Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 34.086
Filtrar
1.
Anal Chem ; 93(28): 9933-9938, 2021 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-34227801

RESUMO

Sensitive detection of the SARS-CoV-2 protein remains a great research interest in clinical screening and diagnosis owing to the coronavirus epidemic. Here, an ultrasensitive chemiluminescence (CL) imaging strategy was developed through proximity hybridization to trigger the formation of a rolling circle-amplified G-quadruplex/hemin DNAzyme for the detection of the SARS-CoV-2 protein. The target protein was first recognized by a pair of DNA-antibody conjugates, Ab-1 and Ab-2, to form a proximity-ligated complex, Ab-1/SARS-CoV-2/Ab-2, which contained a DNA sequence complemental to block DNA and thus induced a strand displacement reaction to release the primer from a block/primer complex. The released primer then triggered a rolling circle amplification to form abundant DNAzyme units in the presence of hemin, which produced a strong chemiluminescent signal for the detection of the target protein by catalyzing the oxidation of luminol by hydrogen peroxide. The proposed assay showed a detectable concentration range over 5 orders of magnitude with the detection limit down to 6.46 fg/mL. The excellent selectivity, simple procedure, acceptable accuracy, and intrinsic high throughput of the imaging technique for analysis of serum samples demonstrated the potential applicability of the proposed detection method in clinical screening and diagnosis.


Assuntos
Técnicas Biossensoriais , COVID-19 , DNA Catalítico , Quadruplex G , DNA Catalítico/metabolismo , Hemina , Humanos , Imunoensaio , Limite de Detecção , Luminescência , SARS-CoV-2
2.
ACS Appl Mater Interfaces ; 13(27): 32013-32021, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34212714

RESUMO

The reported donor donor-acceptor ("DD-A") fluorescence resonance energy transfer (FRET) was typically achieved through random collisions and interactions of DNA molecules in the bulk solution, which has inevitable defects, including weak biological stability, slow reaction kinetics, and low hybridization efficiency. In order to overcome these deficiencies, this work developed a quadrivalent cruciform DNA nanostructure (qCDN)-mediated cascaded catalyzed hairpin assembly (CHA) amplifier for the fluorescence detection of amyloid ß oligomer species (AßOs). First, four H1 and four H2 hairpins were assembled on one qCDN to obtain qCDNH1 and qCDNH2, respectively. In the presence of AßOs, strand C was released from the P1-C hybrid hairpin and then alternately opened qCDNH1 and qCDNH2 to trigger the qCDN-mediated CHA. As a result, double donors in H1 and one acceptor in H2 were mutually closed, and the porous DNA nanonet with a high loading of "DD-A" FRET binary probes was formed. The FRET efficiency was approximately 78%, and the initial reaction rate was 25-fold faster than the conventional CHA. The detection limit of AßOs was as low as 0.69 pM. The combination of the "DD-A" FRET binary probes and qCDN-mediated cascaded amplifier exhibited great promise for detecting biomarkers with trace levels.


Assuntos
Peptídeos beta-Amiloides/química , DNA Cruciforme/química , Transferência Ressonante de Energia de Fluorescência/métodos , Limite de Detecção , Nanoestruturas/química , Multimerização Proteica , Estrutura Quaternária de Proteína
3.
ACS Appl Mater Interfaces ; 13(27): 31710-31724, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34213303

RESUMO

In this study, we have designed a three-fluorophore-labeled Y-shaped DNAzyme with a high catalytic cleavage activity and a three-dimensional (3D) MOF-MoS2NB (metal-organic framework fused with molybdenum disulfide nanobox), which was synthesized as an efficient quencher of the fluorescent biosensor. The synthesized porous 3D MOF-MoS2NBs and Y-shaped DNAzyme exhibited a good analytical response toward the simultaneous multiple detections of Hg2+, Ni2+, and Ag+ ions over the other coexisting metal ions. More specifically, the three kinds of enzyme aptamer and substrate aptamer (SA) were hybridized and annealed to form the Y-shaped DNAzyme structure and labeled with three different fluorophores such as FAM, TAMRA, and ROX over the 3'-end of SA. When the targets were induced, the DNAzyme was triggered to cleave the fluorophore-labeled SAs. Then, the cleaved SAs (FAM-SA, TAMRA-SA, and ROX-SA) were adsorbed on the 3D MOF-MoS2NB surface to quench the fluorescence signal due to a noncovalent interaction (van der Waals and π-π stacking interaction), which transmuted the fluorescence on-state to off-state. As a result, the fluorescence assay confiscated the high selectivity and sensitivity for the target analytes of Hg2+, Ni2+, and Ag+ ions achieved for the detection limits of 0.11 nM, 7.8 µM, and 0.25 nM, respectively. Accordingly, the sensitivity of the developed sensor was explored with a better lower detection limit than the previously reported biosensors. The utility of the designed Y-shaped DNAzyme may find a broad field of application in real water sample analysis with interfering contaminants.


