Laser direct writing biocompatible photoresist composition based on polycaprolactone and photoetching method thereof

Abstract

The invention discloses a laser direct writing biocompatible photoresist composition based on polycaprolactone, which is prepared from the following components in parts by weight: 5 to 10 parts of polycaprolactone, 5 to 20 parts of biocompatible monomer, 0.5 to 2 parts of photoinitiator and 80 to 100 parts of solvent. The photoetching method comprises the following steps: adding raw materials in proportion, spin-coating the obtained photoresist composition on quartz or a silicon wafer to obtain a photoresist film, then baking to remove a residual solvent to obtain a photoresist dry film, and carrying out exposure inscribing and developing on the dry film through a laser direct writing system to obtain a photoetching pattern. The polycaprolactone has good biocompatibility and degradability and can be applied to biological printing, and the printing resolution of the photoresist is improved by adjusting the thickness of the photoresist film according to the formula.

Description

Technical Field

[0001] The invention relates to the technical field of laser micro-nano processing and manufacturing, and in particular to a laser direct-writing biocompatible photoresist composition based on polycaprolactone and a photolithography method thereof. Background Art

[0002] Femtosecond laser direct writing technology is a cutting-edge micro-nano processing technology. It uses the ultrafast pulses and ultra-strong instantaneous energy of femtosecond lasers for direct writing and processing, and can achieve processing accuracy of sub-hundred nanometers. Compared with traditional electron beam processing and continuous laser processing, femtosecond pulse laser processing has the advantages of no need for a vacuum environment, non-contact, flexible processing, a wide range of processing materials, and cold processing. It can achieve three-dimensional, deep nanoscale resolution and maskless processing of arbitrary structural designs. Due to its unique advantages, femtosecond laser direct writing technology has been widely used in many fields such as optical devices, microfluidic chips, fiber optic functional devices, and biomedicine. In the biomedical field, this technology is used to make probes, microbial sensor devices, stents and other devices for drug delivery, disease diagnosis and treatment.

[0003] Polycaprolactone is a non-toxic polymeric organic polyester polymer material with no obvious toxic side effects on human cells and tissues. Due to its good biocompatibility and degradability, polycaprolactone is widely used in the preparation of various medical devices and implants, such as artificial joints, absorbable sutures and cartilage repair materials. Polycaprolactone can also be used to prepare drug carriers. By controlling its degradation rate, it can achieve sustained release of drugs and improve the therapeutic effect of drugs. Polycaprolactone is also widely used in the preparation of three-dimensional scaffolds, vascular substitutes and tissue engineering organs. These scaffold materials can provide appropriate physical and structural support, promote cell adhesion and growth, and provide a good matrix for tissue repair and regeneration.

[0004] The current bioprinting resolution is generally tens of microns. Biofabrication 2015; 7(4): 045009 reported a composite bioprinting hydrogel of polyethylene glycol diacrylate (PEGDA) and gelatin methacrylate (GelMA), but the printing resolution was 50 microns. ACS Biomater Sci Eng 2016; 2(10): 1752-62 reported a bioprinting hydrogel based on silk fibroin, which achieved a resolution of 66 microns in the X direction and 146 microns in the Z direction. With the high-precision processing advantage of sub-hundred-nanometer femtosecond laser direct writing, a higher resolution can be obtained.

[0005] Therefore, in view of the shortcomings of the prior art, the present invention designs a laser direct-writing biocompatible photoresist composition based on polycaprolactone and a photolithography method thereof. Summary of the invention

[0006] The purpose of the present invention is to provide a laser direct-writing biocompatible photoresist composition based on polycaprolactone and a photolithography method thereof. Polycaprolactone has good biocompatibility and degradability, can be applied to bioprinting, and the thickness of the photoresist film can be adjusted by formula to improve its printing resolution.

[0007] A laser direct-writing biocompatible photoresist composition based on polycaprolactone comprises, by weight, 5-10 parts of polycaprolactone, 5-20 parts of biocompatible monomers, 0.5-2 parts of photoinitiators and 80-100 parts of solvents.

[0008] Polycaprolactone has good biocompatibility and degradability, and has basically no toxic side effects on organisms. At the same time, the monomers and initiators used in the formula are also biocompatible. The final photoresist composition is almost non-toxic and can be used in bioprinting.

[0009] The biocompatible monomer is a cross-linking agent in the formula. During the writing process, a large amount of biocompatible monomer wraps the polycaprolactone, cross-links and polymerizes to form a macromolecular compound, which is insoluble in the developer. After development, the engraved pattern is obtained.

[0010] The thickness of the photoresist film is adjusted by the solid content of the photoresist. The higher the solid content, ie, the polycaprolactone and the biocompatible monomer, the thicker the film.

[0011] Furthermore, the polycaprolactone is a terminal hydroxyl group, terminal carboxyl group or ester terminated polymer, and the number average molecular weight of the polycaprolactone is 10,000-80,000.

