Antimicrobial and Photoantimicrobial Activities of Chitosan/CNPPV Nanocomposites.

Multidrug-resistant bacteria represent a global health and economic burden that urgently calls for new technologies to combat bacterial antimicrobial resistance. Here, we developed novel nanocomposites (NCPs) based on chitosan that display different degrees of acetylation (DAs), and conjugated polymer cyano-substituted poly(p-phenylene vinylene) (CNPPV) as an alternative approach to inactivate Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria. Chitosan's structure was confirmed through FT-Raman spectroscopy. Bactericidal and photobactericidal activities of NCPs were tested under dark and blue-light irradiation conditions, respectively. Hydrodynamic size and aqueous stability were determined by DLS, zeta potential (ZP) and time-domain NMR. TEM micrographs of NCPs were obtained, and their capacity of generating reactive oxygen species (ROS) under blue illumination was also characterized. Meaningful variations on ZP and relaxation time T2 confirmed successful physical attachment of chitosan/CNPPV. All NCPs exhibited a similar and shrunken spherical shape according to TEM. A lower DA is responsible for driving higher bactericidal performance alongside the synergistic effect from CNPPV, lower nanosized distribution profile and higher positive charged surface. ROS production was proportionally found in NCPs with and without CNPPV by decreasing the DA, leading to a remarkable photobactericidal effect under blue-light irradiation. Overall, our findings indicate that chitosan/CNPPV NCPs may constitute a valuable asset for the development of innovative strategies for inactivation and/or photoinactivation of bacteria.

Self-aggregates of 3,6-O,O'-dimyristoylchitosan derivative are effective in enhancing the solubility and intestinal permeability of camptothecin.

The aim of this work was to investigate the potential of a new 3,6-O,O'-dimyristoyl derivative amphiphilic chitosan (DMCh), in improving the solubility of camptothecin (CPT), a hydrophobic anticancer drug, and its potential oral delivery. FTIR, 1H NMR and solid-state 13C NMR spectroscopy were used to characterize DMCh and to determine its average degree of substitution (DS¯=6.8%). DMCh/CPT micelles size ranged from (281-357nm), zeta potential (+32-50mV) of encapsulation efficiency of 42-100%. The in vitro cell viability showed that DMCh/CPT micelles were able to reduce the toxicity of CPT. The in vitro permeability of CPT through Caco-2 and Caco-2/HT29-MTX intestinal models was increased up to ten fold when formulated into DMCh micelles, underlining the mucoadhesive properties of the nanocarrier. DMCh/CPT micelles are able to enhance CPT solubility and bioavailability while reduce its cytotoxicity, showing the great potential for intestinal delivery of hydrophobic drugs.