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Ultrasensitive immunoassay

Shaohua Xu, Wenjun Ouyang, Peisi Xie, Yi Lin, Bin Qiu, Zhenyu Lin, Guonan Chen, Longhua Guo
Gold nanoparticles (AuNPs) have been frequently utilized for the construction of diverse colorimetric biosensors. Normally, AuNPs with sharp edges could have better sensitivity. However, the poor monodipersity of AuNPs with sharp edges seriously confines their utility for colorimetric biosensing. Herein, we demonstrate the utility of highly uniform gold nanobipyramids (Au NBPs) for ultrasensitive colorimetric detection of H5N1 virus. The proposed method is based on the fact that alkaline phosphatase (ALP) could catalyze the decomposition of 4-aminophenyl phosphate (4-APP) to generate 4-aminophenol (4-AP), which would then reduce silver nitrate to metal silver and then deposited on Au NBPs...
February 7, 2017: Analytical Chemistry
Priscila M Kosaka, Valerio Pini, Montserrat Calleja, Javier Tamayo
Early detection of HIV infection is the best way to prevent spread of the disease and to improve the efficiency of the antiretroviral therapy. Nucleic acid amplification tests (NAAT) have become the gold-standard for detecting low-concentrations of the virus in blood. However, these methods are technically demanding and cost-prohibitive in developing countries. Immunoassays are more affordable and can be more easily adapted for point-of-care diagnosis. However, the sensitivity so far of these methods has been too low...
2017: PloS One
Xueying Tu, Pir Muhammad, Jia Liu, Yanyan Ma, Shuangshou Wang, Danyang Yin, Zhen Liu
Glycoproteins play significant roles in many biological processes. Assays of glycoproteins have significant biological importance and clinical values, for which immunoassay has been the workhorse tool. However, immunoassay suffers from some disadvantages, such as poor availability of high-specificity antibodies and limited stability of biological reagents. Herein, we present an antibody-free and enzyme-free approach, called molecularly imprinted polymer (MIP)-based plasmonic immunosandwich assay (PISA), for fast and ultrasensitive detection of trace glycoproteins in complex samples...
December 20, 2016: Analytical Chemistry
Ting-Zhi Liu, Rong Hu, Xi Zhang, Kun-Lei Zhang, Yi Liu, Xiao-Bing Zhang, Ru-Yan Bai, Delei Li, Yun-Hui Yang
A novel and simple electrochemical immunoassay for C-reactive protein was developed using metal-organic frameworks (Au-MOFs) as signal unit. In this study, we found MOFs could be used as signal probe. And this new class of signal probe differs from traditional probe. The signal of the copper ions (Cu(2+)) from MOFs could be directly detected without acid dissolution and preconcentration, which would greatly simplify the detection steps and reduce the detection time. Moreover, MOFs contain large amounts of Cu(2+) ions, providing high electrochemical signals...
December 20, 2016: Analytical Chemistry
Yueyun Li, Yihe Zhang, Faying Li, Jinhui Feng, Mingdang Li, Lei Chen, Yunhui Dong
Recently early diagnosis of squamous cell carcinoma antigen (SCCA) as a tumor maker of various cancers has increasingly attracted a lot of attention with heightening of incidence rate of cancer. The SCCA with low concentration in human serum should be diluted before detecting. Thus, an immunoassay with high sensitivity is significant for early detecting SCCA. Therefore, a nonenzymatic sandwich-type electrochemical immunosensor herein was conducted to quantitative detection of squamous cell carcinoma antigen (SCCA)...
January 31, 2017: Biosensors & Bioelectronics
Lin Yang, Ming Xuan Gao, Lei Zhan, Min Gong, Shu Jun Zhen, Cheng Zhi Huang
Early detection of cancer is helpful for the control and prevention of diseases. Due to the low content of cancer biomarkers in the early disease phases, however, an ultrasensitive and selective method is critical. In this contribution, an ultrasensitive surface-enhanced Raman scattering (SERS) immunoassay is newly developed with the principle of introducing a common enzyme-induced deposition (EID) reaction to coat a silver layer on the surface of gold nanoparticles and to form a core-shell nanostructure of Au@Ag...
February 3, 2017: Nanoscale
Dingbin Liu, Xiaoyuan Chen
Enzyme-linked immunosorbent assay (ELISA) is a well-known strategy for biomarker detection with a color change, which can be seen by the naked eyes. However, the moderate sensitivity of conventional ELISA limits its applications in many cases where the concentrations of biomarker are very low, such as cancer diagnosis. Here we describe an ultrasensitive colorimetric assay based on acetylcholinesterase (AChE)-catalyzed hydrolysis reaction, whose products trigger the aggregation of gold nanoparticles (AuNPs), causing a distinct color change of the solution from red to purple...
