KR101971426B1 - UV light and temperature-responsive self-assembled microsphere composed of water-soluble polymer and aromatic compound and method for production thereof - Google Patents

Abstract

The present invention relates to a water-soluble polymer which is formed by a hydrophobic interaction between an aromatic compound and a salt bridge bond with an aromatic compound (cross linking agent) Self-assembled microspheres are characterized by the fact that the microspheres dissolve and release the contents when irradiated with ultraviolet rays. When the temperature rises, the microspheres disintegrate and release the contents.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet and temperature-responsive self-assembling microsphere comprising a water-soluble polymer and an aromatic compound,

The present invention relates to an ultraviolet and temperature-responsive self-assembling microspheres and a method of preparing the same, and more particularly, to self-assembling microspheres composed of a water-soluble polymer and an aromatic compound as a crosslinking agent thereof, and a method for producing the same.

Light-responsive drug delivery systems (eg, liposomes, polymeric micelles, nanogels, and elastomers) have been developed using a variety of photoreactive mechanisms. Liposomes are designed to cause light-responsive release by incorporating photoreactive lipids in the lipid bilayer.

Liposomes containing unsaturated lipids exhibit phase separation of the liposome membrane because unsaturated lipids form a photodimer when irradiated with ultraviolet rays (Kono, K., Hayashi, H., and Takagishi, T. (1994) Journal of Controlled Release, 30: 69-75.).

Bis- (4-N-butylphenyl azo-4'-phenylbutyroyl) -L- alpha -phosphatidylcholine (bis- (Morgan, CG, Thomas, EW, Sandhu, SS, Yianni, < RTI ID = 0.0 > (2000) Photochemistry and Photobiology, 72 (1986), Biochemica et Biophysica Acta (BBA) - Biomembranes, 903: 504-509., Bisby, RH, Mead, C., and Mitchell, AC : 57-61.).

The O-nitrobenzyl-conjugated lipid is photodegraded between the hydrophilic head and the hydrophobic tail. Thus, it can lose its amphiphilicity and be rearranged in the liposome bilayer membrane, and the liposome causes photo-responsive release.

Lipids with a vinyl ether linkage (e.g., plasmenylcholine) are photo-oxidized with the aid of a photo-sensitizer. As a result, it is photolyzed to lysolipids and the liposomes can disintegrate to release the contents (Seo H. J., and Kim, F. C. (2011) Journal of Nanoscience and Nanotechnology, 11: 10262-10270.).

On the other hand, photoreactive drug delivery vehicles using coumarin and its derivatives have been developed. When irradiated with ultraviolet rays, coumarin can be dimerized, and the dimer thus formed can be photodegraded to monomers by irradiation with ultraviolet light of a short wavelength. Light responsive macromolecular micelles, nanogels and endoplasmic reticulum have been developed using the optical response characteristics of coumarin. Recently, a light-responsive microgel was formed in which a polysorbate 20-coumarin conjugate in which coumarin was covalently bonded to a polysorbate head was added to an aqueous solution of a? -Cyclodextrin polymer.

However, there has not been developed a microsphere capable of selectively releasing a drug at a specific site due to irradiation of light (ultraviolet ray) and temperature rise. Therefore, If a microsphere is developed, it will be very useful in the medical and pharmaceutical industries.

Korean Patent No. 10-1355129 (registered on Apr. 17, 2014) discloses a microgel prepared by electrostatically interacting an ionic polymer with an ionic photoreactive substance. Korean Patent No. 10-1077819 (registered on October 24, 2011) discloses a water-soluble biocompatible polymer having a functional group capable of photo-crosslinking.

In the present invention, an ultraviolet ray and a temperature-responsive microsphere comprising a water-soluble polymer and an aromatic compound and emitting an effective ingredient upon irradiation with ultraviolet rays and a temperature rise are developed and provided.

In the present invention, a water-soluble polymer and an aromatic compound are linked by a bridge through a salt bridge bond, and are self-assembled by a hydrophobic interaction between aromatic compounds A material having a UV-responsive release and a temperature-responsive release characteristic and capable of selectively releasing the contained substance to the outside according to irradiation with ultraviolet rays or changes in temperature And provides a self-assembled microsphere.

