WO2023097385A1

WO2023097385A1 - Magnetic cilia composition and method for producing surfaces with magnetic cilia

Info

Publication number: WO2023097385A1
Application number: PCT/BR2022/050474
Authority: WO
Inventors: Aline Grein IANKOVSKI; Watson LOH; Karina Andrighetti De Oliveira BRAGA; Paulo Francisco Guerreiro CARDOSO
Original assignee: Universidade Estadual De Campinas
Priority date: 2021-12-02
Filing date: 2022-12-01
Publication date: 2023-06-08

Abstract

The present invention relates to a magnetic cilia composition forming cilia by aligning magnetic particles immersed in an elastomeric matrix and projected from a surface, and to the method for producing the magnetic cilia. The thus formed cilia are flexible and promptly respond to an external magnetic field, and they can be manipulated to generate a controlled and ordered movement according to the orientation and oscillation frequency of the magnetic source. The activation of the cilia-covered surface by coupling with a portable magnetic pulse generator induces a controlled movement of the structures, causing the possibly formed biofilm to be removed and helping to clear secretions and particulate materials accumulated inside a prosthesis.

Description

COMPOSITION OF MAGNETIC EYELASHES AND THE PROCESS FOR PRODUCTION

OF SURFACES WITH MAGNETIC EYELASHES

Field of Invention

[001] The present invention relates to a magnetic eyelash composition and the process for producing surfaces with magnetic eyelashes. Cilia can be used in the preparation of biomaterials and implants capable of controlling or inhibiting the formation of deposits and biofilms, which can be cleaned by external magnetic action, in the preparation of surfaces resistant to adsorption or that can be cleaned by external magnetic action, as well as in the preparation of materials with active surfaces for the movement of fluids and particles in implants, tubes or microdevices, such as microfluidic systems controlled by external magnetic action.

Fundamentals of the Invention

[002] The growth of polymicrobial biofilms and their evolution to the formation of encrustations and the consequent clogging of devices inserted in humid environments, such as in prostheses implanted in the human body, is an important and recurrent clinical challenge that delays the progress of the treatment and causes a negative impact on the quality of life of patients, requiring the periodic removal of these implants.

[003] In general, the prostheses used in the medical field, such as the silicone T-tube, which is a silicone prosthesis used since 1965 in tracheostomized individuals, consist of a tube of inert material, which acts as a temporary intraluminal support of the trachea .

It is used in patients with benign, malignant, and other structural disorders of the organ that interfere with its patency.

[004] These prostheses do not have any additional mechanism aimed at mimicking the biological function of the airway in question, interfering with the effectiveness of mucociliary transport, which is responsible for the removal of particulate matter and secretions from the central airway. In addition, the permanent contact of the T-tube with inhaled air favors the formation of a polymicrobial biofilm on the surface of the silicone, harboring bacteria and fungi that interact with the mucosa, causing tracheitis and granulomas that ultimately delay the resolution of the stenosis .

[005] Thus, it becomes imperative to improve the functionality of medical prostheses (T-tubes, tracheal endoprostheses) and extend their useful life by inserting an internal coating with programmable mobility artificial eyelashes, mimicking, for example , the natural function of the biological structures present in the airways of mammals . The presence of artificial eyelashes promotes a non-stick surface and acts as a physical and mechanical control method for the formation of microbial biofilms inside the prosthesis.

[006] The fabrication of biocompatible, flexible, and magnetic field-responsive eyelashes inside these prostheses results in a non-stick surface that can be cleaned by external stimuli, promoting prolonged operational viability for these devices.

In addition, these cilia can be used to move fluids and suspended particles in the inside, for example, tubes in biomedical implants or microdevices for different uses, under the controlled action of an external magnetic field .

[007] Still, the activation of the ciliated surface through coupling with a portable magnetic pulsator induces a controlled movement of the structures, leading to the removal of the eventually formed biofilm and helping to clear secretions and particulate materials accumulated inside the prosthesis. The incorporation of biocidal agents into the cilia matrix, which would have controlled and extended release in situ, or the coating with silver nanoparticles, are also examples of possible additional resources to help control the local microbiota . Another potential field of application of the present invention is in tubular cavity drains, both for directing and for enhancing the flow velocity.

[008] In view of the above, the present invention brings a potential solution for the prevention and control of microbiota deposition in these materials, especially in tracheal silicone tubes, acting as an adjuvant in cleaning surfaces, enabling local control of biofilm formation, and assisting in the mobilization and eventual elimination of particulate matter and possible impurities that enter these devices.

