Electrochemical biosensors for point-of-care testing

Point-of-care testing(POCT)is the practice of diagnosing and monitoring diseases where the patient is located,as opposed to traditional treatment conducted solely in a medical laboratory or other clinical setting.POCT has been less common in the recent past due to a lack of portable medical devices capable of facilitating effective medical testing.However,recent growth has occurred in this field due to advances in diagnostic technologies,device miniaturization,and progress in wearable electronics.Among these developments,electrochemical sensors have attracted interest in the POCT field due to their high sensitivity,compact size,and affordability.They are used in various applications,from disease diagnosis to health status monitoring.In this paper we explore recent advancements in electrochemical sensors,the methods of fabricating them,and the various types of sensing mechanisms that can be used.Furthermore,we delve into methods for immobilizing specific biorecognition elements,including enzymes,antibodies,and aptamers,onto electrode surfaces and how these sensors are used in real-world POCT settings.

Wave-shaped microfluidic chip assisted point-of-care testing for accurate and rapid diagnosis of infections

Background:Early diagnosis and classification of infections increase the cure rate while decreasing complications,which is significant for severe infections,especially for war surgery.However,traditional methods rely on laborious operations and bulky devices.On the other hand,point-of-care(POC)methods suffer from limited robustness and accuracy.Therefore,it is of urgent demand to develop POC devices for rapid and accurate diagnosis of infections to fulfill on-site militarized requirements.Methods:We developed a wave-shaped microfluidic chip(WMC)assisted multiplexed detection platform(WMC-MDP).WMC-MDP reduces detection time and improves repeatability through premixing of the samples and reaction of the reagents.We further combined the detection platform with the streptavidin–biotin(SA-B)amplified system to enhance the sensitivity while using chemiluminescence(CL)intensity as signal readout.We realized simultaneous detection of C-reactive protein(CRP),procalcitonin(PCT),and interleukin-6(IL-6)on the detection platform and evaluated the sensitivity,linear range,selectivity,and repeatability.Finally,we finished detecting 15 samples from volunteers and compared the results with commercial ELISA kits.Results:Detection of CRP,PCT,and IL-6 exhibited good linear relationships between CL intensities and concentrations in the range of 1.25–40μg/ml,0.4–12.8 ng/ml,and 50–1600 pg/ml,respectively.The limit of detection of CRP,PCT,and IL-6 were 0.54μg/ml,0.11 ng/ml,and 16.25 pg/ml,respectively.WMC-MDP is capable of good adequate selectivity and repeatability.The whole detection procedure takes only 22 min that meets the requirements of a POC device.Results of 15 samples from volunteers were consistent with the results detected by commercial ELISA kits.Conclusions:WMC-MDP allows simultaneous,rapid,and sensitive detection of CRP,PCT,and IL-6 with satisfactory selectivity and repeatability,requiring minimal manipulation.However,WMC-MDP takes advantage of being a microfluidic device showing the coefficients of variation less than 10%enabling WMC-MDP to be a type of point-of-care testing(POCT).Therefore,WMC-MDP provides a promising alternative to POCT of multiple biomarkers.We believe the practical application of WMC-MDP in militarized fields will revolutionize infection diagnosis for soldiers.

A smartphone-based automated fluorescence analysis system for point-of-care testing of Hg(Ⅱ)

This work demonstrates a smartphone-based automated fluorescence analysis system(SAFAS)for point-of-care testing(POCT)of Hg(Ⅱ).This system consists of three modules.The smartphone module is used to provide an excitation light source,and to collect and analyze fluorescent images.The dark box module is applied to integrate the desired optical elements and offers a dark environment.The cost of the integrated dark box mainly includes the upper cover,box body,lower bottom,¯xture and some optical elements which is about$109.The chip module is used for fluorescence sensing,which is composed of an upper plate,bottom plate and cloth-based chip.Due to the integration of multiple smartphone functions,the SAFAS eliminates the need for additional power sources,light sources and analysis systems.The dark box and upper and bottom plates are made by 3D printer.The cloth-based chip(about$0.005 for each chip)is fabricated using the wax screenprinting technique,with no need for expensive and complex fabrication equipments.To our knowledge,the cloth-based microfluidic fluorescence detection method combined with smartphone functions is first reported.By using optimal conditions,the designed system can realize the quantitative detection of Hg(Ⅱ),which has a linear range of 0.001–100μgmL^(-1)and a detection limit of 0.5 ngmL^(-1).Additionally,the SAFAS has been successfully applied for detecting Hg(Ⅱ)in actual water samples,with recoveries of 100.1%–111%,RSDs of 3.88%–9.74%,and fast detection time of about 1 min.Obviously,the proposed SAFAS has the advantages of high sensitivity,wide dynamic range,acceptable reproducibility,good stability and low cost.Therefore,it is believed that the presented SAFAS has great potential to perform the POCT of Hg(II)in different water samples.

