Comprehensive study of antimicrobial polycaprolactone/clay nanocomposite films: Preparation, characterization, properties and degradation in simulated body fluid

Even though the biodegradability of polycaprolactone (PCL) and its nanocomposites is lower compared to other biodegradable polyesters, this property and good biocompatibility are used for development of materials for drug delivery with a long-term effect. We prepared novel PCL/clay nanocomposite films with antimicrobials chlorhexidine (CH) or octenidine (OCT) combined with ZnO anchored on vermiculite (VER). The intercalation of CH and OCT into the interlayer of VER/ZnOVER was confirmed by XRD, FTIR and SEM. The organically modified nanofillers compared to VER (−46.0 mV) or ZnOVER (−34.9 mV) showed a positive ζ-potential (+30.7 mV (VER_CH), +21.9 mV (VER_OCT), +24.6 mV (ZnOVER_CH)) indicating a relatively stable materials, except ZnOVER_OCT (+8.6 mV), which strongly agglomerated. Thin PCL/clay films were prepared by solvent casting method and the effect of used nanofillers on structural, thermal, mechanical and antimicrobial properties followed by degradation under hydrolytic conditions was studied. The results showed that presence of ZnO significantly decreases thermal and mechanical stability. The nanofillers with the higher hydrophilic character are responsible for the fastest degradation of PCL matrix. Films possessed high antimicrobial efficiency in long time intervals, hence these nanocomposites open new avenues for the possible application of such materials for the drug delivery with a long-term effect. Highlights: Antimicrobial active PCL/clay nanocomposites were prepared. Nanofillers influenced the structure and properties of prepared thin PCL films. ZnO caused lower thermal stability and worse mechanical properties of PCL films. PCL/clay nanocomposite films degraded slowly by a hydrolytic mechanism. High potential as medical materials with long-lasting antimicrobial efficacy.