Designing photothermal anisotropic structures for enhanced light to heat conversion

The unique Localized Surface Plasmon Resonance (LSPR) of plasmonic nanoparticles is the foundation for highly efficient photothermal conversion, which is significantly influenced by their size and shape¹. Gold nanorods are particularly effective, as their anisotropic nature allows for structural tunability and enhanced light absorption in the therapeutic Near-Infrared (NIR) range. However, traditional solid nanorods provide only moderate heat generation. Solid nanorods are limited by relatively small surface area and moderate heat generation^2,3. This work addresses that limitation by developing hollow and porous gold nanorods. This study investigates the effect of varying concentrations of L-cysteamine and polyethylene glycol as a functionalization on gold nanorods to understand its impact on porosity and photothermal efficiency. Our study suggests that porous and hollow gold nanorods are superior to solid nanorods in terms of their photothermal performance, with increase in efficiency from 84% to 96%. Further we show that the surface modification with polymer, PEG for stability and dispersion can enhance this limit to achieve state-of-the art efficiency of 96%. This dual-tagging approach aimed to improve structural integrity, reduce aggregation, and optimize their photothermal properties, making these nanorods highly promising for applications in photothermal therapy, imaging, and other nanotechnology-based biomedical interventions.

References:

1. M. Kim, J.-H. Lee, J.-M. Nam, Plasmonic Photothermal Nanoparticles for Biomedical Applications. Adv. Sci. 2019, 6, 1900471. https://doi.org/10.1002/advs.201900471

2. Cui, X., Ruan, Q., Zhuo, X., Xia, X., Hu, J., Fu, R., Li, Y., Wang, J., & Xu, H. (2023). Photothermal Nanomaterials: A Powerful Light-to-Heat Converter. Chemical reviews, 123(11), 6891–6952. https://doi.org/10.1021/acs.chemrev.3c00159

3. Tanjaya, N. K., Kaur, M., Nagao, T., & Ishii, S. (2022). Photothermal heating and heat transfer analysis of anodic aluminum oxide with high optical absorptance. Nanophotonics (Berlin, Germany), 11(14), 3375–3381. https://doi.org/10.1515/nanoph-2022-0244