Bifunctional defect mediated direct Z-scheme g-C3N4-x/Bi2O3-y heterostructures with enhanced piezo-photocatalytic properties for efficient tooth whitening and biofilm eradication.

Biofilm-associated dental diseases and tooth discoloration have recently become the major barriers to achieve healthy teeth. However, there are few effective strategies to address these issues. Herein, the piezo-photocatalytic process is first proposed to be applied for biofilm eradication and tooth whitening with well-designed direct Z scheme g-C3N4-x/Bi2O3-y heterostructures. DFT calculation and XPS results verify the formation of direct Z scheme g-C3N4/Bi2O3 heterostructures theoretically and experimentally. Using the direct Z scheme g-C3N4-x/Bi2O3-y heterostructure, excellent piezo-photocatalytic effects for tooth whitening and biofilm removal are achieved. For piezo-photocatalytic degradation of the typical food colorant of indigo carmine the degradation rate constant is about quadruple that of piezocatalytic and 2.6 times of photocatalytic treatment. Tooth whitening experiments indicate that g-C3N4-x/Bi2O3-y could whiten the stained teeth through the synergistic piezo-photocatalysis. In addition, excellent antibacterial performances can be obtained on the g-C3N4-x/Bi2O3-y heterostructure through piezo-photocatalytic treatment. Not only the planktonic S. mutans but also those bacteria embedded in biofilms can be effectively killed. The analyses of the piezo-photocatalytic mechanism indicates that the enhanced piezo-photocatalytic performance of the g-C3N4-x/Bi2O3-y heterostructure could be attributed to the much higher separation efficiency of photoexcited charge carriers, increased production amounts of ROS and superior adsorption ability for bacteria than those with bare semiconductors of g-C3N4-x and Bi2O3-y and those treated only with ultrasonic vibration or irradiation. Biosafety results show that the g-C3N4-x/Bi2O3-y heterostructure is biologically safe and piezo-photocatalytic treatment has no harm the tooth structure, demonstrating the great potential of piezo-photocatalytic effect based new tooth whitening and antibacterial technology in future dental care fields.

Design, synthesis and evaluation of wound healing activity for ß-sitosterols derivatives as potent Na+/K+-ATPase inhibitors.

ß-Sitosterols, is a common steroid that can be identified in a variety of plants and their efficacy in promoting wound healing has been demonstrated. Na+/K+-ATPase, more than a pump, its signal transduction function for involvement in cell growth regulation attracts widespread concern. The Na+/K+-ATPase/Src receptor complex can serve as a receptor involved in multiple signaling pathways including promoting wound healing pathways. To finding potent accelerating wound healing small molecular, we choose the high inhibitory activity of Na+/K+-ATPase and non-cardiotoxic natural compound, ß-sitosterol as the substrate. A series of ß-sitosterol derivatives were designed, synthesized and evaluated as potential Na+/K+-ATPase inhibitors. Among them, compounds 31, 47, 49, showed improved inhibitory activity on Na+/K+-ATPase, with IC50 value of 3.0 µM, 3.4 µM, 2.2 µM, which are more potent than ß-sitosterol with IC50 7.6 µM. Especially, compound 49 can induce cell proliferation, migration and soluble collagen production in L929 fibroblasts. Compared to model, compound 49 can accelerate wound healing in SD rats. Further studies indicated that 49 can activate the sarcoma (Src), uptake the protein kinase B (Akt), extracellular signal-regulated kinase (ERK) proteins expression in a concentration dependent manner. Finally, binding mode of compound 49 with Na+/K+-ATPase was studied, which provides insights into the determinants of potency and selectivity. These results proved ß-stitosterol derivative 49 can serve as an effective inhibitor of Na+/K+-ATPase and potential candidate for accelerating wound healing agents.