Subcellular toxicity of gold nanoparticles irradiated with 532 nm pulsed laser.

Objective: Prior to plasmonic photothermal therapy, involving heating of gold nanoparticles (GNPs) by laser, we explored some subcellular events that may threaten the viability of rat kidney cells (RKCs) incubated with GNPs irradiated with pulsed laser.

Background Data: We have previously shown a decrease in the viability of RKCs, on incubation with GNPs irradiated with pulsed laser. This decrease in viability was concomitant to a reduction in GNP diameter size, and reflected the occurrence of subcellular toxic events.

Methods: After incubation of RKCs with GNPs irradiated with 532 nm pulsed laser (50 mJ/pulse energy, 5 ns duration, and 10 Hz repetition rate for 1, 3, and 5 min), we studied the cell membrane integrity, the induction of apoptosis, and the occurrence of oxidative stress. We reported the changes induced on RKCs by GNPs irradiated with pulsed laser and those induced on the same cells and after the same time intervals by unirradiated GNPs; both were related to a negative control.

Results: The decrease in viability of RKCs on incubation with GNPs irradiated with pulsed laser was shown to be mostly secondary to a cell membrane disruption, most probably related to the reduction in GNP diameter sizes. The oxidative stress exerted by smaller GNPs on RKCs, as well as the induction of apoptosis, seem to be tolerated by the RKCs.

Conclusions: Irradiation of GNPs with pulsed laser, to elicit a plasmonic photothermal effect, reduces the GNPs' diameter. The smaller-sized GNPs may lead to lethal cell membrane disruption in healthy RKCs.