Synthesis of urchin-like Au@TiO2 nano-carriers in the drug-loading system toward cancer treatment

Abstract Au@TiO2 core-satellite nanoparticles (Au@TiO2-CSN) hold great potential for targeted drug delivery and cancer treatment due to their large surface area, remarkable stability, and biocompatibility. However, the anisotropic morphology of the gold nanocore could be changed after the thermal preparation process to create the anatase and rutile TiO2 layers. In this study, based on the modified seed-mediated approach, we synthesized high aspect ratio urchin-like gold nanoparticles (ULGNPs) with a dense network of average 49 nm-sized branches. The unique ULGNPs synthesized without surfactants were then covered in amorphous TiO2 thin layers (ULGNPs@TiO2) to increase the stability and dispersibility. Doxorubicin (Dox) was selected as a drug model to evaluate the drug delivery activity of ULGNPs@TiO2 core-satellite nanoparticles. The five layers of Au (111) with three fixed bottom layers and two relaxed top layers, along with the six TiO2 (100) layers were performed through Grimme's DFT-D3 dispersion corrections. The DFT adsorption energy reveals that the amorphous TiO2 enhances the Dox loading activity of ULGNPs with Eads = -3.85 eV, negatively higher than isolated ULGNPs (Eads = -2.87 eV) and TiO2 (Eads = -3,61 eV), good agreement with 86.5% Dox loading and 72.3% Dox release capacity (pH = 5) on ULGNPs@TiO2 from the experiment. The biocompatibility, cell viability, and toxicity of ULGNPs@TiO2-Dox were pre-evaluated utilizing the healthy primary human mammary fibroblast and breast cancer MCF-7 cells under WST-1 assay. The results showed up to 98.7% MCF-7 cancer-cell viability for ULGNPs@TiO2 and over 92.8% MCF-7 cell toxicity of ULGNPs@TiO2-Dox. Besides, the amorphous TiO2 phase junction can absorb light in the ultraviolet (UV), combining with the absorption ability in the visible range of ULGNPs due to the LSPR effect.