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Ultrasensitive immunoassay

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...
September 25, 2016: 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
Dawei Fan, Xiang Ren, Haoyuan Wang, Dan Wu, Di Zhao, Yucheng Chen, Qin Wei, Bin Du
A novel and sensitive sandwich-type photoelectrochemical (PEC) sensor was fabricated using signal amplification strategy for the quantitative detection of the prostate specific antigen (PSA). CdSe nanoparticles (NPs) sensitized lanthanum-doped titanium dioxide (La-TiO2) composites were used to bind the primary antibodies (Ab1). The doping of lanthanum promoted the visible light absorption of TiO2 and remarkably enhanced the photocurrent. Moreover, 0.3%La-TiO2 displayed the highest photocurrent in the La-TiO2 composites, which was twice as much as that of undoped TiO2...
August 31, 2016: Biosensors & Bioelectronics
Lu Han, Cheng-Mei Liu, Shi-Lei Dong, Cai-Xia Du, Xiao-Yong Zhang, Lu-Hai Li, Yen Wei
Electrode materials play a vital role in the development of electrochemical immunosensors (EIs), particularly of label-free EIs. In this study, composites containing reduced graphene oxide with silver nanoparticles (rGO/Ag NPs) were synthesized using binary reductants, i.e. hydrazine hydrate and sodium citrate. Due to the fact that graphene oxide (GO) was fully restored to rGO, and rGO stacking was effectively inhibited by insertion of small Ag NPs between the graphene sheets, the electrical conductivity of rGO/Ag NPs composites was significantly improved compared to rGO alone, with an enhancement factor of 346% at 40wt% of rGO...
August 3, 2016: Biosensors & Bioelectronics
Hong Dai, Shupei Zhang, Zhensheng Hong, Yanyu Lin
It is a great challenge to fabricate multiplex and convenient photoelectrochemical biosensors for ultrasensitive determination of biomarkers. Herein, a fascinating potentiometric addressable photoelectrochemical biosensor was reported for double biomarkers' detection by varying the applied bias in the detection process. In this biosensor, the nanocomposite of cube anatase TiO2 mesocrystals and polyamidoamine dendrimers modified a dual disk electrode as an excellent photoelectrochemical sensing matrix. Subsequently, two important biomarkers in serum for prostate cancer, prostate-specific antigen and human interleukin-6, were immobilized onto the different disks of modified electrode via glutaraldehyde bridges...
October 4, 2016: Analytical Chemistry
Zhiyong Guo, Yuhong Sha, Yufang Hu, Zhongqing Yu, Yingying Tao, Yanjie Wu, Min Zeng, Sui Wang, Xing Li, Jun Zhou, Xiurong Su
A novel Faraday cage-type electrochemiluminescence (ECL) immunosensor devoted to the detection of Vibrio vulnificus (VV) was fabricated. The sensing strategy was presented by a unique Faraday cage-type immunocomplex based on immunomagnetic beads (IMBs) and multi-functionalized graphene oxide (GO) labeled with (2,2'-bipyridine)(5-aminophenanthroline)ruthenium (Ru-NH2). The multi-functionalized GO could sit on the electrode surface directly due to the large surface area, abundant functional groups, and good electronic transport property...
October 2016: Analytical and Bioanalytical Chemistry
Brunah A Otieno, Colleen E Krause, Abby L Jones, Richard B Kremer, James F Rusling
Parathyroid hormone-related peptide (PTHrP) is recognized as the major causative agent of humoral hypercalcemia of malignancy (HHM). The paraneoplastic PTHrP has also been implicated in tumor progression and metastasis of many human cancers. Conventional PTHrP detection methods like immunoradiometric assay (IRMA) lack the sensitivity required to measure target peptide levels prior to the development of hypercalcemia. In general, sensitive, multiplexed peptide measurement by immunoassay represents challenges that we address in this paper...
