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1.
ACS Sens ; 5(9): 2747-2752, 2020 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-32820626

RESUMO

With the current intense need for rapid and accurate detection of viruses due to COVID-19, we report on a platform technology that is well suited for this purpose, using intact measles virus for a demonstration. Cases of infection due to the measles virus are rapidly increasing, yet current diagnostic tools used to monitor for the virus rely on slow (>1 h) technologies. Here, we demonstrate the first biosensor capable of detecting the measles virus in minutes with no preprocessing steps. The key sensing element is an electrode coated with a self-assembled monolayer containing the measles antibody, immobilized through an N-heterocyclic carbene (NHC). The intact virus is detected by changes in resistance, giving a linear response to 10-100 µg/mL of the intact measles virus without the need to label or process the sample. The limit of detection is 6 µg/mL, which is at the lower limit of concentrations that can cause infections in primates. The NHC-based biosensors are shown to be superior to thiol-based systems, producing an approximately 10× larger response and significantly greater stability toward repeated measurements and long-term storage. This NHC-based biosensor thus represents an important development for both the rapid detection of the measles virus and as a platform technology for the detection of other biological targets of interest.


Assuntos
Anticorpos Imobilizados/imunologia , Benzimidazóis/química , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Vírus do Sarampo/isolamento & purificação , Anticorpos Imobilizados/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Ouro/química , Limite de Detecção , Vírus do Sarampo/imunologia
2.
Biosens Bioelectron ; 165: 112361, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32729494

RESUMO

The recent outbreak of the coronavirus disease (COVID-19) has left the world clueless. As the WHO declares this new contagion as a pandemic on the 11th of March 2020, the alarming rate of the spawn of the disease in such a short period has disarranged the globe. Standing against this situation researchers are strenuously searching for the key traits responsible for this pandemic. As knowledge regarding the dynamics and host-path interaction of COVID-19 causing Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is currently unknown, the formulation of strategies concerning antiviral treatment, vaccination, and epidemiological control stands crucial. Before designing adequate therapeutic strategies, it is extremely essential to diagnose the disease at the outset as early detection can have a greater impact on building health system capacity. Hence, a comprehensive review of strategies for COVID-19 diagnosis is essential in this existing global situation. In this review, sequentially, we have provided the clinical details along with genetic and proteomic biomarkers related to COVID-19. The article systematically enlightens a clear overview of the clinically adopted techniques for the detection of COVID-19 including oligonucleotide-based molecular detection, Point-of-Care immunodiagnostics, radiographical analysis/sensing system, and newly developed biosensing prototypes having commercial viability. The commercial kits/analytical methods based-sensing strategies have also been tabulated categorically. The critical insights on the developer, commercial brand name, detection methods, technical operational details, detection time, clinical specimen, status, the limit of detection/detection ability have been discussed comprehensively. We believe that this review may provide scientists, clinicians and healthcare manufacturers valuable information regarding the most recent developments/approaches towards COVID-19 diagnosis.


Assuntos
Betacoronavirus/isolamento & purificação , Técnicas Biossensoriais/métodos , Infecções por Coronavirus/diagnóstico , Dispositivos Lab-On-A-Chip , Pneumonia Viral/diagnóstico , Testes Imediatos , Animais , Anticorpos Imobilizados/química , Betacoronavirus/genética , Biomarcadores/análise , Técnicas Biossensoriais/instrumentação , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Infecções por Coronavirus/sangue , Infecções por Coronavirus/virologia , Desenho de Equipamento , Humanos , Imunoensaio/instrumentação , Imunoensaio/métodos , Nanoestruturas/química , Pandemias , Pneumonia Viral/sangue , Pneumonia Viral/virologia , Intensificação de Imagem Radiográfica/instrumentação , Intensificação de Imagem Radiográfica/métodos , Reação em Cadeia da Polimerase Via Transcriptase Reversa/instrumentação , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos
3.
J Chromatogr A ; 1624: 461227, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32540069

