Gene immobilization on alginate/polycaprolactone fibers through electrophoretic deposition to promote in situ transfection efficiency and biocompatibility

Alginate and polycaprolactone (PCL) were coelectrospun as composite nanofibers for in situ transfection, in which anionic alginate fibers were used to adsorb polyethyleneimine (PEI)/DNA polyplexes and biocompatible PCL fibers were applied to promote cell adhesion. To improve gene immobilization, direct-current electric field (DCEF) was applied to guide cationic polyplexes toward nanofibers on cathode. Fluorescent labeling experiments suggested that the applied DCEF not only accelerated but also increased the saturation levels of gene immobilization. Interestingly, these DCEF also increased the degradation of nanofibers. The water contact angle and Fourier-transform infrared spectrometry results indicated that the degraded component was mainly alginate. It suggested that the DCEF treatment may cause the electrophoresis of calcium ions to destabilize alginates fibers, and thus the degradation rates increased with the applied voltages. This alginate degradation increased the ratio of PCL in composite fibers, so the cell adhesion, viability, and proliferation were improved. Finally, these DCEF-treated fibers were used for substrate-mediated gene delivery. The transfection efficiency highly increased with DCEF when the voltages were lower than 1.5 V. This dynamic scaffold system not only provided a suitable microenvironment for cell ingrowth, but also improved gene immobilization and transfection, and thus promised its therapeutic effect for tissue regeneration.