Enhancing the antibacterial activity of PAMAM dendrimer modified with 1,8-naphthalimides and its copper complex via light illumination

This work describes the synthesis of a new photoactive PAMAM dendrimer of first generation, modified with 4-dimethylamino-1,8-naphthalimide units and its complexation with Cu2+ ions. The photophysical characteristics of the two compounds in organic solvents of different polarity have been determined. The impact of light on reactive oxygen species from the new compounds and on the cotton fabrics dyed with them has been investigated by an iodometric method, consisting of I- transformation into I-3(-), which absorbs light at 288 and 352 nm. It has been determined that their antibacterial activity towards Gram-negative and Gram-positive bacteria enhances upon light illumination, as a resultant synergic effect of the biological activity of the new dendrimers and of the reactive oxygen they generate. The copper complex has been found to be more active than the ligand. Upon their loading onto cotton fabrics both compounds retain their antibacterial activity.