In the self-assembled microsphere of the present invention, the water-soluble polymer may be any one of cationic polymers selected from polyethyleneimine, chitosan and polylysine, for example. have.

In the self-assembled microspheres of the present invention, the water-soluble polymer may be any one selected from among alginate and pectin.

In the self-assembled microspheres of the present invention, the aromatic compounds include, for example, cinnamic acid and 4- (phenylazo) benzoic acid, 4 - [(E) - (4-Aminophenyl) diazenyl] benzoic acid.

The present invention relates to a process for producing a water-soluble polymer by dissolving a water-soluble polymer and an aromatic compound in an aqueous solution to induce crosslinking through salt bridge bonding between a water-soluble polymer and an aromatic compound, And inducing hydrophobic interaction between the microspheres to self-aggregate the microspheres.

In the process for preparing self-assembly microspheres of the present invention, the water-soluble polymer and the aromatic compound are preferably dissolved in an aqueous solution such that the weight ratio of the water-soluble polymer to the aromatic compound is 100: 1 to 1: 100.

When the water-soluble polymer and the aromatic compound are dissolved in the aqueous solution, the total concentration of the water-soluble polymer and the aromatic compound in the aqueous solution is preferably 0.01 to 30% (w / v) .

The present invention relates to ultraviolet and temperature-responsive self-assembled microspheres formed by hydrophobic interactions of a water-soluble polymer with an aromatic compound and a salt bridge and between aromatic compounds, The microspheres are disassembled and the content is selectively released.

1 is a schematic diagram of an ultraviolet ray and temperature responsive microsphere composed of a water-soluble polymer and an aromatic compound of the present invention.
Figure 2 shows the size distribution of the polyethyleneimine / cinnamic acid microspheres.
Fig. 3 shows changes in light transmittance with time of a polyethyleneimine / Shinanami microsphere suspension () irradiated with ultraviolet rays and a polyethyleneimine / Shinanamus microsphere suspension (◯) irradiated with no ultraviolet rays.
Figure 4 is a micrograph of time course (0 hours (A), 1 hour (B), 4 hours (C)) of microsphere suspension treated with ultraviolet light for 30 minutes. The enlargement magnification is 400 times, and the scale bar is 20 μm.
5 shows the ultraviolet-visible light absorption spectrum of cinnamic acid of polyethyleneimine / cinnamic acid microspheres obtained before exposure to ultraviolet light (a), after exposure to ultraviolet light for 30 minutes (? = 365 nm, 400 W) 0 hours (b), 0.5 hours (c), 1 hour (d), 3 hours (e) and 5 hours (f).
Figure 6 shows the temperature dependent transmittance of the polyethyleneimine / cinnamic acid microsphere suspension in the heating () and cooling () cycles at a temperature range of 20 ° C to 90 ° C.
7 is an optical microscope photograph showing the temperature dependent disintegration of microspheres in the heating (30 ° C. → 70 ° C. (B)) and 30 ° C. → 70 ° C. (70 ° C. → 30 ° C. (C)) cycles. The enlargement magnification is 400 times, and the scale bar is 20 μm.
Figure 8 shows the release profile of FITC-dextran loaded on microspheres (O) not treated with ultraviolet light and microspheres (•) treated with ultraviolet light.
Figure 9 shows the release profile of FITC-dextran loaded on the microspheres at 30 占 (?), 40 占 (?) And 50 占 (占).

In order for the carrier containing the target substance (target substance) to effectively exert the effect of the target substance, it is necessary to hold the target substance on the substrate and to actively release the target substance when the release of the target substance is required.

In the present invention, a water-soluble polymer and an aromatic compound are linked by crosslinking through a salt bridge bond and are self-assembled by hydrophobic interaction between aromatic compounds A material having a UV-responsive release and a temperature-responsive release characteristic and capable of selectively releasing the contained substance to the outside according to irradiation with ultraviolet rays or changes in temperature We have developed self-assembled microspheres.

The ionic group of the crosslinking agent in the aqueous solution can bind to the water-soluble polymer by electrostatic attraction, and at the same time the aromatic group of the crosslinking agent can bind by hydrophobic interaction with each other, so that a self-assembly (for example, self- .

