The antiviral mechanism of photosensitizers relies on the generation of singlet oxygen. When a lipophilic dye is incorporated into the viral membrane, it localizes near unsaturated lipids. Upon light exposure, the photosensitizer produces singlet oxygen, which oxidizes the double bonds of fatty acid residues, thereby compromising the integrity of the viral envelope. Complete destruction of the virus is not required; even minor membrane damage can inhibit the fusion of the viral envelope with the host cell membrane. As a result, the virus is unable to transmit its genetic information and, consequently, cannot reproduce .