Assuntos
Biocatálise , Técnicas Biossensoriais/métodos , DNA Catalítico/metabolismo , Dissulfetos/química , Corantes Fluorescentes/química , Estruturas Metalorgânicas/química , Metais Pesados/análise , Molibdênio/química , Adsorção , Catálise , DNA Catalítico/química , Limite de Detecção , Mercúrio/análise , Níquel/análise , Prata/análise
4.
Biosensors (Basel) ; 11(7)2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34201518

RESUMO

Metal-organic framework (MOF) nanozymes, as emerging members of the nanozymes, have received more and more attention due to their composition and structural characteristics. In this work, we report that mixed-valence state Ce-MOF (MVCM) has intrinsic haloperoxidase-mimicking activity. MVCM was synthesized by partial oxidation method using Ce-MOF as a precursor. In the presence of H2O2 and Br-, MVCM can catalyze oxidative bromination of chromogenic substrate phenol red (PR) to produce the blue product bromophenol blue (Br4PR), showing good haloperoxidase-like activity. Because of the special chromogenic substrate, we constructed a ratiometric colorimetric-sensing platform by detecting the absorbance of the MVCM-(PR, Br-) system at wavelengths of 590 and 430, for quantifying H2O2, where the detection limit of the H2O2 is 3.25 µM. In addition, the haloperoxidase-mimicking mechanism of the MVCM is proposed. Moreover, through enzyme kinetics monitoring, the Km (H2O2 and NH4Br) of the MVCM is lower than that of cerium oxide nanomaterials, indicating that the MVCM has a stronger binding affinity for H2O2 and NH4Br than other materials. This work provides more application prospects for the development of nanozymes in the field of biosensors in the future.


Assuntos
Colorimetria , Peróxido de Hidrogênio/análise , Materiais Biomiméticos , Técnicas Biossensoriais , Catálise , Cério , Limite de Detecção , Estruturas Metalorgânicas , Oxirredução
5.
Biosensors (Basel) ; 11(7)2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-34202015

RESUMO

In this study, ratiometric fluorescent glucose and lactate biosensors were developed using a ratiometric fluorescent oxygen-sensing membrane immobilized with glucose oxidase (GOD) or lactate oxidase (LOX). Herein, the ratiometric fluorescent oxygen-sensing membrane was fabricated with the ratio of two emission wavelengths of platinum meso-tetra (pentafluorophenyl) porphyrin (PtP) doped in polystyrene particles and coumarin 6 (C6) captured into silica particles. The operation mechanism of the sensing membranes was based on (i) the fluorescence quenching effect of the PtP dye by oxygen molecules, and (ii) the consumption of oxygen levels in the glucose or lactate oxidation reactions under the catalysis of GOD or LOX. The ratiometric fluorescent glucose-sensing membrane showed high sensitivity to glucose in the range of 0.1-2 mM, with a limit of detection (LOD) of 0.031 mM, whereas the ratiometric fluorescent lactate-sensing membrane showed the linear detection range of 0.1-0.8 mM, with an LOD of 0.06 mM. These sensing membranes also showed good selectivity, fast reversibility, and stability over long-term use. They were applied to detect glucose and lactate in artificial human serum, and they provided reliable measurement results.


Assuntos
Técnicas Biossensoriais , Fluorescência , Glucose/análise , Ácido Láctico/análise , Catálise , Cumarínicos , Corantes Fluorescentes , Glucose Oxidase , Humanos , Limite de Detecção , Oxigênio , Platina , Porfirinas , Espectrometria de Fluorescência , Tiazóis
6.
Molecules ; 26(11)2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-34199388

