to provide real-time measurements. Evaluation of the extent of degradation in bulk samples also requires offline analysis of degraded samples, making these methods time and resource demanding. Real-time analytical methods, such as Quartz Crystal Microbalance (QCM), Surface Plasmon Resonance (SPR), and Scanning Photo-Induced Impedance Microscopy (SPIM) have been previously utilized to decrease the time and increase throughput to study the polymer degradation process. However, these methods are expensive, require special devices, and offer limited analysis of different polymer morphologies. BRIEF SUMMARY OF EXEMPLARY ASPECTS OF THE DISCLOSURE [0007] In some aspects, the present disclosure provides methods for analyzing (e.g., visualizing and quantifying) the enzymatic degradation of at least one polymeric microparticle by adding an enzymatic solution (e.g., statically, dynamically) to the polymeric microparticle and analyzing a change in transparency of the polymeric microparticle. As described herein, this change in transparency is indicative of the extent of enzymatic degradation of the polymeric microparticle. In some aspects, these methods utilize a microfluidic device. [0008] In one aspect, the method for analyzing enzymatic degradation of a polymeric microparticle involves adding an enzymatic solution to at least one polymeric microparticle and analyzing a change in transparency, particle size, porosity, smoothness, and/or brightness of the at least one polymeric microparticle. As described herein, the change in transparency, particle size, porosity, smoothness, and/or brightness may all be used as indicators of the extent of enzymatic degradation of a polymeric microparticle. In some aspects, the devices, systems, and methods described herein may determine or measure any combination of these parameters. For example, in some aspects a change in transparency of the polymeric microparticle may be determined and/or measured by comparing the level of transparency observed at a given time point to a control (e.g., a baseline level of transparency of the same polymeric microparticle determined and/or measured prior to the application of the enzyme(s) being evaluated). In some aspects, the change in transparency may be measured as a percentage change. In some aspects, the change in transparency or any other indicator of degradation described herein may be determined and/or measured at specific time points (e.g., 1, 2, 3, 4, 5, 6, 12, 24, 36, 48 or 60 hours after application of the enzyme(s) being evaluated). [0009] In another embodiment, the method for analyzing enzymatic degradation of a polymeric microparticle is performed in a microfluidic chip involving adding at least one polymeric microparticle in at least one inlet port of the microfluidic chip, followed by adding an enzymatic solution into at least one inlet port at a flow rate (or under static conditions), and analyzing a change in transparency of the at least one polymeric microparticle. As disclosed above, the change in transparency is indicative of enzymatic degradation. [0010] In some exemplary aspects, the change in transparency of at least one polymeric microparticle can be visualized in real-time, e.g., within 1, 2, 3, 4, 5, 6, 12, 18, or 24 hours, or 1, 2, 3, 4, 5, 6, or 7 days of adding the enzymatic solution. In other aspects, the change in transparency, in addition to a change in particle size, porosity, smoothness, and/or brightness, is visualized in real-time within 24, 48, or 72 hours of adding the enzymatic solution, e.g., reducing the time and/or resource expenditure. The determined or measured change of any combination of these parameters (e.g., transparency and particle size) may be used to evaluate the extent of enzymatic degradation of the polymeric microparticle. [0011] In some exemplary aspects, the change in transparency, particle size, porosity, smoothness, and/or brightness is visualized using a microscope. In some aspects, the change in particle size is visualized via inverted phase contrast (IPC) microscopy and/or a scanning electron microscopy (SEM), while the change in smoothness and/or porosity is visualized via scanning electron microscopy (SEM) or confocal laser scanning microscopy. [0012] In some exemplary aspects, the visualization of the change in transparency, particle size, porosity, smoothness, and/or brightness of the polymeric microparticle is quantified. [0013] In some exemplary aspects, the enzymatic solution comprises at least one of hydrolase, lyase, lipase, protease, amylase, cellulase, cutinase, mannanase, urease, xylanase or a plurality of enzymes comprising any combination thereof. [0014] In some exemplary aspects, the polymeric microparticle comprises Poly (1,4-butylene adipate-co-terephthalate) (PBAT). In some exemplary aspects, the polymeric microparticle comprises one or more of: polyesters, PBAT, polylactic acid (PLA), polycaprolactone (PCL), poly butyl acrylate (PBA), polybutylene succinate (PBS), polyurethanes, polyamides, polyureas, polyanhydrides polyesters containing polyurethane moieties and blends, and/or a mixture/blend of the aforementioned polymers. In some exemplary aspects, the polymeric microparticle comprises one or more water-insoluble starches or polysaccharides. In some aspects, a device, method, or system described herein may evaluate a plurality of polymeric microparticles, wherein the plurality of polymeric microparticles comprises a mixture of microparticles formed from one or more of the polymers described herein. [0015] In some exemplary aspects, the disclosure provides a microfluidic chip comprising at least one inlet port, at least one outlet port, and at least one channel having an opening for flow of microparticles and a plurality of slots that are configured to trap at least one microparticle. In some aspects, the plurality of slots are cross-sectional pillars, and the surface density of the cross-sectional pillars increases from the at least one inlet port toward the at least one outlet port. In other aspects, the surface density of the cross-sectional pillars remains constant. In some aspects, the microfluidic chip may comprise crescent-shaped channels configured to trap microparticles which have a particle size above a given threshold, e.g., as shown in FIG.6 and FIG.10. In some aspects, the microfluidic chip comprises pores having a pore volume in the approximate range of 1-3 µL, e.g., 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, or 3.0 µL, or a volume within a range defined by any of the aforementioned values. In other aspects, the microfluidic chip comprises pores having a pore volume in the approximate range of 0.1-1000 µL, e.g., 0.1, 0.5, 1, 5, 10, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000 µL, or a volume within a range defined by any of the aforementioned values. In some aspects, the microfluidic chip comprises a micropatterned polydimethylsiloxane (PDMS) layer. [0016] In some exemplary aspects, the present disclosure provides a microfluidic device comprising a plurality of any of the aforementioned microfluidic chips, arranged in series and/or in parallel. [0017] In some exemplary aspects, the disclosure also provides a system comprising any of the aforementioned microfluidic chips, configured as a device for visualizing and/or screening microparticles based on any of the parameters described herein. BRIEF DESCRIPTION OF THE DRAWINGS [0018] FIG. 1 is a combined representation of CLSM z-stack middle slice pictures of PBAT microparticles stained with Rhodamine B (FIG.1A) before and after degradation in a microfluidic chip (FIG.1B) or bulk (FIG.1C). SEM images of PBAT microparticles after degradation in bulk (FIG.1D), and the microfluidic chip (FIG.1E) are also provided. [0019] FIG. 2 is a schematic representation of a microfluidic chip having at least one inlet port, at least one outlet port, the channels having an opening for the flow of material and slots or cross-sectional pillars to trap at least one polymeric microparticle. [0020] FIG. 3 is a top view of an exemplary microfluidic chip according to the disclosure, showing channels, cross-sectional pillars, and a main channel, which provide a flow path for liquid and material introduced into the microfluidic chip (e.g., from an inlet to an outlet). As illustrated in this figure, a microfluidic chip according to the disclosure may optionally comprise at least one main channel, in addition to a plurality of smaller channels configured to trap materials (e.g., polymeric microparticles). [0021] FIG.4 demonstrates efficient microparticle trapping in the chip with slots or pillars. [0022] FIG.5 shows a schematic of the degradation of the PBAT microparticles in the chip at pH 7.4, and a flow rate of 50 µL/h: lower zoom initial (1) and after 48 h enzymatic degradation (2) (FIG. 5A) single particle at different time points (FIG. 5B) difference of particle sizes after 48 h (FIG.5C) change of transparency values vs time (FIG.5D), and effect of enzyme concentration on transparency values (FIG.5E). [0023] FIG. 6 is a top view of an exemplary microfluidic chip according to another aspect of the disclosure, showing an array of semicircular or crescent-shaped channels configured to trap polymeric microparticles. [0024] FIG. 7 is a schematic of enzymatic degradation in a chip including the degradation system coupled with a device capable of visualizing microparticles in real-time. [0025] FIG.8 is a plot showing the change in relative transparency observed over 93 hours for PBAT treated with Novozym® 51032 at two different flow rates according to Example 2. [0026] FIG. 9A is a plot showing the change in relative transparency observed over 132 hours for PBAT treated with Novozym® 51032 at three different concentrations according to Example 3. FIG.9B is an annotated version of the plot shown in FIG.9A. [0027] FIG.10 is a series of images illustrating the diffusion of enzyme solution to the inner core (as indicated by the fluorescent dye penetrating the particle) of the particles as the degradation proceeded during the course of the experiment described in Example 4. [0028] FIG.11 is a plot showing the change in relative transparency observed over 120 hours for PBS, at two different molecular weights, treated with Novozym® 51032 according to Examples 5 and 6. [0029] FIG. 12 shows change in transparency (FIG. 12A) and change in area (FIG. 12B) observed over 37 hours for PCL treated with Novozym® 51032 in static or dynamic conditions according to Example 7. [0030] FIG. 13 shows change in transparency (FIG. 13A) and change in area (FIG. 13B) observed over 55 hours for PBAT, at three different temperatures, treated with Novozym® 51032 according to Example 8. n = the number of particles tracked. [0031] FIG.14 is a plot showing the change in area observed over 25 hours for PCL treated with three different enzymes according to Example 9. [0032] FIG. 15 shows change in transparency (FIG. 15A) and change in area (FIG. 15B) observed over 48 hours for PBAT/PLA and PBAT/PBS polymer blends treated with Novozym® 51032 according to Example 10. n = the number of particles tracked. [0033] FIG.16 shows change in transparency observed over 60 hours for Elastollan® treated with Novozym® 51032 according to Example 11. [0034] FIG.17 shows change in transparency observed over 90 hours for PBAT treated with Novozym® 51032 in static or dynamic conditions according to Example 12. [0035] FIG.18 shows change in transparency observed over 55 hours for PBAT treated with Novozym® 51032 according to Example 13. [0036] FIG.19 is a plot showing the change in transparency observed over 48 hours for PLA treated with Novozym® 51032 at two different temperatures according to Example 14. [0037] FIG. 20 shows change in area observed over 23 hours for corn starch treated with amylase at 40 ⁰C according to Example 15. [0038] FIG.21 shows change in transparency observed over 21 hours for wheat flour treated with xylanase according to Example 16. [0039] FIG.22 shows a time lapse of enzymatic degradation of PCL particles with ~ ^ ^ ^ μm (top) and ~30 ^ μm (bottom) in radius using 150 LU/g enzyme solution (scale bar = 60 μm) according to Example 17. [0040] FIG.23 shows conversion-time data of enzymatic degradation of PCL microparticles (black dots) and fitted curves of I control mechanism (line); the dashed lines indicate 95% prediction bonds. [0041] FIG. 24 shows a time lapse of enzymatic degradation of PBAT microparticles with ~20 μm (top) and ~15 μm (bottom) in radius using enzyme at 15k LU/g (scale bar = 60 μm) according to Example 17. [0042] FIG.25(A) shows images of PBAT particles (~20 μm) during enzymatic degradation; FIG. 25(B) shows conversion-time data of enzymatic degradation of PBAT micro particles (black dots) and fitted curves with different mechanisms (line); the dashed lines indicate 95% prediction bonds; FIG 25(C) shows relative darkness and conversion (predicted and measured) over time for PBAT particles with ~15 μm and ~20 μm in radius; FIG. 25(D) relative darkness and conversion (predicted and measured) over time for PBAT particles with ~15 μm and ~20 μm in radius; and FIG. 25(E) shows measured τ/A₀ vs. [E] for PBAT microparticles with ~15 μm in radius and fitted curve assuming: according to Example 17.