The aromatic compound is isomerized from trans to cis upon irradiation with ultraviolet light. And, isomerization into the cis form increases the polarity of the aromatic compound. As the polarity of the aromatic compound increases, the hydrophobic interactions between the aromatic compounds weaken or disappear, disintegrating the microspheres and releasing the contents. Also, as the temperature increases, the solubility of the aromatic compound in the water phase increases significantly and the hydrophobic interaction between the aromatic compound molecules may weaken or be lost. Through this, the self-assembly is disassembled by the temperature and the contents are released (Fig. 1).

In the ultraviolet and temperature responsive self-assembling microspheres of the present invention, the water-soluble polymer is preferably selected from cationic polymers or alginates selected from among polyethyleneimine, chitosan and polylysine, It is preferable to use an anionic polymer selected from pectin.

In the ultraviolet and temperature responsive self-assembling microspheres of the present invention, the cross-linking agent is preferably selected from the group consisting of cinnamic acid and 4- (phenylazo) benzoic acid, 4 - [(E) - -Aminophenyl) diazenyl] benzoic acid) is preferably used.

The present invention relates to a process for producing a water-soluble polymer by dissolving a water-soluble polymer and an aromatic compound in an aqueous solution to induce crosslinking through salt bridge bonding between a water-soluble polymer and an aromatic compound, And inducing hydrophobic interaction between the microspheres to self-aggregate the microspheres.

To synthesize microspheres, a proteinoid, which is a polymer composed of several amino acids at high concentration and high temperature, is first synthesized using amino acid as a material. It can be seen that spherical microspheres are formed when the hot protonoid saturated solution thus prepared is cooled slowly. About 100 million microspheres are produced from about 1 mg of the proteoid.

The weight ratio of the water-soluble polymer and the aromatic compound in the step of dissolving the water-soluble polymer and the aromatic compound in the aqueous solution in which the active ingredient is dissolved in the method of producing the ultraviolet and temperature-responsive self-assembling microsphere of the present invention is preferably 100: ~ 1: 100. The amount of the aromatic compound which acts as a crosslinking agent is too small to form the microspheres and the amount of the water-soluble polymer constituting the skeleton of the microspheres is too low in the range higher than the suggested range, . More preferably from 50: 1 to 1:50, and most preferably from 10: 1 to 1:10.

The total concentration ratio of the water-soluble polymer and the aromatic compound in the step of dissolving the water-soluble polymer and the aromatic compound in the aqueous solution is preferably 0.01 to 30% (w / v). If the total concentration of the water-soluble polymer and the aromatic compound is too low, the self-assembly (microsphere) is not formed. If the total concentration of the water-soluble polymer and the aromatic compound is too high, and the self aggregation is not formed due to entanglement. , More preferably 0.1 to 20%, and most preferably 0.2 to 10%.

On the other hand, in the method of producing the ultraviolet and temperature-responsive self-assembling microspheres of the present invention, the target material to be mounted may be dissolved in the aqueous solution so that the target material is mounted inside the microsphere.

In addition, the method of the present invention may further include separating and removing a target material not loaded on the microspheres. For example, centrifugation, filtration, or dialysis . This method can be used to separate and remove target substances that are not mounted on the microspheres.

Hereinafter, the structure of the present invention will be described in detail with reference to the following examples. However, the scope of the present invention is not limited to the following embodiments, and includes modifications of equivalent technical ideas.

[Example 1: Preparation of polyethyleneimine / Shinmin acid microsphere]

And dissolved in Trizma base buffer (30 mM, pH 7.0) so that the concentration of polyethyleneimine was 0.2 g / ml (amino group concentration: 4.59 mM). At the same time, cinnamic acid was dissolved to 0.68 mg / ml (4.59 mM as a carboxyl group concentration) in the same buffer solution. 3 ml of polyethyleneimine solution was mixed with 7 ml of Shin-Na acid solution so that the molar ratio of amino group of polyethyleneimine to carboxyl group of cinnamic acid was 3: 7. The vials were tightly capped and mixed in a dark place for 24 hours in a roller mixer.