[009] Among the methodologies used for the manufacture of elastomeric magnetic eyelashes, it stands out as a differential of the invention proposed here a greater simplicity and versatility of the eyelash manufacturing process, due to the absence of the need for a mold during the preparation. In this way, the cost and time spent on the mold preparation step are eliminated. Another advantage of the absence of a mold is greater flexibility for the manufacture of eyelashes on surfaces with different dimensions and shapes.

[0010] Furthermore, there is also the possibility of adjusting the size of the cilia formed and the density of pillars by simply changing the preparation conditions, such as the initial concentration of the dispersion components, volume used and intensity of the magnetic field. These materials can be used for externally controlled movement of fluids and suspensions inside, for example, tubes, in implants, or microdevices for various purposes (such as in microfluidics systems).

State of the art

[0011] The document Greinlankovski et . al (2020), titled "Template-free preparation of thermoresponsive magnetic cilia compatible with biological conditions" describes the fabrication of artificial cilia that mimic biological functions and which emerged as a promising strategy for handling fluids in miniaturized systems. However, unlike the present invention, the eyelashes of the referred document are composed of different materials: iron oxide nanoparticles (maghemite) functionalized with the thermoresponsive polymer PNnPAm.

[0012] In addition, the manufacturing process of eyelashes uses as a driving force the thermal transition of the PNnPAM polymer, from a soluble state to an aggregated state induced by the increase in temperature and not by the polymerization reaction of an elastomer. Still, the dimensions of the cilia are smaller, in another order of magnitude, being up to 100μm in length and less than 1.0 pm in thickness, having a temporary structure of approximately 24 hours . The formation process is reversible and the ciliated structures need to be kept in a liquid medium, not being possible to dry.

[0013] Document US20190217349A1 refers to topographies of antifouling surfaces with micron-scale pillars of ferromagnetic polymer capable of movement in response to magnetic fields and the method of fabrication of the surfaces. Although this document is part of the general state of the art, it is possible to perceive differences and limitations, such as the fact that the use of iron oxide particles (magnetite) as a magnetic material is observed.

[0014] In addition, the preparation and definition of the shape of the eyelashes are carried out with a prefabricated mold. Furthermore, the magnetic particles are concentrated at the top of the eyelashes and not distributed throughout the structure, and the dimensions of the eyelashes formed are smaller and fixed, being determined and limited by the mold.

[0015] Document W02012058605A1 addresses surfaces designed to reduce bacterial adhesion and the method of manufacturing these surfaces. Said surface comprises a plurality of projected structures, and on each projected structure a plurality of filament-like structures (cilia) are found, with dimensions of at least 0.5 microns and not more than 50 microns. [0016] However, despite the aforementioned document being part of the same technical field, it is possible to perceive relevant differences, such as the fact that the proposed topographic structures include the forms "dome-shaped, post-shaped, shark skin, pri sm-shaped" and suggested additional examples, such as polyhedra, parallelepipeds, prismatoids, conical, pyramidal, spherical, ellipsoid, cylindrical and combinations between them . No mention is made of cilia, flexible filaments, or mobile structures.

[0017] For the manufacture of structures it is suggested the use of techniques such as "casting", "coating" and compression, which require a mold or tool containing the desired structural pattern. For the manufacture of this mold, microfabrication techniques are necessary, such as ablation (chemical, mechanical, laser), photolithography, stereolithography, scoring, etc.

[0018] In addition, the dimensions of the structures are smaller, from nanometric order up to around 100μm in height. Still, no mention is made of holding and? use of magnetic particles of their properties for manipulation and orientation of the system.

[0019] Patent document US10210995B2 protects a method for producing a film comprising three-dimensional magnetic microstructures. The film comprises a non-magnetic matrix and a plurality of three-dimensional magnetic microstructures arranged within the matrix in a predetermined pattern.

[0020] Although said document is part of the general state of the art, a method designed for the manufacture of films containing magnetic structures is proposed three-dimensional devices for separating and trapping magnetic materials, this being a distinct concept of non-stick surfaces proposed in the present invention. The magnetic structures are formed on an already standardized base, which can be considered a mold, as it requires microfabrication techniques, being an additional step in the process. Among the magnetic particles used, the possible use of carbonyl iron (FeC) is not mentioned.

