Exfoliated graphite oxide (GO) sheets with hydroxyl groups and amine groups on the surface were prepared by modification of graphite. Atom transfer radical polymerization (ATRP) initiator molecules were grafted onto the GO sheets by reactions of 2-bromo-2-methylpropionyl bromide with hydroxyl groups and amine groups. Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) chains on the surface of GO sheets were synthesized by in-situ ATRP. X-ray photoelectron spectroscopy, thermogravimetric analysis, and transmission electron microscopy (TEM) results all demonstrated that polymer chains were successfully produced. After grafting of PDMAEMA, the dispersity of GO sheets in solvents was improved significantly. Poly(ethylene glycol dimethacrylate-co-methacrylic acid) particles were deposited on GO sheets via hydrogen bonding between MAA units on polymer particles and amine groups of PDMAEMA. TEM and scanning electron microscopy were used to characterize the structure of the nanocomposites.

Effective healing of skin wounds is essential for our survival. Although skin has strong regenerative potential, dysfunctional and disfiguring scars can result from aberrant wound repair. Skin scarring involves excessive deposition and misalignment of ECM (extracellular matrix), increased cellularity, and chronic inflammation. Transforming growth factor-β (TGFβ) signaling exerts pleiotropic effects on wound healing by regulating cell proliferation, migration, ECM production, and the immune response. Although blocking TGFβ signaling can reduce tissue fibrosis and scarring, systemic inhibition of TGFβ can lead to significant side effects and inhibit wound re-epithelization. In this study, we develop a wound dressing material based on an integrated photo-crosslinking strategy and a microcapsule platform with pulsatile release of TGF-β inhibitor to achieve spatiotemporal specificity for skin wounds. The material enhances skin wound closure while effectively suppressing scar formation in murine skin wounds and large animal preclinical models. Our study presents a strategy for scarless wound repair.

The aim of this work was to investigate the solution properties of a new polymer−surfactant (SP) flooding system, including hydrophobically associating polyacrylamide (HAPAM) and mixed surfactant [mixture of fatty acid disulfonate anionic gemini surfactant (DMES) and non-ionic surfactant Triton X-100 (TX-100)]. The critical micelle concentrations (cmc's) of four gemini surfactants were smaller than 100 mg L −1 . Furthermore, their interfacial tensions (IFTs) could reach an ultralow value with Bohai oil at lower concentrations. Through optimized formulation, we found that DMES-14 had better properties and was selected as the major component of the surfactant. We designed an optimal formulation of the SP system with 1750 mg L −1 HAPAM and 3000 mg L −1 mixed surfactant (the mass ratios of DMES-14 and TX-100 are from 4:1 to 5:1). The SP system (ratio of 4:1) with a very small surfactant concentration could reach ultralow IFT with different crude oils, which proved that the simpler component surfactant had better reservoir compatibility. TX-100 could widen the "window" of increasing viscosity and weaken the disadvantage of the interaction between HAPAM and the surfactant. The stability of this SP system was evaluated by the temperature, mineralized degree, shearing, aging time, adsorption, and chromatographic separation. All of experiments showed that it still keeps higher viscosity and ultralow IFT with different evaluation conditions; therefore, it is feasible to use as a SP combination flooding system for enhanced oil recovery (EOR).

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