Photothermal therapy using near-infrared radiation and local heating agents can induce selective tumor ablation with limited harm to the surrounding normal tissue. Graphene sheets are promising local heating agents because of their strong absorbance of near-infrared radiation. Experimental studies have been conducted to study the heating effect of graphene in photothermal therapy, yet few efforts have been devoted to the quantitative understanding of energy conversion and transport in such systems. Herein, a computational study of cancer photothermal therapy using near-infrared radiation and graphene is presented using a Monte Carlo approach. A three-dimensional model was built with a cancer cell inside a cube of healthy tissue. Functionalized graphene nanosheets were randomly distributed on the surface of the cancer cell. The effects of the concentration and morphology of the graphene nanosheets on the thermal behavior of the system were quantitatively investigated. The interfacial thermal resistance around the graphene sheets, which affects the transfer of heat in the nanoscale, was also varied to probe its effect on the temperature increase of the cancer cell and the healthy tissue. The results of this study could guide researchers to optimize photothermal therapy with graphene, while the modeling approach has the potential to be applied for investigating alternative treatment plans.

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Background and objective: Occlusal trauma is one of the most important local contributing factors of periodontitis. It has been reported that Wnt4, a noncanonical Wnt ligand, can inhibit osteoclast formation and inflammation and promote bone formation in vivo.However, the prospects of Wnt4 application in occlusal trauma and periodontitis have not yet been described. This study aimed to investigate the function and the corresponding mechanism of Wnt4 to regulate bone metabolism in occlusal trauma and periodontitis.Material and methods: Osteogenic-induced MC3T3-E1 cells were treated with or without Porphyromonas gingivalis lipopolysaccharide (Pg. LPS) under cyclic uniaxial compressive stress. After treatment with mouse recombinant protein Wnt4 (rWnt4), the expression of osteogenic markers and activation of the IKK-NF-κB signaling pathway were evaluated in vitro. To investigate whether Wnt4 can promote osteogenesis via the ROCK signaling pathway, the expression of RhoA was evaluated in vitro.Finally, we evaluated the change in bone quantity and the activation of the IKK-NF-κB and ROCK signaling in mice with occlusal trauma and periodontitis to demonstrate the therapeutic efficacy of rWnt4 injection.Results: Stimulation of traumatic force and Pg. LPS stimulation suppressed the expression of osteoblast markers, but their expression was rescued after rWnt4 treatment in vitro. In addition, the inhibition of the ROCK signaling pathway induced by force loading was reversed when rWnt4 was applied in vitro. Micro-CT, H&E, and TRAP staining of the mandibles showed increased bone loss in the occlusal trauma-aggravated periodontitis group, whereas it was rescued after rWnt4 injection. The expression levels of IκBα and p65 were upregulated in occlusal trauma and periodontitis-bearing mice, whereas the expression levels of Runx2 and RhoA were downregulated. After rWnt4 injection, remarkably upregulation of Runx2 and RhoA expression was observed in occlusal trauma and periodontitis-bearing mice. Conclusion:Wnt4 not only inhibits IKK-NF-κB signaling but also activates ROCK signaling to inhibit osteoclast formation and promote bone regeneration in occlusal trauma and periodontitis-bearing mice.

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