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] This invention relates to the field of laser micro-nano fabrication technology, and more particularly to a laser direct-write biocompatible photoresist composition based on polycaprolactone and its photolithography method. Background Technology

[0002] Femtosecond laser direct writing technology is a cutting-edge micro- and nanofabrication technique that utilizes the ultrafast pulses and ultra-intense instantaneous energy of femtosecond lasers for direct writing and processing, achieving sub-nanometer processing precision. Compared to traditional electron beam processing and continuous laser processing, femtosecond pulsed laser processing offers advantages such as no need for a vacuum environment, non-contact processing, processing flexibility, a wide range of processed materials, and cold processing. It enables maskless fabrication with three-dimensional, deep nanoscale resolution and arbitrary structural designs. Due to its unique advantages, femtosecond laser direct writing technology has found widespread application in various fields, including optical devices, microfluidic chips, fiber optic functional devices, and biomedicine. In the biomedical field, this technology is used to fabricate probes, microbial sensors, scaffolds, and other devices for drug delivery, disease diagnosis, and treatment.

[0003] Polycaprolactone (PCL) is a non-toxic polymeric organic polyester material with no significant toxic side effects on human cells and tissues. Due to its excellent biocompatibility and degradability, PCL is widely used in the preparation of various medical devices and implants, such as artificial joints, absorbable sutures, and cartilage repair materials. PCL can also be used to prepare drug carriers; by controlling its degradation rate, sustained drug release can be achieved, improving therapeutic efficacy. PCL is also widely used in the preparation of three-dimensional scaffolds, vascular substitutes, and tissue-engineered organs. These scaffold materials provide appropriate physical and structural support, promote cell adhesion and growth, and provide a good matrix for tissue repair and regeneration.

[0004] Current bioprinting resolution is generally in the tens of micrometers. Biofabrication 2015;7(4):045009 reported a composite bioprinting hydrogel of polyethylene glycol diacrylate (PEGDA) and gelatin methacrylate (GelMA), but the printing resolution was only 50 micrometers. ACS Biomater Sci Eng 2016;2(10):1752-62 reported a silk fibroin-based bioprinting hydrogel, achieving a resolution of 66 micrometers in the X direction and 146 micrometers in the Z direction. With the high-precision processing advantage of sub-100 nanometers achieved by femtosecond laser direct writing, even higher resolution can be obtained.

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

[0006] The purpose of this invention is to provide a laser-written biocompatible photoresist composition based on polycaprolactone and its photolithography method. Polycaprolactone has good biocompatibility and degradability and can be applied to bioprinting. The printing resolution can be improved by adjusting the photoresist film thickness through formulation.

[0007] A laser-written biocompatible photoresist composition based on polycaprolactone, comprising, 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.

[0008] Polycaprolactone has good biocompatibility and degradability, and is basically non-toxic to organisms. At the same time, the monomers and initiators used in the formulation are also biocompatible, and the final photoresist composition is almost non-toxic and can be used for bioprinting.

[0009] Biocompatible monomers act as cross-linking agents in the formulation. During the writing process, a large number of biocompatible monomers encapsulate polycaprolactone, cross-linking and polymerizing to form macromolecular compounds that are insoluble in the developer. After development, the written pattern is formed.

[0010] The thickness of the photoresist film can be adjusted by the solid content of the photoresist. The higher the solid content, i.e., the more polycaprolactone and biocompatible monomers, the greater the film thickness.

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

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

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

[0014] Furthermore, the solvent is ethanol.

[0015] A photolithography method using a polycaprolactone-based laser-written biocompatible photoresist composition includes the following steps: S1: Weigh out polycaprolactone according to the proportion, dissolve it in the solvent, and mix thoroughly to obtain a solution; S2: Add biocompatible monomers and photoinitiators to the solution obtained in step S1, stir in the dark, and obtain a laser direct-write biocompatible photoresist composition based on polycaprolactone. S3: Spin-coat the photoresist composition obtained in step S2 onto a quartz or silicon wafer to obtain a photoresist film, and then bake to remove the residual solvent to obtain a dry photoresist film. S4: Expose and write the dry film using a laser direct writing system; S5: Immerse the exposed photoresist into the developing solution for development to obtain the photolithographic pattern.

[0016] Preferably, the stirring time in step S2 is 24 hours.

[0017] Preferably, the baking temperature in step S3 is 60°C and the baking time is 90 seconds.

[0018] Preferably, the developing solution in step S5 is ethanol, and the developing time is 5 minutes.

[0019] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows: 1. This invention uses polycaprolactone as a solid film-forming resin for femtosecond laser direct writing photoresist. Photoresist films are obtained by spin coating, which can be used for large-area writing with an air objective lens. At the same time, the film thickness can be adjusted by adjusting the solid content of the formula. It can print 2D fine structures on thin films and 3D structures in thick films.

[0020] 2. Polycaprolactone has good biocompatibility and degradability, and is basically non-toxic to organisms. At the same time, the monomers and initiators used in the formulation are also biocompatible, and the final photoresist composition is almost non-toxic and can be used for bioprinting.

[0021] 3. Biocompatible monomers act as cross-linking agents in the formulation. During the writing process, a large number of biocompatible monomers encapsulate polycaprolactone, cross-linking and polymerizing to form macromolecular compounds that are insoluble in the developer. After development, the written pattern is formed. Attached Figure Description

[0022] The invention will now be further described with reference to the accompanying drawings.

[0023] Figure 1 The 3D pattern is obtained by exposing and developing the photoresist composition obtained in Example 2 using a femtosecond laser.

