The development of antibiotic resistance is a natural phenomenon that occurs when bacteria cells exchange resistant traits amongst each other or when mutations occur during replication. This causes bacteria to be able to withstand attack by antibiotic drugs so that standard treatments which have been successful for decades become ineffective in treating common infections. To combat antibiotic resistance an alternate treatment method, photodynamic inactivation (PDI) of bacteria, is currently being explored, and have been shown to be successful with less potential for development of resistance. PDI utilizes light, oxygen, and a photosensitizer to effectively kill bacteria. However, PDI has been shown to be less effective towards killing Gram-negative bacteria because Gram-negative bacteria cells have two cell membranes which makes them impermeable by the photosensitizer compounds. The PS have been changed with positively-charged groups to improve the electrostatic interaction with the negatively-charged outer membrane of the bacteria. In the present project, a series of PS which have positively-charged groups, trimethylammonium, were synthesized and characterized. Dark and light cytotoxicity studies were investigated to examine the charge effect of the cationic PS in the photodynamic inactivation against E. coli, a model for Gram-negative bacteria. Additionally, the mechanism of interaction between the cationic porphyrin and E. coli cells was shown using confocal fluorescence microscopy.