[0021] In addition, the magnetic particles are concentrated at the edges of the magnetic field generated by micromagnets positioned in the cavities of the base and not ordered linearly in the homogeneous direction of the magnetic field, located in the central region of the magnet. The magnetic particle powder is deposited on the base and not dispersed in an elastomeric matrix.

[0022] Regarding the method of manufacturing the films, it is clear that only later is a copolymer added to form a film and act as a binder between the aggregated particles and the way of preparation generates rigid aggregated structures, not capable of simulating movement of biological cilia by the action of a magnetic field. Also, the height of the structures is in the order of 20 pm and the separation distance between them is fixed at 100μm forming a checkered distribution at the base according to the edges of the micromagnets.

[0023] Document CN109876874B protects a superhydrophobic magnetic microcilium array for directional transport of liquid droplets and the method of preparation and application thereof. The arrangement of magnetic microcilia superhydrophobic is characterized by the fact that the height of each microcilia is 1-3.5 mm, and the distance between the tips of each two adjacent microcilia is 0.6-2.0 mm.

[0024] Through an analysis of that document, it is clear that the preparation of the eyelashes uses a mold, initially requiring an additional step for the preparation of the mold and a further step later for the dissolution of the mold and recovery of the eyelashes. In addition, the magnetic particles used are cobalt and the dimensions of the eyelashes are larger, in the order of millimeters:

1-3.5 mm long and 0.6 2 . 0 mm in width and the density of eyelashes on the surface is less.

[0025] And finally, the document Valle et . al (2015), entitled "Evaluation of surface micro topography engineered by direct laser interference for bacterial anti-biofouling" is also part of the general state of the art, and discusses the modification of the surface topography of the biomaterial as a promising strategy for prevent bacterial adhesion and biofilm formation. The direct laser interference pattern (DLIP) was used in the article to modify the surface topography of polystyrene on a submicrometer scale.

[0026] Through an analysis of said document, it is clear that the tested surfaces were polystyrene, polyimide and polyethylene terephthalate and the fabrication of the topography is done using a high-power pulsed laser using the DLIP technique. The applicability of the method on silicone, a material commonly used in the manufacture of prostheses, was not verified. The behavior of bacterial adhesion proved to be dependent on the pattern of topography applied to the surface and the pattern resulting from the process, in turn, may vary according to the material used.

[0027] In view of the above, it is not verified in the state of the art and in the related documents methods that allow the drying of eyelashes facilitating processability, obtaining more robust, mechanically resistant eyelashes with larger dimensions, the possibility of adjusting the dimensions and characteristics of the cilia by simply varying the concentration of the components and the intensity of the applied magnetic field. As well as processes that have lower cost, greater ease and versatility of production, added by the no need for the mold manufacturing step.

[0028] The cilia of the present invention can act to reduce the formation of microbial biofilms by at least three combined mechanisms: promoting the mobilization of particulate material adhered to the surface of the silicone; the reduction of the accumulation of particulate matter in the biofilm due to the irregularity and roughness of the surface due to the presence of cilia; and the displacement with fragmentation and eventual removal of the biofilm through the movement of its structure by the action of an external magnetic field in association with the coughing mechanism. Furthermore, it is still possible to incorporate a biocide into the cilia matrix to act as an additional bacterial inhibition mechanism.

[0029] The magnetic cilia interact with respiratory mucus, a film of secretion that covers almost all of the conducting airways. the respiratory mucus it is a complex mixture of different secretions that form a hydrophilic polymer with viscoelastic properties. In the respiratory tract, its motility is induced by ciliated cells present on the epithelial surface.

Brief description of the invention

[0030] The present invention relates to a composition of magnetic cilia formed by aligning magnetic particles immersed in an elastomeric matrix

(mixture) projected from a surface and the production process of magnetic eyelashes. The formed cilia are flexible and readily respond to an external magnetic field, and can be manipulated generating a controlled and orderly movement according to the orientation and frequency of oscillation of the magnetic source. The activation of the ciliated surface through coupling with a portable magnetic pulsator induces a controlled movement of the structures, leading to the removal of the eventually formed biofilm and helping to clear secretions and particulate materials accumulated inside a prosthesis .

Brief description of figures

[0031] In Figure 1, the preparation of the magnetic eyelashes is shown, showing the vat containing the sample over the magnet

(A) and the final sample obtained after drying and removal from the vat (B and C).

