Turning gray selenium into a nanoaccelerator of tissue regeneration by PEG modification

Selenium(Se)is an essential trace element involved in nearly all human physiological processes but suffers from a narrow margin between benefit and toxicity.The nanoform of selenium has been proven shown to be more bioavailable and less toxic,yet significant challenges remain regarding the efficient and feasible synthesis of biologically active nanoselenium.In addition,although nanoselenium has shown a variety of biological activities,more interesting nanoselenium features are expected.In this work,hydrosoluble nanoselenium termed Nano-Se in the zero oxidation state was synthesized between gray Se and PEG.A zebrafish screen was carried out in zebrafish larvae cocultured with Nano-Se.Excitingly,Nano-Se promoted the action of the FGFR,Wnt,and VEGF signaling pathways,which play crucial roles in tissue regeneration.As expected,Nano-Se not only achieved the regeneration of zebrafish tail fins and mouse skin but also promoted the repair of skin in diabetic mice while maintaining a profitable safe profile.In brief,the Nano-Se reported here provided an efficient and feasible method for bioactive nanoselenium synthesis and not only expanded the application of nanoselenium to regenerative medicine but also likely reinvigorated efforts for discovering more peculiarunique biofunctions of nanoselenium in a great variety of human diseases.

Modification of Titanium Surfaces via Surface-initiated Atom Transfer Radical Polymerization to Graft PEG-RGD Polymer Brushes to Inhibit Bacterial Adhesion and Promote Osteoblast Cell Attachment

Implant-related infection is one of the key concerns in clinical medicine, so the modification of titanium to inhibit bacterial adhesion and support osteoblast cell attachment is important. In this article, two strategies were used to examine the above effects. First, modification of titanium via surface-initiated atom transfer radical polymerization（ATRP） was performed. The surface of the titanium was activated initially by a silane coupling agent. Well-defined polymer brushes of poly（ethylene glycol） methacrylate were successfully tethered on the silane-coupled titanium surface to form hydration shell to examine the anti-fouling effect. Second, functionalization of the Ti-PEG surface with RGD was performed to examine the anti-bacterial adhesion and osteoblast cell attachment ability. The chemical composition of modified titanium surfaces was characterized by X-ray photoelectron spectroscopy（XPS）. Changes in surface hydrophilicity and hydrophobicity were characterized by static water contact angle measurements. Results indicated that PEG-RGD brushes were successfully tethered on the titanium surface. And anti-bacterial adhesion ability and osteoblast cell attachment ability were confirmed by fluorescence microscopy and scanning electron microscopy. Results indicated that PEG can inhibit both bacterial adhesion and osteoblast cell attachment, while PEG-RGD brushes can not only inhibit bacterial adhesion but also promote osteoblast cell attachment.