Inventory of the application of biodegradable polymer electrospinning materials in the biomedical field

Among biological materials, synthetic polymer materials have an absolute advantage in the biomedical field due to their good physical properties, certain biocompatibility, easy processing and moldability, and good production repeatability. Among them, biodegradable materials attract attention. Currently, biodegradable polymers have an absolute advantage in the field of biomedicine. They are prepared into nanofibers through electrospinning, which can be used in tissue engineering scaffold materials, new drug release carriers, and nanotemplate materials.

1. Polyglycolic acid (PGA)

PGA, also known as polyglycolic acid, is a simple aliphatic polyester. It is hydrolyzed to form carbon dioxide and water under the promotion of enzymes or acids or alkalis in microorganisms or organisms. It also has good tissue compatibility. As a linear aliphatic polyester with a simple structure, PGA is one of the earliest commercialized types of absorbable polymers in the body. As early as 1970, PGA medical sutures were commercialized (trade name Dexon). Currently commercialized PGA fibers are obtained by melt extrusion. There are two difficulties in using electrospinning to prepare PGA nanofibers. First, PGA has a high melting point and is thermally degradable, making it difficult to use melt electrospinning. It is prepared by spinning method; secondly, PGA is insoluble in conventional organic solvents, and the range of spinning solvents for the solution is narrow, making it difficult to find a suitable solvent. At present, there have been studies to solve these two problems by using special solvents, such as hexafluoroisopropanol, and other methods.

PGA sewing thread

2. Polylactic acid (PLA)

Polylactic acid is a polyhydroxy acid that can be obtained from corn, sugar beet, etc. through fermentation and distillation. It has good biodegradability, biocompatibility, absorbability, and high heat resistance. It is a biodegradable material widely researched and used. . There are 4 different forms of PLA, namely PLLA, PDLA, D,L-PLA (also known as PDLLA) and meso-PLA. Among them, PLLA and PDLA are commonly used as medical sutures due to their better mechanical strength. Amorphous polymers D and L-PLA are often used as drug controlled release carriers, while meso-PLA is rarely used.

PLLA repairs lost collagen

D,L-PLA is used as drug controlled release carrier

Due to the good biological properties of PLA, the application of PLA nanofibers in tissue engineering and controlled drug release has aroused widespread interest among researchers. Researchers have prepared bioabsorbable non-woven nanofiber membranes, tissue engineering scaffold materials, skin patches and skin protective films that facilitate the exchange of air and moisture between the skin and the atmosphere through classic spinning. There are still some problems in preparing polylactic acid nanofibers by electrospinning: the electrodynamics and its relationship with the polymer fluid are not yet clear and require in-depth study; the yield is very low; the mechanical strength of the obtained fiber is not enough; it needs to be further improved.

3. Polycaprolactone (PCL)

PCL has also been widely studied as a potential biodegradable material. It is one of the fully biodegradable polyesters obtained by the ring-opening polymerization of the cyclic monomer ε-caprolactone catalyzed by organometallic compounds. PCL degrades more slowly than PLA and can be degraded through hydrolysis mechanisms under physiological conditions. PCL has good solubility in most organic solvents, so its processing performance is very good. In recent years, a lot of related research has been conducted using electrospinning technology.

Nanospheres (a,b), nanofibers (c,d), foam materials (e,f), knitted fabrics (g-i) made of PCL, selective laser sintering Bracket (j-o), fused deposition simulation bracket (p-u)

4. Polysuccinate (PBS)

Polybutylene succinate (PBS) is synthesized by condensation polymerization of succinic acid and butylene glycol. It is easily decomposed and metabolized by various microorganisms in nature or enzymes in animals and plants, and is eventually decomposed into carbon dioxide and water. It is a typical Fully degradable polymer material with good biocompatibility and bioabsorbability. Representative products such as PBS-based polyester with the trade name BionolleTM produced by Japan’s Showa Company have a melting point of 110 to 120°C and good heat resistance.

Degradation properties of Bionolle^TM

5. Poly beta-hydroxybutyrate (PHB)

Polyhydroxyalkyl esters (PHA) are a series of natural polymers widely present in microbial cells. Due to their excellent biocompatibility and biodegradability, their application in the biomedical field has attracted more and more scholars’ attention. Pay attention to. However, the material degrades very slowly in the body and may take several years to be fully absorbed. Therefore, its copolymer PHBV with β-hydroxyvalerate is more widely used.

PHBV nanofiber

PHBV has high application value due to its low crystallinity, high softness and easy processing. Current research on PHB-based nanofibers produced by electrospinning mainly focuses on mixed spinning of PHB and additives, PHB copolymer PHBV spinning, and PHB and polymer co-spinning. PHB has broad application prospects as a biodegradable material, especially in biomedicine. The future development of PHB-based nanofibers should mainly focus on two aspects: (1) composite electrospinning of PHB and its biodegradable materials, such as PHB/PLA, etc.; (2) composite electrospinning of PHB and functional nanoparticles.

6. Polyurethane (PU)

Polyurethane is usually a type of polymer material containing urethane groups produced by the addition reaction of polyol and isocyanate, followed by chain extender. From the perspective of molecular structure, polyurethane is a polymer composed of flexible soft segments and rigid hard segments alternately copolymerized. Through the molecular design of polyurethane soft segments and hard segments, various polyurethane materials with different mechanical strengths and degradation properties can be obtained. Segmented polyurethane elastomer has unique mechanical properties and excellent biocompatibility. It has been used as a biomaterial for decades and is mainly used in tissue engineering scaffold materials, blood vessel substitutes, skin wound dressings, etc. Degradable polyurethane has become an important tissue engineering material due to its good biocompatibility and degradability. In addition, polyurethane has the advantages of strong designability of molecular structure, easy processing and molding, and excellent mechanical properties.

Biodegradable vascular stent

Conclusion

As a simple and efficient new processing technology for producing polymer nanofibers, electrospinning is an important scientific topic for preparing degradable polymer fiber materials with low modulus, high flexibility and high strength. After successful research, this type of material can be used to make highly flexible monofilament surgical sutures and tissue engineering scaffolds, which will greatly promote the development and progress of medicine and biology. Therefore, it is necessary to strengthen research in the following research directions in the future: using the principle of electrospinning, by improving the device and controlling parameters, to obtain continuous, uniform size, controllable defects, and regular arrangement of polymer nanofibers; in understanding the electrospinning process and electrospinning polymers Based on the properties of nanofibers, polymer nanofibers with controllable degradation speed, good mechanical properties and biocompatibility have been developed to realize the practical use of nanofibers; the strength can be maintained for a long time in the body and can be used in wounds. Suture materials that can be absorbed within a short period of time after healing are also an important research direction.