Microemulsion diameters of polyethylene imine / Shin-Nansan were measured using an image analyzer (Image-Pro Plus, Media Cybernetics, USA). Optical micrographs of the polyethyleneimine / cinnamic acid suspension were taken on an optical microscope (CX31, OLYMPUS, Japan) to obtain images of polyethyleneimine / Shinan acid microspheres.

The diameter of the microspheres was determined by analyzing the particles in a micrograph using an image analyzer.

Figure 2 shows the size distribution of the polyethyleneimine / cinnamic acid microspheres. The size distribution of the polyethylene imine / Shin-Nansan microspheres was monomodal, with diameters ranging from 0.42 to 19.51 μm and mostly from 1.52 to 6.57 μm. The mean diameter was 4.97 μm and the standard deviation was calculated as ± 2.63 μm.

[Example 2: Observation of photosensitivity of microspheres]

The polyetherimine / cinnamic acid microsphere suspension dispersed in Trizma base buffer (30 mM, pH 7.0) was irradiated with ultraviolet light (λ = 365 nm, 400 W) for 30 min. The change in transmittance of the microsphere suspension irradiated with ultraviolet rays was measured at 600 nm for 5 hours using an ultraviolet-visible light spectrophotometer. At the same time, disintegration of the microspheres contained in the suspension irradiated with ultraviolet rays was observed under an optical microscope (CX31-P, Olympus, Japan). Changes in the transmittance of the suspension not irradiated with ultraviolet rays and disintegration of microspheres contained in the suspension not irradiated with ultraviolet rays were also observed as control samples.

FIG. 3 shows changes in light transmittance of polyethyleneimine / Shinnam acid microsphere suspension irradiated with ultraviolet rays and polyethyleneimine / Shinnan acid microsphere suspension not irradiated with ultraviolet rays with time. When the light transmittance of the polyethyleneimine / Shinnam acid microsphere suspension irradiated with ultraviolet rays and the polyethyleneimine / Shinnan acid microsphere suspension not irradiated with ultraviolet light were changed with time, the light transmittance of the polyethyleneimine / The light transmittance was only about 5% throughout the experiment. The cinnamic acid molecule can be electrostatically bonded to a polyethyleneimine chain to form a polyethyleneimine / cinnamic acid conjugate. Since Shinmin acid is hydrophobic due to phenyl group and polyethylene imine is hydrophilic, the polyethyleneimine / cinnamic acid conjugate can be amphipathically self-aggregated in the water phase to form microspheres. The microspheres, which are self-assembled, can scatter visible light and thus have low light transmittance.

On the other hand, the transmittance of ultraviolet light irradiated polyethyleneimine / cinnamic acid microsphere suspension rapidly increased immediately after ultraviolet irradiation, and the value increased to more than 90% over 300 minutes. This is because the microspheres collapse by ultraviolet irradiation.

On the other hand, FIG. 4 is a microphotograph of the microsphere suspension irradiated with ultraviolet rays with time. Microspheres were found immediately after and after 1 hour of ultraviolet irradiation, but no microspheres were found 4 hours after ultraviolet irradiation. Therefore, it can be said that the change in the transmittance of FIG. 3 is closely related to the disassembly of the microspheres.

When irradiated with ultraviolet light, cinnamic acid undergoes a photoreaction (eg, (2 + 2) cycloaddition and trans / cis isomerization), which in turn leads to an increase in the polarity of cinnamic acid. Therefore, when the microspheres composed of polyethyleneimine and cinnamic acid are irradiated with ultraviolet rays, the polarity of cinnamic acid is increased and the hydrophobic interaction between the cinnamic acid molecules weakens or disappears and the microspheres disintegrate.

On the other hand, microspheres not irradiated with ultraviolet light retained their original shape and size during the whole experimental period (that is, 300 minutes). Unless irradiated with ultraviolet light, most of the cinnamic acid molecules are present in the form of trans, and transcinnamic acid molecules can interact via electrostatic attraction with the polyethyleneimine chains and at the same time, , Shin-Nam-san can exist as a stable cross-linking agent for the polyethylene imine chain.