RESUMO

Affinity chromatography is generally regarded as a powerful tool allowing the single step purification of recombinant proteins with high purity and yields. However, for most protein products, affinity purification methods for industrial applications are not readily available, mainly due to the lack of specific and robust natural counterparts that could function as affinity ligands. In this study, we explored the applicability of nanobody-based peptide-tag immunorecognition systems as a platform for affinity chromatography. Two typical nanobodies (BC2-nb and Syn2-nb) that are capable of recognizing specifically a particular peptide-tag, were prepared through prokaryotic expression and proved to be able to bind with nanomolar affinity to their cognate tag fused to enhanced green fluorescent protein (eGFP). Through an epoxy-based immobilization reaction, the two nanobodies were coupled on a Sepharose CL-6B matrix under the same conditions. The remaining antigen binding activity of the immobilized BC2-nb and Syn2-nb was determined to be 83.1% and 42.9%, yielding the resins with the dynamic binding capacity (DBC) of 21.4 mg/mL and 5.9 mg/mL, respectively. The immobilized affinity ligands exhibited high binding specificity towards their respective target peptides, yielding a product purity above 90% directly from crude bacterial lysates in one single chromatographic step. However, for the both affinity complexes, desorption has been found difficult, and effective recovery of the bound products could be only achieved with competitive elution or after employing harsh conditions such as 10 mM NaOH solution, which will compromise the reuse cycles of the affinity resins. This study shows the potential of nanobody-based affinity chromatography for efficient purification of recombinant proteins especially from complex feedstocks and reveals the primary issues to be addressed to develop a successful application.


Assuntos
Cromatografia de Afinidade/métodos , Peptídeos/imunologia , Anticorpos de Domínio Único/imunologia , Sequência de Aminoácidos , Anticorpos Imobilizados/química , Anticorpos Imobilizados/imunologia , Cromatografia Líquida de Alta Pressão , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Cinética , Peptídeos/química , Peptídeos/isolamento & purificação , Anticorpos de Domínio Único/genética , Anticorpos de Domínio Único/metabolismo
4.
Chemistry ; 26(38): 8400-8406, 2020 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-32240571

RESUMO

One of the main problems in the development of immunosensors is to overcome the complexity of binding antibodies to the sensor surface. Most immobilizing methods lead to a random orientation of antibodies with a lower binding site density and immunoaffinity. In order to control the orientation of antibody immobilization, several resorc[4]arene derivatives were designed and synthesized. After the spectroscopic characterization of resorc[4]arene self-assembled monolayers (SAMs) onto gold films, the surface coverage and the orientation of insulin antibody (Ab-Ins) were assessed by a surface plasmon resonance (SPR) technique and compared with a random immobilization method. Experimental results combined with theoretical studies confirmed the dipole-dipole interaction as an important factor in antibody orientation and demonstrated the importance of the upper rim functionalization of resorcarenes. Accordingly, resorcarene 5 showed a major binding force towards Ab-Ins thanks to the H-bond interactions with the amine protein groups. Based on these findings, the resorcarene-based immunosensor is a powerful system with improved sensitivity providing new insight into sensor development.


Assuntos
Anticorpos Imobilizados/química , Anticorpos/química , Ouro/química , Ressonância de Plasmônio de Superfície/métodos , Sítios de Ligação
5.
Artigo em Inglês | MEDLINE | ID: mdl-32109745

RESUMO

In this study, haptens were designed to produce highly sensitive and specific monoclonal antibodies (mAb) against carbamazepine (CBZ) and its metabolite carbamazepine-10, 11-epoxide (CBZ-EP). According to the results of our competitive enzyme-linked immunosorbent assay (ic-ELISA), the half-maximum inhibitory concentration values for anti-CBZ and anti-CBZ-EP mAb were 0.18 and 0.59 ng/mL, respectively. An immunochromatographic assay (ICA) was developed for the determination of CBZ and CBZ-EP concentrations. This method can provide visible limits of detection ranging from 0.25 to 1 ng/mL, and cut-off limits ranging from 5 to 10 ng/mL, and takes 10 min to evaluate with the naked eye. Importantly, these observations were consistent with those obtained by ic-ELISA and liquid chromatography-mass spectrometry. The ICA assay represented a reliable, fast, and high-throughput method for the determination of CBZ and CBZ-EP in serum samples.