2017: Methods in Molecular Biology
Lucía Blanco-Covián, Verónica Montes-García, Alexandre Girard, M Teresa Fernández-Abedul, Jorge Pérez-Juste, Isabel Pastoriza-Santos, Karen Faulds, Duncan Graham, M Carmen Blanco-López
Establishing a definitive diagnosis of pneumonia using conventional tests is difficult and expensive. Lateral flow immunoassays (LFIAs) are an advantageous point of care (POC) test option, but they have some limitations in terms of detection and quantification. In this work we have developed a lateral flow immunoassay for the ultrasensitive detection of penumolysin employing plasmonic Surface-Enhanced Resonance Raman Scattering (SERRS) tag as labelled probe. The combination of Au@Ag core-shell nanoparticles as plasmonic platform and Rhodamine B Isothiocyanate as Raman reporter has allowed us to fabricate a SERRS tag with high efficiency and reliability...
January 23, 2017: Nanoscale
Xiuli Fu, Lingxin Chen, Jaebum Choo
No abstract text is available yet for this article.
January 3, 2017: Analytical Chemistry
Jessica Gill, Kian Merchant-Borna, Andreas Jeromin, Whitney Livingston, Jeffrey Bazarian
OBJECTIVE: To determine whether tau changes after sport-related concussion (SRC) relate to return to play (RTP). METHODS: Collegiate athletes underwent preseason plasma sampling and cognitive testing and were followed. After a SRC (n = 46), athletes and controls (n = 37) had sampling at 6 hours, and at 24 hours, 72 hours, and 7 days after SRC. A sample of 21 nonathlete controls were compared at baseline. SRC athletes were grouped by long (>10 days, n = 23) and short (≤10 days, n = 18) RTP...
February 7, 2017: Neurology
Chang Feng, Bing Bo, Xiaoxia Mao, Hai Shi, Xiaoli Zhu, Genxi Li
Both the 3D solution and the 2D interface play important roles in bioanalysis. For the former, reactions can be carried out adequately; while for the latter, interfering substance can be eliminated simply through wash. It is a challenge to integrate the advantages of solution-based assays and the interface-based assays. Here, we report an immuno-NRCA (netlike rolling circle amplification) strategy, which integrates immunoassay with NRCA for the ultrasensitive detection of tumor biomarker, by taking the assay of a tumour marker as an example...
2017: Theranostics
Xiaoli Qin, Aigui Xu, Ling Liu, Yuyun Sui, Yunlong Li, Yueming Tan, Chao Chen, Qingji Xie
We report on an ultrasensitive metal-labeled amperometric immunoassay of proteins, which is based on the selective staining of nanocrystalline cadmium sulfide (CdS) on ZnO nanocrystals and in-situ microliter-droplet anodic stripping voltammetry (ASV) detection on the immunoelectrode. Briefly, antibody 1 (Ab1), bovine serum albumin (BSA), antigen and ZnO-multiwalled carbon nanotubes (MWCNTs) labeled antibody 2 (Ab2-ZnO-MWCNTs) were successively anchored on a β-cyclodextrin-graphene sheets (CD-GS) nanocomposite modified glassy carbon electrode (GCE), forming a sandwich-type immunoelectrode (Ab2-ZnO-MWCNTs/antigen/BSA/Ab1/CD-GS/GCE)...
May 15, 2017: Biosensors & Bioelectronics
Zhongxue Tang, Yuanyuan Fu, Zhanfang Ma
In this work, multiple signal amplification strategies for ultrasensitive label-free electrochemical immunoassay for carbohydrate antigen 24-2 (CA242) were developed using redox sodium alginate-Pb(2+)-graphene oxide (SA-Pb(2+)-GO) hydrogel. The SA-Pb(2+)-GO hydrogel was synthesised by simply mixing SA, GO, and Pb(2+) and then implemented as a novel redox species with a strong current signal at -0.46V (vs. Ag/AgCl). After the three-dimensional and porous SA-Pb(2+)-GO hydrogel was in situ generated on a glassy carbon electrode (GCE), chitosan was adsorbed on the obtained electrode to further enrich Pb(2+)...
May 15, 2017: Biosensors & Bioelectronics
Tiantian Dong, Liuyi Hu, Kang Zhao, Anping Deng, Jianguo Li
Electrochemiluminescent (ECL) immunosensor with multiple signal amplification was designed based on gold nanoparticles (AuNPs), polyamidoamine dendrimers (PAMAM) and silver-cysteine hybrid nanoribbon (SNR). Low toxic l-cysteine capped CdSe QDs was chosen as the ECL signal probe. To verify the proposed ultrasensitive ECL immunosensor for β-adrenergic agonists (β-AA), we detected Brombuterol (Brom) as a proof-of-principle analyte. Therein, AuNPs as the substrate can simplify the experiment process, accelerate the electron transfer rate, and carry more coating antigen (Ag-OVA) to enlarge ECL signal...
