Chronic wound healing: A specific antibiofilm protein-asymmetric release system

Abstract

Chronic infection is a major cause of delayed wound-healing. It is recognized to be associated with infectious bacterial communities called biofilms. Currently used conventional antibiotics alone often reveal themselves ineffective, since they do not specifically target the wound biofilm. Here, we report a new conceptual tool aimed at overcoming this drawback: an antibiofilm drug delivery system targeting the bacterial biofilm as a whole, by inhibiting its formation and/or disrupting it once it is formed. The system consists of a micro/nanostructured poly(butylene-succinate-co-adipate) (PBSA)-based asymmetric membrane (AM) with controlled porosity. By the incorporation of hydrophilic porogen agents, polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG), we were able to obtain AMs with high levels of porosity, exhibiting interconnections between pores. The PBSA-PEG membrane presented a dense upper layer with pores small enough to block bacteria penetration. Upon using such porogen agents, under dry and wet conditions, membrane's integrity and mechanical properties were maintained. Using bovine serum albumin (BSA) as a model protein, we demonstrated that protein loading and release from PBSA membranes were affected by the membrane structure (porosity) and the presence of residual porogen. Furthermore, the release curve profile consisted of a fast initial slope followed by a second slow phase approaching a plateau within 24 h. This can be highly beneficial for the promotion of wound healing. Cross-sectional confocal laser scanning microscopy (CLSM) images revealed a heterogeneous distribution of fluorescein isothiocyanate (FITC) labeled BSA throughout the entire membrane. PBSA membranes were loaded with dispersin B (DB), a specific antibiofilm matrix enzyme. Studies using a Staphylococcus epidermidis model, indicate significant efficiency in both inhibiting or dispersing preformed biofilm (up to 80 % eradication). The asymmetric PBSA membrane prepared with the PVP porogen (PBSA-PVP) displayed highest antibiofilm activity. Moreover, in vitro cytotoxicity assays using HaCaT and reconstructed human epidermis (RHE) models revealed that unloaded and DB-loaded PBSA-PVP membranes had excellent biocompatibility suitable for wound dressing applications.

Keywords: Biocompatibility; Biofilm inhibition or dispersion; Biofilm-targeted therapies; Chronic wound dressings; Polymeric asymmetric membranes; Protein adsorption.