Preparation, Formation And Cytocompatibility Of PLA Fibrous Scaffolds For Tissue Engineering

In our work, PLA fibrous scaffolds such as solution electrospinning(S-ES) PLA fibrousscaffolds melt-electrospinning(M-ES) PLA fibrous scaffolds as well as solutionelectrospun(S-ES) yarns were fabricated based on electrospinning.Jet motion in the fiber formation process of was investigated. As a voltage exceeds thecritical voltage, stability of the jet may be viewed as competition between surface tension andsurface charge repulsion. While it is jet motion that gives rise to a sharp decrease in diameter,forming ultra-fine fibers. With this in mind, solvents with different composition andproportion were introduced to affect the charge repulsion in jet motion, especially in thewhipping section. Hence, S-ES PLA fibrous scaffolds and S-ES PLA yarns with differentfiber diameter distribution were successfully prepared. Fridrikh S V model and Rutledge G Cmodel were applied for further investigation on the regulating mechanism.Motion of polymer jet in the fiber formation process during melt-elctrospinning wasinvestigated based on pictures recorded by a high-speed CCD camera. When a voltage abovethe critical voltage applied, the sphere polymer melt at the nozzle tip will be stretched to acone shaped droplet, forming the Taylor cone and jet will then be accelerated downfield. Andthe competition between surface tension and surface charge repulsion results in a jetinstability to whipping, as well as the jet thinning in fiber formation. In addition, M-ES PLAfibrous scaffolds with well aligned fiber structure were prepared by melt-electrospinning.Surface deposition was adopted for surface functionalization of both S-ES and M-ESPLA fibrous scaffolds. Morphology observation shows that surface Ti/Cu deposition on S-ESPLA fibrous scaffold created an uneven and porous structure on the fiber surface. And themetal Ti/Cu show a deposition of certain regions on the fiber surface of M-ES PLA fibrousscaffold in the form of nano-scale particles with an island growth model. Results of contactangle measurement indicate that S-ES fibrous scaffolds are hydrophobic to some extent, whileM-ES fibrous scaffolds are hydrophilic. Both Ti/Cu sputtered S-ES PLA and M-ES fibrousscaffolds exhibit a significant increasing of hydrophilicity as a result of the surface deposition,espesically for the Ti sputtered M-ES PLA fibrous scaffolds. In less than1s, fiber surface ofthe M-ES PLA fibrous scaffolds was entirely wetted. Considering with morphologyobservation results, it can be concluded that the metal particles exhibit a nucleation-growthmodel on the electrospun PLA fiber surface.Investigations on the cytocompatibility of S-ES PLA fibrous scaffold, Ti/Cu sputteredM-ES PLA fibrous scaffolds as well as S-ES PLA fibrous scaffolds were conducted. MTTresults indicate that NIH3T3fibroblasts show an increasing viability over time in theextraction of Ti sputtered scaffolds, even with a higher OD value when cultured for72h.Results of cytotoxicity in vitro show that the Ti sputtered PLA fibrous scaffolds exhibit aslight toxic effects when cultured for24h. However, the toxicity disappear to0degrade. Andviability of cells in the extract of Cu sputtered scaffolds show a slight decrease over time.Evaluation of cytotoxicity in vitro indicates that Cu sputtered scaffolds show a slight toxiceffects on NIH3T3fibroblasts when cultured for as long as72h. Adhesion and proliferation results of S-ES PLA fibrous/yarn scaffolds with differentdiameter distribution indicate that:1) compared with PLA casting film, all fibrous scaffoldsshow a better support both for adhesion and proliferation of NIH3T3fibroblasts;2) NIH3T3fibroblasts proliferated on all fibrous scaffolds at different levels;3) twists of yarnsignificantly affect the proliferation of NIH3T3fibroblasts;4) it is difficult to give aconclusion on the effects of fiber diameter on cell growth due to the complex structure offibrous scaffold.