In Vitro Raman Thermometry Using Gold Nanorod-Decorated Carbon Nanotubes

Anti-Stokes Raman thermometry, a rapidly evolving field in Raman spectroscopy, was investigated for in situ cellular temperature measurements─a critical aspect in photothermal cancer therapy. In this study, multiwalled carbon nanotubes decorated with gold nanorods (MWCNTs-GNRs) were employed as nanothermometer probes. Characterization involved the analysis of individual Raman spectra acquired at various powers and initial temperatures. The changes observed in the Raman spectra of MWCNTs-GNRs, particularly in response to variations in temperature and excitation power, provide the necessary information to develop a reliable Raman thermometry. This methodology facilitated the extraction of the intrinsic photothermal heating coefficient of MWCNTs-GNRs, offering essential insights into their thermometric properties. An evaluation was extended to incubating MWCNTs-GNRs with prostate cancer PC3 cell lines, where anti-Stokes and Stokes signals were measured at different laser powers to assess in situ cellular temperatures. Temperature maps for a selected area were generated for MWCNTs-GNRs and a single PC3 cell incubated with MWCNTs-GNRs with data standard error analysis performed to indicate a certain level of reliability in temperature measurement accuracy. Cell viability was determined through trypan blue assays, and the obtained temperatures were correlated with viability outcomes at different laser powers. Our investigation encompassed a temperature range spanning 60–100 °C, transcending the critical temperature threshold of 50 °C, which is associated with inducing cell demise. The study highlights the potential of MWCNTs-GNRs as nanothermometer probes for targeted photothermal therapies.