重组抗CD52人源化单克隆抗体ELISA检测方法的建立

目的:建立一种灵敏、特异、快速的ELISA方法,用于检测食蟹猴血清中重组抗CD52单克隆抗体的含量。方法:采用双抗夹心ELISA法对重组抗CD52单克隆抗体进行定量。以猴血清吸附的羊抗人Ig G作为包被抗体,稀释的猴血清吸附的羊抗人Ig G-HRP(二抗)作为检测抗体,加入底物显色剂后在酶标仪上读取D450nm值。结果:建立并确证了检测重组抗CD52单克隆抗体的ELISA方法,方法的线性范围为7.81~500 ng/m L,定量下限为7.81 ng/m L,板内及板间精密度和准确度均在±15%以内,室温、冻融、稀释效应稳定性良好。结论:方法学验证表明ELISA法测定食蟹猴血清中重组抗CD52单克隆抗体浓度的特异性、精密度和准确度均满足新生物制药临床前药代动力学研究指导原则要求,可用于重组抗CD52单克隆抗体的检测。     

抗 DR5单克隆抗体 ELISA 检测新方法的建立

目的:建立一种灵敏、特异、快速的 ELISA 方法,用猕猴血清中抗死亡受体5(DR5)单克隆抗体的检测.方法:采用双抗夹心 ELISA 法,用猴血清吸附的羊抗人 IgG 包被96孔酶标板,加入待测样品,用 HRP 标记的猴血清吸附的羊抗人 IgG 进行检测,加底物显色,读取 D450nm值.结果:建立了检测抗 DR5单克隆抗体的 ELISA 方法并进行了确证,方法的线性范围为12.5~800 ng/mL,定量下限为12.5 ng/mL,板内和板间精密度均小15%,准确度为±15%,冻融稳定性和稀释稳定性良好.结论:方法学确证结果表明,本研究建立的抗 DR5单克隆抗体检测方法符合新生物制品临床前药代动力学研究指导则要求,可用抗 DR5单克隆抗体的检测.     

重组人鼠嵌合抗CD20单克隆抗体免疫原性检测方法的建立

目的:建立一种灵敏、特异、操作简单的ELISA方法,用于检测食蟹猴血清中抗CD20单克隆抗体的免疫原性。方法:首先采用桥连ELISA法对抗药物抗体(ADA)进行定性筛选,以抗CD20单克隆抗体作为包被抗体,以生物素标记的抗CD20单克隆抗体作为检测抗体,二者共同结合血清中存在的ADA,以D450/560nm值超过临界值作为阳性判断标准;初筛为阳性的样本采用免疫清除法进一步确证,并同时进行免疫交叉试验考察ADA对供试品和原研对照品的免疫反应有无差异。结果:建立了检测ADA的筛选方法和确证方法,确定了检测的临界值和归一化因子,血清中抗药物抗体的检测灵敏度达3.5 ng/m L,批内/批间精密度介于3.1%~7.4%,准确度介于-1.2%~9.5%;食蟹猴连续给药后,部分个体产生特异性抗体,且抗体滴度随时间延长而增高。结论:建立的ADA筛选方法和确证方法可用于毒性试验的免疫原性检测;动物给药剂量对抗体的产生有较大影响,低剂量连续给药更易诱发特异性抗体产生。     

定量检测重组抗白介素6受体人源化单克隆抗体HS628的ELISA方法的建立及确证

目的:建立一种灵敏、特异、快速、经济的ELISA方法,用于检测食蟹猴血清中重组抗白介素6受体人源化单克隆抗体HS628的含量。方法:对ELISA与生物素-亲和素ELISA(BA-ELISA)方法进行比较,最终采用BA-ELISA法对HS628进行定量。包被抗体为羊抗人Ig G单抗,以生物素标记的重组白介素6受体作为检测抗原,以HRP标记的链霉亲和素作为放大剂,最终用单组分显色液(TMB)显色。结果:建立了特异性检测HS628的ELISA方法并完成方法学确证,该方法的线性范围为1.64~400 ng/m L,灵敏度为1.64 ng/m L,精密度、准确度、回收率及稳定性符合要求,与对照品校正标准曲线吻合。结论:用建立的ELISA方法测定猴血清中HS628的含量能满足新生物制药临床前药代动力学研究指导原则要求,可用于HS628的检测。     

