Plasmonic enhancement of photothermal conversion in hydrogels using gold nanorods

Abstract

This study investigates the size- and shape-dependent photothermal properties of CTAB-capped gold nanorods (Au NRs) and citrate-capped gold nanospheres (Au NSs) incorporated into hydrogel matrices. Au NRs were synthesized using a modified seed-mediated growth method, resulting in varied sizes and aspect ratios (ARs). Nanoparticles were characterized to ensure uniform optical concentration, enabling a direct comparison between Au NRs and Au NS/hydrogels. By equalizing the optical concentration, we ensured that the hydrogels had the same extinction at 785 nm and 808 nm. Under laser irradiation at these wavelengths, the photothermal conversion efficiency (PCE) of Au NR/hydrogels was found to be comparable to that of Au NS/hydrogels, indicating that differences in the size, shape, and aspect ratio do not significantly impact the overall PCE. Thermal stability tests confirmed the robustness of the plasmonic properties of Au NRs within the hydrogel matrix after heating, further supporting their potential for sustainable and efficient photothermal applications. This work offers insights into the design and optimization of nanomaterial-based systems for photothermal energy conversion, paving the way for advanced applications in biomedical and energy fields.