Electrospun nanofibers of a degradable poly(ester amide). Scaffolds loaded with antimicrobial agents

Electrospinning conditions were evaluated to prepare micro/nanofibers of a biodegradable poly(ester amide) constituted by L-alanine, 1,12-dodecanediol and sebacic acid. 1,1,1,3,3,3-Hexafluroroisopropanol appeared as the most appropriate solvent to obtain fibers in a wide range of electrospinning conditions that allowed tuning the final diameter size. Fiber diameter increased with the flow, distance between the needle tip and the collector and decreasing voltage, which made it possible to obtain homogeneous fibers in the 1700320 nm range. Fibers were loaded with antimicrobial agents like silver and chlorohexidine, and the influence of agent concentration in the electrospinning solutions on the fiber diameter size was determined. The polymer was able to crystallize during the electrospinning process, giving rise to a structure slightly different from that obtained by solution crystallization and related to that attained after crystallization from the melt state. Addition of antimicrobial agents had little effect on the degree of crystallinity, although it decreased slightly when chlorhexidine was employed. Scaffolds prepared from the silver and chlorhexidine loaded samples supported cell adhesion and proliferation. Furthermore, a clear and well differentiated antimicrobial effect against both Gram-positive (e. g. M. luteus) and Gram-negative (e. g. E. coli) bacteria was demonstrated.