RESUMO

The chemical fungicide fludioxonil is widely used to control post-harvest fungal disease in cherries. This study was implemented to investigate the dissipation behaviours and residues of fludioxonil on cherries. A reliable and efficient analytical method was established. Cherry samples from four product areas were analyzed by QuEChERS and HPLC-MS/MS methods with acceptable linearity (R2 > 0.99), accuracy (recoveries of 81-94%), and precision (relative standard deviation of 2.5-11.9%). The limits of quantification (LOQs) and limits of detection (LODs) of cherries were 0.01 mg/kg and 0.005 mg/kg. The dissipation of fludioxonil on cherries followed first order kinetics with half-lives of 33.7-44.7 days. The terminal residues of fludioxonil were all lower than 5.00 mg/kg, which is the MRL recommended by the European Commission. According to Chinese dietary patterns and terminal residue distributions, the risk quotient (RQs) of fludioxonil was 0.61%, revealing that the evaluated cherries exhibited an acceptably low dietary risk to consumers.


Assuntos
Exposição Dietética/análise , Dioxóis/análise , Fungicidas Industriais/análise , Prunus/química , Pirróis/análise , Cromatografia Líquida de Alta Pressão , Meia-Vida , Cinética , Limite de Detecção , Estrutura Molecular , Prunus/microbiologia , Espectrometria de Massas em Tandem
7.
Sensors (Basel) ; 21(13)2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34201852

RESUMO

This review critically summarizes the knowledge of imprinted polymer-based electrochemical sensors for the detection of pesticides, metal ions and waterborne pathogenic bacteria, focusing on the last five years. MIP-based electrochemical sensors exhibit low limits of detection (LOD), high selectivity, high sensitivity and low cost. We put the emphasis on the design of imprinted polymers and their composites and coatings by radical polymerization, oxidative polymerization of conjugated monomers or sol-gel chemistry. Whilst most imprinted polymers are used in conjunction with differential pulse or square wave voltammetry for sensing organics and metal ions, electrochemical impedance spectroscopy (EIS) appears as the chief technique for detecting bacteria or their corresponding proteins. Interestingly, bacteria could also be probed via their quorum sensing signaling molecules or flagella proteins. If much has been developed in the past decade with glassy carbon or gold electrodes, it is clear that carbon paste electrodes of imprinted polymers are more and more investigated due to their versatility. Shortlisted case studies were critically reviewed and discussed; clearly, a plethora of tricky strategies of designing selective electrochemical sensors are offered to "Imprinters". We anticipate that this review will be of interest to experts and newcomers in the field who are paying time and effort combining electrochemical sensors with MIP technology.


Assuntos
Técnicas Biossensoriais , Impressão Molecular , Técnicas Eletroquímicas , Eletrodos , Limite de Detecção , Polímeros , Água
8.
Molecules ; 26(11)2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-34205046

RESUMO

A small organic molecule P was synthesized and characterized as a fluorometric and colorimetric dual-modal probe for Hg2+. The sensing characteristics of the proposed probe for Hg2+ were studied in detail. A fluorescent enhancing property at 583 nm (>30 fold) accompanied with a visible colorimetric change, from colorless to pink, was observed with the addition of Hg2+ to P in an ethanol-water solution (8:2, v/v, 20 mM HEPES, pH 7.0), which would be helpful to fabricate Hg2+-selective probes with "naked-eye" and fluorescent detection. Meanwhile, cellular experimental results demonstrated its low cytotoxicity and good biocompatibility, and the application of P for imaging of Hg2+ in living cells was satisfactory.


Assuntos
Corantes Fluorescentes/química , Mercúrio/química , Rodaminas/química , Bibliotecas de Moléculas Pequenas/síntese química , Colorimetria , Células HeLa , Humanos , Citometria de Varredura a Laser , Limite de Detecção , Imagem Molecular , Estrutura Molecular , Bibliotecas de Moléculas Pequenas/química
9.
Anal Chim Acta ; 1174: 338709, 2021 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-34247733

RESUMO

The important role of BV in clinical diagnostics of liver-related diseases has been established in veterinary medicine. However, the sensitivity and selectivity of the current BV assays remain relatively low compromising its wider application in clinical diagnosis. Herein, we developed a rapid and sensitive BV-detecting biosensor based on a novel far-red fluorescent protein smURFP, which produced fluorescence only through specific interaction with its cofactor BV. In our study, the binding of BV to smURFP was then systematically optimized based on the structures of the smURFP + BV complex to increase the sensitivity of our biosensor. A wide linear range from 0 µM to 25 µM was obtained in both chicken and human serum. The limit of detection (LOD) and limit of quantification (LOQ) for BV was as low as 0.4 nM and 1.5 nM in human serum, and 0.4 nM and 1.2 nM in chicken serum. To our knowledge, this is the lowest LOD that has ever been reported for a BV biosensor. Our study sheds light on the biological and clinical analysis of BV.


