Optimized biocompatible gold nanotriangles with NIR absorption for photothermal applications

OTERO, C.M.; BOGGAN SIMAL, G.; SCOCOZZA, MAGALI F.; RUBERT, A.; GRILLO, C.; HANNIBAL, L.; LAVORATO, G.; HUERGO, M.A.; MURGIDA, D.H.; VERICAT, C.

ACS Applied Nano Materials

American Chemical Society

Lugar: Washington DC; Año: 2022 vol. 5 p. 341 - 350

Gold nanotriangles (Au NTs) present singular plasmonic properties that areparticularly attractive for photothermal applications. However, most syntheses rely on the use ofsurfactants which present cytotoxic effects, thus limiting the biomedical possibilities. Moreover,these methods have the disadvantage of producing Au NTs that either present absorption atwavelengths < 750 nm or have side lengths > 200 nm. In this work we present the post-synthesisoptimization and characterization of biocompatible Au NTs produced in a one-step reduction ofAu(III) with thiosulfate ions. We demonstrate that the position of the absorption peaks can be fixedat a desired wavelength by the addition of different SH-containing molecules. In all cases thestabilized Au NTs can be efficiently separated from spherical gold nanoparticles, a by-product ofmost Au NT syntheses, by a method based on depletion forces using sodium dodecyl sulphate(SDS), a low-cost, non-toxic surfactant. In addition, we analyse possible cytotoxic effects ofsurface sulfide species and residual presence of SDS. First, incubation of the Au NTs with theH2S-binding hemoglobin I (Hb I) from Lucina pectinata produced no deleterious effect on theprotein. Secondly, we evaluated cytocompatibility by in vitro cellular tests after incubation withthe purified Au NTs. Finally, laser irradiation at 808 nm of the Au NT dispersions yieldsphotothermal conversion efficiencies around 50%, which remained constant after several heatingcycles.