September 20, 2016: Analytical Chemistry
Dhiraj Acharya, Pradip Bastola, Linda Le, Amber M Paul, Estefania Fernandez, Michael S Diamond, Wujian Miao, Fengwei Bai
Zika virus (ZIKV) is a globally emerging mosquito-transmitted flavivirus that can cause severe fetal abnormalities, including microcephaly. As such, highly sensitive, specific, and cost-effective diagnostic methods are urgently needed. Here, we report a novel electrogenerated chemiluminescence (ECL)-based immunoassay for ultrasensitive and specific detection of ZIKV in human biological fluids. We loaded polystyrene beads (PSB) with a large number of ECL labels and conjugated them with anti-ZIKV monoclonal antibodies to generate anti-ZIKV-PSBs...
2016: Scientific Reports
Wooyoung Hong, Sooyeon Lee, Hee Jin Chang, Eun Sook Lee, Youngnam Cho
Circulating tumor cells (CTCs) are recognized as promising biomarkers for diagnosis and indication of the prognosis of several epithelial cancers. However, at present, CTC monitoring is available only for advanced-stage patients rather than for those at an early stage of cancer. This is because of the extraordinary rarity of CTCs and the limited sensitivity of current methods. Herein, we report the development of multifunctional magnetic nanowires for the efficient isolation and detection of CTCs from the blood of patients, especially those with non-metastatic early-stage cancer...
November 2016: Biomaterials
Jeonghyo Kim, Minji Jang, Kyoung G Lee, Kil-Soo Lee, Seok Jae Lee, Kyung-Won Ro, In Sung Kang, Byung Do Jeong, Tae Jung Park, Hwa-Jung Kim, Jaebeom Lee
Tuberculosis (TB) remains a relevant infectious disease in the 21st century, and its extermination is still far from being attained. Due to the extreme infectivity of incipient TB patients, a rapid sensing system for proficient point-of-care (POC) diagnostics is required. In our study, a plastic-chip-based magnetophoretic immunoassay (pcMPI) is introduced using magnetic and gold nanoparticles (NPs) modified with Mycobacterium tuberculosis (MTB) antibodies. This pcMPI offers an ultrasensitive limit of detection (LOD) of 1...
September 14, 2016: ACS Applied Materials & Interfaces
Danlu Wu, Evaldas Katilius, Edgar Olivas, Milena Dumont Milutinovic, David R Walt
Slow off-rate modified aptamers (SOMAmers) are attractive protein recognition reagents due to their high binding affinities, stable chemical structures, easy production, and established selection process. Here, biotinylated SOMAmer reagents were incorporated into single molecule array (Simoa)-based assays in place of traditional detection antibodies for six cytokine targets. Optimization and validation were conducted for TNF-α as a demonstration using a capture antibody/detection-SOMAmer detection scheme to highlight the performance of this approach...
September 6, 2016: Analytical Chemistry
Lihui Tian, Li Liu, Yueyuan Li, Qin Wei, Wei Cao
A novel and ultrasensitive sandwich-type electrochemical immunosensor was designed for the quantitative detection of carcino-embryonic antigen (CEA). This immunosensor was developed by using the trimetallic NiAuPt nanoparticles on graphene nanosheets (NGs) nanosheets (NiAuPt-NGs) as excellent labels and β-cyclodextrin functionalized reduced graphene oxide nanosheets (CD-NGs) as the platform. The CD-NGs with high specific surface area good biocompatibility and the ideal dispersibility was used to capture the primary antibodies (Ab1) efficiently...
2016: Scientific Reports
Jing Liu, Meirong Cui, Hong Zhou, Shusheng Zhang
A novel ternary composite of hemin-graphene-Au nanorods (H-RGO-Au NRs) with high electrocatalytic activity was synthesized by a simple method. And this ternary composite was firstly used in construction of electrochemiluminescence (ECL) immunosensor due to its double-quenching effect of quantum dots (QDs). Based on the high electrocatalytic activity of ternary complexes for the reduction of H2O2 which acted as the coreactant of QDs-based ECL, as a result, the ECL intensity of QDs decreased. Besides, due to the ECL resonance energy transfer (ECL-RET) strategy between the large amount of Au nanorods (Au NRs) on the ternary composite surface and the CdS:Eu QDs, the ECL intensity of QDs was further quenched...
