NIR-Active Gold Dogbone Nanorattles Impregnated in Cationic Dextrin Nanoparticles for Cancer Nanotheranostics

Theranostic systems, which integrate therapy and diagnosis into a single platform, have gained significant attention as a promising approach for noninvasive cancer treatment. The field of image-guided therapy has revolutionized real-time tumor detection, and within this domain, plasmonic nanostructures have garnered significant attention. These structures possess unique localized surface plasmon resonance (LSPR), allowing for enhanced absorption in the near-infrared (NIR) range. By leveraging the heat generated from plasmonic nanoparticles upon NIR irradiation, target cancer cells can be effectively eradicated. This study introduces a plasmonic gold dogbone-nanorattle (AuDB NRT) structure that exhibits broad absorption in the NIR region and demonstrates a photothermal conversion efficiency of 35.29%. When exposed to an NIR laser, the AuDB NRTs generate heat, achieving a maximum temperature rise of 38 °C at a concentration of 200 μg/mL and a laser power density of 3 W/cm². Additionally, the AuDB NRTs possess intrinsic electromagnetic hotspots that amplify the signal of a Raman reporter molecule, making them an excellent probe for surface-enhanced Raman scattering-based bioimaging of cancer cells. To improve the biocompatibility of the nanorattles, the AuDB NRTs were conjugated with mPEG-thiol and successfully encapsulated into cationic dextrin nanoparticles (CD NPs). Biocompatibility tests were performed on HEK 293 A and MCF-7 cell lines, revealing high cell viability when exposed to AuDB NRT-CD NPs. Remarkably, even at a low laser power density of 1 W/cm², the application of the NIR laser resulted in a remarkable 80% cell death in cells treated with a nanocomposite concentration of 100 μg/mL. Further investigation elucidated that the cell death induced by photothermal heat followed an apoptotic mechanism. Overall, our findings highlight the significant potential of the prepared nanocomposite for cancer theranostics, combining effective photothermal therapy along with the ability to image cancer cells.