DETAILED DESCRIPTION [0043] The present disclosure relates to methods for analyzing the degradation of polymeric microparticles, e.g., using one or more microfluidic chips, as well as related devices and systems. The present methods improve upon prior methods by, e.g., reducing inefficiencies of known enzymatic degradation methods. In particular, the present disclosure provides novel methods that concentrate on the degradation analysis (visualization and quantification) of single microparticles using microfluidic chips or devices. To carry out such methods, microfluidic chips (e.g., comprising polydimethylsiloxane) were designed, optimized, and fabricated through a standard planar soft lithography technique. Enzymatic degradation of polymeric microparticles such as PBAT was studied using such microfluidic chips and enzymatic solutions (e.g., at varying concentrations, with various enzymes), where changes in size, porosity, transparency, smoothness, and/or brightness of the polymeric microparticles were visualized over time. These parameters (e.g., particle size and transparency) may be determined or quantified as illustrated by the examples described herein, in order to evaluate the extent of enzymatic degradation of the polymeric microparticles (e.g., to evaluate enzyme performance). [0044] The disclosure provides for methods for analyzing enzymatic degradation of at least one polymeric microparticle by adding an enzymatic solution to the polymeric microparticle and analyzing a change in transparency of the polymeric microparticle. [0045] The microparticles may have an average diameter of 1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, or 150 μm or any range using these integers (e.g., 10-60 µm, 40- 70 µm, 30-80 µm, 50-120 µm, etc.) The microparticles may be prepared using an oil-in-water solvent evaporation method as shown in the Examples. [0046] The enzyme(s) used may include, but is not limited to, hydrolase, lyase, lipase, protease, amylase, cellulase, cutinase, mannanase, urease, xylanase or a plurality of enzymes comprising any combination thereof. [0047] The enzymatic solution may be added under dynamic or static conditions (e.g., as shown in the Examples). Under static conditions, the enzymatic solution is introduced (e.g., injected) into the channel and then the channel is plugged. The dynamic conditions can vary (e.g., 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 ^L/h). [0048] The polymer used in the polymeric microparticles may include, but are not limited to, polyesters, PBAT, PLA, PCL, PBA, PBS, polyurethanes, polyamides, polyureas, polyanhydrides polyesters containing polyurethane moieties and blends, and/or a mixture/blend of the aforementioned polymers. In other aspects, the polymer comprises one or more water-insoluble starches (e.g., corn starch) or polysaccharides (e.g., wheat flour). [0049] As described herein, the methods involve analyzing a change in transparency, particle size, porosity, smoothness, and/or brightness of at least one polymeric microparticle. Any combination of these parameters may be used as indicators of the extent of enzymatic degradation of a polymeric microparticle. For example, a change in transparency of the polymeric microparticle may be determined and/or measured by comparing the level of transparency observed at a given time point to a control (e.g., a baseline level of transparency of the same polymeric microparticle determined and/or measured prior to the application of the enzyme(s) being evaluated). In other aspects, the change in transparency may be measured as a percentage change. [0050] The change in transparency or any other indicator of degradation described herein may be determined and/or measured at specific time points (e.g., 1, 2, 3, 4, 5, 6, 12, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, or more hours after application of the enzyme(s) being evaluated). In particular aspects, the change in transparency of at least one polymeric microparticle can be visualized in real-time, e.g., within 1, 2, 3, 4, 5, 6, 12, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, or more hours, or 1, 2, 3, 4, 5, 6, or 7 days of adding the enzymatic solution. In other aspects, the change in transparency, in addition to a change in particle size, porosity, smoothness, and/or brightness, is visualized in real-time within 24, 48, 72, 96, or more hours of adding the enzymatic solution (e.g., reducing the time and/or resource expenditure). The determined or measured change of any combination of these parameters (e.g., transparency and particle size) may be used to evaluate the extent of enzymatic degradation of the polymeric microparticle. [0051] The change in transparency, particle size, porosity, smoothness, and/or brightness may be visualized using a microscope. In some aspects, the change in particle size is visualized via inverted phase contrast (IPC) microscopy and/or a scanning electron microscopy (SEM), while the change in smoothness and/or porosity is visualized via scanning electron microscopy (SEM) or confocal laser scanning microscopy. In other aspects, visualization of the change in transparency, particle size, porosity, smoothness, and/or brightness of the polymeric microparticle is quantified. [0052] In some aspects, the methods described herein further comprise a step of isolating the at least one polymeric microparticle in a channel of a microfluidic device prior to determining the change in particle size and/or transparency of the at least one polymeric microparticle. In other aspects, the methods describe herein further comprise a step of measuring and/or quantifying a background level of brightness prior to determining a change in particle size and/or transparency of the at least one polymeric microparticle, wherein the change in transparency is determined based on the background level of brightness. In other aspects, the methods described herein comprising determining a change in particle size and/or transparency of the at least one polymeric microparticle comprises determining a change in particle size and/or transparency of at least 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or more microparticles. In other aspects, the determining step is performed using software configured to identify and track each of the at least 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or more microparticles. [0053] In other aspects, the method comprises analyzing the change in the at least one physical characteristic, wherein the analysis is based on a comparison to a control microparticle, and the change in the at least one physical characteristic provides a time-resolved degradation profile in a predefined environment. In some aspects, the control microparticle comprises: a) a microparticle having the same chemical composition as the at least one polymeric microparticle; and/or b) a microparticle having about the same particle size, transparency, porosity, smoothness, and/or brightness as that of the at least one polymeric microparticle prior to the application of the enzymatic solution. [0054] In other aspects, the methods further comprise staining at least one polymeric microparticle with at least one visible or fluorescent dye, wherein the dye is applied to the at least one polymeric microparticle (a) when the at least one polymeric microparticle is prepared, or (b) after the at least one polymeric microparticle is added to a microfluidic device. In other aspects, the measuring and/or quantifying a change in at least one physical characteristic of the at least one polymeric microparticle occurs while the at least one polymeric microparticle is in the microfluidic device. [0055] The disclosure provides microfluidic chips capable of analyzing polymeric microparticles as described herein. The microfluidic chip comprises at least one inlet port, at least one outlet port, and a plurality of channels having an opening for flow of microparticles and a plurality of slots that are configured to trap at least one microparticle. In some aspects, the plurality of slots are cross-sectional pillars, and the surface density of the cross-sectional pillars increases from the at least one inlet port toward the at least one outlet port. In other aspects, the surface density of the cross-sectional pillars remains constant. [0056] In some aspects, the plurality of channels comprises one or more channels oriented at about a 45º angle to a longitudinal axis between the inlet port and the outlet port. In other aspects, the plurality of channels comprises one or more channels defined by a pair of semicircular or crescent-shaped sidewalls (e.g., configured to trap microparticles which have a particle size above a given threshold such as those shown in FIG.6 and FIG.10). [0057] In other aspects, the sidewalls of the one or more channels are separated by a gap having a length that is less than the diameter of the at least one polymeric microparticle. In other aspects, a longitudinal axis of each of the sidewalls of the one or more channels is position at an oblique angle compared to a longitudinal axis between the inlet port and the outlet port. In other aspects, the plurality of channels is configured to trap the at least one polymeric microparticle by immobilizing the polymeric microparticle in the microfluidic chip. In other aspects, the one or more sidewalls are configured to trap polymeric microparticles such that the enzymatic solution is capable of flowing past the polymeric microparticles and/or through a channel defined by the sidewalls trapping the polymeric microparticles. [0058] In other aspects, the average diameter of the plurality of channels decreases from the inlet port towards the outlet port. In other aspects, the plurality of channels is configured to trap polymeric microparticles having a different diameter at different positions within the microfluidic device. In other aspects, the plurality of channels are configured to have a height of 10 µm, 20 µm, 30 µm, 40 µm, 50 µm, 60 µm, 70 µm, 80 µm, 90 µm, 100 µm, or more. In other aspects, the plurality of channels are configured to have a width of up to 1, 2, 3, 4, or 5 µm more than the maximum diameter of the polymeric microparticles. In other aspects, the plurality of channels are configured to have a height of about 50, 60, 70, 80, 90, or 100 µm. In other aspects, the plurality of channels are arranged in multiple density zones spanning from the inlet port to the outlet port, wherein each zone comprises channels having a width of 80 µm, 60 µm, 50 µm, 40 µm, 30 µm, or 20 µm. [0059] In other aspects, the microfluidic chip is at least partially transparent and configured to allow for visualization of the immobilized polymeric microparticle. [0060] In other aspects, the microfluidic