The effect of surface charge of plasmonic gold nanoparticles on photoacoustic signal

Abstract

We investigated the effects of surface charge of gold nanoparticles (Au NPs) on photoacoustic (PA) signal from cultured cancer cell. We used citrated-coated Au NPs and poly-L-lysine-coated Au NPs as the model of negatively and positively charged Au NPs, respectively. Transmission electron microscopy (TEM) were performed for cellular uptake and intracellular localization. We demonstrated PA signal measurement using ring-shaped piezopolymer (P(VDFTrFE)) film sensor coaxially arranged with an optical fiber. The PA signal intensity of the cationic Au NPs was higher than that of the anionic Au NPs over an incubation period up to 3 hours. We found that the PA signal intensities were highly dependent on the surface charge of the Au NPs because the uptake of Au NPs by cultured cancer cells was dependent on the surface charge. We also found that the aggregation of the Au NPs highly influenced the PA signal intensity. These findings are invaluable to the design and synthesis of Au NPs as PA imaging contrast agents with maximized diagnostic efficacy.