基于抗CD20单克隆抗体的2种夹心ELISA法的建立

目的:建立和比较2种灵敏、特异的夹心ELISA方法,用于准确定量检测食蟹猴血浆中重组抗CD20人源化单克隆抗体(rh-anti-CD20zumab)浓度。方法:以rh-anti-CD20zumab为基础,分别用山羊抗人IgG F(ab')2抗体和驴抗人IgG Fc抗体包被96孔酶标板,加入待测样品,均采用HRP标记的猴血清吸附的山羊抗人IgG抗体进行检测,加底物显色,读取D450nm值。结果:建立了2种定量检测rh-anti-CD20zumab的夹心ELISA方法并进行了确证,样品的前处理分别为1∶20和1∶10,方法的线性范围分别为40~5000和40~12 500 ng/mL,定量下限均为40 ng/mL,两者的板内、板间精密度分别小于16.2%和19.4%,准确度分别为-10.3%~16.6%和-14.4%~12.9%。2种方法均具有良好的特异性和稀释线性,且都未出现钩状效应。结论:方法学确证表明,本研究建立的2种ELISA法均符合新生物制品临床前药代动力学研究指导原则的要求,可用于rh-anti-CD20zumab的检测,为后续rh-anti-CD20zumab在食蟹猴体内的药代动力学研究提供了不同的检测方法。     

检测重组人鼠嵌合抗VEGFR2单克隆抗体的ELISA方法的建立

目的:建立一种新型、快速定量检测食蟹猴血清中抗血管内皮生长因子受体2(VEGFR2)单克隆抗体浓度的方法。方法:将特异性抗原VEGFR2-His包被在固相载体上,加稀释的受试药品血清,然后加入HRP标记的羊抗人IgG-(h+1),再加入TMB显色液,最后加入1 mol/L硫酸终止液,在酶标仪上用双波长读取D_(450/560nm)值。结果:建立了定量检测食蟹猴血清中抗VEGFR2单克隆抗体浓度的ELISA法,方法的线性范围为400~6.25 ng/m L,定量下限为6.25ng/m L,板内精密度介于-13.6%~8.3%,板间精密度介于-6.1%~6.3%,与Avastin、Actemra、Cetuximab均无交叉,室温稳定性及冻融稳定性良好,无稀释效应。结论:通过方法学的确证,本实验建立的方法可满足抗VEGFR2单克隆抗体在食蟹猴体内的药代动力学研究要求,可用于抗VEGFR2单克隆抗体的检测。     

抗体偶联小分子药物T-DM1的ELISA检测方法的建立

目的:建立一种灵敏、特异、快速的ELISA方法,用于检测猕猴血清中T-DM1的含量。方法:采用双抗夹心ELISA法对T-DM1进行定量。以DM1单抗作为一抗包被到96孔板中,加入待检样品,之后再加入稀释好的猴血清吸附的羊抗人IgG-HRP(二抗),使之与结合到一抗上的T-DM1特异性结合,加底物显色,在酶标仪上读取D450nm值。结果:建立了检测T-DM1的ELISA方法并得到确证,方法的线性范围为0.625~80 ng/mL,定量下限为0.625 ng/mL,板内及板间精密度和准确度均在±15%以内,室温、冻融、稀释效应稳定性良好。结论:方法学验证表明ELISA法测定猴血清中T-DM1浓度的特异性、精密度和准确度均满足新生物制药临床前药代动力学研究指导原则要求,可用于T-DM1的检测。     