November 16, 2016: Analytica Chimica Acta
Sheng Xu, Rongli Zhang, Wei Zhao, Ye Zhu, Wei Wei, Xiaoya Liu, Jing Luo
In this work, a novel impedimetric immunosensor was developed based on electrophoretic deposition of polymeric self-assembled nanoparticles for the sensitive determination of carcino-embryonic antigen (CEA). Biocompatible polymeric nanoparticles γ-PGA-DA@CS were prepared by self-assembly of chitosan (CS) and dopamine modified poly(γ-glutamic acid) (γ-PGA-DA) under mild conditions. A dense and nanostructured nanoparticles film was obtained on the electrode surface by electrophoretic deposition of γ-PGA-DA@CS nanoparticles...
October 24, 2016: Biosensors & Bioelectronics
Si Cheng, Jie Sun, Junxing Yang, Jianqiang Lv, Feng Wu, Yanxing Lin, Lishan Liao, Yiyou Ye, Chenfu Cao, Liurong Fang, Qunyi Hua
A fast and ultrasensitive test-strip system combining quantum dots (QDs) with a lateral-flow immunoassay strip (LFIAS) was established for detection of Peste des petits ruminants virus (PPRV) antibody. The highly luminescent water-soluble carboxyl-functionalized QDs were used as the signal output and were conjugated to streptococcal protein G (SPG), which was capable of binding to immunoglobulin G (IgG) from many species through an amide bond to capture the target PPRV IgGs. The PPRV N protein, which was immobilized on the detection zone of the test strip, was expressed by transfecting recombinant Bacmid-PPRV-N with Lipofect into Sf9 insect cells...
January 2017: Analytical and Bioanalytical Chemistry
Zhongxue Tang, Zhanfang Ma
In this work, we presented a ratiometric electrochemical immunosensor based on redox substrate and immunoprobe. Carboxymethyl cellulose-Au-Pb(2+) (CMC-Au-Pb(2+)) and carbon-Au-Cu(2+) (C-Au-Cu(2+)) nanocomposites were firstly synthesized and implemented as redox substrate and immunoprobe with strong current signals at -0.45 V and 0.15 V, respectively. Human immunoglobulin G (IgG) was used as a model analyte to examine the analytical performance of the proposed method. The current signals of CMC-Au-Pb(2+) (Isubstrate) and C-Au-Cu(2+) (Iprobe) were monitored...
October 14, 2016: Scientific Reports
Tuhina Banerjee, Shoukath Sulthana, Tyler Shelby, Blaze Heckert, Jessica Jewell, Kalee Woody, Vida Karimnia, James McAfee, Santimukul Santra
Enterohemorrhagic Escherichia coli O157:H7 presents a serious threat to human health and sanitation and is a leading cause in many food- and waterborne ailments. While conventional bacterial detection methods such as PCR, fluorescent immunoassays and ELISA exhibit high sensitivity and specificity, they are relatively laborious and require sophisticated instruments. In addition, these methods often demand extensive sample preparation and have lengthy readout times. We propose a simpler and more sensitive diagnostic technique featuring multiparametric magneto-fluorescent nanosensors (MFnS)...
October 14, 2016: ACS Infectious Diseases
Pankaj Suman, Sonu Gandhi, Prabhanshu Kumar, Kirti Garg
Preeclampsia is a vascular multisystem disorder that accounts for varying degree of morbidity and mortality of mother and the fetus. This can be significantly averted if diagnosed at an early (18-20 weeks) stage of gestation, as there is no known way to prevent preeclampsia. In spite of extensive work on biomarker discovery, the existing method for its detection is mostly based on colorimetric immunoassays whose sensitivity is ranging in nanomolar range. Further, it has also been observed that change in the expression of a single biomarker is not sufficient to diagnose this condition...
January 2017: American Journal of Reproductive Immunology: AJRI
Nandhinee Radha Shanmugam, Sriram Muthukumar, Shalini Prasad
We demonstrate a flexible, mechanically stable, and disposable electrochemical sensor platform for monitoring cardiac troponins through the detection and quantification of cardiac Troponin-T (cTnT). We designed and fabricated nanostructured zinc oxide (ZnO) sensing electrodes on flexible porous polyimide substrates. We demonstrate ultrasensitive detection is capable at very low sample volumes due to the confinement phenomenon of target species within the ZnO nanostructures leading to enhancement of biomolecular binding on the sensor electrode surface...
2016: Scientific Reports
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