Assuntos
Anticorpos Monoclonais/química , Carbamazepina/análogos & derivados , Carbamazepina/sangue , Imunoensaio/métodos , Anticorpos Imobilizados/química , Anticorpos Imobilizados/metabolismo , Anticorpos Monoclonais/metabolismo , Carbamazepina/isolamento & purificação , Carbamazepina/metabolismo , Cromatografia Líquida , Humanos , Limite de Detecção , Modelos Lineares
6.
Sensors (Basel) ; 20(1)2020 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-31947810

RESUMO

The development of a simple and low cost electrochemical impedance immunosensor based on screen printed gold electrode for rapid detection of Escherichia coli in water is reported. The immunosensor is fabricated by immobilizing anti-E. coli antibodies onto a gold surface in a covalent way by the photochemical immobilization technique, a simple procedure able to bind antibodies upright onto gold surfaces. Impedance spectra are recorded in 0.01 M phosphate buffer solution (PBS) containing 10 mM Fe(CN)63-/Fe(CN)64- as redox probe. The Nyquist plots can be modelled with a modified Randles circuit, identifying the charge transfer resistance Rct as the relevant parameter after the immobilization of antibodies, the blocking with BSA and the binding of E. coli. The introduction of a standard amplification procedure leads to a significant enhancement of the impedance increase, which allows one to measure E. coli in drinking water with a limit of detection of 3 × 101 CFU mL-1 while preserving the rapidity of the method that requires only 1 h to provide a "yes/no" response. Additionally, by applying the Langmuir adsorption model, we are able to describe the change of Rct in terms of the "effective" electrode, which is modified by the detection of the analyte whose microscopic conducting properties can be quantified.


Assuntos
Anticorpos Imobilizados/química , Técnicas Biossensoriais , Água Potável/microbiologia , Escherichia coli O157/isolamento & purificação , Impedância Elétrica , Eletrodos , Escherichia coli O157/patogenicidade , Ouro/química , Humanos , Limite de Detecção , Microbiologia da Água
7.
Nanoscale ; 12(4): 2773-2786, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31957767

RESUMO

Until now, magnetic hyperthermia was used to remove solid tumors by targeting magnetic nanoparticles (MNPs) to tumor sites. In this study, leukemia cells in the bloodstream were directly removed by whole-body hyperthermia, using leukemia cell-specific MNPs. An epithelial cellular adhesion molecule (EpCAM) antibody was immobilized on the surface of MNPs (EpCAM-MNPs) to introduce the specificity of MNPs to leukemia cells. The viability of THP1 cells (human monocytic leukemia cells) was decreased to 40.8% of that in control samples by hyperthermia using EpCAM-MNPs. In AKR mice, an animal model of lymphoblastic leukemia, the number of leukemia cells was measured following the intravenous injection of EpCAM-MNPs and subsequent whole-body hyperthermia treatment. The result showed that the leukemia cell number was also decreased to 43.8% of that without the treatment of hyperthermia, determined by Leishman staining of leukemia cells. To support the results, simulation analysis of heat transfer from MNPs to leukemia cells was performed using COMSOL Multiphysics simulation software. The surface temperature of leukemia cells adhered to EpCAM-MNPs was predicted to be increased to 82 °C, whereas the temperature of free cells without adhered MNPs was predicted to be 38 °C. Taken together, leukemia cells were selectively removed by magnetic hyperthermia from the bloodstream, because EpCAM-modified magnetic particles were specifically attached to leukemia cell surfaces. This approach has the potential to remove metastatic cancer cells, and pathogenic bacteria and viruses floating in the bloodstream.


Assuntos
Hipertermia Induzida/métodos , Nanopartículas de Magnetita/administração & dosagem , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Animais , Anticorpos Imobilizados/administração & dosagem , Anticorpos Imobilizados/química , Linhagem Celular , Sobrevivência Celular , Modelos Animais de Doenças , Molécula de Adesão da Célula Epitelial/imunologia , Molécula de Adesão da Célula Epitelial/metabolismo , Humanos , Separação Imunomagnética , Nanopartículas de Magnetita/química , Camundongos , Camundongos Endogâmicos AKR , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo
8.
Analyst ; 145(4): 1368-1375, 2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-31994546

RESUMO

In this study, a sensitive label-free electrochemical immunosensor was designed based on nanoporous Fe3O4 and a biotin-streptavidin system to specifically detect zearalenone (ZEN). Herein, nanoporous Fe3O4 was employed to carry streptavidin to prepare the highly sensitive immunosensor. The application of nanoporous Fe3O4 and the biotin-streptavidin reaction provided large amounts of antibodies on each conjugate, thus amplifying the detected signal. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were conducted to characterize the modification with ZEN. Factors which might influence the properties of the immunosensor, including concentration of nanoporous Fe3O4, pH of the buffer, incubation time and temperature were studied. Under the best conditions, the immunosensor displayed a highly sensitive response toward ZEN, ranging in concentration from 10.0 pg mL-1 to 3.00 ng mL-1 and 3.00 ng mL-1 to 12.0 ng mL-1, with a low detection limit of 3.7 pg mL-1. The results for analysis of human urine samples were satisfactory. Furthermore, this proposed method may find promising applications in the detection of other mycotoxins.