检测恒河猴血清中trastuzumab浓度的一种直接酶联免疫竞争法

采用ELISA法建立检测恒河猴血清中trastuzumab的酶联免疫竞争法,为研究人体内trastuzumab的药物动力学学和药效学提供依据。方法的测量范围是1～100μg／mL,最低检测限为1．0μg／mL。板内精密度范围91％～107％,相对标准偏差为1．5％～4．9％。板间精密度范围102％～110％,相对标准偏差为2．7％～15．4％。方法中未显示与重组人Ⅱ型肿瘤坏死因子受体-抗体融合蛋白、重组抗CD20单克隆抗体、丙种球蛋白等的交叉反应。此方法的特异性、灵敏度、精密度和准确度均满足恒河猴血清样品的分析,是检测猴和人体内trastuzumab的理想方法。     

采用免疫亲和色谱方法从骆驼血清中纯化抗CD47特异性抗体

本研究从骆驼血清中制备抗CD47特异性抗体并分析其与重组蛋白CD47和EC9706细胞膜表面CD47结合情况。从骆驼血清中纯化出总Ig G,再利用偶联上CD47的CNBr琼脂糖树脂免疫亲和纯化出抗CD47特异性抗体,通过ELISA和Western blotting验证其结合情况,通过细胞ELISA鉴定抗CD47特异性抗体与食管癌细胞膜表面CD47结合。结果显示通过两步免疫亲和色谱成功获得抗CD47特异性抗体,ELISA和Western blotting说明该抗体与重组蛋白CD47有强的结合活性和特异性,细胞ELISA检测抗CD47抗体浓度在20μg/mL时与EC9706细胞表面CD47有较好的结合。本研究首次利用免疫亲和色谱方法从骆驼血清中获得抗CD47特异性抗体,并与食管癌细胞有一定的结合活性,为肿瘤靶向治疗提供了可能。     

抗Trx单克隆抗体用于血吸虫病诊断的研究

目的：建立双抗体夹心ELISA 法检测日本血吸虫硫氧还蛋白（Thioredoxin,Trx）。方法：用重组日本血吸虫Trx（rTrx）蛋白免疫BALB/c 小鼠,筛选高滴度、高特异性的单克隆抗体建立双抗体夹心ELISA法。通过检测日本血吸虫排泄- 分泌物（excretorysecretions,ES）与rTrx的浓度评价该方法的敏感性;通过对健康人血清的检测确定其特异性;通过对布氏姜片吸虫病、华支睾吸虫病、卫氏并殖吸虫病、囊虫病患者血清进行交叉反应试验,评价该方法的特异性。结果：获得2 株稳定分泌抗rTrx 蛋白单克隆抗体的杂交瘤细胞株,命名为McTrx1 和McTrx2。以McTrx1 为包被抗体,HRP-McTrx2 为酶标抗体,建立的双抗体夹心ELISA 可检测出ES的最低浓度为4.8 μg/ml,检测出rTrx 的最低浓度为1.2 滋g/ml。该方法的特异性为96 %。结论：以抗rTrx 蛋白单克隆抗体McTrx1 与McTrx2为基础建立的双抗体夹心ELISA 法具有较高的特异性。     

Epipolarization Microscopic Immunogold Assay: a Combination of Immunogold Silver Staining, Enzyme-Linked-Immunosorbent Assay and Epipolarization Microscopy

We describe a new immunoassay which combines an immunosorbent assay, Immunogold silver staining and epipolarization microscopy. Our new assay procedure features multiple samples on a single microscope slide, and high sensitivity of epipolarization microscope for detection of silver-enhanced colloidal gold as a final immunoassay product. We call the new immunoassay “on slide immunogold assay” (OSIGA). This new method uses biotinylated antibody and streptavidin-gold reaction with silver enhancement technique. With OSIGA it is possible to investigate 30 samples on a single microscopic slide. Our preliminary studies used 10-20 μ1 samples and detected nanogram quantities of a standardized protein solution. Unlike enzyme linked immunosorbent assay (ELISA), which has a limited time for reading the final color products, the OSIGA specimens can be dried or resin mounted for longer storage and future reference.     

