Hybrid Organic–Inorganic Materials Prepared by Sol–Gel and Sol–Gel-Coating Method for Biomedical Use: Study and Synthetic Review of Synthesis and Properties

The need to improve the expectancy and quality of life of subjects affected by disabling pathologies that require the replacement or regeneration of tissues or parts of the body has fueled the development of innovative, better-performing materials that are capable of integrating into and being tolerated by body tissues. Materials with these characteristics, i.e., bio-functionality, bio-safety, and biocompatibility, are defined as biomaterials. One of the many methods for producing such materials is the sol-gel technique. This process is mainly used for the preparation of ceramic oxides at low temperatures, through hydrolysis and polycondensation reactions of organometallic compounds within a hydroalcoholic solution. This study is based on a specific type of biomaterial: organic-inorganic hybrids. The aim of this study is to provide an overview of the advantages and disadvantages of the sol-gel technique, as well as describe the preparation and chemical and biological characterization, uses, and future prospects of these biomaterials. In particular, the use of plant drugs as organic components of the hybrid material is the innovation of this manuscript. The biological properties of plant extracts are numerous, and for this reason, they deserve great attention from the scientific community

Synthesis of WEEE-based geopolymers and their cytotoxicity

Alkali activated metakaolin-based geopolymer materials were used to blend in fine powder glasses from waste electric and electronic equipment. In particular, glasses from funnel and panel parts of cathode ray tubes were recovered and re-utilized, thus obtaining GPVFNL and GPVBa enriched geopolymers. The materials were characterized by means of Fourier Transform InfraRed spectroscopy (FT-IR), and in order to avoid health risk for humans, cytotoxicity was preliminarily assessed by means of MTT test towards NIH-3T3 murine fibroblast cell line. The synthetized geopolymers showed an important anti-bacterial activity vs. Escherichia col

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

The sol-gel route represents a valuable technique to obtain functional materials, in which organic and inorganic members are closely connected. Herein, four hybrid materials, containing caffeic acid entrapped in a silica matrix at 5, 10, 15, and 20 wt.%, were synthesized and characterized through Fourier-Transform Infrared (FT-IR) and Ultraviolet-Visible (UV-Vis) spectroscopy. FT-IR analysis was also performed to evaluate the ability to induce the hydroxyapatite nucleation. Despite some structural changes occurring on the phenol molecular skeleton, hybrid materials showed scavenging properties vs. 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and 2,2 '-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid) radical cation (ABTS center dot(+)), which was dependent on the tested dose and on the caffeic acid wt.%. The SiO2/caffeic acid materials are proposed as valuable antibacterial agents against Escherichia coli and Enterococcus faecalis

A comprehensive in vitro characterization of non-crosslinked, diverse tissue-derived collagen-based membranes intended for assisting bone regeneration

Collagen-based membranes are class III-medical devices widely used in dental surgical procedures to favour bone regeneration. Here, we aimed to provide biophysical and biochemical data on this type of devices to support their optimal use and design/manufacturing. To the purpose, four commercial, non-crosslinked collagen-based-membranes, obtained from various sources (equine tendon, pericardium or cortical bone tissues, and porcine skin), were characterized in vitro. The main chemical, biophysical and biochemical properties, that have significant clinical implications, were evaluated. Membranes showed similar chemical features. They greatly differed in morphology as well as in porosity and density and showed a diverse ranking in relation to these latter two parameters. Samples highly hydrated in physiological medium (swelling-ratio values in the 2.5–6.0 range) and, for some membranes, an anisotropic expansion during hydration was, for the first time, highlighted. Rheological analyses revealed great differences in deformability (150-1500kPa G’) also alerting about the marked variation in membrane mechanical behaviour upon hydration. Samples proved diverse sensitivity to collagenase, with the cortical-derived membrane showing the highest stability. Biological studies, using human-bone-derived cells, supported sample ability to allow cell proliferation and to prompt bone regeneration, while no relevant differences among membranes were recorded. Prediction of relative performance based on the findings was discussed. Overall, results represent a first wide panel of chemical/biophysical/biochemical data on collagen-based-membranes that 1) enhances our knowledge of these products, 2) aids their optimal use by providing clinicians with scientific basis for selecting products based on the specific clinical situation and 3) represents a valuable reference for optimizing their manufacturing

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

Tensile Mechanical Behavior and Bioactivity of PLA/PCL Biopolyester Threads for Suture

In this paper the mechanical tensile static test of threads both in o-knot of blends made by two biopolyesters, polylactic acid (PLA) and poly(-caprolactone) (PCL), compatibilized with a triisocyanate (T) in a low amount (1 phr, per hundred resin), and high amount, 5 phr, is performed. The highest mechanical strength of the PLA/PCL/T threads is of about 30 MPa. PLA, PCL, and T are mixed in a twin extruder and the resulting blend is spinnable by a melt spinning process in order to produce thin threads of about 0.3 mm diameter. Compatibilizing filler improves the mechanical performance of the PLA/PCL blend for the chemical branching and/or cross-linking reactions induced among the two typically immiscible biopolyesters. Chemical reactions link PLA with PCL, whose macromolecular structure complexity grows with the filler load. Blended biopolymers can be considered promising biomaterials because they seem to be bioactive and able to inhibit bacterial growth