Efficient charge transfer in an aggregation-induced nanocavity of Au nanoclusters.

In the last 20 years, extensive research has been reported on the use of plasmonic nanoparticles as a potential photocatalyst. However, the low conversion efficiency has still remained a major concern. Herein, we present a new photocatalytic reaction system based on Au nanoclusters (Au NCs) to enhance the conversion efficiency. Negatively charged Au NCs electrostatically interact with positively charged metal ions and form highly aggregated nanocrystals, which can efficiently capture a chemical substance in the reaction mixture. In such a reaction system, the distance between the electron donor and acceptor can be shortened, resulting in an efficient electron transfer process. We examined the electron transfer behavior in a nanocavity system via resazurin photoreduction and compared the reaction rate with that of a colloidal system, which is a commonly used reaction system. Evidently, the nanocavity system facilitated an enhanced reaction rate compared to that of the colloidal system. Furthermore, this nanocavity reaction system permitted multistep photoreactions and multi-electron transfer processes.

Effects of erythropoietin on osteoblast in the tooth extraction socket in mice periodontitis model.

Periodontitis is an excessive inflammatory event in tooth-supporting tissues and can cause tooth loss. We used erythropoietin (EPO), which has been reported to play an important role in bone healing and modulation of angiogenesis, as a therapeutic agent in vivo and in vitro experimental models to analyze its effect on periodontitis. First, EPO was applied to in vitro MC3T3-E1 cells and human periodontal ligament fibroblast (hPDLF) cells to examine its function in altered cellular events and gene expression patterns. In vitro cultivation of MC3T3-E1 and hPDLF cells with 10 IU/ml EPO at 24 and 48 h showed an obvious increase in cell proliferation. Interestingly, EPO treatment altered the expression of osteogenesis-related molecules, including alkaline phosphatase (ALP), bone morphogenetic protein-2 (BMP-2), and osteocalcin (OC) in MC3T3-E1 cells but not in hPDLF cells. In particular, MC3T3-E1 cells showed increased expression of ALP, BMP-2, and OC on day 5, while hPDLF cells showed increased expression of BMP-2, and OC on day 14. Based on the in vitro examination, we evaluated the effect of EPO on bone formation using an experimentally-induced animal periodontitis model. After the induction of periodontitis in the maxillary left second M, 10 IU/ml of EPO was locally applied to the extraction tooth sockets. Histomorphological examination using Masson's trichrome (MTC) staining showed facilitated bone formation in the EPO-treated groups after 14 days. Similarly, stronger positive reactions against vascular endothelial growth factor (VEGF), cluster of differentiation 31 (CD31), runt-related transcription factor 2 (RUNX2), and osteocalcin (OC) were detected in the EPO-treated group compared to the control. Meanwhile, myeloperoxidase, an inflammatory marker, was decreased in the EPO-treated group on days 1 and 5. Overall, EPO facilitates bone healing and regeneration through altered signaling regulation and modulation of inflammation in the osteoblast cell lineage and to a lesser extent in hPDLF cells.