[0032] In Figure 2, samples obtained using different preparation parameters are presented, illustrating some of the different possibilities for varying the dimensions of the magnetic eyelashes. From left to right, cilia with lengths ranging from 159 ± 55 μm to 722 ± 145 μm, widths between 20 and 50μm and densities between 8 and 21 cilia/mm ² .

[0033] In Figure 3, the scanning electron microscopy (SEM) of the magnetic cilia is shown, showing the details of the morphology of the magnetic cilia obtained and the distribution of the magnetic particles within the polymeric matrix.

[0034] In Figure 4, ciliated plaques are shown in the presence of fresh mucus (Rana Catesbeiana), with the side view with moving cilia (A and B), and the top view showing the interaction and structural preservation of the cilia

(W) .

[0035] Figure 5 shows the flowchart of the eyelash production process.

Detailed description of the invention

[0036] The present invention relates to a composition of magnetic cilia formed by aligning magnetic particles immersed in an elastomeric matrix

(mixture) projected from a surface and the manufacturing process of magnetic eyelashes. The formed cilia are flexible and readily respond to an external magnetic field, and can be manipulated, generating a controlled and ordered movement according to the orientation and frequency of oscillation of the magnetic source, as shown in Figure 1.

[0037] For the manufacture of magnetic eyelashes, the following components are required: magnetic particles, a magnet with sufficient magnetic strength to promote alignment of the respective particles, a polymeric solution of an elastomer to act as the matrix of support of the ciliated structures and a surface as base. An example of a set of starting materials is the use of carbonyl iron magnetic particles coated with SiO2 with an average diameter d ₅₀ = 3.0 - 4.0μm and an NdFeB magnet (N35 grid) in the form of a disk with a diameter of 30 mm and 10 mm high resulting in a magnetic field of 3355 Gauss at the surface.

[0038] As an elastomeric matrix, a PDMS silicone polymer can be used, composed of an elastomeric base (part A) and a curing agent (part B) in a 1 : 1 ratio, solubilized in THE solvent

(Tetrahydrofuran) or ethyl acetate. As a base surface, an 8 mm diameter and 1 mm thick silicone disc can be used.

[0039] In Figure 3, images of scanning electron microscopy (SEM) of the magnetic cilia are shown, showing the details of the morphology of the magnetic cilia obtained and the distribution of magnetic particles within the polymeric matrix, showing that the magnetic particles are homogeneously distributed along the structure of the eyelashes.

[0040] The eyelash preparation process is represented in Figure 5 and begins with the solubilization of the PDMS polymer in the chosen solvent (part A and part B separately), mixed in the appropriate proportion and followed by the addition of the magnetic particles (step a) . This dispersion is homogenized by sonication in an ultrasonic bath for 1 to 5 minutes (step b) and promptly poured onto the surface to be used as a base (step c), positioned inside a teflon vat. the system is immediately positioned centered over the magnet (step d) .

[0041] The magnetic field generated by the magnet induces the alignment of the magnetic particles perpendicularly to the base forming pillars from the surface. With the evaporation of the solvent, the particles are enveloped by the polymer matrix, which is then polymerized under the appropriate conditions of temperature and time, for example, the

65 ° C for 24h to 48h in the case of PDMS silicone, depending on the polymeric proportion used . Immediately after the polymer cures

(step e), the vat is removed (step f) and the ciliated surface is formed and ready for use (step g).

[0042] It is noteworthy that different materials in different dimensions can be used as a base surface, for example silicone, glass, metallic surfaces, polymeric surfaces, among others. The size and/or composition of the magnetic particles can also be varied, for example carbonyl iron particles with diameters of 5.5μm, iron oxide particles or metallic iron. Different solvents can also be used such as THF, ethyl acetate or according to the chemical compatibility with the used polymer.

[0043] The dimensions (length and thickness) of the cilia obtained can be adjusted by varying the mass of magnetic particles used, the volume of dispersion, changing the intensity of the magnetic field by changing the distance of the sample to the magnet or replacing the magnet for another one of greater or lesser magnetic strength, as can be seen in Figure 2. [0044] After the curing process, the length of the lashes can also be adjusted through physical thinning with a cutting blade. Furthermore, the particle:PDMS ratio and the ratio between the base polymer of PDMS and its curing agent in the mixture can also be varied (1:1 or 1:2, for example) to modulate the rigidity of the structures.

