Bioactive Glasses with Low Ca/P Ratio and Enhanced Bioactivity

Additive Manufacturing of Iron Carbide Incorporated Bioactive Glass Scaffolds for Bone Tissue Engineering and Drug Delivery Applications

In this study, we have synthesized a bioactive glass with composition 45SiO2-20Na2O-23CaO-6P2O5-2.5B2O3-1ZnO-2MgO-0.5CaF2 (wt %). Further, it has been incorporated with 0.4 wt % iron carbide nanoparticles to prepare magnetic bioactive glass (MBG) with good heat generation capability for potential applications in magnetic field-assisted hyperthermia. The MBG scaffolds have been fabricated using extrusion-based additive manufacturing by mixing MBG powder with 25% Pluronic F-127 solution as the binder. The saturation magnetization of iron carbide nanoparticles in the bioactive glass matrix has been found to be 80 emu/g. The morphological analysis (pore size distribution, porosity, open pore network modeling, tortuosity, and pore interconnectivity) was done using an in-house developed methodology that revealed the suitability of the scaffolds for bone tissue engineering. The compressive strength (14.3 ± 1.6 MPa) of the MBG scaffold was within the range of trabecular bone. The in vitro test using simulated body fluid (SBF) showed the formation of apatite indicating the bioactive nature of scaffolds. Further, the drug delivery behaviors of uncoated and polycaprolactone (PCL) coated MBG scaffolds have been evaluated by loading an anticancer drug (Mitomycin C) onto the scaffolds. While the uncoated scaffold demonstrated the drug's burst release for the initial 80 h, the PCL-coated scaffold showed the gradual release of the drug. These results demonstrate the potential of the proposed MBG for bone tissue engineering and drug delivery applications.

Unscrambling the Influence of Sodium Cation on the Structure, Bioactivity, and Erythrocyte Compatibility of 45S5 Bioactive Glass

The 45S5 bioglass uttering Class A bioactivity promotes both osteoconduction as well as osteoinduction. Though one of the higher reactive bioactive materials known with structural and physiological influence upon ionic modulation, poor mechanical properties are perceived. The possible solution to overcome the weak stability is to choose material's composition that provides retained bioactivity and improved mechanical stability. Meanwhile, primary burst out of Na⁺ ions increases the local pH, harms cell life, and acts as a well-known disruptive modifying species that weakens the bioactive glass network, decreasing network connectivity, showing faster degradation and lowering mechanical stability. Therefore, in this study, more detailed systematic exploration on structural influence of sodium monovalent cation and its behavior on physiological environment was genuinely studied and reported that bioactivity of the bioactive glass can be highly achieved even without Na⁺ ions. The result exhibits benefits of sodium free bioactive glass (denoted as No Na⁺ BG) over Na⁺ BG and exhibits improved mechanical stability and also possible degradability, having in-built apatite phase even before immersion in simulated body fluid (SBF). Also, sodium free bioglass proved as a superior candidate for erythrocyte compatibility with rapid clotting tendency on interaction with blood and a promising replacement for 45S5 bioglass in all aspects especially in mechanical stability view, which can withstand more than 5 months in phosphate buffer saline (PBS).

The use of bioactive glass (BAG) in dental composites: A critical review

OBJECTIVE

In recent years, numerous studies have analyzed the role of bioactive glass (BAG) as remineralizing additives in dental restorative composites. This current review provides a critical analysis of the existing literature, particularly focusing on BAGs prepared via the melt-quench route that form an "apatite-like" phase when immersed in physiological-like solutions.

METHODS

Online databases (Science Direct, PubMed and Google Scholar) were used to collect data published from 1962 to 2020. The research papers were analyzed and the relevant papers were selected for this review. Sol-gel BAGs were not included in this review since it is not a cost-effective manufacturing technique that can be upscaled and is difficult to incorporate fluoride.

RESULTS

BAGs release Ca²⁺, PO₄^3- and F^- ions, raise the pH and form apatite. There are numerous published papers on the bioactivity of BAGs, but the different glass compositions, volume fractions, particle sizes, immersion media, time points, and the characterization techniques used, make comparison difficult. Several papers only use certain characterization techniques that do not provide a full picture of the behavior of the glass. It was noted that in most studies, mechanical properties were measured on dry samples, which does not replicate the conditions in the oral environment. Therefore, it is recommended that samples should be immersed for longer time periods in physiological solutions to mimic clinical environments.

SIGNIFICANCE

BAGs present major benefits in dentistry, especially their capacity to form apatite, which could potentially fill any marginal gaps produced due to polymerization shrinkage.