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Ultrasensitive immunoassay

Lihua Zhao, Zhanfang Ma
Sensitivity enhancement and proteins adsorption are the common challenges faced in protein immunoassays. In this work, an ultrasensitive and protein-resistant label-free amperometric immunosening platform for carcinoma antigen-125 (CA125) based on redox polyaniline-polythionine hydrogel (PANI-PThi gel) was developed. The as-prepared hydrogel, which was facilely synthesized by electropolymerization, exhibited good conductivity and strong hydrophilicity while the sensitivity and specificity of the immunosensor can be enhanced...
January 2, 2018: Analytica Chimica Acta
Jie Song, Shuo Wu, Xinlan Yang, Jingli Yuan
Graphene nanodisks with good conductivity and plenty of edge sites were synthesized to load glucose oxidase (GRD-GOD) and coupled with a Mn(2+) doped CdS quantum dot (QD) modified TiO2 electrode (CdS:Mn/TiO2) for a highly sensitive photoelectrochemical (PEC) immunoassay. The specific immune-recognition behaviour can bring the GRD-GOD labelled antigen into the antibody immobilized CdS:Mn/TiO2 interface and dramatically enhance the photocurrent response via a dual signal amplification strategy. First, graphene nanodisks with a strong electron transfer capacity can improve the conductivity of both the insulating protein layers and the CdS:Mn/TiO2 matrix, thus facilitating the regeneration of trapped carriers and hot electrons in the CdS:Mn QD films and enhancing the PEC performance...
November 15, 2017: Analyst
Jie Wei, Aori Qileng, Yun Yan, Hongtao Lei, Shengsen Zhang, Weipeng Liu, Yingju Liu
An ultrasensitive photoelectrochemical (PEC) immunoassay based on multiple signal amplification strategy was fabricated for the detection of microcystin-LR (MC-LR). The CdS/TiO2 nanorod arrays (CdS/TiO2 NRAs) modified FTO electrode, which can weaken the self-oxidation by photogenerated holes of CdS nanoparticles, and limit the recombination of electron-hole pairs and broaden optical absorption of TiO2 NRAs, was used as a visible-light driven material to immobilize antigens. Then, Fe3O4 nanoparticles/polydopamine (Fe3O4@PDA) was used as the carrier to load secondary antibody (Ab2) and horseradish peroxidase (HRP), where Fe3O4 nanoparticles and HRP can synergistically accelerate the oxidation of 4-chloro-1-naphthol (4-CN) by H2O2 to produce biocatalytic precipitation (BCP) on the surface of modified electrode...
November 22, 2017: Analytica Chimica Acta
Valentina Fodale, Roberto Boggio, Manuel Daldin, Cristina Cariulo, Maria Carolina Spiezia, Lauren Mary Byrne, Blair R Leavitt, Edward Wild, Douglas Macdonald, Andreas Weiss, Alberto Bresciani
BACKGROUND: The measurement of disease-relevant biomarkers has become a major component of clinical trial design, but in the absence of rigorous clinical and analytical validation of detection methodology, interpretation of results may be misleading. In Huntington's disease (HD), measurement of the concentration of mutant huntingtin protein (mHTT) in cerebrospinal fluid (CSF) of patients may serve as both a disease progression biomarker and a pharmacodynamic readout for HTT-lowering therapeutic approaches...
November 9, 2017: Journal of Huntington's Disease
Liuyi Hu, Jing Zheng, Kang Zhao, Anping Deng, Jianguo Li
In this study, a novel competition-type electrochemiluminescent (ECL) immunosensor for detecting diclofenac (DCF) was fabricated with graphene oxide coupled graphite-like carbon nitride (GO-g-C3N4) as signal probe for the first time. The ECL intensity of carboxylated g-C3N4 was significantly enhanced after being combined with graphene oxide (GO) which exhibited excellent charge-transport property. The sensing platform was constructed by multiwalled carbon nanotubes and gold nanoparticles (MWCNTs-AuNPs), which not only provided an effective matrix for immobilizing a large amount of coating antigen but also facilitated the electronic transmission rate to enhance the ECL intensity...
October 19, 2017: Biosensors & Bioelectronics
Syed Rahin Ahmed, Juan C Corredor, Éva Nagy, Suresh Neethirajan
Nanomaterial-based artificial enzymes or nanozymes exhibit superior properties such as stability, cost effectiveness and ease of preparation in comparison to conventional enzymes. However, the lower catalytic activity of nanozymes limits their sensitivity and thereby practical applications in the bioanalytical field. To overcome this drawback, herein we propose a very simple but highly sensitive, specific and low-cost dual enhanced colorimetric immunoassay for avian influenza A (H5N1) virus. 3,3´,5,5´- Tetramethylbenzidine (TMBZ) was used as a reducing agent to produce gold nanoparticles (Au NPs) with blue colored solution from a viral target-specific antibody-gold ion mixture at first step...