[0045] Table 1 presents an example of the different values of cilia dimensions obtained by varying the concentration of magnetic particles in the initial dispersion and keeping the particle:PDMS ratio constant (0.1), the constant volume (80 μL ) and the silicone base (8 mm x 1 mm) positioned over the magnet at a distance of 1.1 cm.

Table 1 - Dimensions of the cilia formed by varying the mass of CIP-EW magnetic particles and maintaining the particle:PDMS ratio (0.1), volume (80 μL) and distance from the magnet

(1.1 cm) constant.

[0046] Table 2 shows the results obtained by increasing the distance from the base to the magnet and keeping the other parameters constant: particle mass = 0.6 mg, particle ratio: PDMS = 0.1, volume = 80 µL.

Table 2 Dimensions of the cilia formed by varying the distance from the base to the magnet and maintaining the particle mass

CIP-EW (0.6 mg), particle ratio: PDMS (0.1) and volume (80 μL) constant

[0047] Table 3 shows other examples of combinations tested along with the respective results obtained.

Table 3 Dimensions of cilia formed using different combinations of particle mass parameters

CIP-EW, PDMS mass, distance to the magnet and keeping the dispersion volume constant at 80 μL

[0048] In summary, it was demonstrated that it is possible to increase the length of the magnetic cilia by increasing the number of particles in the initial dispersion or by increasing the intensity of the applied magnetic field, for example example, positioning the sample closer to the surface of the magnet. Furthermore, for the same concentration of particles, the closer the sample is to the surface of the magnet during preparation, the greater the density of cilia per area obtained and the smaller the thickness of the cilia. Among the combinations already tested, it was possible to obtain magnetic cilia with lengths around 150 to 1600μm , diameters from 6 to 50 pm and with densities from 8 to 110 cilia/mm ² .

[0049] Tests were carried out for the qualitative evaluation of the cilia and mucus interaction considering different characteristics of ciliary length, ciliary width and density. The tests were performed using fresh frog mucus (.Rana Catesbeiana) in a nebulized environment.

(relative air humidity 90 to 95%) and room temperature. Ciliary movement was determined by manually moving the magnet.

[0050] After the deposition of mucus on the cilia, the ciliary beating was evidenced in all analyzed samples with preservation of the ciliary structure, as shown in Figure 4. The cilia remained well structured, without significant deformation and produced movement when stimulated by the field magnetic .

Claims

1) Composition for magnetic eyelashes, characterized in that it comprises a mixture of magnetic particles immersed in an elastomeric matrix and a disc as the base surface, in which the magnetic particles are preferably carbonyl iron coated with SiO2, and in which the elastomeric matrix is preferably a polymer PDMS silicone, preferably containing the presence of biocidal agents.

2) Composition according to claim 1, characterized in that the base surface comprises different materials, such as silicone, glass, metallic surfaces or polymeric surfaces, preferably silicone.

3) Composition, according to claim 1, characterized in that the magnetic particles preferably have an average diameter d ₅₀ between

3.0 and 5.5μm .

4) Composition, according to claim 1, characterized in that the elastomeric matrix preferably comprises an elastomeric base

(part A) and a curing agent (part B) in a ratio

1:1.

5) Composition, according to claim 1, characterized by the fact that the particle : PMDS ratio between

0.05 and 0.2 and the PDMS : curing agent ratio is 1 : 1 or

1:2. 6) Process for producing a surface with magnetic eyelashes, characterized in that it comprises the steps of:

(a) Solubilization of the PDMS polymer in the solvent

(part A and part B separately), mixed in the desired proportion and followed by addition of the magnetic particles;

(b) Homogenization of the dispersion obtained by sonication in an ultrasonic bath for approx.

1 to 5 minutes;

(c) Adding the dispersion onto the silicone base surface positioned inside a Teflon tank;

(d) Positioning the sample over the magnet;

(e) Curing the polymer at approximately 65°C for approximately 24 to 48 hours;

(f) Removal of the Teflon vat and obtaining the eyelashes.

7) Process, according to claim 6, characterized in that the chosen solvent is preferably THE (tetrahydrofuran) or ethyl acetate.

8 ) Process, according to claim 6, characterized in that the magnet is preferably an NdFeB magnet (N35 grid) in the form of a disk with 30 mm in diameter and 10 mm in height resulting in a magnetic field of 3355 Gauss on the surface .

9) Process according to claim 6, characterized in that the length of the eyelashes is optionally adjusted after curing by means of physical thinning using a cutting blade.