Point-of-Care Testing vs. Laboratory Testing during High Patient Volume Situations

Introduction: Our aim was to determine what patient volume, if any, in-laboratory testing provides results faster than Point-of-Care-Testing (POCT). Methods: To evaluate POCT effectiveness during high volume situations, POCT was compared to in-laboratory testing during busy periods with large numbers of patients. Our setting was an urban level 1 trauma center with an academic emergency medicine department (ED) and annual patient volume of 70,000. Patients seen requiring laboratory testing during peak volume between 11 a.m. and 7 p.m. were enrolled over a five-week period. One tube of blood was sent to the laboratory and the other tube was run in the ED using POCT. Turnaround time was recorded as time from when the tube was received to when the result was available. We also completed a time-motion study to assess the number of POCT machines that would be needed to process the entire average hourly hospital laboratory volume. Results: We collected 539 hematology and chemistry specimens. The POCT group was significantly faster than in-laboratory testing, with mean POCT [complete blood count (CBC) and chemistry] 3.5 minutes compared to in-laboratory CBC test time of 30.9 minutes and chemistry test time of 55 minutes. As the volume of samples peaked, there was a slight but insignificant decrease in POCT turnaround time. If POCT was used to process the entire average hospital laboratory volume which approached 54 samples an hour, 3 POCT machines would be necessary to maintain turnaround times. Conclusion: Even during ED high volume situations, POCT provided results significantly faster than in-laboratory testing.

Point-of-Care Testing Using Three Dimensional Optical Biosensor Based on Microfluidic Technology

We have presented a three dimensional optical protein chip that fulfills the demanding for point-of-care diagnostics in terms of ease-of-use (one step assay), miniaturization (5 μl). The artful combination of magnetic nanoparticles on chip and total internal reflection imaging (TIRI) technology permits the sensitive and rapid detection of hs-CRP (high-sensitivity C-reactive protein). The whole test was complete within 10 min using “all in one step” assay with a limit of detection of 0.1 ng/mL hs-CRP. The measuring range for hs-CRP could be extended to 10 ng/mL. The chip can also be used to detect more parameters in blood samples.

Recent progress on rapid diagnosis of COVID-19 by point-of-care testing platforms

The outbreak of COVID-19 has drawn great attention around the world.SARS-CoV-2 is a highly infectious virus with occult transmission by many mutations and a long incubation period.In particular,the emergence of asymptomatic infections has made the epidemic even more severe.Therefore,early diagnosis and timely management of suspected cases are essential measures to control the spread of the virus.Developing simple,portable,and accurate diagnostic techniques for SARS-CoV-2 is the key to epidemic prevention.The advantages of point-of-care testing technology make it play an increasingly important role in viral detection and screening.This review summarizes the point-of-care testing platforms developed by nucleic acid detection,immunological detection,and nanomaterial-based biosensors detection.Furthermore,this paper provides a prospect for designing future highly accurate,cheap,and convenient SARS-CoV-2 diagnostic technology.

A Point-of-Care Test System for Biochemical Blood Analysis Based on ADUC824

A point-of-care test system has been studied in this paper.It was used to determine substances in blood such as Hemoglobin (HB),Aspartate Aminotransferase (AST),Creatine Kinase (CK) and so on.Based on the principle of amperometric determination,the research on detecting weak current signals was carried on.At the same time as to the weak signals (nA level),magnifying,sampling and processing the signals were also studied.Controlled by ADUC824 and assisted by other units, every substance could be determined automatically and rapidly integrated with the corresponding biosensor.In the experiment, the minimum detectable current of the instrument (YT2005-1) is 0.2 nA.With regard to the 1 nA which the experiment demanded,it could be up to the mustard.And the system can provide results in 180 s with a long term stability.