2017: Nanotheranostics
Philip S J Weston, Teresa Poole, Natalie S Ryan, Akshay Nair, Yuying Liang, Kirsty Macpherson, Ronald Druyeh, Ian B Malone, R Laila Ahsan, Hugh Pemberton, Jana Klimova, Simon Mead, Kaj Blennow, Martin N Rossor, Jonathan M Schott, Henrik Zetterberg, Nick C Fox
OBJECTIVES: To investigate whether serum neurofilament light (NfL) concentration is increased in familial Alzheimer disease (FAD), both pre and post symptom onset, and whether it is associated with markers of disease stage and severity. METHODS: We recruited 48 individuals from families with PSEN1 or APP mutations to a cross-sectional study: 18 had symptomatic Alzheimer disease (AD) and 30 were asymptomatic but at 50% risk of carrying a mutation. Serum NfL was measured using an ultrasensitive immunoassay on the single molecule array (Simoa) platform...
October 25, 2017: Neurology
Fenglei Gao, Fuyi Zhou, Songjie Chen, Yao Yao, Jing Wu, Dengyang Yin, Deqin Geng, Po Wang
A new homogeneous electrochemical immunoassay strategy was developed for ultrasensitive detection of carcinoembryonic antigen (CEA) based on target-induced proximity hybridization coupled with rolling circle amplification (RCA). The immobilization-free detection of CEA was realized by the use of an uncharged peptide nucleic acid (PNA) probe labeled with ferrocene (Fc) as the electroactive indicator on a negatively charged indium tin oxide (ITO) electrode. In the presence of a target protein and two DNA-labeled antibodies, the proximate complex formed in homogeneous solution could unfold the molecular beacon, and a part of the unfolded molecular beacon as a primer hybridized with the RCA template to initiate the RCA process...
October 20, 2017: Analyst
Xu Chen, Wen Xu, Yandong Jiang, Gencai Pan, Donglei Zhou, Jinyang Zhu, He Wang, Cong Chen, Dongyu Li, Hongwei Song
Fabrication of near-infrared light-triggered photoelectrochemical (PEC) sensors based on the upconversion nanophosphors (UCNPs) is a novel approach, which exhibits the advantages of low background signal and non-damage to the biological substance as well as high sensitivity and improved electric detection in PEC sensors. Herein we demonstrate the preparation of novel and high-quality ZnO inverse opal photonic crystals (IOPCs)/Ag/NaYF4:Yb,Tm hybrid films by different advanced film techniques, including colloidal self-assembling, vapor phase deposition and pulsed laser deposition and its application to sensitive detection of alpha-fetoprotein (AFP)...
November 2, 2017: Nanoscale
Luye Mu, Ilia A Droujinine, Jieun Lee, Mathias Wipf, Paschall Davis, Chris Adams, Jennifer Hannant, Mark A Reed
Silicon nanowire field effect transistors (NWFETs) are low noise, low power, ultrasensitive biosensors that are highly amenable to integration. However, using NWFETs to achieve direct protein detection in physiological buffers such as blood serum remains difficult due to Debye screening, nonspecific binding, and stringent functionalization requirements. In this work, we performed an indirect sandwich immunoassay in serum combined with exponential DNA amplification and pH measurement by ultrasensitive NWFET sensors...
November 7, 2017: Analytical Chemistry
Junlin Wen, Shungui Zhou, Zhen Yu, Junhua Chen, Guiqin Yang, Jia Tang
Extracellular respiring bacteria (ERB) are a group of bacteria capable of transferring electrons to extracellular acceptors and have important application in environmental remediation. In this study, a decomposable quantum-dots (QDs)/DNA nanosphere probe was developed for rapid and ultrasensitive detection of ERB. The QDs/DNA nanosphere was self-assembled from QDs-streptavidin conjugate (QDs-SA) and Y-shaped DNA nanostructure that is constructed based on toehold-mediated strand displacement. It can release numerous fluorescent QDs-SA in immunomagnetic separation (IMS)-based immunoassay via simple biotin displacement, which remarkably amplifies the signal of antigen-antibody recognizing event...
September 18, 2017: Biosensors & Bioelectronics
Chengcheng Gu, Panpan Gai, Ting Hou, Haiyin Li, Changhui Xue, Feng Li
Enzymatic fuel cell (EFC)-based self-powered biosensors have attracted considerable attention because of their unique feature of no need for extra power sources during the entire detection process, which endows them with the merits of simplicity, rapidness, low cost, anti-interference, and ease of use. Herein, we proposed, for the first time, an EFC-based self-powered homogeneous immunosensing platform by integrating the target-induced biofuel release and bioconjugate immunoassay for ultrasensitive melamine (ME) detection...
October 18, 2017: ACS Applied Materials & Interfaces
B Mattiasson, K Teeparuksapun, L Lebogang, M Hedström
It is possible to improve the sensitivity of immunoassays by several orders of magnitude by exploiting nanoenvironmental effects. This approach can detect trace amounts of compounds and will better illuminate the presence of signal substances in biological systems. Here we describe a method for ultrasensitive immunoassays using 'normal' antibodies (Abs).
