Latest Advances in Nanoplasmonics and Use of New Tools for Plasmonic Characterization

Effect of Surface Modification of Gold Nanoparticles Loaded with Small Nucleic Acid Sequences on Cytotoxicity and Uptake: A Comparative Study In Vitro

Nanoparticle technology, particularly gold nanoparticles (AuNPs), is being developed for a wide range of applications, including as a delivery system of peptides or nucleic acids (NA). Their use in precision medicine requires detailed engineering of NP functionalization to optimize their function and minimize off-target toxicity. Two main routes can be found in the literature for the attachment of NA strands to AuNPs: covalent binding via a thiol group or passive adsorption onto a specially adapted coating previously applied to the metallic core. In this latter case, the coating is often a positively charged polymer, as polyethylenimine, which due to its high positive charge can induce cytotoxicity. Here, we investigated an innovative strategy based on the initial coating of the particles using calix[4]arene macrocycles bearing polyethylene glycol chains as an interesting alternative to polyethylenimine for NA adsorption. Because any molecular modification of AuNPs may affect the cytotoxicity and cellular uptake, we compared the behavior of these AuNPs to that of particles obtained via a classical thiol covalent attachment in MCF-7 and GC-1 spg cell lines. We showed a high biocompatibility of both AuNPs-NA internalized in vitro. The difference in subcellular localization of both AuNPs-NA in MCF-7 cells compared to GC-1 spg cells suggests that their subcellular target is cell- and coating-dependent. This finding provides valuable insights for developing alternative NA delivery systems with a high degree of tunability.

The Influence of Pore Size on the Photocatalytic and SERS Performance of Nanoporous Au-Ag Shells

Nanoporous metals have garnered significant attention in catalysis due to their unique three-dimensional interconnected network structure and pronounced localized surface plasmon resonance (LSPR) properties. In this study, nanoporous Au-Ag shells with varying pore sizes (8, 10, 12, and 18 nm) were synthesized, and their catalytic efficiencies were systematically evaluated. The conversion of p-nitrothiophenol (PNTP) to dimercapto-azobenzene (DMAB) was used to investigate the influence of pore size on the reaction kinetics and surface-enhanced Raman scattering (SERS) effects. Experimental results reveal that the nanoporous Au-Ag shells with a 12 nm pore size exhibit relatively high catalytic efficiency. Furthermore, tuning the pore size enables the modulation of LSPR in the near-infrared region. These findings highlight the critical role of pore size modulation in determining the photocatalytic performance of nanoporous metallic materials and provide valuable insights for the design and optimization of highly efficient photocatalysts.