Portable and automated analyzer for rapid and high precision in vitro dissolution of drugs

We developed a novel portable and automated dissolution test analyzer for rapid and high precision in vitro dissolution testing of drugs.The analyzer consists of a flow-through-cell drug dissolution system,an automated sequential sampling system,a high-speed capillary electrophoresis(HSCE)system,and a data acquisition system.Combining the high-temporal resolution flow-gating sampling approach with HSCE,which has outstanding advantages of efficient separation and resolution,the analyzer can achieve rapid analysis and exhibits the ability in miniaturization for on-site assessment of different active pharmaceutical ingredients.To integrate the flow-through-cell dissolution system with HSCE,a specially designed flow-gating-injection(FGI)interface was employed.The performance of the analyzer was investigated by analyzing the dissolution of immediate-release drugs including single dose(amoxicillin dispersible tablets)and fixed dose combination(amoxicillin and clavulanate potassium)drug tablets with the high-temporal resolutions of 12 s and 20 s,respectively.The dissolution profiles of different active pharmaceutical ingredients could be simultaneously and automatically monitored with high repeatability and accuracy.The analyzer was successfully utilized for the pharmaceutical quality control and bio-relevant dissolution testing,as well as in vivo-in vitro correlation analysis.Our portable analyzer is miniaturized,convenient and of low-cost,and will provide a valuable tool for dissolution testing in pharmaceutical research and development.

Point-of-care ultrasound for critically-ill patients: A mini-review of key diagnostic features and protocols

Point-of-care ultrasonography(POCUS)for managing critically ill patients is increasingly performed by intensivists or emergency physicians.Results of needs surveys among intensivists reveal emphasis on basic cardiac,lung and abdominal ultrasound,which are the commonest POCUS modalities in the intensive care unit.We therefore aim to describe the key diagnostic features of basic cardiac,lung and abdominal ultrasound as practised by intensivists or emergency physicians in terms of accuracy(sensitivity,specificity),clinical utility and limitations.We also aim to explore POCUS protocols that integrate basic cardiac,lung and abdominal ultrasound,and highlight areas for future research.

A virtual logic analyzer implemented with Arduino

A simple,stable and reliable virtual logic analyzer is presented. The logic analyzer had two modules:one was the test pattern generation module,the other was the logic monitoring module. Combining the two modules,one is able to test a digital circuit automatically. The user interface of the logic analyzer was programmed with LabVIEW. Two Arduino UNO boards were used as the hardware targets to input and output the logic signals. The maximum pattern update rate was set to be 20 Hz. The maximum logic sampling rate was set to be 200 Hz. After twelve thousand cycles of exhaustive tests,the logic analyzer had a 100% accuracy. As a tutorial showing how to build virtual instruments with Arduino,the software detail is also explained in this article.

Point-of-care testing for lysine concentration in swine serum via blue-emissive carbon dot-entrapped microfluidic chip

Lysine is one of the essential amino acids and plays a vital role in the growth,development and health of pigs.Blood lysine concentration is a direct indication of lysine status;however,current methods can not satisfy the demands for rapid and on-site lysine concentration measurement of swine serum.Here,we developed blue-emissive nitrogen-doped carbon dots as a fluorescence probe for the determination of lysine with high fluorescence quantum yield,stability,sensitivity and specificity.The carbon dots were entrapped within hydrogel microstructures to fabricate microfluidic chips for rapid assay for lysine quantification.We further developed an imaging attachment to integrate the microfluidic chip and a smartphone into a portable point-of-care testing platform.This platform requires only 3μL sample and has a linear detection range of 25 to 300μmol/L with a limit of detection less than 16μmol/L,which covers the normal range of lysine concentration in swine serum.We tested lysine concentration in swine serum using this platform with high accuracy,low sample consumption,and within 3 min.Together,these results may provide a rapid and portable platform for dynamic monitoring of swine lysine status and contribute to precise feed formula modulation with low-protein diet strategy.

Quantitative Testing of Defect for Gun Barrels

The magnetic flux leakage (MFL) method is commonly used in the nondestructive evaluation (NDE) of gun barrels. The key point of MFL testing is to estimate the crack geometry parameters based on the measured signal. The analysis of magnetic leakage fields can be obtained by solving Maxwell’s equations using finite element method (FEM). The radial component of magnetic flux density is measured in MFL testing. The peak-peak value, the separation distance between positive and negative peaks of signal and the lift-off value of Hall-sensor are used as the main features of every sample. This paper establishes the multi-regression equations related to the width (the depth) of crack and the main characteristic values. The regression model is tested by use of the magnetic leakage data. The experimental results indicate that the regression equations can accurately predict the 2-D defect geometry parameters and the MFL quantitative testing can be achieved.