[0012] Furthermore, the biocompatible monomer is any one of hydroxyethyl methacrylate, hydroxybutyl acrylate, bisphenol A dimethacrylate glycidyl ester, polyethylene glycol di(meth)acrylate, and dipentaerythritol hexaacrylate, or a mixture of two or more thereof.

[0013] Furthermore, the photoinitiator is camphorquinone or eosin Y.

[0014] Furthermore, the solvent is ethanol.

[0015] A photolithography method using a laser direct-writing biocompatible photoresist composition based on polycaprolactone comprises the following steps:

[0016] S1: Weigh polycaprolactone in proportion and dissolve it in a solvent, and mix them thoroughly to obtain a solution;

[0017] S2: adding a biocompatible monomer and a photoinitiator to the solution obtained in step S1, stirring in the dark, to obtain a laser direct writing biocompatible photoresist composition based on polycaprolactone;

[0018] S3: spin coating the photoresist composition obtained in step S2 on a quartz or silicon wafer to obtain a photoresist film, and then baking to remove the residual solvent to obtain a photoresist dry film;

[0019] S4: Expose and write the dry film through a laser direct writing system;

[0020] S5: immersing the exposed photoresist into a developer for development to obtain a photolithography pattern.

[0021] Preferably, the stirring time in step S2 is 24 hours.

[0022] Preferably, the baking temperature in step S3 is 60° C. and the baking time is 90 seconds.

[0023] Preferably, in step S5, the developing solution is ethanol, and the developing time is 5 minutes.

[0024] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0025] 1. The present invention uses polycaprolactone as a solid film-forming resin for femtosecond laser direct writing photoresist, and obtains a photoresist film by spin coating. It can use an air objective lens for large-area writing, and the film thickness can be adjusted by adjusting the solid content of the formula. It can print 2D fine structures on the thin film and print 3D structures in the thick film.

[0026] 2. Polycaprolactone has good biocompatibility and degradability, and has basically no toxic side effects on organisms. At the same time, the monomers and initiators used in the formula are also biocompatible. The final photoresist composition is almost non-toxic and can be used in bioprinting.

[0027] 3. The biocompatible monomer is a cross-linking agent in the formula. During the engraving process, a large amount of biocompatible monomer wraps the polycaprolactone, cross-linking and polymerizing to form a macromolecular compound, which is insoluble in the developer. After development, the engraved pattern is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below with reference to the accompanying drawings.

[0029] Figure 1 The 3D pattern is obtained by subjecting the photoresist composition obtained in Example 2 to femtosecond laser exposure and development.

[0030] Figure 2 This is a line SEM pattern obtained by subjecting the photoresist composition obtained in Example 4 to femtosecond laser exposure and development. DETAILED DESCRIPTION

[0031] Example 1

[0032] In a yellow light room, 5 g of hydroxy-terminated polycaprolactone with a number average molecular weight of 80,000 was dissolved in 100 g of ethanol, and then 18 g of hydroxyethyl methacrylate, 8 g of dipentaerythritol hexaacrylate and 0.5 g of photoinitiator camphorquinone were added, and stirred for 24 hours to obtain a laser direct-writing biocompatible photoresist composition based on polycaprolactone. The above-mentioned photoresist composition was spin-coated on quartz to obtain a photoresist wet film, and then baked at 60°C on a hot stage for 90 seconds to obtain a photoresist dry film. The baked dry film was exposed using a femtosecond laser direct writing device, and then the exposed photoresist was immersed in ethanol for 5 minutes to obtain a photolithographic pattern.

[0033] Example 2

[0034] In a yellow light room, 10 g of carboxyl-terminated polycaprolactone with a number average molecular weight of 30,000 was dissolved in 90 g of ethanol, and then 2 g of hydroxybutyl acrylate, 12 g of bisphenol A dimethacrylate glycidyl ester and 1 g of photoinitiator camphorquinone were added, and stirred for 24 hours to obtain a laser direct-writing biocompatible photoresist composition based on polycaprolactone. The above-mentioned photoresist composition was spin-coated on quartz to obtain a photoresist wet film, and then baked on a hot stage at 60°C for 90 seconds to obtain a photoresist dry film. The baked dry film was exposed using a femtosecond laser direct writing device, and then the exposed photoresist was immersed in ethanol for 5 minutes to obtain a photolithographic pattern.

[0035] The engraved pattern is a cell fence, see attached Figure 1 The linear width of the cell fence is approximately 1.5um.

[0036] Example 3

[0037] In a yellow light room, 7 g of ester-terminated polycaprolactone with a number average molecular weight of 20,000 was dissolved in 80 g of ethanol, and then 5 g of polyethylene glycol di(meth)acrylate and 1 g of photoinitiator eosin Y were added, and stirred for 24 hours to obtain a laser direct-writing biocompatible photoresist composition based on polycaprolactone. The above-mentioned photoresist composition was spin-coated on a silicon wafer to obtain a photoresist wet film, and then baked on a hot stage at 60°C for 90 seconds to obtain a photoresist dry film. The baked dry film was exposed using a femtosecond laser direct writing device, and then the exposed photoresist was immersed in ethanol for 5 minutes to obtain a photolithographic pattern.

