Processing of Calcium Magnesium Silicates by the Sol–Gel Route

Low temperature preparation of diopside nanoparticles: in-vitro bioactivity and drug loading evaluation

Bioactive diopside (CaMgSi2O6) nanoparticles have recently gained potential usefulness as bone replacement materials and nano vehicles for delivering therapeutics. The structural characteristics of this ceramic have found to be a key factor in bone bonding ability. To attain the desired product for 100% clinical success, it is important to realize the relationship between structure and biological activity. Synthesis of these nanoparticles via the solid-state method has been regarded as a low-cost and easy process in large-scale, but time consuming reactions and high temperature (≈ 1400 °C) are required. On the other side, the wet chemistry can overcome these drawbacks, whereas the presence of byproducts in the final powder has limited this method in large-scale production. The present document has represented a simple, fast and one-pot sol-gel approach for the synthesis of highly pure diopside nano-powders (< 20 nm) by using not-expensive precursors. Calcination of the obtained powder has been conducted at various temperatures (700, 1000 and 1200 °C). The physicochemical and microstructural properties of the products have been characterized by XRD, FTIR, FESEM and TEM. Moreover, the impact of the crystallinity on the bioactivity, drug loading capacity and drug release behavior of the synthesized nanoparticles have been investigated here for the first time. The in-vitro bioactivity results of the prepared diopside samples in a simulated body fluid (SBF) at 37 °C revealed the higher capability of the sintered sample to deposit calcium phosphate, compared with the amorphous one. High quantity of gentamicin (around 10 µg) could attach to the surface of 1 miligram of the sintered diopside during the early stages of contact (3 h), suggesting the potential use of diopside as a new class of nano-vehicles for antibiotics. The release behavior indicated a sustained release of gentamicin (80%) after 24 h. In conclusion, diopside nanoparticles can be a promising candidate as a drug-vehicle for bone filling, implant coating or bone cement applications.

Special Issue: Bioceramics, Bioglasses, and Gels for Tissue Engineering

Undoubtedly, biomaterials such as bioceramics, bioactive glasses, and gels have attracted a wide range of research interest in the field of tissue engineering (TE), as they facilitate the essential support and environment for cells to grow, differentiate, and, specifically, regenerate new tissues [...].

Evaluation of Mechanical Properties of Glass Ionomer Cements Reinforced with Synthesized Diopside Produced via Sol-Gel Method

This study aimed to fabricate a glass ionomer cement/diopside (GIC/DIO) nanocomposite to improve its mechanical properties for biomaterials applications. For this purpose, diopside was synthesized using a sol-gel method. Then, for preparing the nanocomposite, 2, 4, and 6 wt% diopside were added to a glass ionomer cement (GIC). Subsequently, X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM), and Fourier transform infrared spectrophotometry (FTIR) analyses were used to characterize the synthesized diopside. Furthermore, the compressive strength, microhardness, and fracture toughness of the fabricated nanocomposite were evaluated, and a fluoride-releasing test in artificial saliva was also applied. The highest concurrent enhancements of compressive strength (1155.7 MPa), microhardness (148 HV), and fracture toughness (5.189 MPa·m^1/2) were observed for the glass ionomer cement (GIC) with 4 wt% diopside nanocomposite. In addition, the results of the fluoride-releasing test showed that the amount of released fluoride from the prepared nanocomposite was slightly lower than the glass ionomer cement (GIC). Overall, the improvement in mechanical properties and optimal fluoride release of prepared nanocomposites can introduce suitable options for dental restorations under load and orthopedic implants.

Composite Fibers Based on Polycaprolactone and Calcium Magnesium Silicate Powders for Tissue Engineering Applications

The present work reports the synthesis and characterization of polycaprolactone fibers loaded with particulate calcium magnesium silicates, to form composite materials with bioresorbable and bioactive properties. The inorganic powders were achieved through a sol-gel method, starting from the compositions of diopside, akermanite, and merwinite, three mineral phases with suitable features for the field of hard tissue engineering. The fibrous composites were fabricated by electrospinning polymeric solutions with a content of 16% polycaprolactone and 5 or 10% inorganic powder. The physico-chemical evaluation from compositional and morphological points of view was followed by the biological assessment of powder bioactivity and scaffold biocompatibility. SEM investigation highlighted a significant reduction in fiber diameter, from around 3 μm to less than 100 nm after the loading stage, while EDX and FTIR spectra confirmed the existence of embedded mineral entities. The silicate phases were found be highly bioactive after 4 weeks of immersion in SBF, enriching the potential of the polymeric host that provides only biocompatibility and bioresorbability. Moreover, the cellular tests indicated a slight decrease in cell viability over the short-term, a compromise that can be accepted if the overall benefits of such multifunctional composites are considered.

Magnetic Application of Gadolinium Orthoferrite Nanoparticles Synthesized by Sol–Gel Auto-Combustion Method

In this manuscript, we present the synthesis of gadolinium orthoferrite nanoparticles using the sol–gel auto-combustion technique. The obtained gadolinium orthoferrite nanoparticles were annealed at various temperatures, such as 800 °C, 900 °C, 1000 °C, and 1100 °C. The synthesized materials were analyzed by various instrumental characterizations. The vibrational characteristics of the synthesized samples were verified by FTIR. The surface morphology of the gadolinium orthoferrite nanoparticles was analyzed by FE-SEM and HR-TEM, revealing their spherical structural morphology and uniform particle structure. The presence of the elemental features was analyzed in the gadolinium orthoferrite nanoparticles by EDAX. The surface analysis of the core ranges of the XPS-recorded spectra were obtained for the elemental states of the Gd, Fe, and O factors in the samples, and it additionally characterized the different levels of oxidative states by fitting the levels of the high-resolution parameters of Gd 4d, Fe 2p, and O 1s. The magnetic properties of the samples were investigated by VSM. The measurement of the magnetic parameters revealed that gadolinium orthoferrite nanoparticles exhibit a ferromagnetic nature.