Fabrication and characterisation of melt-extruded chitosan/keratin/PCL/PEG drug-eluting sutures designed for wound healing

Diclofenac potassium loaded sutures based upon PEG/PCL/chitosan-keratin blends were fabricated using the hot-melt extrusion technique. Polymer sutures were evaluated based on their physical, thermal and mechanical properties, while the drug-eluting sutures were evaluated for drug release properties. Lastly, the performance of the drug-loaded sutures in the contact with the human keratinocyte cell line HaCat were assessed. Results showed that the sutures extruded homogeneously at a temperature of 63 ± 1 °C providing a uniform thickness of fibres. Analysis by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) showed that completely amorphous and miscible solid dispersions were created. Fourier transform infrared (FTIR) spectroscopy indicated that the presence of hydrogen bonds between the polymers improved material miscibility. Tensile properties of the sutures were clearly affected by the PEG, chitosan and keratin additions. The optimal formulation of tensile strength was obtained when PCL/PEG/chitosan-keratin were combined at a ratio of 80/19/1 w/w. Rapid and sustained drug release rates were achieved with the PEG/PCL/chitosan/keratin blends at various combinations. The composite of PCL/PEG/chitosan-keratin with 30 wt% of diclofenac potassium also exhibited high cell viability and wound healing rates in vitro cytotoxicity testing. The anti-inflammatory properties imparted by the PCL/PEG/chitosan/keratin/drug sutures may further the use of composite sutures for wound healing in clinical settings.