chip comprises pores having a pore volume in the approximate range of 1-3 µL, e.g., 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, or 3.0 µl, or a volume within a range defined by any of the aforementioned values. In other aspects, the microfluidic chip comprises pores having a pore volume in the approximate range of 0.1-1000 µL, e.g., 0.1, 0.5, 1, 5, 10, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1000 µL, or a volume within a range defined by any of the aforementioned values. [0061] In other aspects, the microfluidic chip comprises a micropatterned polydimethylsiloxane (PDMS) layer. [0062] In other exemplary aspects, the disclosure provides a microfluidic device comprising a plurality of any of the aforementioned microfluidic chips, arranged in series and/or in parallel. In other aspects, the disclosure also provides a system comprising any of the aforementioned microfluidic chips, configured as a device for visualizing and/or screening microparticles based on any of the parameters described herein. [0063] The disclosure also provides for methods that use the microfluidic chips and devices described herein. For example, the method for analyzing enzymatic degradation of a polymeric microparticle is performed in a microfluidic chip involving adding at least one polymeric microparticle in at least one inlet port of the microfluidic chip, followed by adding an enzymatic solution into an at least one inlet port at a flow rate, and analyzing a change in transparency of the at least one polymeric microparticle. [0064] In other aspects, the disclosure provides a method for analyzing enzymatic degradation of a polymer in a microfluidic chip by analyzing overall change in transparency of an entire image (e.g., over the entire channel) instead of analyzing the specific area of the image occupied by just polymeric microparticles themselves. See, e.g., Example 13. In some aspects, the analysis involves simultaneously analyzing all of the polymeric microparticles trapped in the chip. In other aspects, the methods involve analyzing the change in transparency over the entire channel of the chip and change in transparency of the polymeric microparticles. [0065] The real-time visualization and quantification of the change in transparency of the microparticles has never been studied before, and therefore the current disclosure presents a novel approach in the realm of microparticle degradation analytics. Physiochemical properties of degraded microparticles were also compared to the conventional bulk methods, and it was confirmed that the results from the degradation processes on both bulk and microfluidic methods were comparable. FIG.1 is a combined representation of CLSM z-stack middle slice pictures of PBAT microparticles stained with Rhodamine B (FIG. 1A) before and after degradation in a microfluidic chip (FIG. 1B) or bulk (FIG. 1C). SEM images of PBAT microparticles after degradation in bulk (FIG.1D), and the microfluidic chip (FIG.1E). After enzymatic degradation, the microparticles demonstrated the high-intensity red color in the middle slice of the z-stack, indicating that the polymer was degraded or hydrolyzed (FIGs.1B and 1C). The microparticles were assessed using SEM images after 48 hours of enzymatic degradation. As illustrated by FIG. 1D, the degraded products in bulk showed a deteriorated and chalky structure as compared to the spherical and slightly smooth polymeric (PBAT) microparticles which could be due to the shear forces applied to the microparticles during the bulk degradation. The microparticles were retrieved from the microfluidic chip after degradation and the microparticles in the microfluidic chip were found to maintain their integrity even after degradation (FIG.1E), but their smooth surface was visibly corrugated and rough after 48 h of enzyme exposure. As illustrated by this study, the microfluidic chip method proved to be a reliable, facile and time-resolved degradation analysis with results comparable to conventional bulk methods. [0066] The microfluidic chip of the present disclosure allows for the analysis of the enzymatic degradation of a single microparticle at one time (e.g., for screening purposes). In some aspects, multiple microparticles can similarly be analyzed and/or screened in real-time. Referring now to the drawings, FIG.2 shows top and side view of a schematic representation of a microfluidic chip according to one embodiment of the present invention with inlet ports, outlet ports, main channels, and chambers having openings and slots or cross-sectional pillars, as shown in FIG. 3. FIG. 6 is a top view of an exemplary microfluidic chip according to an alternative aspect of the disclosure, showing an array of semicircular or crescent-shaped channels configured to trap polymeric microparticles (e.g., which have a particle size or diameter above a given threshold). As illustrated by this example, in some aspects a microfluidic device according to the disclosure may comprise a plurality of channels, each formed by a pair of sidewalls, wherein the longitudinal axis of each sidewall is arranged at an oblique angle as compared to the longitudinal axis of the microfluidic device. In some aspects, each pair of sidewalls may further be separated by a gap. This gap may have a diameter less than the average diameter of the polymeric microparticles being assayed, or a fraction thereof (e.g., 10, 20, 30, 40, 50, 60, 70, 80, or 90% of the average diameter thereof), allowing such particles to remain immobilized for analysis. [0067] In some exemplary aspects, the pillar or slot density increases from the inlet port toward the outlet port to ensure effective trapping (FIG.4) and degradation of microparticles. For example, a PDMS chip with cross-sectional pillars has been shown to illustrate single microparticle degradation more distinctly in a 2D configuration, compared with other chips (PDMS or PMMA) in their 3D configurations. Polymeric microparticles followed by enzymatic solution may be injected into the microfluidic chip via the inlet port. Referring to FIG.7, the enzymatic degradation in a microfluidic chip can also include a degradation system coupled with a device capable of visualizing microparticles in real-time. The visualization of the physical and/or chemical properties of microparticles can be performed, e.g., via inverted phase contrast (IPC) microscopy or via confocal laser scanning microscopy (CLSM). [0068] The change in microparticle transparency as a result of degradation is shown in the Examples. For example, FIG.5 shows PBAT microparticles degraded via a chip-based method according to the disclosure at pH 7.4, and at a flow rate of 50 µL/h. FIG. 5A compares (1) freshly-loaded microparticles to those (2) after 48 h of enzymatic degradation. The difference in transparency can be further observed in an exploded view of the microparticles flowing through the openings amid cross-sectional pillars of the chip (FIG. 5B). The difference in a single particle’s transparency at different time points, as shown in FIG. 5B-D, reveals a significant change in physical properties observed in real-time. Moreover, FIG.5E also shows the direct effect of enzyme concentration on transparency values. Examples [0069] The following non-limiting examples are provided to further illustrate the present disclosure. These examples generally reference two standardized protocols for generating and analyzing polymeric microparticles—General Procedures (1) or (2), which are summarized as follows: General Procedure (1): for preparing polymeric microparticles. [0070] Microparticles are prepared using an oil-in-water solvent evaporation method. Organic phase is prepared by dissolving a polymer (e.g., PBAT) in 50 mL chloroform (10% wt/v). Then, the organic phase is added to the flask containing continuous phase (PVA solution (Mowiol® 10-98), 4% w/v in water) and mixed using a mechanical stirrer (IKA Eurostar 40 digital, Germany). The mixture is stirred at 500 rpm at 45 ^oC and held there for 5-6 hr until all the chloroform evaporated. Then, the particles are isolated using Nylon mesh filters (U-CMN, Component Supply Co., Tennessee, USA, sizes 15-38-60 µm). Collected particles are then washed with ultra-pure water and freeze-dried (-50 ^oC, 0.1 mbar, 24 h) using a Labconco Freezone 1 (USA). General Procedure (2): for loading microparticles on chip, flowing enzyme and following the change in transparency and/or particle diameter. [0071] Device operation involves three consecutive steps. First, the microfluidic device is primed with a dilute Tween 80/ultra-pure water solution (0.25% w/v) to minimize surface adsorption and inadvertent clogging. Second, a microparticle suspension is injected into the device using a density-matched sodium chloride solution (33% w/v) to prevent their agglomeration. To prevent clogging, the sample solution should be sparse, therefore, 4 mg/mL of microparticles in ultra-pure water solution is prepared and Tween 80 (0.25% w/v) is used to assist with the suspension of the microparticles. The solution is vigorously mixed and then injected into the chip. The injection of the sample is visually assessed until a sufficient number of microparticles for the experiment are trapped in the field of view of the microscope. After loading the particles to ensure that the emulsifier was taken out completely, the channels and microparticles are washed with 3-4 mL ultra-pure water for 15 minutes. The position of the device is fixed on the microscope stage and fresh enzymatic solution is injected to start the degradation process with injection speeds, depending on the experiment, between 0-10,000 µL/h. In addition, for microscopic studies, time-lapse images were taken (e.g., at 15-minute intervals) until the degradation is completed. Images were then subjected to image processing using ImageJ software (National Institutes of Health, Bethesda, Maryland, USA) to assess the optical and physical changes in particles upon degradation. [0072] The change of transparency as a function of time may be normalized (e.g., assuming the maximum and minimum transparency of the particles as 100% and 0%, respectively). Example 1 [0073] PBAT (M_w ~110 kg/mol) particles were prepared as described in General Procedure (1) and filtered with mesh size 38 µm. The PBAT microparticles were injected as described in General Procedure (2) into the microfluidic crescent device. Enzyme (Novozym® 51032) solution 15 KLU/g was passed at a rate of 100 µL/h at 20 °C. Image analysis was performed using ImageJ. Results for this experiment are shown in the table below. [0074] This example shows an increase in transparency with a reduction in particle size after 24 hours indicating enzymatic degradation of the PBAT.

