Study of calcium silicate glasses derived from agro-food wastes and minerals for biomedical applications

Abstract

The rapid expansion of the agricultural sector has led to a significant increase in agricultural waste. Crop residues such as corn, rice, sugarcane, and wheat are often openly burned, despite the detrimental environmental consequences. In addition to agricultural waste, a substantial portion of the food produced is also wasted and left to decompose without proper disposal mechanisms. From both environmental and energy perspectives, the most effective waste management strategy involves utilizing these wastes to synthesize value-added products. Rice husk ash (RHA) and eggshells (ES) are among the most abundant agro-food wastes and represent promising sources of SiO2 and CaCO3, respectively. These agro-food wastes/ashes/powders also contain magnesium, potassium, and other trace elements typically required for the production of bioglass and bioglass-ceramics. Furthermore, agro-food wastes offer sustainable and cost-effective alternatives to conventional precursors. This study focuses on the synthesis of bioglasses with a base composition of 43SiO2-25CaO-25Na2O- 7P2O5 (wt%) using biowaste-derived silica and calcium, supplemented with conventional precursors for P2O5, Na2O, and MgO. The effects of systematically substituting CaO with MgO and Na2O with K2O were investigated. The resulting glasses and glass-ceramics were characterized to determine their physical, structural, thermal, and mechanical properties to assess their suitability as biomaterials. Bioactive properties were evaluated in-vitro using simulated body fluid (SBF). Furthermore, biocompatibility was assessed using the 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in human peripheral blood mononuclear cells (PBMC).