14台POCT血气分析仪与中心实验室检测结果的一致性分析

目的分析14台床旁检测(POCT)血气分析仪和中心实验室血气分析仪检测结果的一致性。方法采用中心实验室血气分析仪及14台POCT血气分析仪分别检测3个浓度水平质控品,每天检测2次,连续检测4 d,共24次,根据检测结果计算pH、动脉血二氧化碳分压(PCO_(2))、动脉血氧分压(PO_(2))、K^(+)、Na^(+)、Cl^(-)、Ca^(2+)的均值、标准差和变异系数等;计算14台POCT血气分析仪检测结果与中心实验室检测结果的偏倚及偏倚率;应用ANOVA检验、Passing-Bablok回归分析对14台POCT血气分析仪与中心实验室检测结果一致性进行分析评价。结果14台POCT血气分析仪各比对项目检测结果的变异系数均小于生产商声明的性能范围。14台POCT血气分析各比对项目的检测结果与中心实验室的偏倚均小于国家卫生健康委员会临床检验中心室间质量评价标准。14台POCT台血气分析各比对项目的检测结果比较,差异均无统计学意义(P>0.05)。14台POCT血气分析仪检测结果与中心实验室pH值、PCO_(2)、PO_(2)、K^(+)、Na^(+)、Cl^(-)、Ca^(2+)检测结果模拟回归方程的截距和斜率均在95%置信区间,且P>0.05,与中心实验室检测结果具有高度的一致性。结论14台POCT血气分析仪具有良好的精密度,且14台POCT血气分析仪之间及与中心实验室间均具有较好的一致性。

自动粪便分析仪与人工复核法检测粪便结果的比较分析

目的比较自动粪便分析仪与人工复核法两种粪便检测方法的检验效果。方法收集2022年9月—2023年8月三明市第二医院就诊患者的9402份新鲜粪便标本,分别使用FA160自动粪便分析仪和人工复核法检测粪便有形成分(白细胞、红细胞、脂肪球、真菌)和隐血,记录两种方法的检测结果并进行统计学分析。结果自动粪便分析仪检测白细胞、红细胞、脂肪球、真菌和隐血的阳性检出率分别为4.90%、2.67%、6.31%、4.54%、25.34%,人工复核法阳性检出率分别为4.17%、2.22%、5.55%、5.29%、25.23%,自动粪便分析仪对粪便有形成分的阳性检出率除真菌略低于人工复核外,其他各项指标均高于人工复核,且差异均有统计学意义(均P<0.05),而粪便隐血试验的阳性检出率比较差异无统计学意义(P>0.05)。以人工复核法为标准,自动粪便分析仪检测白细胞、红细胞、脂肪球、真菌、隐血的阳性符合率分别为91.07%、96.17%、94.83%、78.07%、98.19%;阴性符合率分别为98.85%、99.46%、98.90%、99.56%、99.25%;阳性预测值分别为77.44%、80.08%、83.47%、90.87%、97.77%;阴性预测值分别为99.61%、99.91%、99.69%、98.79%、99.39%。结论自动粪便分析仪与人工复核法的检测结果虽然符合率较高,但还存在漏检和误检。因此对自动分析结果必须进行人工复核,提高检测结果的准确性,为临床提供可靠的参考依据。

三种石英晶体谐振器频率测试方法对比分析研究

测试石英晶体谐振器频率的传统方法有间接计算法、信号源起振法和网络分析仪法,三种方法各有大的缺陷。根据石英晶体谐振器频率的特点,提出三种新的测试方法:示波器测试法、频率计测试法和频谱仪测试法。这三种方法在基本测试原理、设备配置要求、测试精度和适用环境等方面存在差异。对三种方法的优缺点进行了详细比较,并针对不同应用条件提出了选用建议:如果只单纯测量石英晶体谐振器频率,选用频谱仪测试法;如果需要测量频率的同时还需要知道频率的特性等内容,宜选用频率计测试法;示波器测试法则可用在对石英晶体谐振器频率定性的粗测。此外,还根据各自的优势探讨了仪器协作测试的可能性。

泌尿系统疾病诊断中应用尿液沉渣隐血检验及尿液分析仪的价值

目的探讨尿液沉渣隐血检验及尿液分析仪在泌尿系统疾病诊断中的应用价值,以期为临床早期明确诊断、制订治疗方案提供参考依据。方法选取我院2020年6月至2022年6月就诊的260例泌尿系统疾病患者作为研究对象,入院后均行尿液沉渣隐血检验及尿液分析仪检测,以干化学试带法检验结果为“金标准”,比较尿液沉渣隐血检验、尿液分析仪检测单独、联合检查对红细胞、白细胞阳性诊断结果、诊断效能,并比较其对于不同类型泌尿系统疾病的检出率。结果与尿液沉渣隐血检验、尿液分析仪单独诊断比较,联合诊断对于红细胞阳性诊断灵敏度96.20%、准确度95.38%较高,漏诊率3.80%较低(P<0.05);与尿液沉渣隐血检验、尿液分析仪单独诊断比较,联合诊断对于白细胞阳性诊断灵敏度95.06%、准确度95.38%较高,漏诊率4.94%较低(P<0.05);且联合诊断对肾小球病、肾结石、急性肾炎综合征、肾肿瘤检出率高于尿液沉渣隐血检验、尿液分析仪单独诊断(P<0.05)。结论尿液沉渣隐血检验、尿液分析仪联合应用可有效提高泌尿系统疾病诊断效能,为临床早期诊断、鉴别疾病类型提供参考,以针对性制订治疗方案,改善预后。

