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1.
Sensors (Basel) ; 21(17)2021 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-34502675

RESUMO

Optical biosensors are used in numerous applications and analytical fields. Advances in these sensor platforms offer high sensitivity, selectivity, miniaturization, and real-time analysis, among many other advantages. Research into bioactive natural products serves both to protect against potentially dangerous toxic compounds and to promote pharmacological innovation in drug discovery, as these compounds have unique chemical compositions that may be characterized by greater safety and efficacy. However, conventional methods for detecting these biomolecules have drawbacks, as they are time-consuming and expensive. As an alternative, optical biosensors offer a faster, simpler, and less expensive means of detecting various biomolecules of clinical interest. In this review, an overview of recent developments in optical biosensors for the detection and monitoring of aquatic biotoxins to prevent public health risks is first provided. In addition, the advantages and applicability of these biosensors in the field of drug discovery, including high-throughput screening, are discussed. The contribution of the investigated technological advances in the timely and sensitive detection of biotoxins while deciphering the pathways to discover bioactive compounds with great health-promoting prospects is envisaged to meet the increasing demands of healthcare systems.


Assuntos
Técnicas Biossensoriais
2.
Sensors (Basel) ; 21(17)2021 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-34502753

RESUMO

While mRNA vaccines have been well-studied in vitro and in animals prior to their use in the human population during the Covid-19 pandemic, their exact mechanisms of inducing immunity are still being elucidated. The large-scale collection of data necessary to fully understand these mechanisms, and their variability across heterogeneous populations, requires rapid diagnostic tests that accurately measure the various biomarkers involved in the immune response following vaccination. Recently, our lab developed a novel "Disposable Photonics" platform for rapid, label-free, scalable diagnostics that utilizes photonic ring resonator sensor chips combined with plastic micropillar cards able to provide passive microfluidic flow. Here, we demonstrate the utility of this system in confirming the presence of SARS-CoV-2 spike protein in the serum of recently vaccinated subjects, as well as tracking a post-vaccination rise in anti-SARS-CoV-2 antibodies. A maximum concentration in SARS-CoV-2 spike protein was detected one day after vaccination and was reduced below detectable levels within 10 days. This highlights the applicability of our rapid photonic sensor platform for acquiring the data necessary to understand vaccine mechanisms on a large scale, as well as individual patient responses to SARS-CoV-2 mRNA vaccines.


Assuntos
Técnicas Biossensoriais , COVID-19 , Animais , Anticorpos Antivirais , Vacinas contra COVID-19 , Humanos , Óptica e Fotônica , Pandemias , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus , Vacinação
3.
Sensors (Basel) ; 21(17)2021 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-34502760

RESUMO

A 3-aminopropyl-triethoxysilane (APES) fiber-optic sensor based on a Mach-Zehnder interferometer (MZI) was demonstrated. The MZI was constructed with a core-offset fusion single mode fiber (SMF) structure with a length of 3.0 cm. As APES gradually attaches to the MZI, the external environment of the MZI changes, which in turn causes change in the MZI's interference. That is the reason why we can obtain the relationships between the APES amount and resonance dip wavelength by measuring the transmission variations of the resonant dip wavelength of the MZI. The optimized amount of 1% APES for 3.0 cm MZI biosensors was 3 mL, whereas the optimized amount of 2% APES was 1.5 mL.


Assuntos
Técnicas Biossensoriais , Hominidae , Animais , Tecnologia de Fibra Óptica , Interferometria , Fibras Ópticas
4.
Analyst ; 146(18): 5542-5549, 2021 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-34515703

