Sol-Gel synthesis, spectroscopic and thermal behavior study of SiO2/PEG composites containing different amount of chlorogenic acid

In this work, new phenol-based materials have been synthesized by the sol-gel method, in which different amounts of the phenolic antioxidant chlorogenic acid (CGA) (from 5 wt % to 20 wt %) were embedded in two different silica matrices: pure silica and silica-based hybrids materials, containing 50 wt % of polyethylene glycol (PEG). The incorporation of CGA in different sol-gel matrices might protect them from degradation, which could cause the loss of their properties. The two series of materials were chemically characterized by Fourier transform infrared (FTIR) spectroscopy. In addition, the thermal behavior of both series of materials containing CGA was studied by thermogravimetry under both air and inert N2flowing gas atmosphere. The bioactivity was evaluated by soaking the synthesized hybrids in a simulated body fluid, showing that the bioactivity of the silica matrix is not modified by the presence of PEG and CGA

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

Surface Modifications for Implants Lifetime extension: An Overview of Sol-Gel Coatings

The limited lifetime of implants entails having patients undergo replacement surgeries, several times throughout life in young patients, with significant risks for them and extensive cost for healthcare service. The overcoming of such inconvenience is still today a hard challenge for the scholars of the biomedical and biomaterial fields. The improvement of the currently employed implants through surface modification by coatings application is the main strategy proposed to avoid implants failure, and the sol-gel coating is an ideal technology to achieve this goal. Therefore, the present review aims to provide an overview of the most important problems leading to implant failure, the sol-gel coating technology, and its use as a strategy to overcome such issues

Zirconia/Hydroxyapatite Composites Synthesized Via Sol-Gel: Influence of Hydroxyapatite Content and Heating on Their Biological Properties

Zirconia (ZrO2) and zirconia-based glasses and ceramics are materials proposed for use in the dental and orthopedic fields. In this work, ZrO2 glass was modified by adding different amounts of bioactive and biocompatible hydroxyapatite (HAp). ZrO2/HAp composites were synthesized via the sol-gel method and heated to different temperatures to induce modifications of their chemical structure, as ascertained by Fourier transform infrared spectroscopy (FTIR) analysis. The aim was to investigate the effect of both HAp content and heating on the biological performances of ZrO2. The materials’ bioactivity was studied by soaking samples in a simulated body fluid (SBF). FTIR and scanning electron microscopy (SEM)) analyses carried out after exposure to SBF showed that all materials are bioactive, i.e., they are able to form a hydroxyapatite layer on their surface. Moreover, the samples were soaked in a solution containing bovine serum albumin (BSA). FTIR analysis proved that the synthesized materials are able to adsorb the blood protein, the first step of cell adhesion. WST-8 ([2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt]) assay showed that no cytotoxicity effects were induced by the materials’ extract. However, the results proved that bioactivity increases with both the HAp content and the temperature used for the thermal treatment, whereas biocompatibility increases with heating but is not affected by the HAp content

Bioactivity, biocompatibility, thermal behavior and antibacterial properties of calcium silicate composites containing Ag

In biomaterials field, surface modifications of bio-inert implants allow optimization of their surface properties while retaining favorable bulk properties. The objective of this work has been the preparation of dental implants with potential antibacterial properties. The sol gel method, coupled with dip coating techniques, was used to synthesize the materials with different silver amount and to coat titanium implants with them. The chemical characterization of the materials was carried out by Fourier Transform InfraRed (FTIR) spectroscopy and simultaneous thermogravimetry/differential thermal analysis (TG/DTA). The coating morphology was evaluated by Scanning electron microscopy (SEM). In order to investigate the bioactivity and biocompatibility of the materials as a function of Ag content, they were soaked in simulated body fluid (SBF) and WST-8 assay on NIH-3T3 cells was used. Furthermore, the antibacterial activity was evaluated. The results have shown that both the bioactivity and biocompatibility of coatings decrease slightly at high Ag contents and on the contrary antibacterial activity of the films increases against the Staphylococcus aureus

Synthesis, thermal behavior and physicochemical characterization of ZrO2/PEG inorganic/organic hybrid materials via solâ\u80\u93gel technique

Six zirconia–polyethylene glycol (ZrO2/PEG) inorganic/organic hybrid materials were synthesized by the sol–gel technique with different amount of polyethylene glycol (PEG) (corresponding to 6, 12, 24, 50, 60 and 70 mass%). Scanning electron microscopy and Fourier transform infrared spectroscopic (FT-IR) techniques were used in a recent study to characterize the materials with PEG content up to 50 mass%, while in the present one this characterization was extended to the more promising materials with higher PEG content (60 and 70 mass%). All the six materials confirmed their nanocomposite hybrid nature and the formation of hydrogen bonds between the inorganic zirconia matrix and the water-soluble organic component, which involve the Zr–OH groups and both the terminal OH groups and oxygen atoms in the ethereal units of the polymer chains. Moreover, the occurrence of interactions between PEG and acetylacetone, an inhibitor used during the sol–gel synthesis, was observed in the samples with high polymer content. The thermal behavior of all six hybrid materials was studied for the first time by thermogravimetry and differential thermal analysis from room temperature to 1023 K, aiming at identifying all physical and chemical processes occurring in these interesting materials, with particular reference to the decomposition of PEG to establish their thermal stabilities and the most suitable temperature condition for a further thermal treatment. The results revealed that PEG degradation occurs in the range temperature 473–873 K, and the degradation temperature decreases with increasing the PEG content. A probable explanation for PEG-rich materials is due to free PEG (not involved in the formation of H bonds) not affected by the stabilizing effect of the linkage with the inorganic matrix that causes a shift of degradation temperature toward lower values

A multi-technique approach to characterize bioactive silicate composites

In the present work the ternary SiO2·CaO·P2O5composite, which differ in the Ca/P molar ratio, were synthesized by means of a sol-gel route. In order to investigate the influence of the relative amount of each phase the thermal properties of the synthesized gel-glass materials were studied as a function of the Ca/P molar ratio using thermogravimetric and differential thermal analysis (TG/DTA). After dehydration (in a single step), described from a kinetic point of view as a simple water evaporation without rupture of chemical bonds, all gels undergo a complex multi-step decomposition with endo and exothermic effects, followed by crystallization of calcium silicate phases at about 950°C. Furthermore, Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscopy, coupled with energy dispersive spectroscopy (SEM/EDS), allowed us to detect the chemical modifications induced by modifying the Ca/P molar ratio and the sintering. This process is obtained by thermal treatment of the materials after analyzing their thermal behavior in the temperature range 600-1000°C, with the aim of making them suitable for their applications. The results revealed that when temperature is up to 900°C, crystallization occurs and pseudowollastonite and wollastonite were formed. Finally, the amount of pseudowollastonite decreased with increasing the sintering temperature, while that of wollastonite increased