Assuntos
Técnicas Biossensoriais/métodos , Biotina/química , Técnicas Eletroquímicas/métodos , Óxido Ferroso-Férrico/química , Nanoporos , Estreptavidina/química , Zearalenona/urina , Anticorpos Imobilizados/química , Técnicas Biossensoriais/instrumentação , Biotina/imunologia , Técnicas Eletroquímicas/instrumentação , Eletrodos , Humanos , Imunoensaio , Limite de Detecção , Reprodutibilidade dos Testes
9.
Anal Chim Acta ; 1096: 61-68, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31883592

RESUMO

Sensitive and reliable detection of biomarkers is of vital importance in tumor early detection and clinical therapy. A novel fluorescent/electrochemical dual-responsive immunosensing platform for reliable and sensitive quantification of biomarkers was designed based on cation-exchange reaction. To construct such a versatile platform, the model analyte, carcinoembryonic antigen (CEA), was captured by magnetic Fe3O4 nanoparticles bound with primary antibodies (Fe3O4-Ab1) and then recognized by the detection antibodies conjugated complex containing poly(amidoamine) (PAMAM), carbon nanotube (CNT) and carboxyl functionalized CdSe nanocrystals (NCs) (CNT-PAMAM-CdSe NCs-Ab2). Via ligand exchange, the stable CdSe nanocrystals were easily functionalized with carboxylate ion (CdSe-COO-) and showed high hydrophilicity. The CdSe-COO- was effectively and densely conjugated to CNT coated dendrimer PAMAM that possesses large specific surface area. Finally, the target CEA was detected based on cation-exchange reaction (CER) by adding Ag+ to release thousands of cations Cd2+, which were detected by fluorescence and electrochemistry simultaneously. The electrochemical measurement was performed by directly detecting Cd2+ through square wave voltammetry (SWV), which displayed an excellent correlation with CEA from 5 pg/mL to 50 ng/mL, with a limit of detection (LOD) of 1.7 pg/mL. The fluorescence detection was implemented since free Cd2+ could trigger the weak fluorescence metal-sensitive dyes (Rhod-5N) to generate extremely high fluorescence signal. The fluorescence results showed the LOD for CEA detection was 0.25 pg/mL with a calibration curve range from 1 pg/mL to 20 ng/mL. The dual signal outputs showed an attractively self-correcting ability, which provides the capability of avoiding false positive signal and making the detection result more reliable. The proposed dual-responsive platform holds great promises for biomarkers detection in clinical diagnostics and therapy.


Assuntos
Anticorpos Imobilizados/química , Técnicas Biossensoriais/métodos , Compostos de Cádmio/química , Antígeno Carcinoembrionário/sangue , Nanopartículas/química , Compostos de Selênio/química , Antígeno Carcinoembrionário/análise , Cátions/química , Dendrímeros/química , Técnicas Eletroquímicas/métodos , Corantes Fluorescentes/química , Humanos , Imunoensaio/métodos , Limite de Detecção , Nanopartículas de Magnetita/química , Nanotubos de Carbono/química , Espectrometria de Fluorescência/métodos
10.
Biosens Bioelectron ; 148: 111800, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31678824

RESUMO

Circling exosomal PD-L1 can be expected as a predictor for the clinical responds of anti-PD-1/PD-L1 therapy. Here, we present a simple method integrating capture and analysis of exosomal PD-L1 directly from serum. Firstly, Fe3O4@TiO2 nanoparticles were used to enrich exosomes through the binding of TiO2 shell and hydrophilic phosphate head of the exosome phospholipids. Model exosomes can be enriched and separated from solution within 5 min with a capture efficiency of 96.5%. Secondly, anti-PD-L1 antibody modified Au@Ag@MBA SERS tags were added to label the exosomal PD-L1 for quantification. The whole process can be finished within 40 min with a detection limit of 1 PD-L1+exosome/µL. Furthermore, this method was used for personalized exosomal PD-L1quantification by using a 4 µL clinical serum sample individually. Based on the personalized SERS signal analysis, NSCLC patients can be distinguished from the healthy controls easily. More important, the advantage of clearly individual quantification may help the doctor to discover the relationship of exosomal PD-L1 and the immnuotherapy responds in individual level.


