Bioactive Chitosan Nanoparticles and Photodynamic Therapy Inhibit Collagen Degradation in vitro

This study evaluated the ability of photodynamic therapy (PDT), chitosan nanoparticles (CSnp), or their combination, to inhibit bacterial collagenase-mediated degradation of collagen. Rat type 1 fibrillar collagen matrices were untreated or treated with 2.5% glutaraldehyde (GD), 2.5% GD followed by 1% CSnp, 1% CSnp, PDT, or 1% CSnp followed by PDT. Samples, except untreated controls, were exposed to Clostridium histolyticum collagenase. The soluble digestion products were assessed by hydroxyproline assay and the remaining adherent collagen was quantified by picrosirius red (PSR) staining. Collagen treated with CSnp, PDT, or a combination of CSnp and PDT, exhibited less degradation than controls. The abundance of posttreatment residual collagen correlated with the extent of degradation. Fourier transform infrared (FTIR) spectroscopy analysis showed that PDT treatment enhanced collagen cross-linking. Immunoblotting of sedimented CSnp indicated that CSnp and collagenase bound with low affinity. However, CSnp-bound collagenase showed a significant reduction in collagenolytic activity compared with controls.MAS