Multifunctional green AuNPs towards a potential application in nanomedicine for tissue repair: In depth-XRPD and HPLC-MS/MS characterization

The primary aim of this study is to explore the use of green-synthesized gold nanoparticles, produced by reducing HAuCl4 with a water-based polyphenolic extract derived from Grape Pomace, a winemaking by-product, for promoting tissue repair and modulating inflammation. A deepest study about their features has been performed by X-Ray Powder Diffraction analysis that provided a multiscale investigation into the nanocrystals' microstructure, revealing how the green synthesis conditions influence these features, strengthened by Transmission Electron Microscopy analyses' statements. Subsequently, a validated HPLC-MS/MS analysis identified the specific polyphenols that were retrieved on gold nanoparticles. Notably, polyphenols with glycosylation and higher molecular weight, such as hyperoside and phloridzin, were retrieved to a minor extent, whereas aglycones like catechin, gallic acid, and quercetin were predominantly found on the nanoparticles' surfaces. Based on these findings, a preliminary evaluation of the transdermal permeation potential of the gold nanoparticles was achieved in porcine skin, as a model, using Franz diffusion cells. The results indicated that the nanoparticles themselves were not retained within the skin, suggesting minimal accumulation. Moreover, if polyphenols tightly bound to the gold nanoparticles, such as catechin and gallic acid, were released moderately, exhibiting limited transdermal permeation, in contrast, compounds weakly linked as chlorogenic acid, showed a significant release and thus higher permeation rates through skin. Importantly, beyond their physicochemical and transdermal characteristics, the synthesized gold nanoparticles demonstrated promising biological activities. They were found to promote angiogenesis in endothelial progenitor cells, supporting vascular formation, while simultaneously exerting anti-inflammatory effects on murine macrophages. This unique combination of pro-angiogenic and anti-inflammatory properties suggests their potential for application in regenerative medicine and vascular therapies.