RESUMO

Tumor-related exosomes, which are heterogeneous membrane-enclosed nanovesicles shed from cancer cells, have been widely recognized as potential noninvasive biomarkers for early cancer diagnosis. Herein, an artificial enzyme cascade amplification strategy based on a switchable DNA tetrahedral (SDT) scaffold was proposed for quantification of breast cancer-derived exosomes. The SDT scaffold is composed of G-quadruplex mimicking DNAzyme sequences on its two single-stranded edges and glucose oxidase (GOx) on the four termini of the complementary strands. In the initial state, the SDT scaffold is blocked by the switch strand which consists of partial complementary domains with the DNA tetrahedron and a MUC1 aptamer. MCF-7 exosomes could release the quadruplex-forming sequences through the recognition of the MUC1 aptamer. The newly formed DNAzyme brings GOx into spatial proximity and induces high-efficiency enzyme cascade catalytic reactions on the SDT. Consequently, high sensitivity toward MCF-7 exosome analysis was obtained with a wide linear range of 3.8 × 106 to 1.2 × 108 particles per mL and a limit of detection of 1.51 × 105 particles per mL. In addition, such a DNAzyme reconfiguration strategy was able to distinguish MCF-7 exosomes from other breast cancer cell derived exosomes, indicating its excellent method specificity. The proposed enzyme cascade strategy not only provides a novel signal transformation and amplification nanoplatform for quantifying the specific populations of exosomes, but also can be further expanded to the analysis of multiple cancer biomarkers.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Neoplasias da Mama , DNA Catalítico , Exossomos , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/genética , DNA Catalítico/genética , Exossomos/genética , Feminino , Humanos , Limite de Detecção
5.
Analyst ; 146(18): 5474-5495, 2021 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-34515706

RESUMO

Acute myocardial infarction (AMI) is the main cause of death from cardiovascular diseases. Thus, early diagnosis of AMI is essential for the treatment of irreversible damage from myocardial infarction. Traditional electrocardiograms (ECG) cannot meet the specific detection of AMI. Cardiac troponin I (cTnI) is the main biomarker for the diagnosis of myocardial infarction, and the detection of cTnI content has become particularly important. In this review, we introduced and compared the advantages and disadvantages of various cTnI detection methods. We focused on the analysis and comparison of the main indicators and limitations of various cTnI biosensors, including the detection range, detection limit, specificity, repeatability, and stability. In particular, we pay more attention to the application and development of electrochemical biosensors in the diagnosis of cardiovascular diseases based on different biological components. The application of electrochemical microfluidic chips for cTnI was also briefly introduced in this review. Finally, this review also briefly discusses the unresolved challenges of electrochemical detection and the expectations for improvement in the detection of cTnI biosensing in the future.


Assuntos
Técnicas Biossensoriais , Infarto do Miocárdio , Biomarcadores , Diagnóstico Precoce , Humanos , Infarto do Miocárdio/diagnóstico , Troponina I
6.
Analyst ; 146(18): 5528-5532, 2021 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-34515710

RESUMO

Conventional photoelectrochemical (PEC) analysis mostly utilizes photoactive material modified planar indium tin oxides (ITOs) to obtain photocurrent responses for the measurement of analytes in solution. In this work, a CdS quantum dot (QD) modified nanopipette was prepared for the PEC analysis of the alkaline phosphatase (ALP) activity in single MCF-7 cells. The nanopipette was filled with ascorbic acid 2-phosphate (AAP) that was egressed outside the nanopipette by electrochemical pumping. Next, AAP was catalyzed by ALP to generate ascorbic acid (AA), which is an efficient electron donor for CdS QDs under illumination. Based on the result that the nanopipette showed a linear photocurrent response to AA, a nearly linear correlation between the photocurrent and the activity of ALP was established. Accordingly, using these CdS QD modified nanopipettes, the ALP activity in single MCF-7 cells was determined to be 0.12 U mL-1 by PEC analysis. This work does not expand the application of PEC bioanalysis, but offers a new strategy for single cell analysis.


