Silica/quercetin sol–gel hybrids as antioxidant dental implant materials

Abstract

The development of biomaterials with intrinsic antioxidant properties could represent a valuable strategy for preventing the onset of peri-implant diseases. In this context, quercetin, a naturally occurring flavonoid, has been entrapped at different weight percentages in a silica-based inorganic material by a sol–gel route. The establishment of hydrogen bond interactions between the flavonol and the solid matrix was ascertained by Fourier transform infrared spectroscopy. This technique also evidenced changes in the stretching frequencies of the quercetin dienonic moiety, suggesting that the formation of a secondary product occurs. Scanning electron microscopy was applied to detect the morphology of the synthesized materials. Their bioactivity was shown by the formation of a hydroxyapatite layer on sample surface soaked in a fluid that simulates the composition of human blood plasma. When the potential release of flavonol was determined by liquid chromatography coupled with ultraviolet and electrospray ionization tandem mass spectrometry techniques, the eluates displayed a retention time that was 0.5 min less than quercetin. Collision-activated dissociation mass spectrometry and untraviolet-visible spectroscopy were in accordance with the release of a quercetin derivative. The antiradical properties of the investigated systems were evaluated by DPPH and ABTS methods, whereas the 2,7-dichlorofluorescein diacetate assay highlighted their ability to inhibit the H2O2-induced intracellular production of reactive oxygen species in NIH-3T3 mouse fibroblast cells. Data obtained, along with data gathered from the MTT cytotoxicity test, revealed that the materials that entrapped the highest amount of quercetin showed notable antioxidant effectiveness.

Entrapping quercetin in silica/polyethylene glycol hybrid materials: Chemical characterization and biocompatibility

“…Comparing these vibrational features to those exhibited by silica/quercetin hybrids, high PEG percentages seemed to prevent the marked quercetin oxidation recorded for silica/quercetin hybrids. FT-IR spectra of these latter materials showed a band at 1720 cm − 1 , which was hypothesized to be formed by oxidative γ-pyrone ring opening and recyclization; an aurone-like derivative occurred [12].…”

“…4). The acquired spectra were compared to those obtained elsewhere [12,14,23] for quercetin, PEG, silica/quercetin and silica/PEG based materials. Pure quercetin and PEG vibration bands were assigned by comparing the absorption frequencies with values reported in the literature [24,25].…”

“…Recently, entrapping quercetin in a silica matrix, a new biocompatible and bioactive material was synthetized [12] by the sol-gel technique. That material proved able to provide antioxidant functionality and without exacerbating the body's normal oxidant and inflammatory response.…”

“…To further investigate the potential use of flavonol in dental and orthopedic applications, silica-PEG based materials, differing in their PEG amount (6,12,24, and 50 wt%) and entrapping quercetin, were synthetized in the present work. Polyethylene glycol (PEG) is a wellknown degradable biopolymer which allowed highly biocompatible hybrid materials to be prepared [14,15] Moreover, PEG-functionalized silica nanoparticles (PSiNPs) demonstrated the capability to seal damaged cells and tissues providing neuroprotection subsequent to spinal cord trauma [16,17].…”

“…Polyethylene glycol (PEG) is a wellknown degradable biopolymer which allowed highly biocompatible hybrid materials to be prepared [14,15] Moreover, PEG-functionalized silica nanoparticles (PSiNPs) demonstrated the capability to seal damaged cells and tissues providing neuroprotection subsequent to spinal cord trauma [16,17]. The addition of the flavonol was set at the weight percentage of 5 and 10 wt% to allow a comparison with the data obtained in previous work [12,13]. The new materials were characterized by FT-IR and UV-Vis spectroscopy.…”