Table 1. Relative transparency and particle diameter results observed over 24 hours for PBAT treated with Novozym® 51032 according to Example 1. Example 2 [0075] Example 1 was followed except two enzyme flow rates are used: 100 µL/hr and 10 µL/hr at a concentration of 15 KLU/g. Results are shown in the table below and the plot provided as FIG.8. [0076] This example illustrates that changing to slower enzyme flow rate, slows the rate of PBAT degradation, which is illustrated by an increase in time at which a change in transparency occurs.

Table 2. Relative transparency results observed over 48 hours for PBAT treated with Novozym® 51032 at two different flow rates according to Example 2. Example 3 [0077] Example 1 was followed except three enzymes concentrations were used 150 LU/g, 15 LU/g, 1.5 LU/g using a flow rate of 10 µL/h. Results for this experiment are shown in the table below and the plots provided as FIGs.9A and 9B. The second plot shows that the initial decrease in transparency illustrates the enzymatic rate limiting step. After the decrease in transparency, degradation increased with a similar slope independent of the enzyme concentration used. Particles, in general, experience an increase in opacity as a result of adsorption of the enzyme molecules to the surface available for degradation. [0078] This example shows that decreasing enzyme concentration using a constant enzyme flow rate, results in decrease in enzymatic degradation which is illustrated by an increase in the time at which a change in transparency occurs.