[Example 3: Optical isomerization of cinnamic acid in microspheres]

After irradiating ultraviolet light (? = 365 nm, 400 W) to 2.5 ml of the microsphere suspension dispersed in Trizma base buffer (30 mM, pH 7.0), the ultraviolet-visible light absorption spectrum of the microsphere suspension was measured by ultraviolet- The effect of ultraviolet irradiation on photoisomerization of cinnamic acid in microspheres was investigated by recording with time on a photometer.

FIG. 5 shows the results of exposure to ultraviolet light (λ = 365 nm, 400 W) for 30 minutes, 0.5 hour, 1 hour, and 3 hours after exposure to ultraviolet light of Shin-Nam San acid of polyethyleneimine / And ultraviolet-visible light absorption spectrum obtained after 5 hours. One characteristic peak was observed at 267 nm and another characteristic peak was observed at 213 nm before exposure to ultraviolet light. The two characteristic peaks are due to the ultraviolet absorption characteristics of trans-cinnamic acid (trans-CA). Shinnam acid molecules are present in the form of trans in natural light conditions.

On the other hand, after 0.5 hour exposure to ultraviolet light, the characteristic peak shifted to a shorter wavelength and the intensity of the peak decreased because the trans-type cinnamic acid was partially transformed into a cis molecule. As the time elapsed to 5 hours, the intensity of the peak gradually decreased. This indicates that trans-to-cis isomerization still occurs for 5 hours after 30 minutes of UV irradiation.

Actually, the permeability of the polyethyleneimine / cinnamic acid microsphere suspension gradually increased (FIG. 3) and after 30 minutes of ultraviolet irradiation, the microspheres on the optical microscope photograph gradually disappeared for 5 hours (FIG. 4). These results show that the microspheres were exposed to ultraviolet radiation and then disintegrated by trans-to-cis isomerization of cinnamic acid.

[Example 4: Observation of temperature sensitivity of microspheres]

The temperature-dependent transmittance of the microsphere suspension dispersed in Trizma base buffer (30 mM, pH 7.0) was measured at 600 nm using an ultraviolet-visible spectrophotometer equipped with a temperature controller (Peltier Controller, Jenway, UK) . The microsphere suspension was heated and cooled at a rate of 2 캜 / min from 20 캜 to 90 캜.

In parallel, temperature dependent disassembly of the microspheres in the suspension was observed under an optical microscope equipped with a hot stage (HS82, Mettler Toledo, USA) and a temperature controller (HS1, Mettler Toledo, USA). A rubber O-ring (1.0 cm in diameter, 0.2 cm in thickness) was fixed to the surface of the cover glass using an adhesive, the space of the O-ring was filled with a microsphere suspension, and covered with another cover glass. The sample prepared as described above was placed on a heating device, and the shape and size of the microspheres were observed as the temperature was raised and lowered.

Figure 6 shows the temperature dependent transmittance of a polyethyleneimine / cinnamic acid microsphere suspension in a heating and cooling cycle at a temperature range of 20 占 폚 to 90 占 폚. The permeability was less than 5% and was almost constant while the suspension was heated from 20 占 폚 to 30 占 폚. The transmittance increased sharply at about 40 ° C and was more than 90% at 80 to 90 ° C. When the heated suspension was cooled, the transmittance decreased to an initial value at about 40 ° C.

Figure 7 shows the temperature dependent dissociation of the microspheres in the heating and cooling cycles in the temperature range of 30 to 70 占 폚. Microspheres were observed when the temperature of the suspension was 30 ° C. However, when the suspension was heated to 70 캜, the microspheres disappeared and were not found. Thus, the increase in the permeability of the suspension during heating of the suspension (Fig. 6) is due to disassembly of the microspheres. As the microspheres heat up, the disintegration increases as the solubility of cinnamic acid increases with temperature, and the polyethyleneimine / cinnamic acid conjugate loses its amphiphilic property at high temperatures. That is, when the temperature rises, the solubility of Shin-Nam-san increases and the microspheres disintegrate because the hydrophobic interaction between Shin-Na acid molecules disappears.

