Aptasensor Based on Screen-Printed Carbon Electrodes Modified with CS/AuNPs for Sensitive Detection of Okadaic Acid in Shellfish

Okadaic acid(OA),a small molecule substance derived from shellfish,is one of the most widely distributed marine toxins with acute symptoms of vomiting and diarrhea after accidental ingestion.For this,there is an urgently need for sensitive and reliable methods to detect OA in real shellfish samples.In this study,a simple aptasensor based on screen-printed carbon electrode(SPCE)with modification of chitosan(CS)and gold nanoparticles(Au NPs)was designed for electrochemical determination of OA,and the electrode surface was modified with Au NPs by potential-sweeping electrodeposition,which greatly improved the electrochemical response.The entire detection and characterization process were carried out by cyclic voltammetry(CV)with a linear correlation in the range of 0.01-100 ng/m L and a limit of detection(LOD)of 6.7 pg/m L.Furthermore,recovery rates of 92.3-116%were obtained demonstrating excellent accuracy through the recovery trial of mussel and scallop samples.

氧化石墨烯对红细胞功能的影响

纳米材料的生物相容性是人们关注的热点。氧化石墨烯是一种被广泛应用于生物医学的纳米材料,但其毒性不容忽视。本文从溶血率、红细胞脆性、乙酰胆碱酯酶活性三方面研究了氧化石墨烯对血液系统的毒性。结果表明,红细胞的溶血率在氧化石墨烯浓度低于100μg/mL时均低于8%(P<0.01);低浓度氧化石墨烯(<5μg/mL)对红细胞的脆性没有显著影响,高浓度氧化石墨烯(如10μg/mL)会提高红细胞的脆性(P=0.01);氧化石墨烯能增加红细胞上乙酰胆碱酯酶的活性,浓度为20μg/mL的直径>5μm的氧化石墨烯(LGO)可将乙酰胆碱酯酶的活性提高42.67%(P<0.05)。之后利用分子动力学模拟研究氧化石墨烯与乙酰胆碱酯酶相互作用并提高其活性的机理,推测氧化石墨烯会附着在细胞膜上并提供一个电负性环境,帮助水解产物更快地从活性位点脱离,从而提高乙酰胆碱酯酶的活性。

State of the art:Lateral flow assay(LFA) biosensor for on-site rapid detection

Recently, lateral flow assay （LFA） has attracted researchers＇ attention because of its considerable advantages of superior portability, rapid detection, cost-effectiveness and ease of use. This review provides a brief overview of latest researches of LFA, including the practical use of LFA in both qualitative and quantitative analysis in different areas. Though bio-recognition molecules in the LFA used to be antibodies, a new kind of recognition element called aptamer, showing significant advantages, is developed rapidly in recent years. The highly specific recognition of aptamers/antibodies and targets are combined with the excellent properties of a dry-reagent strip biosensor that enables efficiently detection in point-of-care applications. Herein, we compared the aptamers with antibodies, summarized the principle of LFAs, and three main elements for the LFAs （recognition molecule, signal transduction element, the targets）. Additionally, we summarized different optimal experimental conditions in the recent LFA-related studies to give detailed overview of the LFA development. We hope the review can give a general guide for the development of LFAs.

The protective effect of icariin on glucocorticoid-damaged BMECs explored by microfluidic organ chip

Osteonecrosis of the femoral head(ONFH)is a devastating musculoskeletal disease characterized by the impaired circulation of bone.The purpose of this study was to explore the underlying mechanisms of the protective effect of icariin on the glucocorticoid-induced injury of bone microvascular endothelial cells(BMECs).Normal BMECs were extracted from the femoral heads by enzymatic isolation and magneticactivated cell sorting methods.Dexamethasone and icariin were used to intervene BMECs in microfluidic organ chips,and phalloidin staining was conducted to observe the cell morphology and viability.Then next-generation transcriptome sequencing and real-time quantitative reverse transcription-polymerase chain reaction(q RT-PCR)were performed to identify the differentially expressed genes(DEGs)in different groups.Through the microfluidic organ chip,it can be observed that after dexamethasone intervention,the filamentous structure in cell fibers disappeared and the cell morphology changed from spindle to round until death.Icariin could relieve these changes and showed a protective effect on glucocorticoiddamaged BMECs.In addition,201 DEGs were detected between the icariin protection group and the dexamethasone group,which were significantly enriched in 17 signaling pathways.8 of the top ten selected hub genes(IL6,PTGS2,VEGFA,etc.)were confirmed by q RT-PCR.Transcription factors(TFs)-gene network showed 63 connections between 18 TFs and 12 DEGs.For instance,GATA2 could regulate 5 DEGs.The associations between 92 mi RNA and 12 DEGs were visualized in a mi RNA-gene network.The hub mi RNA,has-mir-335–5 p was predicted to interact with 8 DEGs(PTGS2,VEGFA,etc.).Microfluidic organ chips could provide excellent morphological results for cell experiments,by which it could be observed that icariin showed a protective effect on the glucocorticoid-induced injury of BMECs.Beside,these DEGs,possible regulatory TF(GATA2,FOXC1,etc.)and mi RNA(has-mir-335–5 p)might be dysregulated in the initiation of ONFH and have prospective importance in ONFH diagnosis and therapy.

Spatiotemporal Variability of Surface Wind Speed during 1961-2017 in the Jing-Jin-Ji Region,China

Wind speed variations are influenced by both natural climate and human activities.It is important to understand the spatial and temporal distributions of wind speed and to analyze the cause of its changes.In this study,data from 26 meteorological stations in the Jing-Jin-Ji region of North China from 1961 to 2017 are analyzed by using the Mann-Kendall(MK)test.Over the study period,wind speed first decreased by−0.028 m s^-1 yr^-1(p<0.01)in 1961^-1991,and then increased by 0.002 m s^-1 yr^-1(p<0.05)in 1992-2017.Wind speed was the highest in spring(2.98 m s^-1),followed by winter,summer,and autumn.The largest wind speed changes for 1961-1991 and 1992-2017 occurred in winter(−0.0392 and 0.0065 m s^-1 yr^-1,respectively);these values represented 36%and 58%of the annual wind speed changes.More than 90.4%of the wind speed was concentrated in the range of 1-5 m s^-1,according to the variation in the number of days with wind speed of different grades.Specifically,the decrease in wind speed in 1961^-1991 was due to the decrease in days with wind speed of 3-5 m s^-1,while the increase in wind speed in 1992-2017 was mainly due to the increase in days with wind speed of 2-4 m s^-1.In terms of driving factors,variations in wind speed were closely correlated with temperature and atmospheric pressure,whereas elevation and underlying surface also influenced these changes.

A cytoprotective graphene oxide-polyelectrolytes nanoshell for single-cell encapsulation

Graphene oxide(GO)has been increasingly utilized in the fields of food,biomedicine,environment and other fields because of its benign biocompatible.We encapsulated two kinds of GO with different sizes on yeast cells with the assistance of polyelectrolytes poly(styrene sulfonic acid)sodium salt(PSS)and polyglutamic acid(PGA)(termed as Y@GO).The result does not show a significant difference between the properties of the two types of Y@GO(namely Y@GO1 and Y@GO2).The encapsulation layers are optimized as Yeast/PGA/PSS/PGA/GO/PGA/PSS based on the morphology,dispersity,colony-forming unit,and zeta potential.The encapsulation of GO increases the roughness of the yeast.It is proved that the Y@GO increases the survival time and enhance the activity of yeast cells.The GO shell improves the resistance of yeast cells against pH and salt stresses and extends the storage time of yeast cells.