Casein-Coated Molybdenum Disulfide Nanosheets Augment the Bioactivity of Alginate Microspheres for Orthopedic Applications.

Defects and disorders of the bone due to disease, trauma, or abnormalities substantially affect a person's life quality. Research in bone tissue engineering is motivated to address these clinical needs. The present study demonstrates casein-mediated liquid exfoliation of molybdenum disulfide (MoS 2 ) and its coupling with alginate to create microspheres to engineer bone graft substitutes. Casein-exfoliated nano-MoS 2 was chemically characterized using different analytical techniques. The UV-visible spectrum of nano-MoS 2 -2 displayed strong absorption peaks at 610 and 668 nm. In addition, the XPS spectra confirmed the presence of the molybdenum (Mo, 3d), sulfur (S, 2p), carbon (C, 1s), oxygen (O, 1s), and nitrogen (N, 1s) elements. The exfoliated MoS 2 nanosheets were biocompatible with the MG-63, MC3T3-E1, and C2C12 cells at 250 μg/mL concentration. Further, microspheres were created using alginate, and they were characterized physiochemically and biologically. Stereomicroscopic images showed that the microspheres were spherical with an average diameter of 1 ± 0.2 mm. The dispersion of MoS 2 in the alginate matrix was uniform. The alginate-MoS 2 microspheres promoted apatite formation in the SBF (simulated body fluid) solution. Moreover, the alginate-MoS 2 was biocompatible with MG-63 cells and promoted cell proliferation. Higher alkaline phosphatase activity and mineralization were observed on the alginate-MoS 2 with the MG-63 cells. Hence, the developed alginate-MoS 2 microsphere could be a potential candidate for a bone graft substitute.