纳米金信号探针/石墨烯修饰免疫传感器检测微囊藻毒素

利用石墨烯纳米片层(GS)偶联牛血清白蛋白(BSA)标记的微囊藻毒素(MCLR)(BSA-MCLR)构建了纳米金(Au NPs)为信号探针的电流型免疫传感器。分别用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和紫外-可见吸收光谱对合成纳米材料进行表征;用循环伏安法研究修饰电极表面的电化学特性。通过待测MCLR与固定的BSA-MCLR竞争结合抗体(anti-MCLR),之后恒电位将Au NPs氧化为Au Cl-4,再利用差分脉冲伏安法(DPV)进行阴极电位扫描,还原Au Cl-4为Au,以产生的峰电流值为检测信号,测定MCLR浓度。最佳实验条件下,用免疫传感器测定MCLR的线性范围为0.1~50μg/L,检出限为0.05μg/L。对传感器的重现性、稳定性和选择性进行了考察。相较于酶标探针,以Au NPs为信号探针标记抗体,可使检测过程更经济便捷,稳定性更强,检测效果良好。     

液态金属原位引发制备半互穿网络水凝胶构建低污染电化学传感界面

复杂组分在传感界面的非特异性吸附会严重影响传感器的灵敏度与准确度。虽然构建致密的亲水性抗污涂层能够抑制表面非特异性吸附,但是其绝缘性又会显著增大传感界面阻抗,严重削弱响应电流。因此,如何兼顾传感界面抗污性与导电性,构建灵敏的传感基底是电化学免疫传感器目前急需解决的关键问题。为此,利用镓化铟液态金属（Liquid Metal, LM）原位引发乙烯基吡咯烷酮（N-vinylprrolidone, NVP）聚合,同时利用壳聚糖（Chitosan, CS）与聚乙烯基吡咯烷酮（poly（N-vinylprrolidone）, pNVP）之间强烈的氢键结合作用,再分步交联成功获得一种半互穿网络水凝胶传感界面,并以此构建电化学免疫传感器。研究表明,所构建的传感器能够对胃动素实现灵敏检测,线性范围为10 pg/mL~10 μg/mL,检测限为6.91 pg/mL（S/N=3）,并且在5%的血清样品中检测结果不受影响。此外,所构建的免疫传感器也显示出优异的重复性、稳定性和选择性。以上结果成功证明了基于液态金属纳米复合凝胶作为电化学传感基底的可行性,也为其它电化学免疫传感器的构建提供重要的借鉴意义。     

Electrochemical Immunosensor for the Sensitive Detection of Alzheimer's Biomarker Amyloid-β (1–42) Using the Heme-amyloid-β (1–42) Complex as the Signal Source

The amyloid-β peptide (1–42) (Aβ₄₂) can provide high diagnostic accuracy for the early diagnosis of Alzheimer's disease (AD). In this study, an immunosensor based on the peroxidase-like activity of heme-Aβ₄₂ was designed for Aβ₄₂ detection. The glassy carbon electrode (GCE) was electrodeposited Au particles (GCE/Au). The GCE/Au was modified using polythionine-methylene blue (PTH−MB), AuNPs, monoclonal antibody (anti-Aβ₄₂), and bovine serum albumin (BSA), successively. The GCE/Au/PTH−MB/AuNPs/anti-Aβ₄₂/BSA could competitively recognize Aβ₄₂ and heme-Aβ₄₂. The anchored heme-Aβ₄₂ showed strong electrocatalytic activity between H₂O₂ and ferrocenemethanol. Under optimum conditions, we determined detection limits of 17.3 pM in PBS pH 7, 25.2 pM in serum, and 23.8 pM in saliva. The recovery ranged from 71.0 % to 117.8 %.     

Use of polyclonal antibodies to ochratoxin A with a quartz–crystal microbalance for developing real-time mycotoxin piezoelectric immunosensors

A piezoelectric immunosensor was tested for ochratoxin A (OTA) mycotoxin detection through the immobilization of OTA–bovine serum albumin (OTA–BSA) conjugate on gold-coated quartz crystals (AT-cut/5 MHz). Immunoassays were performed in a flow-injection system through frequency decreases in a quartz–crystal microbalance (QCM) because of a mass increasing during immunoreaction with anti-OTA antibodies. Three immobilization procedures for OTA–BSA (direct adsorption and covalent attachment to two alkane thiol self-assembled monolayers) were characterized with QCM in real time. Covalent attachment of the OTA–BSA conjugates through gold nanoparticles was also tested for amplifying the signal. Binding of the excess of antibodies to the immobilized OTA in an indirect competitive analysis decreased linearly the resonant frequency in the range of the OTA concentration from 10 to 128 ng/mL, with a detection limit of 8 ng/mL (signal/noise ratio of 3). A pepsin 2 mg/mL (pH = 2.1) solution was used to release antigen–antibody complexes, regenerating the biorecognition surface.     