Assuntos
Biliverdina , Técnicas Biossensoriais , Humanos , Limite de Detecção
10.
Molecules ; 26(11)2021 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-34200415

RESUMO

Homovanillic acid (HVA) and vanillylmandelic acid (VMA) are end-stage metabolites of catecholamine and are clinical biomarkers for the diagnosis of neuroblastoma. For the first time in Korea, we implemented and validated a liquid chromatography tandem mass spectrometry (LC-MS/MS) assay to measure urinary concentrations of HVA and VMA according to Clinical and Laboratory Standards Institute guidelines. Our LC-MS/MS assay with minimal sample preparation was validated for linearity, lower limit of detection (LOD), lower limit of quantification (LLOQ), precision, accuracy, extraction recovery, carryover, matrix effect, and method comparison. A total of 1209 measurements was performed to measure HVA and VMA in spot urine between October 2019 and September 2020. The relationship between the two urinary markers, HVA and VMA, was analyzed and exhibited high agreement (89.1% agreement, kappa's k = 0.6) and a strong correlation (Pearson's r = 0.73). To our knowledge, this is the first study to utilize LC-MS/MS for simultaneous quantitation of spot urinary HVA and VMA and analyze the clinical application of both markers on a large scale for neuroblastoma patients.


Assuntos
Ácido Homovanílico/química , Neuroblastoma/diagnóstico , Neuroblastoma/metabolismo , Ácido Vanilmandélico/química , Bioensaio/métodos , Biomarcadores/metabolismo , Criança , Pré-Escolar , Cromatografia Líquida/métodos , Feminino , Seguimentos , Humanos , Lactente , Recém-Nascido , Limite de Detecção , Masculino , República da Coreia , Espectrometria de Massas em Tandem/métodos
11.
BMC Infect Dis ; 21(1): 665, 2021 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-34238234

RESUMO

BACKGROUND: As SARS-CoV-2 testing expands, particularly to widespread asymptomatic testing, high sensitivity point-of-care PCR platforms may optimise potential benefits from pooling multiple patients' samples. METHOD: We tested patients and asymptomatic citizens for SARS-CoV-2, exploring the efficiency and utility of CovidNudge (i) for detection in individuals' sputum (compared to nasopharyngeal swabs), (ii) for detection in pooled sputum samples, and (iii) by modelling roll out scenarios for pooled sputum testing. RESULTS: Across 295 paired samples, we find no difference (p = 0.1236) in signal strength for sputum (mean amplified replicates (MAR) 25.2, standard deviation (SD) 14.2, range 0-60) compared to nasopharyngeal swabs (MAR 27.8, SD 12.4, range 6-56). At 10-sample pool size we find some drop in absolute strength of signal (individual sputum MAR 42.1, SD 11.8, range 13-60 vs. pooled sputum MAR 25.3, SD 14.6, range 1-54; p < 0.0001), but only marginal drop in sensitivity (51/53,96%). We determine a limit of detection of 250 copies/ml for an individual test, rising only four-fold to 1000copies/ml for a 10-sample pool. We find optimal pooled testing efficiency to be a 12-3-1-sample model, yet as prevalence increases, pool size should decrease; at 5% prevalence to maintain a 75% probability of negative first test, 5-sample pools are optimal. CONCLUSION: We describe for the first time the use of sequentially dipped sputum samples for rapid pooled point of care SARS-CoV-2 PCR testing. The potential to screen asymptomatic cohorts rapidly, at the point-of-care, with PCR, offers the potential to quickly identify and isolate positive individuals within a population "bubble".