Assuntos
Técnicas Biossensoriais , Pontos Quânticos , Fosfatase Alcalina , Técnicas Eletroquímicas
7.
Talanta ; 235: 122694, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517578

RESUMO

This work reports a simple strategy for Candida auris genomic DNA (gDNA) detection, a multi-resistant fungus associated with nosocomial outbreaks in healthcare settings, presenting high mortality and morbidity rates. The platform was developed using gold electrode sensitized with specific DNA capture probe and ninhydrin as a novel DNA hybridization indicator. The genosensor was able to detect C. auris in urine sample by differential pulse voltammetry and electrochemical impedance spectroscopy. The biosensor's analytical performance was evaluated by differential pulse voltammetry, detecting up to 4.5 pg µL-1 of C. auris gDNA in urine (1:10, V/V). Moreover, the genosensor was reused eight times with no loss in the current signal response. The genosensor showed selectivity and stability, maintaining 100% of its response up to 80 days of storage. In order to analyze interactions of single and double-stranded DNA with ninhydrin, SEM, AFM and molecular dynamics studies followed by docking simulations were performed. Theoretical calculations showed ninhydrin interactions more favorably with dsDNA in an A-T rich binding pocket rather than with the ssDNA. Therefore, the proposed system is a promising electrochemical detection device towards a more accurate detection of C. auris gDNA in biological samples.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Candida/genética , DNA , Ninidrina
8.
Talanta ; 235: 122717, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517585

RESUMO

Groundnut bud necrosis orthotospovirus (GBNV) is one of the causative plant viruses responsible for the outbreak of many viral epidemics in food crops across India and other south-Asian countries. Its management is a major challenge due to fast vector transmission, and the non-availability of appropriate agrochemical treatment. The timely detection of GBNV becomes indispensable for the effective management of viral infection and the periodic monitoring of plant health. We report the fabrication of graphene oxide (GO) based electrochemical immunosensor for the rapid and sensitive detection of GBNV. The immunoelectrode is prepared by depositing GO onto indium-tin oxide (ITO) coated glass substrates and functionalized by anti-GBNV antibodies using N-ethyl-N'-(3- dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide (EDC-NHS) conjugation chemistry. The response measurements of the immunoelectrodes revealed a sensitivity of 221 ± 1 µA µg-1 mL-1(n = 3) and limit of detection (LOD) of 5.7 ± 0.7 ng mL-1(n = 3) for the standard concentrations of GBNV antigen. Further, the GBNV detection was carried out in infected leaf extracts of three different host plants i.e., Tomato, Cowpea, and N. benthamiana, and the results have been compared with the conventionally used direct antigen coated enzyme-linked immunosorbent assay (DAC-ELISA) technique. The comparable results obtained for the detection of GBNV in infected plants using electrochemical immunosensing and DAC-ELISA techniques advocated the immense potential of GO based immunosensor as a point-of-care sensing device that is poised to overcome the limitations of the traditional methods of virus detection in field conditions and may transform the diagnostics in agriculture.


Assuntos
Técnicas Biossensoriais , Grafite , Tospovirus , Produtos Agrícolas , Técnicas Eletroquímicas , Humanos , Imunoensaio , Necrose , Doenças das Plantas
9.
Talanta ; 235: 122726, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517594

RESUMO

Two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides (MXene) have emerged as a rising family of atomic layered nanomaterials which undergoes intensive investigations in interdisciplinary applications. The large surface-to-volume ratio, excellent mechanical strength, desirable biocompatibility, along with tunable electronic and optical properties, render 2D MXenes exceptional attractive as versatile nanoplatforms for biosensing. Herein, advanced progress and novel paradigms of MXene-based biosensors are reviewed, focusing on the combination of MXenes with various detection techniques that promotes target recognition and signal transducing. Regarding the nature of transducing signals, MXene-based biosensors are categorized into two groups where MXenes serve as electrical platforms or optical platforms, respectively. The merits of MXenes are critically compared with other 2D materials to illustrate the distinctive advantages of MXenes in biosensing, while challenges such as environmental vulnerability was discussed to guide the sensor design. Facing with the rapid development of wearable electronics and internet of medical things, as well as escalating demanding in precision medicine, perspectives are provided to elucidate the potential of MXenes in propelling advances in these trending biomedical applications.