阳极溶出伏安法便携式重金属分析仪性能测试方法研究

阳极溶出伏安法便携式重金属分析仪被广泛应用于水体、土壤、食品、固态物质的重金属含量检测。除镉、铅、铜外,使用该分析仪检测砷、汞、锌、铬、锰、镍、锡、铊、铁、钴、硒、银、碲、金、铋等重金属时,需选择合适的计量性能测试项目及测试方法。同时,JJF 2037-2023《便携式溶出伏安法重金属检测仪校准规范》对测量镉、铅、铜元素的便携式溶出伏安法重金属检测仪的计量特性及校准方法做出了要求。

基于顺序等效采样的DAC测试方法设计

当前数模转换器(DAC)测试面临不能兼顾采样精度与采样速率的问题,测试时通常只能二者选其一,随着DAC器件的发展,常规测试系统不能满足当前测试领域需求。针对采样速率提升导致系统噪声提高,最终使采样系统有效分辨率恶化的问题,在分析对比了当前采样技术和系统噪声影响的基础上,提出了基于顺序等效采样的DAC测试方法。该方法将高频的原始信号在时间域上展开,其核心是制造采样周期与输入信号的周期的固定频差以进行分周期采样。对采样时钟抖动对系统有效位数的影响进行分析,确定了系统的最大时钟抖动,根据被测信号周期特征设计了测试系统的采样结构与周期。并对一款16bit、500MHz输出的DAC进行了测试,其结果与传统外挂频谱仪的测试结果进行对比。对比结果表明两次实验获得的频谱特征一致,采用本文设计的测试系统获得的测试结果得到了约4dBc无杂散范围提升,约3dBc双音交调参数提升,证明基于顺序等效采样DAC测试方法的有效性。

异侧竖缝式鱼道的数值模拟及试验研究

竖缝式鱼道具有隔板型式简单、水流条件好、主流位置明确等特点,适宜喜爱不同水层鱼类洄游,是目前应用最为广泛的过鱼工程。参考规范要求,以实际工程为例,初步设计3种鱼道池室隔板型式,利用数值模拟的方法,以第1种鱼道池室结构搭建数学模型计算出的竖缝位置流速和池室表层水流流态,与物理模型试验结果进行对比,验证数学模型隔板型式尺寸优化的合理性。根据池室内的水力特性优化隔板型式,对确定的优化隔板型式以比尺为1∶5的局部物理模型试验对不同竖缝处不同水深进行流速测量,以尺为1∶20的整体物理模型试验对竖缝处流速以及沿程水深进行测量。试验结果表明,当鱼道出口水深不小于进口水深时,即运行工况1和运行工况4,各隔板竖缝附近流速均小于设计流速1.2 m/s,当鱼道出口水深小于进口水深时,即运行工况2和运行工况3,鱼道进口处隔板竖缝附近流速较大,运行工况2时,最大流速为1.319 m/s;运行工况3时,最大流速为1.561 m/s,均超过设计流速1.2 m/s。建议鱼道在工况1和工况4条件下运行。同时对始水状态下鱼道的水力特性进行分析,建议采用流速为4 m/s的冲击流速值加强对鱼道首部数级水池隔板与导板的结构设计。

某独居石精矿污染物的去除技术研究

针对某独居石精矿在综合回收过程中出现碱转矿浆变红、酸溶矿浆黏稠起泡沫导致产品变色、生产能力下降问题,采用扫描电子显微镜、红外光谱分析等手段对矿石污染物成分进行分析,并通过条件试验和半工业试验研究了煅烧法对独居石精矿污染物的去除效果。结果表明:碱转变色主要是由覆盖在独居石表面的含羧基、苯环或环烷烃的有机质造成;在煅烧温度400℃、煅烧时间40min条件下,碱转矿浆COD去除率大于94%,有机质去除效果较好,能解决生产处理能力下降30%的问题,还能降低电耗、能耗,解除生产中冒槽引发的职业健康等安全环保风险,同时保证铀、稀土回收率。该法完善了独居石加工流程,具有一定推广价值。