Degradation of electrospun nanofiber scaffold by short wave length ultraviolet radiation treatment and its potential applications in tissue engineering

Development in the field of tissue engineering has brought much attention in the fabrication and preparation of scaffold with biodegradable synthetic polymer nanofibers. Electrospun biodegradable polymeric nanofibers are increasingly being used to fabricate scaffolds for tissue engineering applications as they provide high surface area-to-volume ratio and possess high porosity. One common way to sterilize polymeric nanofiber scaffolds is 254-nm ultraviolet (UV) irradiation. In this study, we aim to evaluate the effects of UV radiation on the degradation in polymeric nanofibers, and then capitalize on UV-induced degradation and UV photolithography in polymeric nanofiber scaffolds for tissue engineering applications. Poly(D,L-lactic-co-glycolic) acid (PLGA, 75:25) and poly(L-lactide-co-epsilon-caprolactone) [P(LLA-CL), 70:30] nanofibrous meshes were produced by electrospinning. The nanofibers were irradiated by commercial germicide UV (lambda=254 nm) lamp for different intervals. We found that UV sterilization induced significant degradation of nanofiber. At 1 h UV irradiation, the average molecular weight of PLGA and P(LLA-CL) nanofibers were reduced by 46% and 35%, respectively, with corresponding reduction in the tensile strength of 26% for PLGA and 28% for P(LLA-CL). Hence, precautions may have to be taken into consideration when sterilizing polymeric nanofibers by UV treatment. UV-induced degradation on nanofibers was applied to fabrication of a three-dimensional (3D) tissue engineering scaffold by UV photolithography. Masked exposure to UV could generate patterned holes (d=100 microm) on the nanofibrous mesh. Cell culture study showed that smooth muscle cells were able to migrate into the holes. This method can be used to fabricate a 3D nanofibrous scaffold with micropores.