[ Example  5: Shin-Nam-san  Temperature-dependent solubility determination]

Excess cinnamic acid was added to 5 ml of Trizma base buffer (30 mM, pH 7.0) in a 10 ml vial. The lid of the vial was covered and shaken in a thermostat controlled room temperature at 25 캜, 30 캜, 40 캜, 50 캜 and 60 캜 for 24 hours in a dark condition. The undissolved Shin-Nans acid was removed using a syringe filter (processing size 0.45 μm) and the absorbance of the filtrate was measured at 283 nm using an ultraviolet-visible light spectrophotometer (6505 UV / Vis Spectrophotometer, Jenway, UK) . The absorbance of the filtrate on the calibration curve (Y = 64.0404X + 0.0007, where X is the concentration of cinnamic acid in mg / ml and Y is the absorbance at 283 nm) The corresponding concentrations were read and determined.

The solubilities of cinnamic acid in Trizma base buffer (30 mM, pH 7.0) were 0.72 mg / ml, 0.86 mg / ml and 0.91 mg / ml, respectively, when media temperatures were 25 ℃, 30 ℃, 40 ℃, ml, 0.93 mg / ml, and 1.21 mg / ml, respectively.

The solubility increased with increasing temperature, and at low temperatures (e.g., 25 < 0 > C), the cinnamic acid molecules attached to the polyethyleneimine chain could interact with each other with hydrophobic attraction due to the phenyl groups, Microspheres can be generated. When the neunnamic acid molecules are easily dissolved in the aqueous solution, the neunnamic acid molecules lose their hydrophobic interactions between the phenyl groups and lose their ability to assemble the water soluble polymer chains, so that the self-assemblies such as microspheres disintegrate. This can explain why the microspheres disintegrate when the microsphere suspension is heated.

[Example 6: Observation of light and temperature sensitive emission]

FITC-dextran (fluorescent dye) was dissolved in Trizma base buffer (30 mM, pH 7.0) to 1 mg / ml. 5 ml of the dye solution was placed in a 10 ml vial with an equal volume of polyethyleneimine / cinnamic acid microsphere suspension and sealed with a lid. The vials were then rolled using a roller mixer and the contents were stirred for 12 hours. In order to remove the dye not loaded on the microspheres, a mixture suspension of fluorescent dye and microsphere was placed in a dialysis membrane (MWCO 10,000) and sealed. Then, the dialyzed membrane was put into 500 ml of the buffer contained in the 1 L beaker and dialyzed in the dark at room temperature . In order to observe the effect of ultraviolet radiation on the% release of the dye loaded on the microspheres, 5 ml of the dye-loaded microsphere suspension in 50 ml of the buffer contained in a 50 ml beaker was irradiated with ultraviolet light (? = 365 nm, 400 W). 0.5 ml of dialysis solution was taken at the given time for 5 hours, and the fluorescence intensity was measured at 516 nm by filtration at 494 nm. The percent release is expressed as a percentage of the amount of dye released based on the total weight of the dye loaded on the microspheres. To investigate the effect of temperature on the degree of release of the dye loaded on the microspheres, 5 ml of the dye-loaded microsphere suspension was dialyzed in 50 ml of buffer solution at temperatures of 30, 40 and 50 ° C. The% release was measured according to the same procedure as above.

Figure 8 shows the release profile of FITC-dextran loaded on microspheres treated with ultraviolet light and on microspheres not treated with ultraviolet light. When the microsphere was not treated with ultraviolet light, the degree of release gradually increased within 5 hours. The fluorescent dye diffuses through the cross-linked polyethyleneimine matrix of the microspheres. Since the dye is a polymer (M.W. 4,000) and entangled in a polyethyleneimine chain, the diffusion occurs slowly and the dye is slowly released from the microspheres.

On the other hand, when the microspheres were treated with ultraviolet light, the emission rate increased sharply to 72% in 5 hours. The rapid and high emission percentage was thought to be due to disintegration of the microspheres due to UV irradiation. In fact, the microspheres disintegrated after irradiation with ultraviolet light (Figs. 3 and 4). Trans-to-cis photoisomerization of cinnamic acid occurred (Fig. 5), resulting in disassembly of the microspheres and rapid release. The release pattern of the dye will depend strongly on the disintegration pattern of the microspheres because the dye loaded is released immediately when the microsphere is disassembled. In practice, the percent release increased gradually with saturation curve (Fig. 8), which was similar to the pattern in which the disintegration of the microspheres progressively increased over the saturation curve (Fig. 3).

