5-aminolevulinic Acid Conjugated Gold Nanoparticles for Cancer Treatment

In photodynamic therapy (PDT) for cancer treatment, effective delivery of photosensitizer to the target tumor and minimal damage to the healthy cell is of paramount importance. In this study novel biocompatible positively charged (ξ = +33 mV) gold nanoparticles (30 nm average diameter) are conjugated with a photosensitizing precursor, 5-aminolevulinic acid (ALA) at physiological pH (pH 7.2 to 7.6). As verified by fluorescence spectroscopy of protoporphyrin IX (PpIX), they are preferentially accumulated on the tumor cells. They are found to promote the formation of reactive oxygen species (ROS) and significantly increase the killing efficiency of WT cells. Furthermore, the gold nanoparticles exhibit surfaceenhanced Raman scattering (SERS) activity, making them a powerful imaging vehicle for the monitoring of cellular molecular events during cancer treatment using PDT.