Targeted alleviation of ischemic stroke reperfusion via atorvastatin-ferritin Gd-layered double hydroxide

In acute ischemic stroke therapy,potent neuroprotective agents are needed that prevent neural injuries caused by reactive oxygen species(ROS)during ischemic reperfusion.Herein,a novel 2D neuroprotective agent(AFGd-LDH)is reported,comprising Gd-containing layered double hydroxide nanosheets(Gd-LDH,as a drug nanocarrier/MRI contrast agent),atorvastatin(ATO,as a neuroprotective drug)and the ferritin heavy subunit(FTH,as a blood brain barrier transport agent).Experiments revealed AFGd-LDH to possess outstanding antioxidant activity,neuroprotective properties,blood‒brain barrier transit properties,and biocompatibility.In vitro studies demonstrated the ROS scavenging efficiency of AFGd‒LDH to be~90%,surpassing CeO_(2)(50%,a ROS scavenger)and edaravone(52%,a clinical neuroprotective drug).Ischemia‒reperfusion model studies in mice showed AFGd‒LDH could dramatically decrease apoptosis induced by reperfusion,reducing the infarct area by 67%and lowering the neurological deficit score from 3.2 to 0.9.AFGd-LDH also offered outstanding MRI performance,thus enabling simultaneous imaging and ischemia reperfusion therapy.

TFM imaging of aeroengine casing ring forgings with curved surfaces using acoustic field threshold segmentation and vector coherence factor

The aeroengine casing ring forgings have complex cross-section shapes,when the conventional ultrasonic or phased array is applied to detect such curved surfaces,the inspection images always have low resolution and even artifacts due to the distortion of the wave beam.In this article,taking a type of aeroengine casing ring forging as an example,the Total Focusing Method(TFM)algorithms for curved surfaces are investigated.First,the Acoustic Field Threshold Segmentation(AFTS)algorithm is proposed to reduce background noise and data calculation.Furthermore,the Vector Coherence Factor(VCF)is adopted to improve the lateral resolution of the TFM imaging.Finally,a series of 0.8 mm diameter Side-Drilled Holes(SDHs)are machined below convex and concave surfaces of the specimen.The quantitative comparison of the detection images using the conventional TFM,AFTS-TFM,VCF-TFM,and AFTS-VCF-TFM is implemented in terms of data volume,imaging Signal-to-Noise Ratio(SNR),and defect echo width.The results show that compared with conventional TFM,the data volume of AFTS-VCF-TFM algorithm for convex and concave is decreased by 32.39%and 73.40%,respectively.Moreover,the average SNR of the AFTS-VCF-TFM is gained up to 40.0 dB,while the average 6 dB-drop echo width of defects is reduced to 0.74 mm.

Function toggle of tumor microenvironment responsive nanoagent for highly efficient free radical stress enhanced chemodynamic therapy

In contrast to reactive oxygen species(ROS),the generation of oxygen-irrelevant free radicals is oxygen-and H2O2-independent in cell,which can offer novel opportunities to maximum the chemodynamic therapy(CDT)efficacy.Herein,an H2O2-independent“functional reversion”strategy based on tumor microenvironment(TME)-toggled C-free radical generation for CDT is developed by confining astaxanthin(ATX)on the NiFe-layered double hydroxide(LDH)nanosheets(denoted as ATX/LDH).The unique ATX/LDH can demonstrate outstanding TME-responsive C-free radical generation performance by proton coupled electron transfer(PCET),owing to the specific ATX activation by unsaturated Fe sites on the LDH nanosheets formed under TME.Significantly,the Brönsted base sites of LDH hydroxide layers can promote the generation of neutral ATX C-free radicals by capturing the protons generated in the ATX activation process.Conversely,ATX/LDH maintain antioxidant performance to prevent normal tissue cancerization due to the synergy of LDH nanosheets and antioxidative ATX.In addition,C-free radical can compromise the antioxidant defense in cells to the maximum extent,compared with ROS.The free radicals burst under TME can significantly elevate free radical stress and induce cancer cell apoptosis.This strategy can realize TME-toggled C free radical generation and perform free radical stress enhanced CDT.