Bioactivity of chlorogenic acid/SiO2/PEG composite synthesized via sol-gel

Sol-gel chemistry is an attractive approach in the design of new antioxidant biomaterials. Its versatility was exploited to obtain organic-inorganic hybrid materials in which a natural antioxidant compound, namely chlorogenic acid (CGA), was entrapped, in different percentage, in matrices variously constituted in silica and PEG400. The synthetized hybrids were chemically characterized by means of FTIR and UV–Vis spectroscopy and UHPLC-HRMS techniques. The hydroxyapatite nucleation on the surfaces of all samples was detected by FT-IR analysis and confirmed by XRD analysis. The scavenging capacity towards DPPH and ABTS+ radicals appeared strongly dependent on the CGA/PEG ratio, suggesting that CGA structural features, commonly recognized to be responsible for its antioxidant capacity, may be masked or evidenced by chemical interactions in the established network. Furthermore, in vitro cytotoxicity tests by MTT highlighted a certain selectivity against tumour cells. In fact, no cytotoxic effects were observed on NIH-3T3 fibroblast cell line up to the highest exposure dose; as a matter of fact, a marked cell viability increase was observed when hybrids with low PEG amount (6%) and high CGA (15%) were directly exposed to fibroblasts. On the contrary, viability and morphology of SH-SY5Y neuroblastoma cell line resulted markedly compromised. This evidence could be due to pro-oxidant effects exerted by the synthetized materials that let us to hypothesize a selective interference vs. tumour cells’ growth.