Assuntos
Antígeno B7-H1/análise , Antígeno B7-H1/sangue , Exossomos/química , Óxido Ferroso-Férrico/química , Análise Espectral Raman/métodos , Titânio/química , Células A549 , Anticorpos Imobilizados/química , Antígeno B7-H1/isolamento & purificação , Técnicas Biossensoriais/métodos , Linhagem Celular , Humanos , Imunoensaio/métodos
11.
Biosens Bioelectron ; 148: 111815, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31689595

RESUMO

In this work, we demonstrate label-free electrochemical impedance spectroscopy (EIS) based alkaline phosphatase (ALP) detection using gold nanoparticles (AuNPs), electrochemically engineered Au-nano-Dendroids, and graphene oxide (GO) nanocomposite. These nanomaterials were sequentially deposited on to the screen-printed carbon electrode (SPCE) and antibodies against ALP (anti-ALP) were immobilized using carbodiimide bioconjugation process. The sensor probe has been characterized extensively using TEM, EDX, SAED, XRD, FE-SEM, FTIR, DIC, and electrochemical techniques. The analytical performance of fabricated biosensor has been evaluated using EIS, where linear dynamic range and limit of detection were obtained to be 100-1000 U/L and 9.10 (±0.12) U/L, respectively. The developed biosensor showed high selectivity towards ALP with negligible interference (ksel « 1; n = 3) due to coexisting molecules. The sensor probe has successfully recovered ALP between 108.84% and 172.50% (n = 3) in human serum samples. The sensor has been used to estimate ALP in clinical serum samples, where the level was found to be 83.15 U/L and was comparable with standard technique used in the hospitals. The shelf life, stability, and reproducibility have also been evaluated.


Assuntos
Fosfatase Alcalina/sangue , Técnicas Biossensoriais/instrumentação , Espectroscopia Dielétrica/instrumentação , Ouro/química , Grafite/química , Nanocompostos/química , Anticorpos Imobilizados/química , Desenho de Equipamento , Humanos , Imunoensaio/instrumentação , Limite de Detecção
12.
Biosens Bioelectron ; 148: 111809, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31706176

RESUMO

A flexible two-step photoelectrochemical (PEC)-colorimetric immunoassay was proposed for ultrasensitive detection of lipolysis stimulated lipoprotein receptor (LSR) which is found to be closely related to ovarian cancer (OC). In this paper, the Cu nanoclusters (CuNCs) enhanced multiple mixed TiO2 mesocrystals junction (MMMJ) was fabricated via effective combination of multiple different phases TiO2 mesocrystals (Anatase and Rutile) layers and used as a sensing platform. The strong interaction between different phases layers caused multiple amplification of signal and introduction of Cu NCs further improve PEC properties and catalytic activity to hydrogen peroxide (H2O2) what can catalyze lecuo-methylene blue (lecuo-MB) from colorless to blue. As antibody and target antigen captured onto the MMMJ in turn, both PEC properties and catalytic activities were inhibited, leading to decreased photocurrent responses and multiply vivid color variations in lecuo-MB functionalized colorimetric films. Thus, a versatile dual-modal sensing system was developed just by utilizing enhanced MMMJ as a photoelectrode and lecuo-MB as a color change reporter molecule for PEC and colorimetric monitoring of target. Combing all of these advantages, the designed dual-modal immunoassay considerately reduced false positive or negative results during the measurement, and the unique approach for MMMJ construction may also provide a valuable guidance for designing other mixed phase junctions with superior PEC performance.


Assuntos
Colorimetria/métodos , Cobre/química , Nanoestruturas/química , Receptores de Lipoproteínas/sangue , Titânio/química , Anticorpos Imobilizados/química , Técnicas Biossensoriais/métodos , Compostos de Cádmio , Técnicas Eletroquímicas/métodos , Humanos , Imunoensaio/métodos
13.
Biosens Bioelectron ; 148: 111836, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31731074