Table 3. Relative transparency results observed over 132 hours for PBAT treated with Novozym® 51032 at three different concentrations according to Example 3. Example 4 [0079] Example 1 was repeated except 0.1 mg/mL of FITC dextran was added to the enzyme solution and images were taken at both bright field and fluorescent (~500 nm) field. Results for this experiment are shown in FIG.10, which provides images illustrating the diffusion of enzyme solution to the inner core (as indicated by the fluorescent dye penetrating the particle) of the particles as the degradation proceeds. Example 5 [0080] PBS (M_w ~110,000 g/mol) particles were prepared as described in General Procedure (1) and filtered with mesh sizes 15 µm and 38 µm. The PBS microparticles were injected as described in General Procedure (2) into the crescent containing microfluidic device. Enzyme Novozym® 51032 solution at 15 LU/g was passed at a rate of 10 µL/h at 20 °C. Image analysis was performed using ImageJ. Example 6 [0081] Example 5 was repeated but using PBS (Mw ~149,000 g/mol). Results for both Examples 5 and 6 are shown in the table below and in the plot provided as FIG.11. Examples 5 and 6 demonstrate that the higher molecular weight PBS degraded at a slower rate.

Table 4. Relative transparency results observed over 120 hours for PBS microparticles, at two different molecular weights, treated with Novozym® 51032 according to Examples 5 and 6. Example 7 [0082] PCL (Mw 160,000 g/mol) particles were prepared as described in General Procedure (1) and filtered with mesh size of 38 µm. The PCL microparticles were injected as described in General Procedure (2) into the microfluidic crescent containing device. Enzyme Novozym® 51032 solution (15 KLU/g) at 20 °C was either (1) passed at a flow rate of 50 µL/hr or (2) injected into the channel and sealed. Results for Example 7 can be seen in the plot provided as FIG.12. [0083] Upon exposure to flowing enzyme, PCL degradation is illustrated by a decrease in transparency, which correlates to a decrease in particle diameter as seen in FIG.12A and FIG. 12B. Upon exposure to static enzyme, PCL degradation is illustrated by an initial decrease in transparency followed by an increase in transparency as can be seen in FIG. 12A. Upon exposure to static enzyme, particle size stays consistent until the transparency stops changing, at which point the size starts rapidly decreasing (FIG.12B). Example 8 [0084] Example 1 was followed except the enzyme was passed at a flow rate of 50 µL/hr at three different temperatures: 20 ⁰C, 40 ⁰C, and 60 ⁰C. Results are shown in Table 5 below and the plots provided as FIG. 13A and FIG. 13B. In these figures, n = the number of particles tracked.

Table 5. Transparency results observed over 48 hours for PBAT treated with Novozym® 51032 at three different temperatures according to Example 8. [0085] This example illustrates that increasing the temperature of the experiment, increases the rate of PBAT degradation. This is illustrated by an increase in the rate of change of transparency (Table 5, FIG.13A) and a more rapid decrease in particle size (FIG.13B). Example 9 [0086] The dynamic conditions (50 µL/hr, 20 ⁰C) of Example 7 were followed except three different enzyme solutions were used: (1) Novozym® 51032(15 KLU/g) (the same as example 7), (2) Lipozyme ® CALBL (5 KLU/g) or (3) Lipolase 100 L (100 KU/g). Results are shown in the plot provided as FIG.14. [0087] This example illustrates that Novozym® 51032 is more active than Lipozyme® CALB L and Lipolase 100L as seen by a more rapid decrease in particle area. Example 10 [0088] PBAT (Ecoflex F Blend C1200)/PLA (Total Corbion LX175) blend particles were prepared by dissolving PBAT and PLA in chloroform in a ratio of 70 PBAT: 30 PLA. Then particles were prepared as described in General Procedure (1) and filtered with mesh sizes 60, 38, and 15 µm. The PBAT (Ecoflex F Blend C1200)/PBS (BioPBS FZ91 grade) particles were prepared by dissolving PBAT and PBS in chloroform in a ratio of 30 PBAT: 70 PBS. The microparticles were injected as described in General Procedure (2) into the microfluidic crescent device. Enzyme (Novozym® 51032) solution 15 KLU/g was passed at a rate of 50 µL/h at 20°C. Image analysis was performed using ImageJ. Results are shown in Table 6 below and the plot provided as FIG.15A and FIG.15B.