One-step enzyme immunochromatographic assay for theophylline

The convenience of the previously described enzyme immunochromatography method for visually quantifying theophylline in whole blood has been improved with the development of a one-step protocol. The capillary migration and color generation in the two-step enzyme immunochromatographic assay have been combined into a single step. Ascorbic acid is used as a signal inhibitor to delay enzymatic color product formation until the inhibitor itself is consumed. The concept of internal delay reaction is presented and the mechanism of ascorbate's action as an inhibitor to temporarily delay color generation is described. The internal delay reaction has been applied to a practical one-step quantitative visual enzyme immunochromatographic assay for theophylline in whole blood.     

A simple activity staining protocol for lipases and esterases

A simple activity staining protocol for rapid detection and differentiation of lipases and esterases was developed based on pH drop due to fatty acids released following lipolysis. Though the detection of lipolysis as a function of drop in pH is not new, the present method has been made more sensitive by the judicious selection of the initial pH of the chromogenic substrate, which has been set near the end point of the dye so that even a slight drop in pH results in immediate color change. In the present case, the dye phenol red was taken, which has the end point at pH 7.3–7.4 where the color is pink. A slight drop due to fatty acid release results in yellow coloration. The assay has high reproducibility and can detect as low as 0.5 p-NPP enzyme units within 15 min. In addition, this method can be used for various lipidic substrates such as oils and tributyrin, making it suitable for both lipases and esterases.     

A method for screening penicillin G acylase-producing bacteria by means of 2-nitro-5-phenylacetaminobenzoic acid test paper

A simple, rapid assay for screening penicillin G acylase-producing bacteria is presented. The method is based on the formation of yellow 2-nitro-5-aminobenzoic acid by penicillin G acylase acting on 2-nitro-5-phenylacetaminobenzoic acid (NIPAB). NIPAB test paper is briefly applied to bacterial colonies on the agar surface, which are subsequently scored individually on the paper by color; bright yellow indicates the presence of penicillin G acylase, natural color its absence. The present method is suitable not only for screening penicillin G acylase-production by a variety of bacteria but also for detection from a large number of transformant colonies of clones containing a gene encoding for the enzyme.     

Hydroxamate-based colorimetric method for direct screening of transglutaminase-producing bacteria

Microbial transglutaminase (MTGase) is a commercial enzyme that has been applied to many protein containing foods to improve their textural property. The screening of MTGase-producing microorganisms from various sources might lead to the discovery of a new MTGase with different characteristics. This report demonstrates the use of a direct detection method for MTGase-producing bacteria grown on an agar plate by filter paper disc (FPD) assay. The principle of the assay is the formation of a red burgundy color by the hydroxamate-ferric complex. The color developed intensity was linearly correlated by the concentration of hydroxamic acid in the range of 0.1-0.8 μM and was visually scored at 4 levels: 0, 1, 2 and 3. Streptoverticillium mobaraense DSM 40847, a positive MTGase-producer, was chosen for the verification and improving of the proposed method. The colonies grown on the nutrient agar plate at 37°C for 24 h were covered with FPDs and 30 μl of substrates (CBZ-Gln-Gly and hydroxylamine). After incubation, 10 μl of the ferric-TCA-HCl solution was placed on the FPD. The optimal time taken to catalyze the formation of CBZ-Gln-Gly-hydroxamic acid by the MTGase and the time taken for the hydroxamate-ferric complex to form color were 180 and 60 min, respectively. Using this assay, 30 of 189 colonies isolated from wastewater and floating-floc samples showed MTGase-positive colonies which were well correlated to the quantitative screening of MTGase activity (R(2) = 0.9758). The results revealed that the FPD assay could be used for the qualitative screening of MTGase-producing bacteria.     

