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Carboxyl groups at the periphery of reduced graphene oxide (RGO) sheets are converted to amine groups by reaction with N-hydroxysuccinimide and 1,3-diaminopropane, and a free-radical polymerization initiator is anchored to the RGO sheets. Poly(acrylamide) (PAM) polymer brushes on RGO sheets (RGO/PAM) are synthesized by in situ free-radical polymerization. The heavy metals, Pb(II), and the benzenoid compounds, methylene blue, (MB) were selected and adsorbed by RGO/PAM composites, and the adsorption capacity of RGO/PAM for Pb(II) and MB was measured. The experimental data of RGO/PAM isotherms for Pb(II) and MB followed the Langmuir isotherm model. The RGO/PAM displays adsorption capacities as high as 1000 and 1530 mg/g for Pb(II) and MB, respectively, indicating RGO/PAM is a good adsorbent for the adsorption of Pb(II) and MB. The adsorption kinetics of Pb(II) and MB onto RGO/PAM can be well fitted to the pseudo-second-order model. The adsorption processes of Pb(II) and MB onto RGO/PAM are spontaneous at 298, 308, and 318 K.

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There is an urgent demand for wound healing biomaterials because of the increasing frequency of traffic accidents, industrial contingencies, and natural disasters. Borate bioactive glass has potential applications in bone tissue engineering and wound healing; however, its uncontrolled release runs a high risk of rapid degradation and transient biotoxicity. In this study, a novel organic-inorganic dressing of copper-doped borate bioactive glass/poly(lactic- co-glycolic acid) loaded with vitamin E (0-3.0 wt % vitamin E) was fabricated to evaluate its efficiency for angiogenesis in cells and full-thickness skin wounds healing in rodents. In vitro results showed the dressing was an ideal interface for the organic-inorganic mixture and a controlled release system for Cu and vitamin E. Cell culture suggested the ionic dissolution product of the copper-doped and vitamin E-loaded dressing showed the best migration, tubule formation, and vascular endothelial growth factor (VEGF) secretion in human umbilical vein endothelial cells (HUVECs) and higher expression levels of angiogenesis-related genes in fibroblasts in vitro. Furthermore, this dressing also suggested a significant improvement in the epithelialization of wound closure and an obvious enhancement in vessel sprouting and collagen remodeling in vivo. These results indicate that the copper-doped borate bioactive glass/poly(lactic- co-glycolic acid) dressing loaded with vitamin E is effective in stimulating angiogenesis and healing full-thickness skin defects and is a promising wound dressing in the reconstruction of full-thickness skin injury.

The hypoxia-inducible factor 1-alpha (HIF-1a) pathway plays a key role in regulating angiogenesis during wound healing. However, the diabetic condition hampers the stabilization of HIF-1a and thus inhibits the subsequent angiogenesis, and meanwhile, the function and phenotype transition of macrophage are impaired in the diabetic condition, which leads to prolonged and chronic inflammation. Both angiogenesis inhibition and inflammatory dysfunction make diabetic wound healing a major clinical challenge. Here, borosilicate (BS), a new group of bioceramics with a coupled network of interconnected [BO3] and [SiO4] which can incorporate therapeutic ions such as Cu2+, is synthesized and combined with silk fibroin (SF), a biocompatible natural amino acid polymer whose composition and structure are similar to a natural extracellular matrix (ECM), to obtain a compound system which can transform into a SF-MA-BS hydrogel under UV radiation via methacryloyloxy (MA) groups modified on both BS and SF. When in use, the compound system can thoroughly spread to the whole wound surface and be in situ photo-cross-linked to form an integral SF-MA-BS hydrogel that firmly adheres to the wound, protects the wound from external contamination, and further spontaneously promotes wound regeneration by releasing therapeutic ions. The wound repair of Streptozotocin-induced diabetic rats shows that diabetic wound healing is obviously accelerated by SF-MA-BS, interestingly the HIF-1a pathway is restored via interaction between HIF-1a and Cu2+, and angiogenesis is therefore enhanced. Meanwhile, inflammation is well regulated by SF-MA-BS, and long-term detrimental inflammation is avoided. These findings indicate that the SF-MA-BS hydrogel regenerates diabetic wounds, and further clinical trials are anticipated.

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