Table 6. Transparency results observed over 48 hours for blends of PBAT with PLA or PBS, treated with Novozym® 51032, according to Example 10. [0089] This example illustrates that the blend of PBAT/PBS degrades more quickly than the blend of PBAT/PLA. A literature study comparing home composting data of the same blends shows that the PBAT/PBS blend degrades to about 75% in 200 days, while the PBAT/PLA blend degrades to about 50% in 200 days. See Nomadolo N, Dada OE, Swanepoel A, Mokhena T, Muniyasamy S. A Comparative Study on the Aerobic Biodegradation of the Biopolymer Blends of Poly(butylene succinate), Poly(butylene adipate terephthalate) and Poly(lactic acid). Polymers (Basel). 2022 May 5;14(9):1894. doi: 10.3390/polym14091894. PMID: 35567063; PMCID: PMC9101927. Therefore, our analysis method is providing trends that align with what is observed using more traditional composting methods. Example 11 [0090] Thermoplastic polyurethane microparticles were prepared by dissolving Elastollan®, a polyester based thermoplastic polyurethane, in THF at 10 wt%. The solution was then mixed with chloroform and General Procedure (1) was followed. Instead of filtering, particles were kept in solution, washed several times with water, and then injected directly into the microfluidic crescent device to avoid microparticle aggregation. Enzyme (Novozym® 51032) solution 15 KLU/g was passed at a rate of 50 µL/h at 20 °C. Image analysis was preformed using ImageJ. Results are shown in Table 7 below and the plot provided as FIG.16. [0091] This example illustrates that Elastollan undergoes an increase in transparency upon exposure to enzyme.

Table 7. Relative transparency results observed over 60 hours for Elastollan treated with Novozym® 51032according to Example 11. Example 12 [0092] Example 1 was followed except the enzyme was either (1) passed at a flow rate of 50 µL/hr or (2) injected into the channel and sealed. Results are shown in the plot provided as FIG.17. [0093] This example illustrates that under static conditions, PBAT degradation takes longer to occur than it does under dynamic conditions. Example 13 [0094] Example 1 was followed except during image analysis using ImageJ, the transparency changes were tracked over the entire channel instead of isolating an individual particle as done in previous examples. Results are shown in the plot provided as FIG.18. [0095] This example illustrates that PBAT degradation in terms of transparency changes can be tracked by measuring the transparency changes of specific particles or over the whole image. Example 14 [0096] PLA (Natureworks 4044D) particles were prepared as described in General Procedure (1) and injected as described in General Procedure (2) into the microfluidic crescent containing device. Enzyme Novozym® 51032 solution (15 KLU/g) was passed at a flow rate of 50 µL/hr at two different temperatures: 20 ⁰C and 60 ⁰C. Results are shown in the plot provided as FIG. 19. [0097] This example illustrates that PLA degradation in terms of transparency change occurs at elevated temperatures, while PLA does not seem to degrade at room temperature; thus, temperature is a key component to regulate while assessing enzymatic degradation. This behavior is likely due to the highly crystalline nature and high glass transition temperature of PLA. Example 15 [0098] Corn starch and α-amylase from Bacillus sp. were purchased from Sigma-Aldrich and used as received. Corn starch was dispersed in water, injected into a microfluidic crescent device, and washed with water. The device was then heated to 40 ⁰C, α-amylase was injected into the chip, and then the channel was sealed. Results can be seen in FIG.20. [0099] This example illustrates that corn starch decreases in size upon exposure to α- amylase. Example 16 [00100] Insoluble wheat flour Arabinoxylan was purchased from Megazyme and used as received. Arabinoxylan was dispersed in water, injected into a microfluidic crescent device, and washed with water. Enzyme xylanase was passed at a flow rate of 50 µL/hr at 20 ⁰C. Image analysis was conducted by measuring the change in transparency over the entire channel. Results can be seen in FIG.21. [00101] This example illustrates that Arabinoxylan displays an increase in transparency upon degradation by xylanase. [00102] In conclusion, Examples 1-16 illustrate that the rate of enzymatic degradation of insoluble polymer particles could be followed by a change in particle transparency. This is accomplished by trapping microparticles on a transparent microfluidic chip and allowing dynamic or static exposure to an enzyme solution. In some exemplary aspects, the systems, methods, and devices described herein may be used to determine the rate of degradation of particles or compare the relative rates of degradation of different types of particles. In some aspects, different concentrations of enzymes, feed rates, temperatures, or different enzymes (e.g., mutants of naturally-occurring or synthetic enzymes having one or more point mutations or other modifications) may be evaluated to determine efficacy of enzymatic degradation. Transparency of the microfluidic devices allowed for microscopic imaging of microparticles that may be interpreted using image analysis software (e.g., ImageJ). Example 17 [00103] This example shows a method for analyzing enzymatic degradation of polymer microparticles using a modified shrinking particle model (SPM) and shrinking core model (SCM). In these models, three distinct steps involved in enzymatic degradation were mathematically elucidated to predict the time-resolved conversion of the substrate. These steps are enzyme-polymer intermediate formation, enzymatic bond cleavage, and enzyme diffusion through the layer of degraded substrate (only for SCM). Time-conversion equations and their relation to the time for full degradation time (characteristic time τ) is summarized in the following table.