Assuntos
Técnicas Biossensoriais , Nanoestruturas , Elementos de Transição
10.
Talanta ; 235: 122727, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517595

RESUMO

An end-modified 2'-O-methyl molecular beacon (eMB) with unique nuclease resistance was designed and prepared. The eMB can resist the enzymatic digestion by DNase I, which would otherwise occur upon the hybridization of the eMB with a complementary sequence. As a result, the coupling use of eMBs and DNase I allows highly sensitive detection of miRNA with a limit of detection (LOD) of 2.5 pM. The analytical strategy was further used for detection of tumor exosomal microRNA-21, and down to 0.86 µg mL-1 A375 exosomes were detected. Overall, the present method can effectively quantify tumor-derived exosomes for cancer diagnosis.


Assuntos
Técnicas Biossensoriais , Exossomos , MicroRNAs , Neoplasias , Desoxirribonuclease I , Exossomos/genética , Humanos , Limite de Detecção , MicroRNAs/genética , Neoplasias/diagnóstico , Neoplasias/genética
11.
Talanta ; 235: 122728, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517596

RESUMO

With the emergence of microRNA (miRNA) as a key player in early clinical disease diagnosis, development of rapidly sensitive and quantitative miRNA detection methods are imperative. Herein, a label-free SERS assay coupled with duplex-specific nuclease (DSN) signal amplification strategy was proposed for facilely ultrasensitive and quantitative analysis of miRNA-21. Firstly, magnetic beads assembled with excessive capture DNA were utilized to hybridize the target miRNA-21. These DNA-RNA heteroduplexes were cleaved by DSN to generate small nucleotide fragments into the supernatant and the miRNA-21 released and rehybridized another DNA, going to the next DSN cycle. Consequently, numerous of small nucleotide fragments of capture DNA were released from magnetic beads and the miRNA-21 signal was transferred and amplified by the SERS signals of total phosphate backbones which are abundant in nucleotide. Furthermore, iodide-modified Ag nanoparticles (AgINPs) was employed to generate a strong and reproducible SERS signal. The proposed method displayed excellent performance for miRNA-21 detection with the linear range from 0.33 fM to 3.3 pM, and a lower detection limit of 42 aM. Moreover, this strategy exhibited effectively base discrimination capability and was successfully applied for monitoring the expression levels of miRNA-21 in different cancer cell lines and human serum.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , MicroRNAs , Ouro , Humanos , Iodetos , Limite de Detecção , MicroRNAs/genética , Técnicas de Amplificação de Ácido Nucleico , Prata
12.
Talanta ; 235: 122732, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517600

RESUMO

A novel competitive mechanism electrochemiluminescence (ECL) immunoassay based on resonance energy transfer was used to detect florfenicol for the first time. In this work, CeO2@TiO2 nanocomposite, which was used as a donor, was prepared in sol-gel method and the effective band gap of TiO2 could be reduced by CeO2, which promoted the ECL emission of TiO2 and made the ECL performance of the donor more outstanding. The absorption spectrum of Cu2S and the ECL emission spectrum of the donor could be highly matched, which ensured the occurrence of electrochemiluminescence resonance energy transfer (ECL-RET). In addition, the snowflake-like structure of cuprous sulfide could load more antibodies. It is worth mentioning that as far as we know, there have been no reports of this material as an ECL receptor before. Furthermore, the ECL-RET system based on this has shown excellent performance in the detection of florfenicol. The proposed immunoassay showed satisfactory sensitivity with a wide linear range from 0.001 to 1000 ng mL-1 and a low detection limit (0.3 pg mL-1). Due to the remarkable quenching effect and simple assembly process, the immunoassay is of great practical significance and has reference value for the detection of florfenicol or other biological small molecules.