Detection of proteins using a colorimetric bio-barcode assay

The colorimetric bio-barcode assay is a red-to-blue color change-based protein detection method with ultrahigh sensitivity. This assay is based on both the bio-barcode amplification method that allows for detecting miniscule amount of targets with attomolar sensitivity and gold nanoparticle-based colorimetric DNA detection method that allows for a simple and straightforward detection of biomolecules of interest (here we detect interleukin-2, an important biomarker (cytokine) for many immunodeficiency-related diseases and cancers). The protocol is composed of the following steps: (i) conjugation of target capture molecules and barcode DNA strands onto silica microparticles, (ii) target capture with probes, (iii) separation and release of barcode DNA strands from the separated probes, (iv) detection of released barcode DNA using DNA-modified gold nanoparticle probes and (v) red-to-blue color change analysis with a graphic software. Actual target detection and quantification steps with premade probes take approximately 3 h (whole protocol including probe preparations takes approximately 3 days).     

Determination of L-carnitine by flow injection analysis with NADH fluorescence detection

A flow injection analysis method for determining L-carnitine is reported. The system uses the enzyme L-carnitine dehydrogenase covalently immobilized to Eupergit C. The NADH produced by the action of the enzyme, which is proportional to the L-carnitine concentration, is quantified using fluorescence detection. The system response was rapid and had a wide range of linearity. At a flow rate of 0.2 ml/min, a detection limit of 1 microM (20 pmol) was obtained for L-carnitine, peak areas were linear up to 100 microM, and samples could be injected every 4 min. The method performed well as a routine assay, showing high sensitivity (54,000 AU/microM), a precision of 0.96%, and the ability to carry out 144 consecutive assays with an RSD of 1.47% (good stability). Comparisons were made with other known methods for L-carnitine determination. Presence of D-carnitine had no effect on L-carnitine assay. The analysis was valid for determining L-carnitine concentrations in commercial pharmaceutical preparations.     

单管可视化环介导等温扩增技术快速检测恶性疟原虫

目的:建立一种基于环介导等温核酸扩增技术(Loop-mediated Isothermal Amplification,LAMP)的恶性疟原虫高灵敏可视化闭管检测方法。方法:针对恶性疟原虫核糖体DNA的序列保守区设计LAMP引物,通过优化LAMP体系中的Mg2+、甜菜碱浓度和反应温度等因素,建立环介导等温扩增法;并结合蜡封反应管对产物进行检测,检测结果可直接通过肉眼观察SYBR Green I荧光显色进行判定。结果:本方法可检测到70个拷贝/管的恶性疟原虫核酸片段,并具有高特异性,可区分检测常见的血液病毒。该法具有如下优点:1、整个反应恒温进行,无需热循环仪;2、闭管检测,极大降低了扩增产物交叉污染的风险;3、检测速度快,整个检测过程只需30 min。结论:该法的建立为恶性疟原虫的现场快速筛检提供了一种简便、高灵敏、高特异的工具。     

Recent developments in colorimetric immunoassays using nanozymes and plasmonic nanoparticles

Enzyme-linked immunosorbent assay (ELISA) is a popular detection technique for the screening and diagnosis of diseases. The sensitivity of ELISA can be increased by the incorporation of nanoparticles. Through this article, we discuss the utilization of nanoparticles in ELISA. Nanoparticles possess an intrinsic biological peroxidase-like activity which allows it to act as an enzyme mimic for the development of an improved analysis method. Different nanoparticles (gold nanoparticles, silver nanoparticles, etc.) carry different peroxidase-mimic characteristics. Besides this, nanoparticles can also perform as a colorimetric substrate in ELISA where it gives a more prominent color change compared to the commonly used colorimetric substrate TMB. This article also focuses on the mechanisms behind this color change including aggregation, in situ nanoparticle growth, seeding, and etching.