Encapsulation of photosensitizer in niosomes for promotion of antitumor and antimicrobial photodynamic therapy

Abstract

Photodynamic therapy (PDT) combines light with photosensitizers (PS) to produce reactive oxygen species (ROS) that can eliminate pathogenic microorganisms and tumor cells. Niosomes (NSs) are efficient nanocarriers and able to disperse insoluble drugs in water. Zinc phthalocyanine (ZnPc) is an excellent PS with water solubility problem that can be resolved by encapsulation in NSs. It is possible to apply PDT without inducing resistance to microorganisms or cells, since ROS interact in different cellular structures, such as proteins, lipid membranes and nucleic acids, avoiding the activation of resistance mechanisms. This work aims to develop NSs containing ZnPc to promote PDT against skin infections caused by pathogenic microorganisms and melanoma, the most severe type of skin cancer. Experimental planning was used to optimize the preparation of NSs with an average size of 233 ± 5.6 nm with PdI of 0.22 ± 0.07 nm and charge of −36.73 ± 0.65 mV, showing spherical and regular shape. Cationic NSs were also produced by surface modification of vesicles with chitosan and exhibited superior photobiological activity. NSs (anionic and cationic) containing ZnPc showed low dark cytotoxicity and intense photobiological activity after light irradiation. Antitumor and antimicrobial photobiological activities of NSs were tested on melanoma cells, methicillin-resistant Staphylococcus aureus (MRSA) and Candida albicans. The system showed excellent production of ROS in cell culture and apoptosis can be probably the main mechanism of cell death. The results show that NSs containing PS are versatile and can eliminate pathogenic microorganisms, such as bacteria and fungi of clinical interest and tumor cells.