2016: Scientific Reports
Jiaojiao Li, Yong Zhang, Xuan Kuang, Zhiling Wang, Qin Wei
Taking advantage of CdSe/melamine network as label and Au-TiO2 as substrate, this work developed a novel kind of signal amplification strategy for fabricating photoelectrochemical (PEC) immunoassay. The melamine, a star-shaped triamino molecule, was firstly used for readily capturing CdSe QDs and forming a CdSe/melamine network, which was formed through strong interactions between the carboxyl groups of TGA-stabilized CdSe QDs and the three amino groups of each melamine molecule. In this strategy, the primary antibody (Ab1) was immobilized onto Au-TiO2 substrate, which made the photoelectric conversion efficiency increase significantly...
November 15, 2016: Biosensors & Bioelectronics
Xiao Li, Xinyu Liu
The first microfluidic paper-based origami nano-biosensor featuring zinc oxide nanowires and an electrochemical impedance spectroscopy biosensing mechanism, for label-free, ultrasensitive immunoassays is reported by X. Li and X. Liu on page 1326. The sensor consists of cellulose paper, a carbon ink electrode, and zinc oxide nanowires directly grown on the top. Possible parallelization of assays and high storage stability render the sensor promising for clinical diagnostics applications.
June 2016: Advanced Healthcare Materials
Shorena Janelidze, Erik Stomrud, Sebastian Palmqvist, Henrik Zetterberg, Danielle van Westen, Andreas Jeromin, Linan Song, David Hanlon, Cristina A Tan Hehir, David Baker, Kaj Blennow, Oskar Hansson
Implementation of amyloid biomarkers in clinical practice would be accelerated if such biomarkers could be measured in blood. We analyzed plasma levels of Aβ42 and Aβ40 in a cohort of 719 individuals (the Swedish BioFINDER study), including patients with subjective cognitive decline (SCD), mild cognitive impairment (MCI), Alzheimer's disease (AD) dementia and cognitively healthy elderly, using a ultrasensitive immunoassay (Simoa platform). There were weak positive correlations between plasma and cerebrospinal fluid (CSF) levels for both Aβ42 and Aβ40, and negative correlations between plasma Aβ42 and neocortical amyloid deposition (measured with PET)...
2016: Scientific Reports
Hui Cheng, Lingling Xu, Haili Zhang, Aimin Yu, Guosong Lai
A nanoporous gold nanosphere (pAu NS) was synthesized to load high-content glucose oxidase (GOx) and ferrocene (Fc) for the successful preparation of a new gold nanoprobe. After the specific recognition of the tumor biomarker of carcinoembryonic antigen (CEA) at a gold electrode based aptasensor, this GOx and Fc dually functionalized pAu NS nanoprobe was further used for sandwich immunoreaction and signal tracing. Based on the Fc-mediated GOx-catalytic reaction, the gold nanoprobes quantitatively captured onto the electrode surface produced a sensitive electrochemical signal corresponding to the protein recognition events, which led to the development of a new biosensing method for CEA measurement...
July 21, 2016: Analyst
Lingshan Gong, Hong Dai, Shupei Zhang, Yanyu Lin
In this work, we first exposed that the application of p-type semiconductor, silver iodide-chitosan nanoparticle (SICNP), acted as peroxidase mimetic to catalyze the bioprecipitation reaction for signal-amplification photocathodic immunosensing of human interleukin-6 (IL-6). After immobilization of captured antibody onto a polyethylenimine-functionalized carbon nitride (CN) matrix, SICNPs as photoactive tags and peroxidase mimetics were labeled on secondary antibodies, which were subsequently introduced onto the sensing interface to construct sandwich immunoassay platform through antigen-antibody specific recognition...
June 7, 2016: Analytical Chemistry
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