Assuntos
Técnicas Biossensoriais , Ouro , Técnicas Eletroquímicas , Transferência de Energia , Imunoensaio , Limite de Detecção , Medições Luminescentes , Tianfenicol/análogos & derivados
13.
Talanta ; 235: 122735, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517602

RESUMO

Accumulative evidences have indicated that abnormal expression of microRNAs (miRNAs) is closely associated with many health disorders, making them be regarded as potentialbiomarkers for early clinical diagnosis. Therefore, it is extremely necessary to develop a highly sensitive, specific and reliable approach for miRNA analysis. Catalytic hairpin assembly (CHA) signal amplification is an enzyme-free toehold-mediated strand displacement method, exhibiting significant potential in improving the sensitivity of miRNA detection strategies. In this review, we first describe the potential of miRNAs as disease biomarkers and therapeutics, and summarize the latest advances in CHA signal amplification-based sensing strategies for miRNA monitoring. We describe the characteristics and mechanism of CHA signal amplification and classify the CHA-based miRNA sensing strategies into several categories based on the "signal conversion substance", including fluorophores, enzymes, nanomaterials, and nucleotide sequences. Sensing performance, limit of detection, merits and disadvantages of these miRNA sensing strategies are discussed. Moreover, the current challenges and prospects are also presented.


Assuntos
Técnicas Biossensoriais , MicroRNAs , Nanoestruturas , Catálise , Corantes Fluorescentes , Limite de Detecção , MicroRNAs/genética , Técnicas de Amplificação de Ácido Nucleico
14.
Talanta ; 235: 122744, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517612

RESUMO

The detection of trace tumor-related serum miRNA biomarkers is in great demand for the early diagnosis of cancer. Herein, for the first time, an electrochemical sensing platform based on atom transfer radical polymerization (ATRP) signal amplification strategy for ultrasensitive determination of the breast and prostate cancer marker miRNA-141 has been developed. The hairpin DNAs were immobilized on the benzoic acid modified electrode to capture the target miRNA-141, the recognition of miRNA-141 released thiol groups on the end of probes, followed by the association of ATRP initiators modified gold nanoparticles with thiol groups, and then triggered the polymerization on electrode surface, causing a great number of ferrocene (Fc) signal molecules grafted on the sensor interface. As a result, the electrochemical signal intensity of signal molecule has been greatly increased. The proposed biosensor has a linear range from 10 pM to 10 aM with a detection limit of 3.23 aM for miRNA-141, opening a new and promising path for ultrasensitive analysis of tumor-related miRNAs.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , MicroRNAs , Técnicas Eletroquímicas , Ouro , Humanos , Limite de Detecção , Masculino , Polimerização
15.
Talanta ; 235: 122749, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517617

RESUMO

Signal output mode is the important part of biosensor. In general, "signal on" and "signal off" are two common output modes. The development of dual signals-based ratio analysis as a powerful diagnostic tool has attracted widespread attention in the biosensor field in recent years. Dual signals ratio sensors with "signal on" and "signal off" are more favored because of their low background signal and better sensitivity and selectivity. In this study, inspired by the idea that EcoR V can cut specific sites of DNA to produce two corresponding fragments, and by using the capturing probe as guy wires, a reliable and sensitive method for EcoR V assay is developed based on the ratio of dual chemiluminescence (CL) signals for the first time. In particular, in the existence of the objective EcoR V, the substrate DNA would be degraded into two double stranded oligonucleotides with blunt ends which include the sequence I and the sequence II, then they can separately compete with two different corresponding capture probes on magnetic beads (MBs). One of capture probe hybridized with the sequence I containing more guanine (G) bases that reacted with the phenylglyoxal (PG) to produce chemical reaction which triggered a positive CL signal output I + CL as "signal-on"; another capture probe is priority to hybridize the sequence II, which triggered the weaker reporter DNA linked with horseradish peroxidase (HRP) probe to fall off the MBs, thereby outputting a negative CL signal I-CL as "signal-off". By comparing the linear relation and the correlation coefficient, the I-CL/I + CL ratio method has better linear relation (0.01-10 U/mL) and higher sensitivity (0.0045 U/mL). In addition, this developed strategy of high selectivity which can directly detect low concentration of target EcoR V in human serum, and thus this dual ratio biosensor might offer a promising detection approach for clinical diagnostics.


