Authors: M.K. Khaing Oo, X. Yang, H. Wang, H. Du
Affilation: Stevens Institute of Technology, United States
Pages: 12 - 15
Keywords: photodynamic therapy, photosensitizer, nanoparticles, surface-enhanced Raman scattering
To improve 5- aminolevulinic acid’s (5-ALA) selective retention in tumor cells and efficient damage tumor cells in photodynamic therapy (PDT), biocompatible gold (Au) nanoparticles were proposed as the carrier to selectively deliver 5-ALA into tumor-like cells and meanwhile as the enhancer to promote the ROS formation in this study. 5-ALA was successfully immobilized onto Au nanoparticles (average diameter=30nm) with positive surface charge (+33 mV) at physiological pH (pH 7.2 to 7.6). The formed ALA-Au nanoparticles alone showed no cytotoxicity in cell culture experiments at dark. In addition, Au nanoparticles did not interfere with the intracellular conversion of 5-ALA into the photosentizer product protoporphyrin IX (PpIX). However, respective culture of ALA-Au with normal human dermal fibroblasts (NHDF) or tumor fibroblasts (WT) revealed a significant accumulation and higher production of PpIX in WT cells than in NHDF cells. In the PDT study using co-culture cell model, selective damage of WT cells by ALA-Au particles was confirmed using fluorescently labeled cells. The efficiency of killing WT cells was significantly increased (approximately 30-50% increase) in the ALA-Au treated group compared to ALA treated group by MTT assay. This enhancement most likely results from the plasmon resonance effect of Au nanoparticles.