RESUMO

This work reports a customized methodology for the fabrication of 3D CdS nanosheet (NS)-enwrapped carbon fiber framework (CFF) and its utilization for sensitive split-type CuO-mediated PEC immunoassay. Specifically, the 3D CdS NS-CFF was fabricated via a solvothermal process, while the sandwich immunocomplexing was allowed in a 96 well plate with CuO nanoparticles (NPs) as the signaling labels. The subsequent release of the Cu2+ ions was directed to interact with the CdS NS, generating trapping sites and thus inhibiting its photocurrent generation. In such a protocol, the 3D CdS NS-CFF photoelectrode could not only guarantee its sufficient contact with the Cu2+-containing solution but also supply plenty CdS surface for the Cu2+ ions. Because of the target-dependent release of the Cu2+ ions and its proper coupling with the 3D CdS NS-CFF photoelectrode, a sensitive split-type PEC immunoassay was achieved for the detection of brain natriuretic peptide (BNP). This proposed system exhibited good stability and selectivity, and its applicability for real sample analysis was also demonstrated via comparison with the commercial BNP enzyme-linked immunosorbent assay (ELISA) kit. We expect this work could stimulate more interest in the design and utilization of 3D photoelectrodes for novel PEC bioanalysis.


Assuntos
Anticorpos Imobilizados/química , Técnicas Biossensoriais/métodos , Compostos de Cádmio/química , Fibra de Carbono/química , Cobre/química , Peptídeo Natriurético Encefálico/sangue , Sulfetos/química , Técnicas Eletroquímicas/métodos , Humanos , Imunoensaio/métodos , Limite de Detecção , Nanoestruturas/química , Peptídeo Natriurético Encefálico/análise , Processos Fotoquímicos
14.
Biosens Bioelectron ; 148: 111739, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31731075

RESUMO

A competitive-type PEC immunosensor for 17ß-estradiol (E2) detection was successfully fabricated using ZnIn2S4@NH2-MIL-125(Ti) composite as matrix. The excellent PEC behavior of ZnIn2S4@NH2-MIL-125(Ti) composite could be attributed to that the Ti4+-Ti3+ intervalence cycles in the titanium oxo-cluster of NH2-MIL-125(Ti) as well as the matching energy level between ZnIn2S4 and NH2-MIL-125(Ti) promote the migration and separation of photocarrier. Besides, polydopamine (PDA) with abundant amino- and quinone-groups was selected to further improve the PEC signals and capture antibody, which implement through the covalent bonding of PDA and BSA-E2 or carboxyl-group functionalized Mn:ZnCdS QDs in the competitive-type strategy. Concretely, the quinone functional groups in PDA film was applied to immobilize BSA-E2 through Michael reactions, and the PDA nanosphere loaded Mn:ZnCdS quantum dot (PDA NS/Mn:ZnCdS QDs) was used as antibodies' labels to amplify PEC signals. After PDA NS/Mn:ZnCdS-anti-E2 immobilized on the modified electrode, a remarkable increase of photocurrent signal was observed owing to the specific bonding of antigen and antibody. Based on the competitive binding of PDA NS/Mn:ZnCdS-anti-E2 with either free E2 or bovine serum albumin (BSA)-E2 causing the change of the photocurrent signal, the standard sample free E2 could be accuracy detect. Under optimal conditions, the competitive-type PEC immunosensor exhibited the linear range from 0.0005 ng/mL to 20 ng/mL and a limit detection of 0.3 pg/mL (S/N = 3). Meanwhile, the acceptable stability, selectivity and reproducibility of the proposed PEC immunosensing platform indicating the promising detection of small molecular environmental pollutants.


Assuntos
Técnicas Biossensoriais/métodos , Estradiol/análise , Indóis/química , Nanocompostos/química , Polímeros/química , Titânio/química , Poluentes Químicos da Água/análise , Anticorpos Imobilizados/química , Compostos de Cádmio/química , Técnicas Eletroquímicas/métodos , Imunoensaio/métodos , Limite de Detecção , Dietilamida do Ácido Lisérgico/análogos & derivados , Dietilamida do Ácido Lisérgico/química , Nanocompostos/ultraestrutura , Pontos Quânticos/química , Pontos Quânticos/ultraestrutura , Sulfetos/química , Água/análise , Zinco/química
15.
Anal Bioanal Chem ; 412(4): 811-818, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31865415

RESUMO

Early diagnosis of the infection caused by human immunodeficiency virus type-1 (HIV-1) is vital to achieve efficient therapeutic treatment and limit the disease spreading when the viremia is at its highest level. To this end, a point-of-care HIV-1 detection carried out with label-free, low-cost, and ultra-sensitive screening technologies would be of great relevance. Herein, a label-free single molecule detection of HIV-1 p24 capsid protein with a large (wide-field) single-molecule transistor (SiMoT) sensor is proposed. The system is based on an electrolyte-gated field-effect transistor whose gate is bio-functionalized with the antibody against the HIV-1 p24 capsid protein. The device exhibits a limit of detection of a single protein and a limit of quantification in the 10 molecule range. This study paves the way for a low-cost technology that can quantify, with single-molecule precision, the transition of a biological organism from being "healthy" to being "diseased" by tracking a target biomarker. This can open to the possibility of performing the earliest possible diagnosis.


