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Silica and calcium silicate amorphous materials, mixed with sodium ampicillin, a broad-spectrum antibiotic, have been synthesized by sol-gel method. The amorphous nature of the gels was ascertained by X-ray diffraction analysis. The bioactivity of the synthesized materials has been put into evidence by the appearance of a crystal of hydroxyapatite on the surface of the samples soaked in a fluid simulating the composition of the human blood plasma, as detected through FTIR measurements and SEM micrographs. The present work refers to a series of in-vitro biocompatibility tests, which has been performed on silicate and CaO rich calcium silicate gel-glasses, to study the cell behavior when seeded on 1 cm(2) material fragments, introduced into an in-vitro culture system. 3T3 cell lines have been used and the viability has been evaluated by WST-8 test. The composition of the adopted glasses can be expressed by the following general formula: x CaO• (1 - x) SiO2 with x = 0.00; 0.30; 0.40; 0.50; 0.60. Subsequently, release kinetics in a simulate body fluid (SBF) has been investigated. The amount of sodium ampicillin released has been detected by UV-Vis spectroscopy. The release kinetics has appeared to occur in more than one stage. All data have shown that those materials could be used as drug delivery bioactive systems.

The need to improve the tolerability and life time of the metallic implants, lead our research group to develop implantable therapeutic systems able to release an anti-inflammatory agent in the implant site. Therefore, in the present work, a sol-gel dip coating route has been optimized to coat titanium implant with two organic-inorganic hybrid materials: the first consisted of a glass zirconia matrix in which indomethacin (IND) was embedded, the second of a zirconia glass, the polyester poly (e-caprolactone) (PCL) and the IND. PCL was added into the materials to modulate the release kinetic of the IND. Moreover, coatings consisting of a different numbers of layers, were applied to a substrates to modulate the dosage of the released drug. The obtained coatings were characterized and the drug release was investigated as a function of the PCL content and of the layers’ number.The need to improve the tolerability and life time of the metallic implants, lead our research group to develop implantable therapeutic systems able to release an anti-inflammatory agent in the implant site. Therefore, in the present work, a sol-gel dip coating route has been optimized to coat titanium implant with two organic-inorganic hybrid materials: the first consisted of a glass zirconia matrix in which indomethacin (IND) was embedded, the second of a zirconia glass, the polyester poly (e-caprolactone) (PCL) and the IND. PCL was added into the materials to modulate the release kinetic of the IND. Moreover, coatings consisting of a different numbers of layers, were applied to a substrates to modulate the dosage of the released drug. The obtained coatings were characterized and the drug release was investigated as a function of the PCL content and of the layers’ number.

Many studies reported that the use of gravity-free environments to improve some industrial processes. The sol-gel method is ideal technology to design of new organic-inorganic hybrid materials by entrapping various organic polymers in a glassy matrix for aerospace field. Two different hybrid materials were prepared. The SiO2and ZrO2were used as inorganic matrix, in which different percentages of polyethylene glycol (PEG) and poly(ϵ-caprolactone) (PCL) were incorporated, respectively. The chemical structure of the obtained materials was investigated by Fourier transform infrared (FTIR) spectroscopy, X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). Furthermore, in order to understand how the diamagnetic susceptibility is influenced by variation of both the inorganic matrix and organic component was used the Superconducting Quantum Interference Device (SQUID) magnetometry.

Natural Fibers Reinforced Composites (NFRC) are finding much interest as substitutes for glass- or carbon-reinforced composites thanks to their lightness, easy handling, processing and recyclability. However, their polarity makes them incompatible with hydrophobic thermoplastic matrices, leading to extended moisture adsorption which causes the debonding between fibers and matrix, affecting, thus, the mechanical properties of NFRCs. In the present work, NFRCs were manufactured using hemp fibers previously chemically treated with NaOH alkali solutions or (3-Glycidyloxypropyl) trimethoxysilane (GPTMS) solutions of various concentrations. To assess the effectiveness of the used chemical treatments in hindering the moisture adsorption and the entailed mechanical failure of the NFRCs, untreated and treated hemp fibers based composites were subjected to moisture adsorption test and then to tensile testing as a function of the chemical treatment, temperature and concentration of reagents. The results show that the treatments with 5 wt% of both NaOH and GPTMS are the most effective, reducing composites' water uptake from 7.74% to 6.46% and 5.58% respectively at room temperature, and from 9.67% to 8.19% and 8.13% respectively at 50 °C. Moreover, the comparison between the mechanical testing results carried out before and after the moisture adsorption test, shows that the water uptake induces mainly a stiffness decrease (about 50% when alkali treatments were used and about 60% using silane treatment), while not significantly affect the loading capability of the composites regardless of chemical treatment. However, the specimen obtained using 5 wt% GPTMS is more effective in the prevent the failure of the composite induced by water uptake.