[0024] Figure 2 The image shows a line SEM pattern obtained by exposing and developing the photoresist composition obtained in Example 4 using a femtosecond laser. Detailed Implementation

[0025] Example 1 In a photoluminescence chamber, 5g of polycaprolactone with a number-average molecular weight of 80,000 was dissolved in 100g of ethanol. Then, 18g of hydroxyethyl methacrylate, 8g of dipentaerythritol hexaacrylate, and 0.5g of the photoinitiator camphorquinone were added, and the mixture was stirred for 24 hours to obtain a polycaprolactone-based laser-written biocompatible photoresist composition. The above photoresist composition was spin-coated onto a quartz substrate to obtain a wet photoresist film, which was then baked at 60°C for 90 seconds to obtain a dry photoresist 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.

[0026] Example 2 In a photoluminescence chamber, 10g of polycaprolactone with a number-average molecular weight of 30,000 was dissolved in 90g of ethanol. Then, 2g of hydroxybutyl acrylate, 12g of bisphenol A dimethacrylate glycidyl ester, and 1g of photoinitiator camphorquinone were added, and the mixture was stirred for 24 hours to obtain a polycaprolactone-based laser-written biocompatible photoresist composition. The above photoresist composition was spin-coated onto a quartz substrate to obtain a wet photoresist film, which was then baked at 60°C for 90 seconds to obtain a dry photoresist 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.

[0027] The inscribed pattern is a cell fence, see attached. Figure 1 The straight-line width of the cell fence is approximately 1.5 μm.

[0028] Example 3 In a photoluminescence chamber, 7g of ester-terminated polycaprolactone with a number-average molecular weight of 20,000 was dissolved in 80g of ethanol. Then, 5g of polyethylene glycol di(meth)acrylate and 1g of photoinitiator eosin Y were added, and the mixture was stirred for 24 hours to obtain a polycaprolactone-based laser-written biocompatible photoresist composition. The above photoresist composition was spin-coated onto a silicon wafer to obtain a wet photoresist film, which was then baked at 60°C for 90 seconds to obtain a dry photoresist film. The baked dry film was exposed using a femtosecond laser direct writing device, and then the exposed photoresist was immersed in ethanol for development for 5 minutes to obtain a photolithographic pattern.

[0029] Example 4 In a photoluminescence chamber, 5g of carboxyl-terminated polycaprolactone with a number-average molecular weight of 10,000 was dissolved in 80g of ethanol. Then, 2g of bisphenol A dimethacrylate glycidyl ester, 3g of dipentaerythritol hexaacrylate, and 2g of the photoinitiator camphorquinone were added and stirred for 24 hours to obtain a polycaprolactone-based laser-written biocompatible photoresist composition. The above photoresist composition was spin-coated onto a quartz substrate to obtain a wet photoresist film, which was then baked at 60°C for 90 seconds to obtain a dry photoresist 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.

[0030] The inscribed lines are at the 100-nanometer level, see attached. Figure 2 The widths of the two magnified lines are 120.5nm and 111.9nm, respectively.

[0031] Example 5 In a photoluminescence chamber, 8g of hydroxyl-terminated polycaprolactone (PVP) with a number-average molecular weight of 25,000 was dissolved in 100g of ethanol. Then, 10g of polyethylene glycol di(meth)acrylate and 1g of the photoinitiator camphorquinone were added, and the mixture was stirred for 24 hours to obtain a PVP-based laser-written biocompatible photoresist composition. The above photoresist composition was spin-coated onto a quartz substrate to obtain a wet photoresist film, which was then baked at 60°C for 90 seconds to obtain a dry photoresist film. The baked dry film was exposed using a femtosecond laser direct writing device, and then the exposed photoresist was immersed in ethanol for development for 5 minutes to obtain the photolithographic pattern.

[0032] Comparing Example 2 with Example 4, the solid content of the raw material in Example 4 is less than that in Example 2. By adjusting the film thickness, the photolithography pattern obtained in Example 4 can be more refined.

[0033] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A polycaprolactone-based laser direct-write biocompatible photoresist composition, characterized by: 5-10 parts of polycaprolactone, 5-20 parts of biocompatible monomer, 0.5-2 parts of photoinitiator and 80-100 parts of solvent by weight.

2. The polycaprolactone-based laser direct writing biocompatible photoresist composition according to claim 1, characterized in that: The polycaprolactone is a hydroxyl-terminated, carboxyl-terminated or ester-terminated polymer, and the number average molecular weight of the polycaprolactone is 10000-80000.

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

4. The polycaprolactone-based laser direct writing biocompatible photoresist composition of claim 1, wherein: The photoinitiator is camphorquinone or eosin Y.

5. The polycaprolactone-based laser direct writing biocompatible photoresist composition of claim 1, wherein: 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 by, The method comprises the following steps: S1: polycaprolactone is weighed in proportion and dissolved in a solvent, and the solution is obtained by fully mixing; S2: biocompatible monomer and photoinitiator are added to the solution obtained in step S1, and the solution is stirred in the dark to obtain a polycaprolactone-based laser direct writing biocompatible photoresist composition; S3: the photoresist composition obtained in step S2 is spin-coated on a quartz or silicon wafer to obtain a photoresist film, and then residual solvent is removed by baking to obtain a dry photoresist film; S4: the dry film is exposed and written by a laser direct writing system; S5: the exposed photoresist is immersed in a developing solution for development to obtain a photoetching pattern.

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

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

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

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