Enhancing Functions Of Fibroblasts On Electrospun PHEMA Aligned Nanofibers

A substantial number of healthy tissues possess fiber structures which are organized in a parallel manner such as the skeletal muscular,nervous,and ligament fibroblast tissue.Thus,it stands to reason that parallel fibrous scaffolds can play a major role in controlling the morphology cells to be more natural and biologically-inspired.This paper chose 2-phenoxyethyl methacrylate(pHEMA)as basic material.pHEMA is a biodegradable polymer with biocompatibility,low toxicity,and hydrophilicity,which widely investigated in conventional form for numerous biological applications.First,in chapter 1,this paper reviewed the application and development of tissue engineering and electrospinning technology.Also,this paper discussed the preparation method of parallel electrospun nanofibrous scaffold and its application in tissue engineering.In chapter 2,this study explored the parameters of electrospinning,such as solution concentration,applied voltage and received distance,and analyzed their influence on the morphology and diameters.Results showed that with an increase of concentration of pHEMA,the percent of droplet decreased,while the percent of nanofiber increased.Also,with an increase of applied voltage,diameters of the biggest,smallest,and average decreased;whereas the uniformity of nanofibers fell when applied voltage was too high.Besides,with an increase of received distance,diameters of the biggest,smallest,and average increased,while the uniformity of nanofibers was best when received distance was 15 cm.Therefore,the optimal solution concentration of electrospinning was 12%,the applied voltage was 25 kV,and the received distance was 15 cm.Then,in this study,randomly oriented and aligned pHEMA nanofibrous scaffolds were fabricated by electrospinning technology.Results showed that randomly oriented and highly oriented nanofibrous scaffolds were generated when rotation speeds were at lower speeds of 300 rpm and higher speeds of 2000 rpm,respectively.Also,despite considerable research to develop pHEMA based materials for tissue engineering applications,the swelling of pHEMA in water remains a major concern.To address this issue,in chapter 3,we further post-treated electrospun scaffolds using a freeze-drying and thermal treatment method.Results demonstrated that the freeze-drying treatment method had a lower swelling property than the thermal treatment method at 24 h for reducing pHEMA swelling;advantages of the thermal treatment towards reducing pHEMA swelling increased afterward 24 h of treatment.Also,water contact angle,scaffold swelling,XRD and FTIR illustrated that it was possible to improve the swelling through the freeze-drying method or the thermal treatment method.In chapter 5,human dermal fibroblast cells(HDFs)adhered to freeze-drying treated nanofibrous substrates with a significant faster rate,whereas HDFs proliferated significantly with a higher cell growth rate on thermal treated pHEMA nanofibrous substrates.In summary,these results demonstrated that the structural properties of electrospun pHEMA nanofibrous scaffolds and cell behaviors were found to significantly depend on subsequent treatment processes.The presently developed freeze-drying method and thermal treatment method were promising for improving the properties of pHEMA scaffolds for numerous tissue engineering applications.Moreover,this paper suggested that aligned pHEMA nanofibrous scaffolds had a tendency to induce regular HDFs orientation and unidirectionally oriented actin cytoskeletons over randomly oriented pHEMA nanofibrous scaffolds.Finally,in chapter 5,this study realized industrial-scale production of parallel nanofibrous scaffolds by the blown bubble spinning.