An interesting research field with medical applications is represented today by ceramics, as they can be used to obtain useful biomaterials for the production of implants (Vallet-Regi, 2001, 2006a, 2006b, 2006c); many parts of the human body, in fact, can be replaced or repaired with biomaterials and more specifically with bioceramics (Black & Hastings, 1998). Regardless of the ceramic type and the application procedure, the introduction of an implant in a living body always causes inflammation phenomena and frequently infection processes as well. Those problems can be overcome by using local drug delivery methods to confine pharmaceuticals such as antibiotics, anti-inflammatory, anti-carcinogens, etc. (Arcos et. al., 2001; Ragel & Vallet-Regi, 2000; Vallet-Regi et al., 2000). The possibility of introducing certain drugs into the ceramic matrices employed for bone and teeth repair is undoubtedly an added value to be taken into account. The traditional use of high temperature procedures to model glasses and ceramics to the desired shape is very well known; on the other hand, the degradation temperature of a pharmaceutical compound is usually around 100°C, which is very low if compared with the high ones needed to compact the components (around 1000°C). Consequently, the main problem is how to include pharmaceuticals in conventional glass and ceramic implants. The scientific community is currently investigating new procedures to incorporate drugs into implantable biomaterials. The sol-gel process, among others, has proved to be a versatile one and has been widely used in the preparation of amorphous and or hybrid materials (Hench & West, 1990; Judeinstein & Sanchez, 1996; Novak, 1993), with applications, for example, in non-linear optical materials (Hsiue et al., 1994) and mesomoporous materials (Wei et al., 1999). The family of organicinorganic hybrid materials has attracted considerable attention because of its interesting properties such as molecular homogeneity, transparency, flexibility and durability. A key issue that remains unresolved in these organic-modified materials is the degree of mixing of the organic-inorganic components, i.e., phase homogeneity. The high optical transparency to visible light indicates that the organic-inorganic phase separation, if any, is on a scale of ≤ 400nm. Such hybrids are promising materials for various applications, e.g.: solid state lasers (optical components), replacements for silicon dioxide as insulating materials in the

Surgical site infection (SSI) is one of the most frequently reported types of hospital-acquired infections, associated with severe morbidity and sometimes mortality. It leads to an increase in the clinical and economic burden of surgery, due to the direct costs incurred by prolonged hospitalization, diagnostic tests, outpatient visits, systemic antibiotic treatments, and often reoperations. The SSI is frequently caused by the suture threads material which can become an infection vector. The present mini-review shows how the research is bringing new skills and knowledge in the design of new suture threads for SSI prevention and the wound healing process improvement.

The thermal behavior of pure ZrO2 and hydroxyapatite (denoted as Z and HAp, respectively), as well as three composites with different content of Z and HAp (Z90HAp10, Z70HAp30 and Z50HAp50) prepared via sol-gel method has been studied by thermogravimetry (TG) and first-order derivative of TG up to 1200 °C under inert gas atmosphere. Dehydration, loss of alcohol and acetylacetone and a multi-step thermal decomposition processes has been identified by analyzing the gases evolved in each step by Fourier transform infrared spectroscopy (FTIR). Fresh samples of Z-rich composites undergo an abrupt ejection of material from the crucible around 200 °C with noticeable increase of the sample temperature. During the occurrence of this phenomenon FTIR spectra demonstrated the evolution of gases (CO, CO2, acetone and ethylene) due to the simultaneous decomposition of acetylacetone and ethanol, not present in the samples calcined at 120 °C. As far as the structural study is concerned, pure Z crystallizes at 1000 °C in the monoclinic system, but the presence of HAp in the composite materials enables the crystallization of Z in the tetragonal phase. Finally, the amorphization degree increases with increasing the content of Z in all the composites treated at 600 and 1000 °C.

SiO2-based organic-inorganic hybrids (OIHs) are versatile materials whose properties may change significantly because of their thermal treatment. In fact, after their preparation at low temperature by the sol-gel method, they still have reactive silanol groups due to incomplete condensation reactions that can be removed by accelerating these processes upon heating them in controlled experimental conditions. In this study, the thermal behavior of pure SiO2 and four SiO2-based OIHs containing increasing amount (6, 12, 24 and 50 wt %) of poly(ε-caprolactone) (PCL) has been studied by simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC). The FTIR analysis of the gas mixture evolved at defined temperatures from the samples submitted to the TG experiments identified the mechanisms of thermally activated processes occurring upon heating. In particular, all samples already release ethanol at low temperature. Moreover, thermal degradation of PCL takes place in the richest-PCL sample, leading to 5-hexenoic acid, H2O, CO2, CO and ε-caprolactone. After the samples' treatment at 450, 600 and 1000 °C, the X-ray diffraction (XRD) spectra revealed that they were still amorphous, while the presence of cristobalite is found in the richest-PCL material. © 2018 by the authors.

Geopolymers are inorganic aluminosilicates mainly proposed as environmentally friendly building materials, which are obtained by alkali activation of natural minerals, calcined clay (e.g., metakaolin) and other aluminosilicate sources. The wide range of chemical and mineralogical compositions of these raw materials influences several properties of the obtained geopolymers. In the present work, pure Al2O3·2SiO2 powders were synthesized via the sol-gel technique and proposed as pure aluminosilicate sources to prepare alkali activated geopolymers. Samples differing in the ratio between the SiO2 precursor and the H2O used in the sol-gel process were prepared, in order to study the effect of water content on the material structure and reactivity. The chemical structure of all the obtained Al2O3·2SiO2 powders were characterized by Fourier transform infrared (FT-IR) and solid-state nuclear magnetic resonance (27Al and 29Si MAS NMR) spectroscopies and compared to that of a reference metakaolin. Moreover, material reactivity was evaluated by alkali activation of the samples. After 28 days of ageing, 27Al and 29Si MAS NMR and FT-IR spectra ascertained the formation of a geopolymeric network in the activated samples. The results showed that lower water content allows obtaining a homogeneous Al-rich geopolymer similar to that obtained, using metakaolin as raw material.