[00104] To prepare microparticles, General procedure 1 was followed except the rpm of the mechanical stirrer was adjusted to either 500 rpm or 700 rpm to target particles with radius >20 µm and >10 µm, respectively. General procedure 2 was followed with particle size and darkness were measured over time using ImageJ software (NIH, Bethesda, MD. 1.53q). Mathematical modelling and curve fitting was performed by non-linear least-square regression method (Trust-region algorithm) using Matlab software (Mathworks, Inc. 2022a). OriginPro 2022.b. (OriginLab Corp., Northampton, MA.) was used to perform statistical analysis. Shrinking Particles [00105] Enzymatic degradation of PCL particles using enzyme at 150 LU/g with a flow rate of 10 ^L/h follows a shrinking particle pattern (FIG.22). At this condition, the I control mechanism accurately predicts τ equal to 94 mins and 275 mins for particles with average radius of 16.2 μm and 28.8 μm, respectively (FIG. 23). Since ^{^^} ^^₀ for 30 μm particles (2.6 ± 2 × 10⁻²) and 15 μm particles (2.8 ± 0.4 × 10⁻²) are not significantly different (Table 8), it is safe to assume that the degradation is governed by I control mechanism. [00106] Now that the governing mechanism of degradation is found, K and n can be calculated performing similar experiments on ~15 μm particles by using enzyme solution at different concentrations. Surprisingly, degradation kinetics of PCL were found independent of enzyme concentration from 15 kLU/g to 150 LU/g (Table 8). This concludes that the enzymatic degradation of PCL particles is governed by I control mechanism and zero order with respect to enzyme concentration (n=0). The rate of degradation of PCL particles transforms to

[00107] Table 8: Detailed results for enzymatic degradation of PCL microparticles assuming I control degradation mechanism

* Predicted by the model Different letter in each row indicates significant statistical difference by one-way ANOVA Tukey’s test (p<0.05). Values were given as mean±SD. Core-Shrinking Particles [00108] PBAT particles, upon enzymatic degradation, do not experience a shrinkage, rather, their appearance transforms from dark to transparent particles. The core shrinks as the degradation goes on, which complies with shrinking-core model. In order to find the governing mechanism of degradation, PBAT particles with ~15 ^m and ~20 ^m in radius were subjected to degradation using 15 kLU/g enzyme solution (FIG. 24). Their appearance was monitored over time and once the particles’ darkness gets to their minimum, the degradation is assumed completed. τ was measured ~ 33 h (15 ^m particles) and ~68 h (20 ^m particles). Since for

μm particles (1.06 ± 0.14 × 10 ) and 15 ^m particles (1.08 ± 0.07 × 10 ) are not significantly different, it can be assumed that the I control mechanism is the rate determining step (FIG. 25C). Monitoring the change in the particles’ darkness fails to accurately provide time-resolved conversion rate of the core. In this regard, enzyme solution was spiked with Fluorescein dye and fluorescent imaging technique was used to measure the changes in the size of the unreacted core, which is distinguishable from the ash (FIG. 25A). Fitting the results from fluorescent imaging with I control mechanism confirms the mode of degradation (FIG. 25B and Table 9). Degradation of 15 μm particles was further studied using enzyme solution at different concentrations to calculate K and n. The change in particles’ darkness over time is depicted in (FIG.25C) to measure The relation between and enzyme concentration is

demonstrated in (FIG. 25D). Fitting the experimental results with the above equation demonstrates that the degradation of PBAT is a first-order reaction with regards to the enzyme concentration (n = 0.98 ± 0.04) were and depicted in

(FIG.25E). [00109] Table 9:

Different letter in each row indicates significant statistical difference by one-way ANOVA Tukey’s test (p<0.05). Values were given as mean ± SD.

Claims

CLAIMS 1. A method for analyzing enzymatic degradation of at least one polymeric microparticle, comprising: applying an enzymatic solution to the at least one polymeric microparticle; and determining a change in particle size and/or transparency of the at least one polymeric microparticle, wherein the change in particle size and/or transparency is indicative of the enzymatic degradation of the at least one polymeric microparticle. 2. The method of claim 1, wherein the change in particle size and/or transparency is determined in real-time. 3. The method of claim 1, wherein the change in particle size and/or transparency is determined within 1, 2, 3, 4, 5, 6, 12, 24, 48, or 72 hours of applying the enzymatic solution. 4. The method of any one of claims 1-3, wherein the change in particle size and/or transparency is determined using a microscope. 5. The method of any one of claims 1-4, wherein determining the change in transparency comprises measuring and/or quantifying a change in particle size and/or transparency. 6. The method of any one of claims 1-5, further comprising a step of isolating the at least one polymeric microparticle in a channel of a microfluidic device prior to determining the change in particle size and/or transparency of the at least one polymeric microparticle. 7. The method of any one of claims 1-6, further comprising a step of measuring and/or quantifying a background level of brightness prior to determining a change in particle size and/or transparency of the at least one polymeric microparticle, wherein the change in transparency is determined based on the background level of brightness. 8. The method of any one of claims 1-7, wherein determining a change in particle size and/or transparency of the at least one polymeric microparticle comprises determining a change in particle size and/or transparency of at least 5, 15, 20, 25, 30, 35, 40, 45, 50 or more microparticles and the determination is performed using software configured to identify and track each of the at least 5, 15, 20, 25, 30, 35, 40, 45, 50 or more microparticles. 9. A method for analyzing enzymatic degradation of a polymeric microparticle, comprising: applying an enzymatic solution to at least one polymeric microparticle; and measuring and/or quantifying a change in at least one physical characteristic of the at least one polymeric microparticle, wherein the physical characteristic comprises a particle size, transparency, porosity, smoothness, or brightness of the at least one polymeric microparticle; analyzing the change in the at least one physical characteristic, wherein the analysis is based on a comparison to a control microparticle, and the change in the at least one physical characteristic provides a time-resolved degradation profile in a predefined environment. 10. The method of claim 9, wherein the control microparticle comprises: a) a microparticle having a same chemical composition as the at least one polymeric microparticle; and/or b) a microparticle having about the same particle size, transparency, porosity, smoothness, and/or brightness as that of the at least one polymeric microparticle prior to the application of the enzymatic solution. 11. The method of claims 9 or 10, wherein the change in the at least one physical characteristic is measured and/or quantified in real-time. 12. The method of any one of claims 9-11, wherein the change in the at least one physical characteristic is analyzed within 24, 48, or 72 hours of applying the enzymatic solution. 13. The method of any one of claims 9-12, wherein the change in the at least one physical characteristic is analyzed using an optical microscope. 14. The method of any one of claims 9-12, wherein the change in the at least one physical characteristic comprises a change in particle size and is analyzed using inverted phase contrast (IPC) microscopy and/or a scanning electron microscopy (SEM).

15. The method of any one of claims 9-12, wherein the change in the at least one physical characteristic comprises a change in porosity and is analyzed using scanning electron microscopy (SEM) or confocal laser scanning microscopy. 16. The method of any one of claims 9-12, further comprising a step of: staining the at least one polymeric microparticle with at least one visible or fluorescent dye, wherein the dye is applied to the at least one polymeric microparticle (a) when the at least one polymeric microparticle is prepared, or (b) after the at least one polymeric microparticle is added to a microfluidic device; and wherein the measuring and/or quantifying a change in at least one physical characteristic of the at least one polymeric microparticle occurs while the at least one polymeric microparticle is in the microfluidic device. 17. The method of any one of claims 9-12, wherein analyzing the change in the at least one physical characteristic comprises analyzing a change in particle size, wherein the analysis is based on an average diameter of at least 50 polymeric microparticles. 18. The method of any one of claims 1-17, wherein the enzymatic solution comprises one or more hydrolase, lyase, lipase, protease, amylase, cellulase, cutinase, mannanase, urease, xylanase or any combination thereof. 19. The method of any one of claims 1-17, wherein the at least one polymeric microparticle comprises one or more polymers, and at least one polymer comprises polyester, poly (1,4- butylene adipate-co-terephthalate) (PBAT), polylactic acid (PLA), polycaprolactone (PCL), poly butyl acrylate (PBA), polybutylene succinate (PBS), polyurethane, polyamide, polyurea, polyanhydride polyester containing polyurethane moieties and blends, and/or a combination thereof. 20. The method of any one of claims 1-17, wherein the at least one polymeric microparticle comprises a plurality of microparticles having an average diameter between: a) 50-120 µm; b) 30-80 µm; c) 40-70 µm; or d) 10-60 µm;