Assuntos
Técnicas Biossensoriais/instrumentação , Proteína do Núcleo p24 do HIV/análise , HIV-1/isolamento & purificação , Transistores Eletrônicos , Anticorpos Imobilizados/química , Infecções por HIV/diagnóstico , Infecções por HIV/virologia , Humanos , Imunoensaio/instrumentação , Limite de Detecção , Modelos Moleculares
16.
Mikrochim Acta ; 187(1): 10, 2019 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-31797114

RESUMO

A lateral-flow immunochromatographic assay with excellent sensitivity and wide application potential is described. The bovine serum albumin (BSA) antibody was immobilized in the test line for universality, and preincubation was introduced for high method sensitivity. Carboxy-modified CdSe/ZnS core-shell nanoparticles were used as label, and the fluorescence peaking at 605 nm was detected. The fluorescence in the test line was negative against the relevant analyte content. The chloramphenicol (CAP) and the aflatoxin M1 (AFM1) in milk were detected using the same strip to validate the universality. After optimization, the detection limit for CAP is 10 pg·mL-1, which is three times less that of a conventional assay (30 pg·mL-1). The detection limit for AFM1 was 6 pg·mL-1, which was 13 times less than that of a conventional assay (8 pg·mL-1). The method was applied in the analysis of spiked milk samples. The performance was compared with that of the commercial ELISA kit, and good agreement was observed. Graphical abstractSchematic representation of the universal and sensitive combined immunochromatographic assay (USICA) and conventional immunochromatographic assay (TICA) of chloramphenicol (CAP) and aflatoxin M1.


Assuntos
Aflatoxina M1/análise , Anticorpos Imobilizados/química , Compostos de Cádmio/química , Cloranfenicol/análise , Imunoensaio/métodos , Nanopartículas/química , Compostos de Selênio/química , Sulfetos/química , Compostos de Zinco/química , Aflatoxina M1/química , Anticorpos Imobilizados/imunologia , Cloranfenicol/química , Limite de Detecção , Soroalbumina Bovina/imunologia
17.
Sensors (Basel) ; 20(1)2019 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-31878178

RESUMO

Assessing levels of neuropeptide Y (NPY) in the human body has many medical uses. Accordingly, we report the quantitative detection of NPY biomarkers applying guided-mode resonance (GMR) biosensor methodology. The label-free sensor operates in the near-infrared spectral region exhibiting distinctive resonance signatures. The interaction of NPY with bioselective molecules on the sensor surface causes spectral shifts that directly identify the binding event without additional processing. In the experiments described here, NPY antibodies are attached to the sensor surface to impart specificity during operation. For the low concentrations of NPY of interest, we apply a sandwich NPY assay in which the sensor-linked anti-NPY molecule binds with NPY that subsequently binds with anti-NPY to close the sandwich. The sandwich assay achieves a detection limit of ~0.1 pM NPY. The photonic sensor methodology applied here enables expeditious high-throughput data acquisition with high sensitivity and specificity. The entire bioreaction is recorded as a function of time, in contrast to label-based methods with single-point detection. The convenient methodology and results reported are significant, as the NPY detection range of 0.1-10 pM demonstrated is useful in important medical circumstances.


Assuntos
Técnicas Biossensoriais/métodos , Neuropeptídeo Y/análise , Anticorpos Imobilizados/química , Anticorpos Imobilizados/imunologia , Biomarcadores/análise , Humanos , Imunoensaio , Neuropeptídeo Y/imunologia , Polímeros/química
18.
Biomed Microdevices ; 22(1): 6, 2019 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-31844990

