Conjugates of fullerene C60 and protoporphyrin ix with chitosan to photoinactivate bacteria

N. GSPONER; D. A. HEREDIA; M. E. MILANESIO; E. N. DURANTINI

Simposio; XII Simposio Argentino de Polímeros; 2017

Chitosan (CS) has a wide range of applications in the fields of biomedicine and food industries, agriculture and environmental science. Moreover, CS exhibits a broad range of antibacterial and antifungal activity. The key considerations that justify this interest are that this natural linear polycationic biopolymer is biocompatible and biodegradable. Antibacterial activity of CS was assessed for a wide range of Gram-negative and Gram-positive bacteria. Previous investigations provide evidence that CS may disrupt the barrier properties of bacteria. In this sense, photodynamic inactivation (PDI) of microorganisms has been proposed as an alternative to controlling bacterial infections. In this work, two conjugated of chitosan were synthetized, one by the addition of amine groups to fullerene C60 and the other by forming amide bound with protoporphyrin IX (ProIX). C60-CS showed a sharp peak at 430 nm with a broader range of absorption up to almost 710 nm, while ProIX-CS was characterized by the typical Soret band at ~410 nm and the four Q-bands between 515-650 nm. In vitro PDI experiments were performed using Staphylococcus aureus. Photooxidation of 9,10-dimethylanthracene indicated that both conjugated produced singlet molecular oxygen in microbial cells. Cells treated with 5 MICROM conjugated and irradiated for 30 min with visible light produced a photoinactivation >99.99%. Photoinactivation capacities were also evaluated in S. aureus cells immobilized on agar surfaces. These conjugates were effective to eradicate bacteria growing on a surface. Therefore, these results indicate that C60-CS and ProIX-CS are promising antimicrobial photosensitizers against infectious disease.