Single-Cell Adenosine Triphosphate Content Monitoring during Hyperthermia Cell Death by Using Plasmonic Fluorescent Nanoflare.

Gold nanorods-based plasmonic photothermal therapy (AuNRs-PPTT) is a prospective anticancer approach in which AuNRs absorb near-infrared (NIR) light and convert it into heat, leading to cell death. Investigating the molecular energy metabolism of single cells, especially cancer cells, during the hyperthermia cell death process is therefore of great significance, as it can help us to better understand the photothermal lethal mechanism of cancer cells and design new photothermal probes more rationally. However, during the AuNRs-PPTT process, how the cells respond to heat stimulation and how their energy metabolism changes have rarely been studied. Herein, we selected adenosine triphosphate (ATP) as a target molecule, and by preparing a plasmonic and turn-on type fluorescent nanoprobe, we examined the ATP metabolism difference between cancerous cells and normal cells during the AuNRs-PPTT process. We found that the fluorescence intensity increased ∼60% after 5 min laser irradiation as compared to the initial intensity in single HeLa cells, but only ∼20% increase was observed for single H8 cells; obviously, the increase of ATP content in cancerous cells was notably higher than that in normal cells during the hyperthermia cell death.