Assuntos
Técnicas Biossensoriais , DNA de Cadeia Simples , DNA/genética , DNA de Cadeia Simples/genética , Peroxidase do Rábano Silvestre , Humanos , Luminescência
16.
Talanta ; 235: 122753, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517621

RESUMO

The design and fabrication of high sensitive and selective biosensing platforms areessential goals to precisely recognize biomaterials in biological assays. In particular, determination of adenosine triphosphate (ATP) as the main energy currency of the cells and one of the most important biomolecules in living organisms is a pressing need in advanced biological detection. Recently, aptamer-based biosensors are introduced as a new direct strategy in which the aptamers (Apts) directly bind to the different targets and detect them on the basis of conformational changes and physical interactions. They can also be conjugated to optical and electronic probes such as quantum dot (QD) nanomaterials and provide unique QD aptasensing platforms. Currently, these Apt-based biosensors with excellent recognition features have attracted extensive attention due to the high specificity, rapid response and facile construction. Therefore, in this review article, recent achievements and advances in aptasensing detection of ATP based on different detection methods and types of QDs are discussed. In this regard, the optical and electrochemical aptasensors have been categorized based on detection methods; fluorescence (FL), electrochemiluminescence (ECL) and photoelectrochemical (PEC) and they have been also divided to two main groups based on QDs; metal-based (M-based) and carbon-based (C-based) materials. Then, their advantages and limitations have been highlighted, compared and discussed in detail.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Pontos Quânticos , Trifosfato de Adenosina , Técnicas Eletroquímicas , Oligonucleotídeos
17.
Talanta ; 235: 122763, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517624

RESUMO

The disease diagnosis by detecting single microRNAs (miRNAs) can produce high false positive rate. Herein, a novel fluorescence biosensor method for one-step simultaneous detection of multiple miRNAs was proposed by using single-stranded DNA (ssDNA) functionalized double quantum dots (QDs) and black hole quencher (BHQ)-decorated magnetic nanobeads (MNs). MNs were linked with two black hole quenchers (BHQ1 and BHQ3) via a complementary DNA (cDNA). The ssDNA/cDNA hybridization contributed to the fluorescence quenching of double QDs due to the fluorescence resonance energy transfer (FRET) between double QDs and BHQ. In the presence of target miRNA-33 (miR-33) and miRNA-125b (miR-125b), the ssDNA1 and ssDNA2 were respectively hybridized with miR-33 and miR-125b to form more stable duplexes. Thus, the double QDs were released into supernatant after the magnetic separation, leading to the fluorescence signals recovery at 537 nm and 647 nm. A wide linear range (0.5 nM-320 nM for miR-33 and 0.1 nM-250 nM for miR-125b) and low limits of detection (0.09 nM for miR-33 and 0.02 nM for miR-125b) were achieved. Moreover, our approach has been demonstrated to simultaneously detect miR-33 and miR-125b in cell extracts. With advantages of high sensitivity, strong specificity, low background and low cost, the strategies show great potentials for the detection of various targets in bioanalysis and disease diagnosis.


Assuntos
Técnicas Biossensoriais , MicroRNAs , Pontos Quânticos , DNA de Cadeia Simples/genética , Transferência Ressonante de Energia de Fluorescência , MicroRNAs/genética , Hibridização de Ácido Nucleico
18.
Talanta ; 235: 122772, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517631