壳聚糖-纳米金复合膜修饰电化学发光免疫传感器检测人免疫球蛋白G

利用壳聚糖与纳米金良好的生物相容性及蛋白固定能力,制备了兼具导电性和透光性的人免疫球蛋白G(IgG)修饰膜,用于修饰玻碳电极,研制了新型电化学发光免疫传感器,并通过扫描电镜(SEM)及交流阻抗技术(EIS)考查了传感器表面性质.基于竞争免疫分析模式,以Ru(bpy)32+标记的羊抗人IgG为发光示踪物,采用新型共反应剂二丁基乙醇胺(DBAE)对光信号进行放大,建立了人IgG的检测方法,线性范围20ngmL-1～1.0μgmL-1,检测限6.5ngmL-1.将该电化学发光传感器应用于人血中IgG的检测,结果令人满意.     

A Simple and Low-Cost Electrochemical Immunosensor for Ultrasensitive Determination of Calreticulin Biomarker in Human Serum

An early on time detection of breast cancer significantly affects the treatment process and outcome. Herein, a new label-free impedimetric biosensor is developed to determine the lowest change in the level of calreticulin (CALR), which is a new biomarker of breast carcinoma. The proposed immunosensor is fabricated by using reduced graphene oxide/amino substituted polypyrrole polymer (rGO-PPyNH₂) nanocomposite modified disposable electrode. The anti-CALR antibodies are first attached on the rGO-PPyNH₂ nanocomposite coated electrode through glutaraldehyde crosslinking; the CALR antigens are then immobilized with the addition of CALR antigens to form an immunocomplex on the sensing surface. This immunocomplex induces considerably larger interfacial electron transport resistance (R_ct). The variation in the R_ct has a linear relationship with CALR level in the detection range of 0.025 to 75 pg mL⁻¹, with a detection limit of 10.4 fg mL⁻¹. The suggested biosensor shows high selectivity to CALR, good storage stability (at least 5 weeks) and suitable reproducibility results as shown in quality control chart. The designed immunosensor is utilized to analyze CALR levels in human sera with satisfying results. This immunosensor provides a novel way for the clinical determination of CALR and other cancer biological markers.     

Label‐free Electrochemical Immunosensor for Cardiac Troponin T Based on Exfoliated Graphite Nanoplatelets Decorated with Gold Nanoparticles

This paper describes the application of exfoliated graphite nanoplatelets (xGnP) decorated with gold nanoparticles (AuNP) for the development of a label‐free electrochemical immunosensor for the determination of human cardiac troponin T (TnT), an important cardiac biomarker in the diagnosis of acute myocardial infarction (AMI). Heparin‐stabilized AuNP (AuNP‐Hep) were synthesized, characterized and supported on xGnP. The material obtained (AuNP‐Hep‐xGnP) was used as a platform to immobilize the anti‐TnT by adsorption and this was then applied in the construction of an immunosensor. Under optimized conditions, using differential pulse voltammetry (DPV) and an incubation time of 20 min, the proposed immunosensor showed linearity in the range of 0.050 to 0.35 ng mL⁻¹ TnT, with a calculated limit of detection of 0.016 ng mL⁻¹. The interday precision (n=7) showed a coefficient of variation of 6.5 %. Some potential interferents commonly present in blood plasma samples were investigated and the degree of interference was found to be low (less than 10 %), demonstrating adequate selectivity for analytical applications. The biosensor was successfully applied in the determination of TnT in fortified samples of human blood plasma.     

基于一维DNA组装磁性纳米探针的夹心型安培免疫传感器研究

采用Fe3O4(核)/ZrO2(壳)纳米磁珠(ZMPs)标记待测物识别抗体,并用HRP酶封闭和DNA链接,建立了一类新型的"珠链状"一维磁性纳米探针制备方法。将甲胎蛋白(AFP)一抗固定于纳米金修饰的玻碳电极表面,构建了免疫电极(GCE?AFP Ab1)。基于该电极和上述合成探针,通过双抗体夹心法测定免疫产物上HRP酶对过氧化脲(CP)氧化对苯二酚反应的催化电流,研制了一类基于一维纳米结构组装的夹心型安培免疫传感器。研究表明:此一维纳米结构探针不仅大大增加了酶在电极表面的富集量,成倍扩增了催化电流,显著提高了传感器的灵敏度,而且易于通过外磁场与背景液可控分离,简化了分析步骤,并提高了结果的重复性。此传感器对AFP检测的线性范围为0.01~25 mg/L;检出限达4 ng/L(3σ),并被用于人血清中痕量AFP的测定,结果满意。     

基于碳纳米管修饰玻碳电极的唾液sIgA可再生免疫传感器

将壳聚糖(CHI)分散的羧基化多壁碳纳米管(MWCNT)吸附到玻碳电极(GCE)表面,形成负电荷界面,利用静电吸附和金-氮(Au-N)、金-硫(Au-S)共价键作用将阳离子电子媒介体硫堇(THI)和纳米金颗粒(GNPs)层层自组装到电极表面,通过纳米金单层吸附唾液分泌性免疫球蛋白A(sIgA),最后用辣根过氧化物酶(H...     

非标记液晶型免疫传感器检测赭曲霉素A

研制了一种基于液晶取向改变的非标记液晶型免疫传感器,并用于检测赭曲霉素A(0TA).采用戊二醛交联法将OTA同定在由自组装膜修饰的玻璃肇底表面.自组装膜能诱导液晶分子垂直排列,而连接OTA抗体后则扰乱了液晶分子取向的有序排列,导致液晶分子在化学敏感膜表面的取向发生变化,使光学信号的亮度及色彩发生变化,以此实现对OTA的...