Assuntos
Teste para COVID-19/métodos , COVID-19/diagnóstico , COVID-19/virologia , Testes Imediatos , SARS-CoV-2/isolamento & purificação , Escarro/virologia , Testes Diagnósticos de Rotina , Humanos , Limite de Detecção , Nasofaringe/virologia , Sensibilidade e Especificidade , Carga Viral
12.
Molecules ; 26(11)2021 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-34198808

RESUMO

Volatile methylsiloxanes (VMSs) constitute a group of compounds used in a great variety of products, particularly personal care products. Due to their massive use, they are continually discharged into wastewater treatment plants and are increasingly being detected in wastewater and in the environment at low concentrations. The aim of this work was to develop and validate a fast and reliable methodology to screen seven VMSs in water samples, by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography with flame ionization detection (GC-FID). The influence of several factors affecting the extraction efficiency was investigated using a design of experiments approach. The main factors were selected (fiber type, sample volume, ionic strength, extraction and desorption time, extraction and desorption temperature) and optimized, employing a central composite design. The optimal conditions were: 65 µm PDMS/Divinylbenzene fiber, 10 mL sample, 19.5% NaCl, 39 min extraction time, 10 min desorption time, and 33 °C and 240 °C as extraction and desorption temperature, respectively. The methodology was successfully validated, showing low detection limits (up to 24 ng/L), good precision (relative standard deviations below 15%), and accuracy ranging from 62% to 104% in wastewater, tap, and river water samples.


Assuntos
Siloxanas/análise , Microextração em Fase Sólida/métodos , Poluentes Químicos da Água/análise , Ionização de Chama , Água Doce/química , Cromatografia Gasosa-Espectrometria de Massas , Limite de Detecção , Rios/química , Águas Residuárias/química
13.
Molecules ; 26(11)2021 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-34198893

RESUMO

In this work, a low-cost and rapid electrochemical resistive DNA biosensor based on the current relaxation method is described. A DNA probe, complementary to the specific human papillomavirus type 16 (HPV-16) sequence, was immobilized onto a screen-printed gold electrode. DNA hybridization was detected by applying a potential step of 30 mV to the system, composed of an external capacitor and the modified electrode DNA/gold, for 750 µs and then relaxed back to the OCP, at which point the voltage and current discharging curves are registered for 25 ms. From the discharging curves, the potential and current relaxation were evaluated, and by using Ohm's law, the charge transfer resistance through the DNA-modified electrode was calculated. The presence of a complementary sequence was detected by the change in resistance when the ssDNA is transformed in dsDNA due to the hybridization event. The target DNA concentration was detected in the range of 5 to 20 nM. The results showed a good fit to the regression equation ΔRtotal(Ω)=2.99 × [DNA]+81.55, and a detection limit of 2.39 nM was obtained. As the sensing approach uses a direct current, the electronic architecture of the biosensor is simple and allows for the separation of faradic and nonfaradaic contributions. The simple electrochemical resistive biosensor reported here is a good candidate for the point-of-care diagnosis of HPV at a low cost and in a short detection time.


Assuntos
Técnicas Biossensoriais/instrumentação , DNA Viral/análise , Papillomavirus Humano 16/isolamento & purificação , Infecções por Papillomavirus/diagnóstico , Técnicas Eletroquímicas/instrumentação , Eletrodos , Ouro/química , Papillomavirus Humano 16/genética , Humanos , Limite de Detecção , Testes Imediatos
14.
Biosensors (Basel) ; 11(6)2021 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-34202953

RESUMO

Aflatoxin B1 (AFB1), a mycotoxin, is hepatotoxic, carcinogenic, and nephrotoxic in humans and animals, and contaminate a wide range of maize. In this study, an immunochromatographic assay (ICA) based on polystyrene microspheres (PMs) was developed for sensitive and quantitative detection of AFB1 in maize. The amounts of PMs, the condition for activating carboxyl groups of PMs, the amount of monoclonal antibody (mAb), and the volume of the immune probe were optimized to enhance the performance PMs-ICA for point-of-care testing of AFB1 in maize. The PMs-ICA showed the cut-off value of 1 ng/mL in phosphate buffer (PB) and 6 µg/kg in maize samples, respectively. The quantitative limit of detection (qLOD) was 0.27 and 1.43 µg/kg in PB and maize samples, respectively. The accuracy and precision of the PMs-ICA were evaluated by analysis of spiked maize samples with recoveries of 96.0% to 107.6% with coefficients of variation below 10%. In addition, the reliability of PMs-ICA was confirmed by the liquid chromatography-tandem mass spectrometry method. The results indicated that the PMs-ICA could be used as a sensitive, simple, rapid point-of-care testing of AFB1 in maize.