21. The method of any one of claims 1-17, wherein the at least one polymeric microparticle comprises a plurality of microparticles prepared using an oil-in-water solvent evaporation method. 22. A microfluidic chip comprising at least one inlet port, at least one outlet port, and a plurality of channels, wherein the plurality of channels is configured to trap at least one polymeric microparticle. 23. The microfluidic chip of claim 22, wherein the plurality of channels comprises one or more channels oriented at about a 45º angle to a longitudinal axis between the inlet port and the outlet port. ^{24. The microfluidic chip of claim 22, wherein the plurality of channels comprises one or} _{more channels defined by a pair of semicircular or crescent-shaped sidewalls.} 25. The microfluidic chip of claims 22 or 24, wherein the sidewalls of the one or more channels are separated by a gap having a length that is less than the diameter of the at least one polymeric microparticle. 26. The microfluidic chip of any one of claims 22, 24, or 25, wherein a longitudinal axis of each of the sidewalls of the one or more channels is position at an oblique angle compared to a longitudinal axis between the inlet port and the outlet port. 27. The microfluidic chip of any one of claims 22-27, wherein the plurality of channels is configured to trap the at least one polymeric microparticle by immobilizing the polymeric microparticle in the microfluidic chip. 28. The microfluidic chip of claim 27, wherein the microfluidic chip is at least partially transparent and configured to allow for visualization of the immobilized polymeric microparticle. 29. The microfluidic chip of any one of claims 22-28, wherein an average diameter of the plurality of channels decreases from the inlet port towards the outlet port.

30. The microfluidic chip of any one of claims 22-29, wherein the plurality of channels is configured to trap polymeric microparticles having a different diameter at different positions within the microfluidic device. 31. The microfluidic chip of any one of claims 22-30, wherein the plurality of channels are configured to have a height of 10-100 µm. 32. The microfluidic chip of any one of claims 23-31, wherein the plurality of channels are configured to have a width of up to 5 µm more than the maximum diameter of the polymeric microparticles. 33. The microfluidic chip of any one of claims 22-32, wherein the plurality of channels are configured to have a height of about 50 µm, 60 µm, 70 µm, 80 µm, 90 µm or 100 µm. 34. The microfluidic chip of any one of claims 22-33, wherein the plurality of channels are arranged in multiple density zones spanning from the inlet port to the outlet port, wherein each zone comprises channels having a width of 80 µm, 60 µm, 50 µm, 40 µm, 30 µm, or 20 µm. 35. The microfluidic chip of any one of claims 22-34, wherein a pore volume of the microfluidic chip is in the range of 1-3 µL. 36. The microfluidic chip of any one of claims 22-35, wherein the microfluidic chip comprises a micropatterned polydimethylsiloxane layer. 37. A microfluidic device comprising a plurality of the microfluidic chips of any one of claims 22-36. 38. A system comprising at least one microfluidic chip of any one of claims 22-36, and a microscope configured to visualize the polymeric microparticles trapped within the microfluidic chip. 39. A method for analyzing enzymatic degradation of at least one polymeric microparticle in the microfluidic chip of any one of claims 22-36, comprising: introducing the at least one polymeric microparticle into the microfluidic chip via the at least one inlet port; trapping the at least one polymeric microparticle in one of the plurality of channels of the microfluidic chip; introducing an enzymatic solution into the microfluidic chip via the at least one inlet port at a flow rate; and measuring and/or quantifying a change in at least one physical characteristic of the at least one polymeric microparticle, wherein the physical characteristic comprises a particle size, transparency, porosity, smoothness, and/or brightness of the at least one polymeric microparticle; analyzing a change in the at least one physical characteristic of the at least one polymeric microparticle, thereby providing a time-resolved degradation profile in a predefined environment. 40. The method of claim 39, wherein the polymeric microparticle comprises polyester, poly (1,4-butylene adipate-co-terephthalate) (PBAT), polylactic acid (PLA), polycaprolactone (PCL), poly butyl acrylate (PBA), polybutylene succinate (PBS), polyurethane, polyamide, polyurea, polyanhydride polyester containing polyurethane moieties and blends, and/or a combination thereof. 41. The method of claim 40, wherein the at least one polymeric microparticle is suspended in a buffer and/or emulsifier. 42. The method of claim 40, wherein the flow rate is: a) about 50 µL/h; b) 1-50 µL/h; c) 50-100 µL/h; d) 1-1,000 µL/h; e) about 500 µL/h; f) 1-500 µL/h; or g) 500-1,000 µL/h. 43. The method of claim 40, wherein the at least one polymeric microparticle has a size of: a) 50-120 µm; b) 30-80 µm; c) 40-70 µm; or d) 10-60 µm. 44. The method of claim 40, further comprising: collecting a flow-through liquid comprising the enzymatic solution and degradation products, from the at least one outlet port; and analyzing the flow-through liquid. 45. A method for evaluating enzymes, comprising: applying an enzymatic solution to at least one polymeric microparticle, wherein the polymeric microparticle comprises one or more polymers; and determining a change in particle size and/or transparency of the at least one polymeric microparticle, wherein the change in particle size and/or transparency is indicative of the enzymatic degradation of the at least one polymeric microparticle; wherein the enzymatic solution comprises: a) at least one recombinant enzyme; b) at least one enzyme having a polypeptide sequence comprising one or more point mutations as compared to a naturally-occurring enzyme; and/or c) a plurality of naturally-occurring and/or recombinant enzymes. 46. The method of claim 45, further comprising: determining whether the enzymatic solution is capable of degrading the one or more polymers based on the change in particle size and/or transparency of the at least one polymeric microparticle. 47. The method of claims 45 or 46, wherein the degradation of at least one polymeric microparticle occurs in the microfluidic chip of any one of claims 22-36. 48. The method of any one of claims 39-43, wherein the method comprises introducing and trapping a plurality of polymeric microparticles and simultaneously analyzing the plurality of trapped polymeric microparticles.

49. The method of any one of claims 1-21 or 39-48, further comprising analyzing kinetics of enzymatic degradation of the polymer microparticles using a modified shrinking particle model (SPM) and shrinking core model (SCM). 50. The method of any one of claims 1-21 or 39-49, wherein the method is performed under static conditions.