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Abstract Large skin wounds are one of the most important health problems in the world. Skin wound repair and tissue regeneration are complex processes involving many physiological signals, and effective wound healing remains an enormous clinical challenge. Therefore, there is an urgent need for a strategy to rapidly kill bacteria, promote cell proliferation and accelerate wound healing. At present, electrical stimulation (ES) is often used in the clinical treatment of skin wounds and can simulate the endogenous biological current of the body and accelerate the repair process of skin wounds. However, a single ES strategy has difficulty covering the entire wound area, which may lead to unsatisfactory therapeutic effects. To overcome this deficiency, it is essential to develop a collaborative treatment strategy that combines ES with other treatments. In this study, gold nanoparticles and antibacterial peptides (Os) were loaded on the surface of poly(lactic-co-glycolic acid) (PLGA) material through the reducibility and adhesion of polydopamine (PDA) and improved the electrical activity, anti-inflammatory, antibacterial and biocompatibility properties of the polymer material. At the same time, this composite membrane material (Os/Au-PDA@PLGA) combined with ES was used in wound therapy to improve the wound healing rate. The results show that the new wound repair material has good biocompatibility and can effectively promote cell proliferation and migration. Through the combined application of gold nanoparticles and antibacterial peptides Os, the polymer materials have more efficient bactericidal and antioxidant effects. The antibacterial experiment results showed that gold nanoparticles could further enhance the antibacterial activity of antibacterial peptides. Furthermore, the Os/Au-PDA@PLGA composite membrane has good hydrophilicity and electrical activity, which can provide a more favorable cell microenvironment for wound healing. In vivo studies using a full-thickness skin defect model in rats showed that the Os/Au-PDA@PLGA composite membrane had a better therapeutic effect than the pure PLGA material. More importantly, the combination of the Os/Au-PDA@PLGA composite with ES significantly accelerated the rate of vascularization and collagen deposition and promoted wound healing compared with non-ES controls. Therefore, the combination of the Au/Os-PDA@PLGA composite membrane with ES may provide a new strategy for the effective treatment of skin wounds.

Abstract We investigate the fluorescence from submonolayer rhodamine 6G molecules near gold nanoparticles (NPs) at a well-controlled poly (methyl methacrylate) (PMMA) interval thickness from 1.5 to 21 nm. The plasmonic resonance peaks of gold NPs are tuned from 530 to 580 nm by the PMMA spacer of different thicknesses. Then, due to the plasmonic resonant excitation enhancement, the emission intensity of rhodamine 6G molecules at 562 nm is found to be enhanced and shows a decline as the PMMA spacer thickness increases. The variation of spectral intensity simulated by finite-difference time-domain method is consistent with the experimental results. Moreover, the lifetime results show the combined effects to rhodamine 6G fluorescence, which include the quenching effect, the barrier effect of PMMA as spacer layer and the attenuation effect of PMMA films.

Electroconductive biomaterials combined with bioelectrical stimulation as a treatment for nerve injury has attracted extensive attention in recent years. This study investigated the effect of AuNPs@PDA-PLGA nanomembrane combined with electrical stimulation (ES) on promoting functional recovery of spinal cord injury (SCI). In this study, an AuNPs@PDA-PLGA was prepared and its characterization and biological properties were determined by means of scanning electron microscope (SEM), atomic force microscope (AFM) and X-ray diffraction (XRD). The effects of AuNPs@PDA-PLGA nanomembranes combined with ES on NSCs were evaluated in vitro. Finally, BBB score and immunohistochemical staining were used to confirm the therapeutic effect of AuNPs@PDA-PLGA nanomembrane combined with ES on recovery of SCI. The results showed that AuNPs@PDA-PLGA nanomembrane had good property for NSCs growth. Nanomembrane combined with ES could effectively promote the proliferation and differentiation of NSCs. Animal experiments results showed that the combination of AuNPs@PDA-PLGA nanomembrane and ES could promote the regeneration of new neurons and the formation of neuronal synapses, thus decrease cavity area, which all contribute to the functional recovery of spinal cord injury. Our results suggest that AuNPs@PDA-PLGA nanomembrane combined with ES can effectively promote functional recovery of SCI and provide a promising therapeutic option for SCI treatment.

An ultrafast and low-power all-optical tunable metamaterial-induced transparency is realized, using polycrystalline barium titanate doped gold nanoparticles and multilayer tungsten disulfide microsheets as nonlinear optical materials. Large nonlinearity enhancement is obtained associated with quantum confinement effect, local-field effect, and reinforced interaction between light and multilayer tungsten disulfide. Low threshold pump intensity of 20 MW/cm² is achieved. An ultrafast response time of 85 ps is maintained because of fast carrier relaxation dynamics in nanoscale crystal grains of polycrystalline barium titanate. This may be useful for the study of integrated photonic devices based on two-dimensional materials. [ABSTRACT FROM AUTHOR]

The massive death of nerve cells and the inflammatory microenvironment resulting from the release of reactive oxygen species after spinal cord injury (SCI) hinders the subsequent reconstruction of motor function. Owing to complex pathological changes, combination therapy is a potential new way to treat SCI. In this study, a novel multifunctional hydrogel containing an MXene-Au complex was constructed, and neural stem cells (NSCs) loaded in the hydrogel were combined with electrical stimulation to promote the recovery of motor function after SCI in rats. The constructed MAu-GelMA hydrogel had good reactive oxygen species-scavenging ability, electrical conductivity, and antibacterial ability. Simultaneously, electrical stimulation promoted the proliferation and differentiation of NSCs into nerve cells and promoted the establishment of synaptic connections between neurons. In the rat SCI model, combined treatment using MAu-GelMA hydrogel carrying NSCs and electrical stimulation reduced the formation of cavities and glial scars, enhanced neuronal differentiation and myelin regeneration of NSCs in the injured area, and promoted the recovery of motor function after SCI. In conclusion, in this study, we constructed a novel multifunctional hydrogel capable of carrying NSCs, which upon combining with electrical stimulation during treatment, effectively promoted the recovery of motor function in rats with SCI, thereby providing a new combination therapy strategy for SCI. [ABSTRACT FROM AUTHOR]

All-optical tunable metamaterial-induced transparency is realized using polycrystalline lithium niobate doped with gold nanoparticles and multilayer molybdenum disulfide microsheets as a third-order nonlinear optical material. A low threshold pump intensity of 90 kW cm−2 is obtained based on nonlinearity enhancement associated with the quantum confinement effect, the local-field enhancement effect, and reinforced interaction between photons and the multilayer molybdenum disulfide microsheets. An ultrafast response time of 27.4 ps is maintained owing to the fast relaxation dynamics of bound electrons in the polycrystalline lithium niobate. This work may pave a way for the realization of ultrahigh speed information processing chips based on metamaterials. [ABSTRACT FROM AUTHOR]