Controllable Release Of Photo-crosslinked Collagen Drug-loaded Nanofibers

Collagen is widely distributed in animal bones,tendons,cartilage and skin as the main component of the extracellular matrix(ECM).So it own excellent biocompatibility and biodegradability and has been widely used as a carrier for drug delivery,wound dressings and tissue engineering.Drug-loaded collagen nanofibers have high specific surface area and porosity,resulting in higher drug loading efficiency,but it causes easily brust release due to high solubility in water.Therefore it's water resistance needs to be improved.In order to avoid the side effects of chemical cross-linking agents in the biomedical field,the drug burst release will be decreased respectively by means of UV-crosslinked collagen and co-spins ethyl cellulose.The vinylated collagen(CMA)with the carbon-carbon double bonds was synthetized by the reaction between collagen and methacrylic anhydride.The vinylated collagen(CMA)electrospinning nanofibers were prepared under UV-radiation to form collagen molecular cross-linking network.The morphology and chemical structures of UV-crosslinked vinylated collagen fibers(UV-CMA)were characterized by SEM and FTIR.The UV-crosslinking did not destroy the morphology of fibers and improved the water resistance and mechanical property.The UV-CMA have the lowest water absorption rate,reduced by 11.78%compared to pure collagen fibers and the tensile strength is twice as high as that of pure collagen fibers to 2MPa.The porous vinylated collagen(CMA)electrospinning nanofiber mats containing 5-Fluorouracil(5-FU)as model drug were prepared under UV-radiation for the assessment of drug delivery system.In vitro release studies have shown that drug-loaded CMA nanofibers effectively control drug release after UV-crosslinking.Only 60%of the total amount of the drug was released within 2h and sustained for 10h,while the pure collagen fibers were all released.The drug release mechanism is the Fickian diffusion mechanism.The drug-loaded collagen/ethyl cellulose(EC)nanofiber membrane was prepared by electrospinning.The morphology of the co-spun fiber was smooth and complete and there was no obvious phase separation by SEM and TEM.The average diameter of the fibers decreases with the increasing EC content.FTIR result showed that the collagen and ethyl cellulose molecules were connected by hydrogen bond and the two phase molecular structure did not have been broken.As the EC content increases,the water contact angle and the water resistance increase.When the EC content is 50%,the COL content of the surface layer of the blended fiber is 15.3%,the water contact angle is 133°,and the dissolution rate is only 2.9%after 24h of water immersion.When the EC content is 20%,the fiber profile can still be seen after immersion for 24h and the water contact angle is reduced to 106°.The drug is uniformly dispersed in the blended fiber and there are no obvious drug crystal particles on the surface and inside of the fiber.As the drug content increases,the average diameter of the blended fibers decreases.When EC accounts is 50%,the blended fiber released 80.16%of the total amount drug within 12h and the sustained release time was 80h,while the pure collagen fiber was completely released for 2h,which improved the utilization rate of the drug.At the same time,the drug release process with release time is controlled by controlling the EC content,which is very important for the treatment of diseases.