A MXene-functionalized paper-based electrochemical immunosensor for label-free detection of cardiac troponin I

Convenient,rapid,and accurate detection of cardiac troponin I(cTnI)is crucial in early diagnosis of acute myocardial infarction(AMI).A paper-based electrochemical immunosensor is a promising choice in this field,because of the flexibility,porosity,and cost-efficacy of the paper.However,paper is poor in electronic conductivity and surface functionality.Herein,we report a paper-based electrochemical immunosensor for the label-free detection of cTnI with the working electrode modified by MXene(Ti_(3)C_(2))nanosheets.In order to immobilize the bio-receptor(anti-cTnI)on the MXene-modified working electrode,the MXene nanosheets were functionalized by aminosilane,and the functionalized MXene was immobilized onto the surface of the working electrode through Nafion.The large surface area of the MXene nanosheets facilitates the immobilization of antibodies,and the excellent conductivity facilitates the electron transfer between the electrochemical species and the underlying electrode surface.As a result,the paper-based immunosensor could detect cTnI within a wide range of 5-100 ng/mL with a detection limit of 0.58 ng/mL.The immunosensor also shows outstanding selectivity and good repeatability.Our MXene-modified paper-based electrochemical immunosensor enables fast and sensitive detection of cTnI,which may be used in real-time and cost-efficient monitoring of AMI diseases in clinics.

Catalysis-based specific detection and inhibition of tyrosinase and their application

Tyrosinase is an important enzyme in controlling the formation of melanin in melanosome,and plays a key role in the pigmentation of hair and skin.The abnormal expression or activation of tyrosinase is associated with several diseases such as albinism,vitiligo,melanoma and Parkinson disease.Excessive deposition of melanin could cause diseases such as freckles and brown spots in the human body,and it is also closely related to browning of fruits and vegetables and insect molting.Detecting and inhibiting the activity of tyrosinase is of extraordinary value in the progress of diagnosis and treatment of these diseases.Therefore,many selective optical detection probes and small molecular inhibitors have been developed,and have made significant contributions to the basic and clinical research on these diseases.In this paper,the detection and inhibition of tyrosinase and their application in whitening products are reviewed,with special emphasis on development of fluorescent probes and inhibitors.Hopefully,this review will help design more efficient and sensitive tyrosinase probes and inhibitors,as well as shed light on novel treatment of diseases such as melanoma.

Enhancing maize's nitrogen-fixing potential through ZmSBT3, a gene suppressing mucilage secretion∞

Maize(Zea mays)requires substantial amounts of nitrogen,posing a challenge for its cultivation.Recent work discovered that some ancient Mexican maize landraces harbored diazotrophic bacteria in mucilage secreted by their aerial roots.To see if this trait is retained in modern maize,we conducted a field study of aerial root mucilage(ARM)in 258 inbred lines.We observed that ARM secretion is common in modern maize,but the amount significantly varies,and only a few lines have retained the nitrogen‐fixing traits found in ancient landraces.The mucilage of the high‐ARM inbred line HN5‐724 had high nitrogen‐fixing enzyme activity and abundant diazotrophic bacteria.Our genome‐wide association study identified 17 candidate genes associated with ARM across three environments.Knockouts of one candidate gene,the subtilase family gene ZmSBT3,confirmed that it negatively regulates ARM secretion.Notably,the ZmSBT3 knockout lines had increased biomass and total nitrogen accumulation under nitrogen‐free culture conditions.High ARM was associated with three ZmSBT3 haplotypes that were gradually lost during maize domestication,being retained in only a few modern inbred lines such as HN5‐724.In summary,our results identify ZmSBT3 as a potential tool for enhancing ARM,and thus nitrogen fixation,in maize.

Two-photon dual-channel fluorogenic probe for in situ imaging the mitochondrial H_(2)S/viscosity in the brain of drosophila Parkinson’s disease model

H2S is an essential gas signal molecule in cells,and viscosity is a key internal environmental parameter.Recent studies have shown that H_(2)S acts as a cytoarchitecture agent and gas transmitter in many tissues,e.g.,as a regulator of neuroendocrine in the brain for mediating vascular tone in blood vessels.Mitochondrial viscosity is an important parameter for judging whether mitochondrial function is normal.It has been reported that oxidative stress and mitochondrial dysfunction are connected with Parkinson’s disease(PD),and the protective role of H_(2)S in PD models has been extensively demonstrated.Herein,Mito-HS,a new two-photon fluorescent probe was demonstrated to detect cross-talk between the two channels of mitochondrial viscosity and H_(2)S content.Moreover,this probe could detect the relative amount of and changes in mitochondrial H2S in situ due to the reduced mitochondrial targeting ability after reaction with H_(2)S.The results show that H2S in mitochondria is inversely related to viscosity.The PD model has a lower H2S in mitochondria and a higher mitochondrial viscosity than did the normal.This result is important for our deep understanding of PD and its causes.

Maize Gene Regulatory Network for Phenolic Metabolism

The translation of the genotype into phenotype, represented for example by the expression of genes encod- ing enzymes required for the biosynthesis of phytochemicals that are important for interaction of plants with the environment, is largely carried out by transcription factors （TFs） that recognize specific cis-regulatory elements in the genes that they control. TFs and their target genes are organized in gene regulatory net- works （GRNs）, and thus uncovering GRN architecture presents an important biological challenge necessary to explain gene regulation. Linking TFs to the genes they control, central to understanding GRNs, can be car- ried out using gene- or TF-centered approaches. In this study, we employed a gene-centered approach uti- lizing the yeast one-hybrid assay to generate a network of protein-DNA interactions that participate in the transcriptional control of genes involved in the biosynthesis of maize phenolic compounds including gen- eral phenylpropanoids, lignins, and flavonoids. We identified 1100 protein-DNA interactions involving 54 phenolic gene promoters and 568 TFs. A set of 11 TFs recognized 10 or more promoters, suggesting a role in coordinating pathway gene expression. The integration of the gene-centered network with informa- tion derived from TF-centered approaches provides a foundation for a phenolics GRN characterized by in- terlaced feed-forward loops that link developmental regulators with biosynthetic genes.

非传统溶液外延法在金属硫化物纳米片表面生长有机无机杂化钙钛矿纳米晶（英文）

基于外延异质结构的有机-无机杂化钙钛矿/二维纳米片复合材料在光电领域具有很好的应用前景,但目前使用的固相制备方法大大限制了这一目标的实现.我们通过精细调节溶剂环境,成功利用外延沉积的方式实现了在三角/六方相MoS_2纳米片表面生长立方相MAPbBr_3(MA=CH_3NH^+_3)钙钛矿纳米晶.虽然MAPbBr_3与MoS_2存在较大的晶格不匹配度,但是由于MoS_2纳米片性质柔软且表面缺失悬挂键,可以在两条不同方向上观察到较高容忍度(～1%错位)的外延生长关系.这种外延界面的形成有利于MAPbBr_3与MoS_2之间有效的能量转移,因此基于MAPbBr_3/MoS_2异质结的纸质器件与MAPbBr_3或MoS_2器件相比具有更优异的光电性能.此外,除了提高光吸收能力和能量传递, MoS_2纳米片的存在还为离散的MAPbBr_3纳米晶提供柔性和连续的基底,从而改善了MAPbBr_3纳米晶粒的成膜能力.这种液相外延法可用于高性能的有机无机杂化钙钛矿与二维材料的异质结构材料的大规模制备,将推动异质结构材料在光电领域的广泛使用.