(198ab) Chitosan Electrospun Nanofibers Functionalized with Collagen By Carboxamide Bond Formation

Natural polymers are biomaterials of high biotechnological value. Their biodegradability, biocompatibility and high availability are some attributes that make them attractive materials for multiple innovative applications. They have been object of study for a wide range of novel biomedical applications due to their biocompatibility with living tissues. Among other polymers, chitosan and collagen are very attractive in the biomedical field.

Chitosan is an amino-polysaccharide derived from chitin, which is particularly important as a promoter of tissue regeneration; it has hemostatic and immunomodulatory properties and a wide antimicrobial and antifungal potential. Chitosan has been combined with polyethylene glycol, polyvinylpyrrolidone, gelatin, polyvinyl alcohol and especially collagen to produce hybrid materials. Whereas, collagen is one of the most important and abundant biopolymers with high biocompatibility and particular characteristics that distinguishes from synthetic polymers. Its abundance and structural properties confers to collagen a wide range of biomedical applications, especially in tissue engineering. Collagen directly affects the morphology and physiology of connective and epithelial tissue cells, and has great potential to be use as basis for scaffolds and biomaterials production; it is well know that it can interact with living tissue and provides adequate biomechanical and biochemical environments for living tissue.

Because of the above mentioned, chitosan and collagen have inspired the development of hybrid materials, and different procedures had been widely studied in order to obtain potentially useful materials focused on tissue engineering. Chitosan/collagen combination does not occur by itself in nature; nonetheless, this combination is very attractive and suitable to generate hybrid advanced biomaterials with unique mechanical and biomedical properties. The versatility of these polymers to be processed into different structural shapes has created high expectation for the development of novel functional materials, and electrospun nanofibers are of especial interest. There are several reports about the exploration of electrospining conditions and parameters to produced chitosan and collagen based nanofibers, however, the processability of chitosan through this technique, to obtain collections of nanofibers of good quality requires the use of additives or harmful solvents, such as trifuoroacetic acid (ATF), and the produced nanofibers are highly soluble. While in the case of collagen, besides its low spinnability, it has been reported that the electrospinning process can significantly affect the bioactivity of native collagen reducing its regenerative potential. To address these problems, this work presents the surface functionalization of chitosan electrospun nanofiber mats with collagen, as a better alternative to include collagen into a composite electrospun biomaterial preserving the bioactivity. Taking advantage of the amino groups of chitosan and the carboxylic acid groups of collagen as binding sites under precise conditions, post-electrospun coupling is feasible via carboxamide bond formation between both polymers promoted by EDC/HOBt. This strategy allows the achievable inclusion of collagen on chitosan nanostructures without affecting the bioactivity of both polymers.