Assuntos
Aflatoxina B1/análise , Zea mays/microbiologia , Animais , Anticorpos Monoclonais , Cromatografia de Afinidade , Humanos , Imunoensaio , Limite de Detecção , Microesferas , Micotoxinas , Poliestirenos/química , Reprodutibilidade dos Testes
15.
Biosensors (Basel) ; 11(6)2021 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-34204823

RESUMO

In order to improve the interpretation of measurement results and to achieve the optimal performance of microfluidic biosensors, advanced mathematical models of their time response and noise are needed. The random nature of adsorption-desorption and mass transfer (MT) processes that generate the sensor response makes the sensor output signal inherently stochastic and necessitates the use of a stochastic approach in sensor response analysis. We present a stochastic model of the sensor time response, which takes into account the coupling of adsorption-desorption and MT processes. It is used for the analysis of response kinetics and ultimate noise performance of protein biosensors. We show that slow MT not only decelerates the response kinetics, but also increases the noise and decreases the sensor's maximal achievable signal-to-noise ratio, thus degrading the ultimate sensor performance, including the minimal detectable/quantifiable analyte concentration. The results illustrate the significance of the presented model for the correct interpretation of measurement data, for the estimation of sensors' noise performance metrics important for reliable analyte detection/quantification, as well as for sensor optimization in terms of the lower detection/quantification limit. They are also incentives for the further investigation of the MT influence in nanoscale sensors, as a possible cause of false-negative results in analyte detection experiments.


Assuntos
Técnicas Biossensoriais , Microfluídica , Adsorção , Cinética , Limite de Detecção , Modelos Teóricos , Razão Sinal-Ruído
16.
Biosensors (Basel) ; 11(6)2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-34204930

RESUMO

The early detection of the human immunodeficiency virus (HIV) is of paramount importance to achieve efficient therapeutic treatment and limit the disease spreading. In this perspective, the assessment of biosensing assay for the HIV-1 p24 capsid protein plays a pivotal role in the timely and selective detection of HIV infections. In this study, multi-parameter-SPR has been used to develop a reliable and label-free detection method for HIV-1 p24 protein. Remarkably, both physical and chemical immobilization of mouse monoclonal antibodies against HIV-1 p24 on the SPR gold detecting surface have been characterized for the first time. The two immobilization techniques returned a capturing antibody surface coverage as high as (7.5 ± 0.3) × 1011 molecule/cm2 and (2.4 ± 0.6) × 1011 molecule/cm2, respectively. However, the covalent binding of the capturing antibodies through a mixed self-assembled monolayer (SAM) of alkanethiols led to a doubling of the p24 binding signal. Moreover, from the modeling of the dose-response curve, an equilibrium dissociation constant KD of 5.30 × 10-9 M was computed for the assay performed on the SAM modified surface compared to a much larger KD of 7.46 × 10-5 M extracted for the physisorbed antibodies. The chemically modified system was also characterized in terms of sensitivity and selectivity, reaching a limit of detection of (4.1 ± 0.5) nM and an unprecedented selectivity ratio of 0.02.


Assuntos
Bioensaio/métodos , Proteína do Núcleo p24 do HIV , Ressonância de Plasmônio de Superfície , Técnicas Biossensoriais , Ouro/química , HIV-1 , Limite de Detecção
17.
Biosensors (Basel) ; 11(6)2021 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-34205541

RESUMO

A magnetic beads (MB)-involved amperometric immunosensor for the determination of ST2, a member of the IL1 receptor family, is reported in this work. The method utilizes a sandwich immunoassay and disposable screen-printed carbon electrodes (SPCEs). Magnetic immunoconjugates built on the surface of carboxylic acid-microsized magnetic particles (HOOC-MBs) were used to selectively capture ST2. A biotinylated secondary antibody further conjugated with a streptavidin peroxidase conjugate (Strep-HRP) was used to accomplish the sandwiching of the target protein. The immune platform exhibits great selectivity and a low limit of detection (39.6 pg mL-1) for ST2, allowing the determination of soluble ST2 (sST2) in plasma samples from healthy individuals and patients diagnosed with pancreatic ductal adenocarcinoma (PDAC) in only 45 min once the immunoconjugates have been prepared. The good correlation of the obtained results with those provided by an ELISA kit performed using the same immunoreagents demonstrates the potential of the developed strategy for early diagnosis and/or prognosis of the fatal PDAC disease.