Figure 9 shows the release profile of FITC-dextran loaded on the microspheres at 30 캜, 40 캜 and 50 캜. When the temperature of the release medium was 30 ° C, the release occurred slowly and the release rate was about 17% for 5 hours. Release occurs slowly because the fluorescent dye diffuses through the microsphere matrix. The emission percentage also increased gradually at 40 캜. However, the% release at 40 캜 was higher than the% release at 30 캜 over the entire release experiment period. For example, the percent release at 28 ° C for 5 hours at 40 ° C was 28%, which was higher than the 17% release at 5 ° C for 5 hours.

According to Fick's law, the flux of the solute is proportional to the diffusion coefficient and concentration gradient. The concentration gradient was the same regardless of the emission temperature, since the microspheres used in the emission experiments carried out at different temperatures carried the same amount of fluorescent dye. Accordingly, the concentration gradient can be excluded from the cause of the difference in the release speed depending on the temperature.

On the other hand, the diffusion coefficient is proportional to the absolute temperature of the emission medium. The diffusion coefficient at 40 캜 was calculated to be about 1.03 times the diffusion coefficient at 30 캜. However, the% release at 40 占 (28% at 5 hours) was about 1.6 times the% release observed at 30 占 (17% at 5 hours). Thus, it can be seen that the thermal dependence of the diffusibility of the dye does not significantly affect the difference in the% emission by temperature.

However, the microspheres began to decompose in the temperature range of 30 to 40 ° C (FIG. 6). Thus, when the temperature of the release medium is 40 ° C, some microspheres will disintegrate and some other microspheres will remain intact. This disassembly of microspheres was considered to be the main cause of accelerated release at 40 ℃. Rapid release occurred during the first hour when the temperature of the release medium was 50 캜, slow release occurred during the rest of the release experiment, and the release rate for 5 hours was about 65%.

According to the temperature-dependent transmittance of the microsphere suspension (Figure 6), a significant amount of microspheres will dissolve at 50 占 폚 because the light transmittance of the suspension at 50 占 폚 is as high as about 50% and its value is a measure of microsphere disassembly .

Therefore, the rapid release of the dye in the early stages is due to the dissolution of the microspheres by heat, and the slow release in the latter is due to the continued diffusion of the dye from undissolved microspheres. The polyethyleneimine / cinnamic acid microspheres released most of the loading (ie, FITC-dextran) at 50 ° C, which is above the physiological temperature range.

If nanoparticles (e.g., gold nanoparticles) representing surface plasmon resonance (SPR) are contained in the polyethyleneimine / cinnamic acid microspheres, the medium can be heated to 50 DEG C or higher by near-infrared irradiation Therefore, polyethylene imine / Shinan acid microspheres may release the contents in response to near-infrared irradiation.

In conclusion, the ultraviolet and temperature-responsive self-assembled microspheres proposed in the present invention exhibit the property of being disassembled upon irradiation with ultraviolet rays and temperature rise, .

Claims (7)

The polyethyleneimine and cinnamic acid are dissolved in a molar ratio of 3: 7 so that polyethyleneimine and cinnamic acid are crosslinked through a salt bridge bond. And the average diameter is 4.97 ± 2.63 μm,
The present invention relates to a self-assembled microsphere having a characteristic of exhibiting UV-responsive release and temperature-responsive release characteristics and capable of selectively releasing the contained substance to the outside according to ultraviolet irradiation or temperature change. (self-assembled microsphere).
delete delete delete The polyethyleneimine solution and the cinnamic acid solution were mixed in a dark place so that the molar ratio of the amino group of polyethyleneimine to the carboxyl group of cinnamic acid was 3: 7, and a salt bridge of polyethyleneimine and cinnamic acid , And inducing hydrophobic interaction between cinnamic acids to self-aggregate, thereby producing microspheres with an average diameter of 4.97 +/- 2.63 mu m. A method for manufacturing a temperature-responsive self-assembled microsphere.
delete 6. The method of claim 5,
When polyethyleneimine and cinnamic acid are dissolved in an aqueous solution, the total concentration of polyethyleneimine and cinnamic acid,
Wherein the solution is 0.01 to 30% (w / v) in an aqueous solution.

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