Exposed bone fractures (EBF) require multifunctional biomaterials capable of simultaneously providing structural adaptability, physicochemical stability, and biological support under dynamic physiological conditions. In this study, a smart multi-network hydrogel (HD hydrogel) composed of guar gum, polyvinyl alcohol, gelatin, collagen, tannic acid, and manganese phosphate/chitosan organo-inorganic complex (CS-MnP) was developed and compared with a Control hydrogel lacking the bioactive components. CS-MnP exhibited spherical and quasi-spherical morphologies with an average diameter of 232 nm ± 70 nm by SEM, a Z-average of 160 nm, and a multimodal nanoscale distribution by DLS. FTIR and EDS analyses confirmed phosphate incorporation and interactions between Mn-containing species and chitosan functional groups. The HD hydrogel exhibited enhanced physicochemical and rheological performance compared with the Control hydrogel, including porosity (0.85-0.88 vs 0.75-0.82), improved water absorption (47.16% vs 40.38%), faster self-healing (40-90 s vs ~3 min), and superior rheological recovery (90-95% modulus restoration after cyclic deformation). Furthermore, HD hydrogel maintained structural stability in PBS for up to 24 h, whereas the Control hydrogel underwent structural collapse before 8 h. Thermal resistance was also improved, with the HD hydrogel maintaining structural integrity up to ~69°C compared to ~62°C for the Control formulation, while also exhibiting enhanced low-temperature stability by resisting freezing down to -18°C, compared to -16°C for the Control hydrogel. Both hydrogels exhibited non-Newtonian shear-thinning behavior and high wettability (contact angle <20°). Cytocompatibility assay using MC3T3-E1 pre-osteoblast demonstrated cell viability values above 70%, while scratch assay revealed concentration-dependent modulation of cellular migration. Collectively, the synergistic integration of dynamic borate-diol crosslinking, hydrogel bonding, and CS-MnP-mediated interactions resulted in a mechanically adaptive, stimuli-responsive, and biological compatible hydrogel system with promising potential as an auxiliary material for EBF treatment.
Valdez-Salas et al. (Fri,) studied this question.