Chlorogenic Acid Entrapped in Hybrid Materials with High PEG Content: A Strategy to Obtain Antioxidant Functionalized Biomaterials?

Abstract

The formation of pro-oxidant species after implantation of biomaterials could be responsible for the failure of the implant itself, because of oxidative stress-induced damage. In this work, the SiO2/polyethylene glycol (PEG)/chlorogenic acid (CGA) hybrids synthesized by the sol–gel method with 50 wt% of the polymer and different amounts of CGA (5, 10, 15 and 20 wt%) were studied. The hybrids soaked in simulated body fluid (SBF) showed the formation of hydroxyapatite layers on their surface, suggesting that the hybrids are bioactive. Their radical scavenging capacity towards DPPH· and ABTS·+ (2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid), evaluated at three different doses (0.5, 1 and 2 mg), showed probe- and dose-dependent behavior. In addition, the antioxidant properties of CGA were not affected by the presence of high amounts of the polymer. The in vitro biocompatibility in three cell lines (NIH 3T3, HaCaT and SH-SY5Y) was assessed by using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Apart from SH-SY5Y, the cell viability—expressed as mitochondrial redox activity percentage of cells directly exposed to powders—and morphology was not affected, suggesting that the hybrids have the ability to interfere and act selectively against tumor cells. The antibacterial properties of the different materials against Escherichia coli and Enterococcus faecalis were affected by different amounts of the natural antioxidant component.

New SiO2/Caffeic Acid Hybrid Materials: Synthesis, Spectroscopic Characterization, and Bioactivity

“…On the contrary, other papers underlined that the susceptibility was mainly strain-specific [38,42]. It should be noted that, in analogy with previous hypotheses regarding 5-O-caffeoylquinic acid [15], the bacterial cell membrane impairment could also be the result of a decrease in reactive oxygen species (ROS) levels in the bacteria induced by caffeic acid, which leads to cellular malfunction and finally to death. This deduction is in line with the antioxidant behavior of the considered phenol.…”

“…In particular, sol-gel chemistry shows a number of advantages, including the ability to produce a solid-state material from a chemically homogeneous precursor [13]. The sol-gel route is a consolidated technique in our laboratories, and it was effectively applied with the aim of obtaining new biocompatible and bioactive organic-inorganic hybrid materials, in which different natural compounds were embedded in a silica matrix, with or without the addition of polymers (e.g., polyethylene glycol, poly(ε-caprolactone)) [14][15][16][17][18][19].…”

“…In the present work, caffeic acid represented the organic constituent of hybrid materials, whereas the silica matrix was the inorganic constituent. Four materials were synthesized, which differed in terms of the amount of caffeic acid incorporated (5,10,15, and 20 wt.%). Their chemical characterization was achieved through Fourier-transform infrared (FT-IR) and Ultraviolet-visible (UV-Vis) spectroscopy.…”

New SiO₂/Caffeic Acid Hybrid Materials: Synthesis, Spectroscopic Characterization and Bioactivity

“…On the contrary, other papers underlined that the susceptibility was mainly strain-specific [37,41]. It should be noted that, in analogy with previous hypotheses regarding 5-O-caffeoylquinic acid [15], the the bacterial cell membrane impairment could be also the result of a decrease of ROS levels in the bacteria induced by caffeic acid, which led to cellular malfunction and finally to death. This deduction is in line with the antioxidant behaviour of the considered phenol.…”

“…The sol-gel route represented a consolidated technique in our laboratories, effectively applied with the aim to obtain new biocompatible and bioactive organic-inorganic hybrid materials, in which different natural compounds were embedded in a silica matrix, with or without the addition of polymers (e.g. polyethylene glycol, poly(ε-caprolactone)) [14][15][16][17][18][19].…”