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 SHSY5Y 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

Coating of Titanium Substrates with ZrO2 and ZrO2-SiO2 Composites by Sol-Gel Synthesis for Biomedical Applications: Structural Characterization, Mechanical and Corrosive Behavior

The use of metallic materials as implants presents some major drawbacks, such as their harmful effects on the living organism, especially those induced by corrosion. To overcome this problem, the implant surface of titanium implants can be improved using a coating of bioactive and biocompatible materials. The aim of this work is the synthesis of SiO2/ZrO2 composites with different percentages of zirconia matrix (20, 33 and 50 wt.%), by the sol-gel method to coat commercial Grade 4 titanium disks using a dip coater. Attenuated total reflectance Fourier transform infrared (ATR/FTIR) spectroscopy was used to evaluate the interactions between the inorganic matrices. Furthermore, the mechanical properties and corrosive behavior of the SiO2/ZrO2 coatings were evaluated as a function of the ZrO2 content. The bioactive properties of the substrate coated with different composites were evaluated using simulated body fluid (SBF). The antibacterial activity was tested against gram-negative and gram-positive Escherichia coli and Enterococcus faecalis, respectively, to assess the release of toxic products from the different composites and to evaluate the possibility of using them in the biomedical field