Strontium alginate hybrid (inorganic/organic) nanoparticles as a novel promising nanosystem for bone regeneration: in-vitro optimization and in-vivo assessment

Strontium (Sr) is a bone-seeking element characterized by its dual function of stimulating bone growth and preventing bone resorption. On the other hand, alginates (Alg) have distinct physicochemical characteristics from other natural polysaccharides because of their ability to encapsulate proteins and drugs. This work aimed to prepare novel hybrid inorganic/organic strontium alginate (Sr-Alg) nanoparticles for use as a targeting ligand in bone regeneration. These hybrid nanoparticles were prepared by a simple precipitation technique and different formulation variables were studied. The optimized formulation showed the most promising particle size (133.80 ± 2.40 nm) and zeta potential (-31.5 ± 1.45 mV). Moreover, the selected formulation was subjected to characterization using FTIR and X-ray diffraction to confirm the formation of the hybrid structure. The selected formulation was subjected to an <i>in vivo</i> study and compared with calcium alginate nanoparticles. Mice treated with Sr-containing formulation showed significant improvement in Ca/P and Ca + Sr/P ratios reached 1.799 ± 0.01 and 1.89 ± 0.01, respectively. An <i>in vivo</i> toxicity study was also assessed based on biochemical assays and histological examination of liver and kidney tissues and confirmed that non-significant nephrotoxic or hepatotoxic effects were demonstrated in the treated groups. Therefore, Sr-Alg could be considered a promising targeted ligand for bone regeneration with enhanced safety and efficacy.