Amino acids are one kind of basic life unit in biological systems. Modification with amino acids may bring interesting properties to the principal molecules. In this work, BDP was modified with L-aspartic acid (Asp) and D-Asp to obtain BDP-LAsp and BDP-DAsp, respectively. The as-synthesized BDPs can self-assemble into uniform nanoparticles (NPs) due to the hydrophilicity of Asp. We found that BDP-LAsp NPs possessed higher photodynamic therapeutic efficacy than BDP-DAsp NPs in fighting against cancer cells and bacteria. This provides a simple design strategy for the modification of photosensitizers in the biomedical field.