November 2017: Trends in Biotechnology
Xiaohan Zhang, Xianyin Ping, Huisheng Zhuang
Extensive polybrominated diphenyl ethers (PBDEs) use has resulted in its increasingly widespread presence in the environment. PBDEs release from existing products can still persist and accumulate in the environment as well as in human and wildlife magnifying through the food web. Due to its ultra-trace amount in the environment, a novel ultrasensitive nano-rt-iPCR assay has been developed to determine polybrominated diphenyl ethers in natural samples. Numerous amino-DNA and polyclonal antibody (anti-PBDE) were immobilized onto the single-walled carbon nanotubes (SWCNTs) to form antibody-SWCNTs-DNA signal amplifier used in the proposed immunoassay system...
September 20, 2017: Scientific Reports
Jungwoo Hahn, Eunghee Kim, Young Sang You, Sundaram Gunasekaran, Seokwon Lim, Young Jin Choi
On-site detection for sensitive identification of foodborne pathogens on fresh produce with minimal use of specialized instrumentation is crucial to the food industry. A switchable linker (SL)-based immunoassay was designed for ultrasensitive on-site detection of Salmonella in tomato samples. The assay is based on large-scale aggregation of gold nanoparticles (GNPs), induced by a quantitative relationship among the biotinylated Salmonella polyclonal antibody (b-Ab) used as the SL, the functionalized GNPs, and Salmonella...
October 2017: Journal of Food Science
Priscila M Kosaka, Montserrat Calleja, Javier Tamayo
Most of the cancer deaths could be avoided by early detection of the tumor when it is confined to its primary site and it has not metastasized. To this aim, one of the most promising strategies is the discovery and detection of protein biomarkers shed by the young tumor to the bloodstream. Proteomic technologies, mainly mass spectrometry and multiplexed immunoassays, have rapidly developed during last years with improved limits of detection and multiplexing capability. Unfortunately, these developments together major investments and large international efforts have not resulted into new useful protein biomarkers...
August 31, 2017: Seminars in Cancer Biology
Harutsugu Tatebe, Takashi Kasai, Takuma Ohmichi, Yusuke Kishi, Tomoshi Kakeya, Masaaki Waragai, Masaki Kondo, David Allsop, Takahiko Tokuda
BACKGROUND: There is still a substantial unmet need for less invasive and lower-cost blood-based biomarkers to detect brain Alzheimer's disease (AD) pathology. This study is aimed to determine whether quantification of plasma tau phosphorylated at threonine 181 (p-tau181) is informative in the diagnosis of AD. METHODS: We have developed a novel ultrasensitive immunoassay to quantify plasma p-tau181, and measured the levels of plasma p-tau181 in three cohorts. RESULTS: In the first cohort composed of 20 AD patients and 15 age-matched controls, the plasma levels of p-tau181 were significantly higher in the AD patients than those in the controls (0...
September 4, 2017: Molecular Neurodegeneration
Agnieszka Kamińska, Myroslav Sprynskyy, Katarzyna Winkler, Tomasz Szymborski
An ultrasensitive surface-enhanced Raman scattering (SERS) immunoassay based on diatom biosilica with integrated gold nanoparticles (AuNPs) for the detection of interleukin 8 (IL-8) in blood plasma has been developed. The SERS sensing originates from unique features of the diatom frustules, which are capable of enhancing the localized surface-plasmon resonance of metal nanostructures. The SERS immune tags ware fabricated by functionalizing 70-nm Au nanoparticles with DTNB (i.e., 5,5'-dithiobis(2-nitrobenzoic acid)), which acted as a Raman reporter molecule, as well as the specific antibodies...
November 2017: Analytical and Bioanalytical Chemistry
Bahareh Babamiri, Rahman Hallaj, Abdollah Salimi
A multiplex ultrasensitive electrochemiluminescence (ECL) immunoassay was developed for the simultaneous determination of two different tumor markers, cancer antigen 153 (CA 15-3) and cancer antigen 125 (CA 125) using polyamidoamine dendrimer-quantum dots (PAMAM-QDs) and PAMAM-sulfanilic acid-Ru(bpy)3(2+) as the signal probes and Fe3O4-SiO2 as a magnetic bead. The CdTe@CdS- QDs and Ru(bpy)3(2+) at the presence of tripropyl amine (TPA) as coreactant generate ECL at an applied voltage of + 1.2V (vs Ag/AgCl) in two different wavelengths 500 and 620nm, respectively...
January 15, 2018: Biosensors & Bioelectronics
Jing Wu, Yiping Chen, Mingzhu Yang, Yu Wang, Cheng Zhang, Mo Yang, Jiashu Sun, Mengxia Xie, Xingyu Jiang
Simultaneous, sensitive and quantitative detection of biomarkers in infectious disease is crucial for guiding antimicrobial treatment and predicting prognosis. This work reported an ultrasensitive and quantitative microfluidic immunoassay combined with the streptavidin-biotin-peroxidase (SA-B-HRP) nanocomplex-signal amplification system (MIS) to detect two inflammatory biomarkers, procalcitonin (PCT, for discriminating bacterial infections from nonbacterial infections) and interleukin-6 (IL-6, for monitoring the kinetics of infectious disease) simultaneously...
August 22, 2017: Analytica Chimica Acta
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