The growing resistance developed by microbes towards antimicrobial agents has driven our focus on developing alternative treatment modalities such as Photodynamic antimicrobial chemotherapy (PACT). It would be difficult for the microbes to develop resistance towards singlet oxygen generated during the PACT process. Photosensitizers are the vehicles of the transfer and translation of light energy into a type II chemical reaction (singlet oxygen generation) in photodynamic antimicrobial chemotherapy. PACT is proposed as a potential, low cost approach to treatment of locally occurring infection.
Photodynamic inactivation (PDI) of Escherichia coli and Staphylococcus aureus has been studied in cultures treated with photoactivated copper pthalocyanine. Phototoxic Copper pthalocyanine, a structural analog of porphyrin, is tested for its antibacterial activity using visible light. In the presence of the visible light, the generally nontoxic copper pthalocyanine is photoactivated, causing cell death. The main limitation of this technique would be the uptake kinetics of photosensitizers in to the microorganism. Nanoencapsulated photosensitizer drug carrier system is believed to penetrate the polymicrobial species with in the biofilms. The generation of the singlet oxygen had been confirmed using the singlet oxygen sensor green studies