RESUMO

Advancements in health care monitoring demand a rapid, accurate and reliable early diagnosis of "Heart Attack" (acute myocardial infarction) with an objective to develop a cost-effective, rapid and label-free point of care diagnostic test kit for the detection of cardiac troponin I (cTnI) on paper-based multi-frequency impedimetric transducers. Paper based sensing platforms were developed by integrating carboxyl group functionalized multi-walled carbon nanotubes (MWCNT) with antibodies of cardiac troponin I (anti-cTnI) biomarker and was characterized using Electrochemical Impedance Spectroscopy (EIS). Various concentrations of cTnI with anti cTnI were studied as a function of impedance change. The suitability of the proposed immunosensor is demonstrated by spiking cTnI in blood serum samples. The limit of detection (LoD) and sensitivity of the proposed sensor was determined to be 0.05 ng/mL and 1.85 mΩ/ng/mL respectively, with a response time of ~1 min. The shelf life of the fabricated sensor was nearly 30 days. The rapid response, very low detection limit, and cost effectiveness offer a portable platform to detect cTnI in blood serum samples. The proposed immunosensor, therefore, offers an affordable healthcare diagnostic platform in resource limited areas.


Assuntos
Imunoensaio/métodos , Miocárdio/metabolismo , Papel , Sistemas Automatizados de Assistência Junto ao Leito , Troponina I/análise , Anticorpos Imobilizados/química , Anticorpos Imobilizados/imunologia , Biomarcadores/análise , Biomarcadores/sangue , Impedância Elétrica , Eletroquímica , Eletrodos , Humanos , Limite de Detecção , Nanotubos de Carbono/química , Troponina I/sangue , Troponina I/metabolismo
19.
Exp Oncol ; 41(4): 363-365, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31868327

RESUMO

AIM: To analyze the performance of biosensor based on nanoparticles of zinc oxide for the detection of spermine and spermidine in solution and in cell culture. MATERIALS AND METHODS: Zinc oxide nanoparticles were used for preparing biosensor containing antibodies to spermine and spermidine. Polyamine concentration is solutions of spermine and spermidine as well as in lyophilisate of MCF-7 cells was measured by luminescence of the samples excited by laser beam at 380 nm. RESULTS: The minimum concentration for the detection of polyamines in model solutions is 10 ng/ml, and maximum one is 100 ng/ml. A higher level of luminescence intensity of nanoparticles was found during analysis the polyamines in MCF-7 lyophilisate allowing for detecting polyamines at concentrations from 100 cells/ml to 100,000 cells/ml. CONCLUSIONS: The proposed biosensor system for determining the level of biogenic polyamines in cell lyophilisate using the optical properties of zinc oxide nanoparticles is promising for further improvement of the methodology and its implementation for detection and measurement of polyamines in biological systems.


Assuntos
Anticorpos Imobilizados/química , Técnicas Biossensoriais/métodos , Nanopartículas/química , Poliaminas/análise , Óxido de Zinco/química , Humanos , Células MCF-7 , Espermidina/análise , Espermina/análise
20.
ACS Appl Mater Interfaces ; 11(50): 46472-46478, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31746586

RESUMO

Here, a paper-based radial flow chromatographic immunoassay (RFCI) employing gold nanoparticles (AuNPs) as chromatic agents was developed for the detection of Escherichia coli O157:H7 in whole milk. A 4-repeated gold-binding peptide-tagged (4GBP) streptococcal protein G (SPG) fusion protein was constructed as a bifunctional linker to immobilize antibodies on the surface of AuNPs with a well-oriented form based on the specific affinity of GBP and SPG to the gold and Fc portion of the antibody, respectively. 4GS@AuNPs prepared with the bifunctional linker protein exhibited excellent colloidal stability even at high salt concentrations of up to 500 mM, which is a critical requirement for its application to a broad range of biological and food samples. The enhanced colloidal stability and excellent binding capability of the immuno-4GS@AuNPs toward target bacteria lowered the detection limit of RFCI for target pathogenic bacteria in whole milk as low as 103 CFU/mL, which is by an order of magnitude lower than that of conventional immuno-AuNPs prepared with physical adsorption of antibodies. The RFCI pattern could also be converted into a grayscale value by simple image processing for quantitative determination of target pathogenic bacteria. This paper-based detection system would provide an effective means of monitoring the presence of food-borne pathogens in real food samples with naked eyes.


Assuntos
Técnicas Biossensoriais , Infecções por Escherichia coli/diagnóstico , Escherichia coli O157/isolamento & purificação , Leite/microbiologia , Animais , Anticorpos Imobilizados/química , Bovinos , Infecções por Escherichia coli/microbiologia , Escherichia coli O157/patogenicidade , Ouro/química , Humanos , Imunoensaio/métodos , Limite de Detecção , Nanopartículas Metálicas/química
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