RESUMO

In many cases of in-situ or point-of-care testing (POCT), the single pursuit of good detection performance cannot meet the testing requirements, and thus no-wash testing has become one of the most effective methods to develop sustainable biosensing assay, providing more convenient operation procedures and shorting the detection time. Herein, a disposable POC biosensing assay was prepared based on the RGB color detector software on the smartphone and the peroxide-like activity of gold nanoparticles (Au NPs) for aflatoxin B1 (AFB1) sensitive detection. Using syringe filters for a simple physical separation procedure can easily realize washing free detection, which is superior to most biosensing assays with cumbersome detection procedures. The syringe filters with 200 nm pore diameter could only pass through small Au NPs (30 nm) while the large-sized SiO2 nanoparticles (300 nm) was blocked on the membrane. In this work, Au NPs utilized their inherent peroxidase-like activity to catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to ox-TMB under acidic conditions, which results in blue color in aqueous solution. The color change due to different antigen concentrations was quantitatively determined by measuring the color intensity with a smartphone and the RGB color detector. By measuring the color intensity, it was known that the linear concentration range of the biosensing assay was 100 fg mL-1 to 50 ng mL-1, and the detection limit of AFB1 was 33 fg mL-1 (S/N = 3). Additionally, the designed biosensing assay exhibited excellent selectivity, storage stability and reproducibility. More importantly, the innovation of detecting and analyzing technology is the outstanding advantage of the biosensing assay, providing a more flexible and convenient strategy for some other small molecule analysis.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Aflatoxina B1/análise , Colorimetria , Ouro , Peróxido de Hidrogênio , Limite de Detecção , Sistemas Automatizados de Assistência Junto ao Leito , Reprodutibilidade dos Testes , Dióxido de Silício
19.
Talanta ; 235: 122779, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517637

RESUMO

To ensure the safety of dairy products, especially milk, and consequently protect human health, accurate and simple analytical techniques are highly necessary to determine the low concentration of aflatoxin M1 (AFM1) as an important carcinogen. Herein, a novel, accurate and simple fluorescent aptasensor was designed for selective detection of AFM1 based on bivalent binding aptamer-cDNA (BBA-cDNA) structure. Moreover, MoS2 nanosheets (MoS2 NSs) were used as the fluorescent quencher and FAM-labeled complementary strand of aptamer (FAM-CS) was applied as a fluorescent probe. In this study, we achieved a new result. Unlike previous studies, in this work, the BBA-cDNA structure was not disassembled in the presence of the target. Therefore, as the AFM1 concentration increased, more targets were attached to the BBA-cDNA structure and as a result, the BBA-cDNA structure/AFM1 could not be placed on the surface of MoS2 NSs, leading to the more fluorescent intensity detection. Under optimized conditions, the developed fluorescent analytical method revealed great selectivity toward AFM1 with a limit of detection (LOD) of 0.5 nM and a linear range from 0.7 to 10 nM. This fabricated aptasensor indicated excellent analytical performance for AFM1 detection in milk samples with LOD of 0.1 nM. Overall, the proposed approach could provide an effective basis for small molecule analysis to guarantee food and human safety using appropriate aptamer sequences.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Aflatoxina M1/análise , Animais , DNA Complementar , Humanos , Limite de Detecção , Leite/química , Molibdênio
20.
Talanta ; 235: 122783, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34517641

RESUMO

As the light-harvesting "antenna", G-rich oligonucleotides (such as the G-quadruplex) can interact with lanthanide (III) to bring a luminescent enhancement response. In this study, phenomenon of luminescent enhancement of G-triplex/terbium (III) (G3/Tb3+) and interaction between G3 and Tb3+ were first reported and characterized. Based on G3/Tb3+ luminescence, a label-free aptasensor for the detection of ofloxacin (OFL) residues in the food was developed. The OFL triggered the action of rolling circle amplification (RCA) allowed for the amplification product of G3-forming sequences in the single-stranded DNA, which promoted the conformational transition of the G3/Tb3+ complexes once the addition of Tb3+. Under the optimal conditions, the logarithmic correlation between the G3/Tb3+ luminescence intensity and the concentration of OFL was found to be linear in the range of 5-1000 pmol L-1 (R2 = 0.9949). The limit of detection was 0.18 pmol L-1 (3σ/slope). Additionally, the good recoveries of 90.19-108.89 % and the relative standard deviations values of 0.59-5.87 % were obtained in the application of the aptasensor detecting OFL in the practical samples. These results confirmed that the present aptasensor has a good analytical performance and bright prospect for detecting ofloxacin residues in food.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , DNA de Cadeia Simples , Limite de Detecção , Luminescência , Ofloxacino , Térbio
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