Antimicrobial core-shell nanofiber wound dressing with chloramphenicol-liposomes

In the context of a rising incidence of chronic wounds worldwide, developing more efficient wound dressings is in demand. In this setting, nanofiber dressings have shown promising features. We combined three biopolymers: beta-glucan (βG), chitosan (CHI) and pectin into the same nanofibers. In addition, antimicrobial activity was provided adding chloramphenicol (CAM), which also was entrapped in liposomes for a more sustained drug release. Applying a coaxial electrospinning setup allowed fabricating core-shell nanofibers, with βG and CHI in the shell, and pectin with CAM liposomes in the core. Initially, challenges during electrospinning with gel-clogging of the needle tip emerged, due to the formation of a polyelectrolyte complex between the positively charged CHI and negatively charged pectin. This happened although pectin and CHI were separated in the coaxial electrospinning setup. Here, the critical intervention to solve this problem was reducing the pH of the pectin-containing core-solution. The successful electrospun core-shell nanofibers (Coax-LipCAM), with a mean diameter of around 200 nm, was confirmed by SEM and TEM images. Among the control nanofibers, a mono-axial control-nanofiber, Mono-core-CAM, was prepared. This control formulation contained the same polymers as present in the core of the Coax-LipCAM together with "free" CAM (not entrapped in liposomes). When Mono-core-CAM was compared with Coax-LipCAM, Coax-LipCAM exhibited enhanced tensile strength and higher stability in simulated wound fluid. Furthermore, CAM release from Coax-LipCAM was extended, with 80 % of the drug released after eight hours. Finally, all CAM-containing nanofibers showed antimicrobial activity comparable to pure CAM when tested against Escherichia coli and S. aureus. In conclusion, core-shell nanofibers with CAM-liposomes in a pectin-core and with a shell contained βG and CHI, were successfully prepared. Their promising morphological and mechanical characteristics, favorable stability and swelling properties, sustained CAM release, and preserved antimicrobial activity encourages further clinical evaluation targeting the treatment of chronic wounds.