Exosome/metformin-loaded self-healing conductive hydrogel rescues microvascular dysfunction and promotes chronic diabetic wound healing by inhibiting mitochondrial fission

Chronic diabetic wounds remain a globally recognized clinical challenge.They occur due to high concentrations of reactive oxygen species and vascular function disorders.A promising strategy for diabetic wound healing is the delivery of exosomes,comprising bioactive dressings.Metformin activates the vascular endothelial growth factor pathway,thereby improving angiogenesis in hyperglycemic states.However,multifunctional hydrogels loaded with drugs and bioactive substances synergistically promote wound repair has been rarely reported,and the mechanism of their combinatorial effect of exosome and metformin in wound healing remains unclear.Here,we engineered dual-loaded hydrogels possessing tissue adhesive,antioxidant,self-healing and electrical conductivity properties,wherein 4-armed SH-PEG cross-links with Ag^(+),which minimizes damage to the loaded goods and investigated their mechanism of promotion effect for wound repair.Multiwalled carbon nanotubes exhibiting good conductivity were also incorporated into the hydrogels to generate hydrogen bonds with the thiol group,creating a stable three-dimensional structure for exosome and metformin loading.The diabetic wound model of the present study suggests that the PEG/Ag/CNT-M+E hydrogel promotes wound healing by triggering cell proliferation and angiogenesis and relieving peritraumatic inflammation and vascular injury.The mechanism of the dual-loaded hydrogel involves reducing the level of reactive oxygen species by interfering with mitochondrial fission,thereby protecting F-actin homeostasis and alleviating microvascular dysfunction.Hence,we propose a drug-bioactive substance combination therapy and provide a potential mechanism for developing vascular function-associated strategies for treating chronic diabetic wounds.

Nanoscale electric field sensing using a levitated nano-resonator with net charge

The nanomechanical resonator based on a levitated particle exhibits unique advantages in the development of ultrasensitive electric field detectors. We demonstrate a three-dimensional, high-sensitivity electric field measurement technology using the optically levitated nanoparticle with known net charge. By scanning the relative position between nanoparticle and parallel electrodes, the three-dimensional electric field distribution with microscale resolution is obtained. The measured noise equivalent electric intensity with charges of 100e reaches the order of 1 μV·cm^(-1)·Hz^(-1/2)at 1.4 × 10^(-7) mbar. Linearity analysis near resonance frequency shows a measured linear range over 91 d B limited only by the maximum output voltage of the driving equipment. This work may provide an avenue for developing a high-sensitivity electric field sensor based on an optically levitated nano-resonator.

Yoctonewton force detection based on optically levitated oscillator

Optically levitated oscillators in high vacuum have excellent environmental isolation and low mass compared with conventional solid-state sensors,which makes them suitable for ultrasensitive force detection.The force resolution usually scales with the measurement bandwidth,which represents the ultimate detection capability of the system under ideal conditions if sufficient time is provided for measurement.However,considering the stability of a real system,a method based on the Allan variance is more reliable to evaluate the actual force detection performance.In this study,a levitated optomechanical system with a force detection sensitivity of 6.33±1.62 zN/Hz^(1/2)was demonstrated.And for the first time,the Allan variance was introduced to evaluate the system stability due to the force sensitivity fluctuations.The force detection resolution of 166.40±55.48 yN was reached at the optimal measurement time of 2751 s.The system demonstrated in this work has the best force detection performance in both sensitivity and resolution that have been reported so far for optically levitated particles.The reported high-sensitivity force detection system is an excellent candidate for the exploration of new physics such as fifth force searching,high-frequency gravitational waves detection,dark matter research and so on.

Insight into the rapid growth of graphene single crystals on liquid metal via chemical vapor deposition

Previous reports about the growth of large graphene single crystals on polycrystalline metal substrates usually adopted the strategy of suppressing the nucleation by lowering the concentration of the feedstock, which greatly limited the rate of the nucleation and the sequent growth. The emerging liquid metal catalyst possesses the characteristic of quasi-atomically smooth surface with high diffusion rate. In principle, it should be a naturally ideal platform for the lowdensity nucleation and the fast growth of graphene. However,the rapid growth of large graphene single crystals on liquid metals has not received the due attention. In this paper, we firstly purposed the insight into the rapid growth of large graphene single crystals on liquid metals. We obtained the millimeter-size graphene single crystals on liquid Cu. The rich free-electrons in liquid Cu accelerate the nucleation, and the isotropic smooth surface greatly suppresses the nucleation.Moreover, the fast mass-transfer of carbon atoms due to the excellent fluidity of liquid Cu promotes the fast growth with a rate up to 79 μm s^-1. We hope the research on the growth speed of graphene on liquid Cu can enrich the recognition of the growth behavior of two-dimensional(2 D) materials on the liquid metal. We also believe that the liquid metal strategy for the rapid growth of graphene can be extended to various 2 D materials and thus promote their future applications in the photonics and electronics.