<i>In Vitro</i> Raman Thermometry Using\nGold Nanorod-Decorated Carbon Nanotubes

Anti-Stokes\nRaman thermometry, a rapidly evolving field in Raman\nspectroscopy, was investigated for <i>in situ</i> cellular\ntemperature measurementsa critical aspect in photothermal\ncancer therapy. In this study, multiwalled carbon nanotubes decorated\nwith gold nanorods (MWCNTs-GNRs) were employed as nanothermometer\nprobes. Characterization involved the analysis of individual Raman\nspectra acquired at various powers and initial temperatures. The changes\nobserved in the Raman spectra of MWCNTs-GNRs, particularly in response\nto variations in temperature and excitation power, provide the necessary\ninformation to develop a reliable Raman thermometry. This methodology\nfacilitated the extraction of the intrinsic photothermal heating coefficient\nof MWCNTs-GNRs, offering essential insights into their thermometric\nproperties. An evaluation was extended to incubating MWCNTs-GNRs with\nprostate cancer PC3 cell lines, where anti-Stokes and Stokes signals\nwere measured at different laser powers to assess <i>in situ</i> cellular temperatures. Temperature maps for a selected area were\ngenerated for MWCNTs-GNRs and a single PC3 cell incubated with MWCNTs-GNRs\nwith data standard error analysis performed to indicate a certain\nlevel of reliability in temperature measurement accuracy. Cell viability\nwas determined through trypan blue assays, and the obtained temperatures\nwere correlated with viability outcomes at different laser powers.\nOur investigation encompassed a temperature range spanning 60–100\n°C, transcending the critical temperature threshold of 50 °C,\nwhich is associated with inducing cell demise. The study highlights\nthe potential of MWCNTs-GNRs as nanothermometer probes for targeted\nphotothermal therapies.