Chitosan-chondroitin sulfate-daidzein nanoconjugate ameliorates glucocorticoid induced osteoporosis in vivo.

The use of nanotechnology and polymer-based carriers in osteoporosis treatment offers promising avenues for targeted drug delivery and enhanced therapeutic efficacy. In this study, we developed a novel nanoconjugate composed of Chitosan (CH), Chondroitin Sulfate (CS), and Daidzein (DZ) to treat glucocorticoid-induced osteoporosis in an in vivo zebrafish model. The CH-CS-DZ nanoconjugate were synthesized using the ionic gelation method, with a CH: CS ratio of 1:1 and a 3 % DZ concentration was identified as optimal for further analysis. The resulting nanoparticles exhibited a particle size of 401.2 ± 0.87 nm. The polydispersity index (PDI) and zeta potential of nanoconjugate were of 0.147 ± 0.04 and 43.55 ± 0.68 mV respectively. Drug release studies demonstrated that 79.66 ± 4.04 % of DZ was released under physiological conditions (pH 7.5) after 96 h, indicating a sustained release profile beneficial for prolonged therapeutic effects. In vivo, studies using zebrafish larvae revealed a significant reduction in oxidative stress and apoptosis in the CH-CS-DZ treated group compared to the glucorticoid dexamethasone (Dex) treated group. Specifically, reactive oxygen species (ROS) levels were reduced, and lipid peroxidation was markedly decreased (p < 0.001) in the CH-CS-DZ treated group. Additionally, the survival and hatching rates of CH-CS-DZ-treated larvae were 94 % and 95 %, respectively, significantly higher than those in the Dex-treated group. The CH-CS-DZ nanoconjugate also restored bone mineralization, as evidenced by a significant increase in calcium deposition (p < 0.001) and alkaline phosphatase (ALP) activity (122 ± 0.4 U/L), compared to the Dex group (84 ± 0.7 U/L). Gene expression analysis showed upregulation of OPG and ALP and downregulation of RANKL and RUNX2b, further indicating the anti-osteoporotic potential of the CH-CS-DZ nanoconjugates. These findings suggest that polymer-based nanoconjugates like CH-CS-DZ can effectively mitigate osteoporosis through targeted delivery and sustained release, offering a potent strategy for bone health restoration.