Assuntos
Técnicas Biossensoriais , Imunoensaio , Neoplasias/diagnóstico , Anticorpos , Carbono , Técnicas Eletroquímicas , Eletrodos , Ensaio de Imunoadsorção Enzimática , Humanos , Peróxido de Hidrogênio , Limite de Detecção , Magnetismo
18.
Anal Chem ; 93(27): 9621-9627, 2021 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-34197082

RESUMO

Manganese dioxide nanosheets combined with cysteine-assisted emitting manganese dioxide nanospheres (Cys-MnO2 nanospheres) is fabricated for the first time as an "off-on" fluorescence detection platform for glutathione (GSH). In this sensing system, Cys-MnO2 nanospheres served as energy donors, while MnO2 nanosheets were used as both energy acceptors and recognition units. MnO2 nanosheets can effectively quench the fluorescence of Cys-MnO2 nanospheres through the fluorescence resonance energy transfer (FRET). The addition of GSH could reduce MnO2 nanosheets into Mn2+, disrupting the FRET process and restoring the fluorescence of Cys-MnO2 nanospheres. Under the optimum conditions, the "switch-on" platform we established has a wide response to GSH with a range of 5-50 µM and 150-800 µM, as well as a superior specificity. Importantly, all components of the sensor are nontoxic, biocompatible, easily prepared, and have a high utilization of raw materials. Moreover, the sensing system achieved satisfactory results in human serum, showing a tremendous potential in the field of biomedicine.


Assuntos
Glutationa/análise , Compostos de Manganês , Nanosferas , Cisteína , Transferência Ressonante de Energia de Fluorescência , Humanos , Limite de Detecção , Óxidos
19.
Biosensors (Basel) ; 11(6)2021 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-34200338

RESUMO

The detection of cancer antigens is a major aim of cancer research in order to develop better patient management through early disease detection. Many cancers including prostate, lung, and ovarian secrete a protein disulfide isomerase protein named AGR2 that has been previously detected in urine and plasma using mass spectrometry. Here we determine whether a previously developed monoclonal antibody targeting AGR2 can be adapted from an indirect two-site ELISA format into a direct detector using solid-phase printed gold electrodes. The screen-printed gold electrode was surface functionalized with the anti-AGR2 specific monoclonal antibody. The interaction of the recombinant AGR2 protein and the anti-AGR2 monoclonal antibody functionalized electrode changed its electrochemical impedance spectra. Nyquist diagrams were obtained after incubation in an increasing concentration of purified AGR2 protein with a range of concentrations from 0.01 fg/mL to 10 fg/mL. In addition, detection of the AGR2 antigen can be achieved from cell lysates in medium or artificial buffer. These data highlight the utility of an AGR2-specific monoclonal antibody that can be functionalized onto a gold printed electrode for a one-step capture and quantitation of the target antigen. These platforms have the potential for supporting methodologies using more complex bodily fluids including plasma and urine for improved cancer diagnostics.


Assuntos
Técnicas Biossensoriais , Mucoproteínas/análise , Proteínas Oncogênicas/análise , Anticorpos Monoclonais , Técnicas Eletroquímicas , Eletrodos , Ouro , Humanos , Limite de Detecção , Nanopartículas Metálicas , Neoplasias
20.
Biosensors (Basel) ; 11(6)2021 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-34200643

RESUMO

In this study, we developed the portable chemiluminescence (CL)-based lateral flow assay (LFA) platform for the detection of cortisol in human serum. Cortisol is well-known as a stress hormone due to its high relevancy for human mental and physical health, such as hypertension or depression. To date, a number of optical devices have provided the sensitive determination of levels of analytes. However, this modality type still requires costly optical modules. The developed CL platform is simply composed of two detection modules along with a loading part for the LFA strip. The LFA membrane contains gold nanoparticle probes conjugated with antibodies against cortisol and horseradish peroxidase (HRP), which can also efficiently increase the luminescent signal by providing many areas for anti-cortisol antibody and HRP. The measured voltage signals coming from the photodiode in a CL reader were compared with a standard microplate reader for the evaluation of accuracy. The linear range observed for cortisol was measured to be 0.78-12.5 µg/dL (R2 = 0.99) with a limit of detection (LOD) of 0.342 µg/dL. In addition, the CL-LFA reader showed a high correlation (R2 = 0.96) with the standard cortisol console (COBAS 8000, Roche), suggesting that our developed CL-based LFA platform can be usable in situ.


Assuntos
Técnicas Biossensoriais , Hidrocortisona/sangue , Anticorpos , Ouro , Peroxidase do Rábano Silvestre , Humanos , Imunoensaio , Limite de Detecção , Luminescência , Medições Luminescentes , Nanopartículas Metálicas , Aplicativos Móveis , Testes Imediatos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...