[0038] Example 4

[0039] In a yellow light room, 5 g of carboxyl-terminated polycaprolactone with a number average molecular weight of 10,000 was dissolved in 80 g of ethanol, and then 2 g of bisphenol A dimethacrylate glycidyl ester, 3 g of dipentaerythritol hexaacrylate and 2 g of photoinitiator camphorquinone were added, and stirred for 24 hours to obtain a laser direct-writing biocompatible photoresist composition based on polycaprolactone. The above-mentioned photoresist composition was spin-coated on quartz to obtain a photoresist wet film, and then baked on a hot stage at 60°C for 90 seconds to obtain a photoresist dry film. The baked dry film was exposed using a femtosecond laser direct writing device, and then the exposed photoresist was immersed in ethanol for 5 minutes to obtain a photolithographic pattern.

[0040] The engraved lines reach the level of hundreds of nanometers, see attached Figure 2 The widths of the two enlarged lines are 120.5nm and 111.9nm respectively.

[0041] Example 5

[0042] In a yellow light room, 8 g of hydroxy-terminated polycaprolactone with a number average molecular weight of 25,000 was dissolved in 100 g of ethanol, and then 10 g of polyethylene glycol di(meth)acrylate and 1 g of photoinitiator camphorquinone were added, and stirred for 24 hours to obtain a laser direct-writing biocompatible photoresist composition based on polycaprolactone. The above-mentioned photoresist composition was spin-coated on quartz to obtain a photoresist wet film, and then baked on a hot stage at 60°C for 90 seconds to obtain a photoresist dry film. The baked dry film was exposed using a femtosecond laser direct writing device, and then the exposed photoresist was immersed in ethanol for 5 minutes to obtain a photolithographic pattern.

[0043] Comparing Example 2 with Example 4, the solid content of the raw material in Example 4 is less than that in Example 2, and the film thickness is adjusted, so the photolithography pattern obtained in Example 4 can be finer.

[0044] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent replacements or modifications made based on the present invention to solve basically the same technical problems and achieve basically the same technical effects are all included in the protection scope of the present invention.

Claims

1. A laser direct writing biocompatible photoresist composition based on polycaprolactone, characterized in that: The invention comprises, by weight, 5-10 parts of polycaprolactone, 5-20 parts of biocompatible monomer, 0.5-2 parts of photoinitiator and 80-100 parts of solvent.

2. A polycaprolactone-based laser direct writing biocompatible photoresist composition according to claim 1, characterized in that: The polycaprolactone is a terminal hydroxyl group, terminal carboxyl group or ester-terminated polymer, and the number average molecular weight of the polycaprolactone is 10,000-80,000.

3. A polycaprolactone-based laser direct writing biocompatible photoresist composition according to claim 1, characterized in that: The biocompatible monomer is any one of hydroxyethyl methacrylate, hydroxybutyl acrylate, bisphenol A dimethacrylate glycidyl ester, polyethylene glycol di(meth)acrylate, and dipentaerythritol hexaacrylate, or a mixture of two or more thereof.

4. The polycaprolactone-based laser direct writing biocompatible photoresist composition according to claim 1, characterized in that: The photoinitiator is camphorquinone or eosin Y.

5. The polycaprolactone-based laser direct writing biocompatible photoresist composition according to claim 1, characterized in that: The solvent is ethanol.

6. A photolithography method using the polycaprolactone-based laser direct writing biocompatible photoresist composition according to any one of claims 1 to 5, characterized in that: The steps include: S1: Weigh polycaprolactone in proportion and dissolve it in a solvent, and mix them thoroughly to obtain a solution; S2: adding a biocompatible monomer and a photoinitiator to the solution obtained in step S1, stirring in the dark, to obtain a laser direct writing biocompatible photoresist composition based on polycaprolactone; S3: spin coating the photoresist composition obtained in step S2 on a quartz or silicon wafer to obtain a photoresist film, and then baking to remove the residual solvent to obtain a photoresist dry film; S4: Expose and write the dry film through a laser direct writing system; S5: immersing the exposed photoresist into a developer for development to obtain a photolithography pattern.

7. A photolithography method of a polycaprolactone-based laser direct writing biocompatible photoresist composition according to claim 6, characterized in that: The stirring time in step S2 is 24h.

8. A photolithography method of a polycaprolactone-based laser direct writing biocompatible photoresist composition according to claim 6, characterized in that: The baking temperature in step S3 is 60° C. and the baking time is 90 seconds.

9. A photolithography method of a polycaprolactone-based laser direct writing biocompatible photoresist composition according to claim 6, characterized in that: In step S5, the developing solution is ethanol, and the developing time is 5 minutes.

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