RESUMO
The OPECT biosensing platform, which connects optoelectronics and biological systems, offers significant amplification and more possibilities for research in biological applications. In this work, a homogeneous organic photoelectrochemical transistor (OPECT) biosensor based on a Bi2S3/Bi2MoO6 heterojunction was constructed to detect METTL3/METTL14 protein activity. The METTL3/METTL14 complex enzyme was used to catalyze adenine (A) on an RNA strand to m6A, protecting m6A-RNA from being cleaved by an E. coli toxin (MazF). Alkaline phosphatase (ALP) catalyzed the conversion of Na3SPO3 to H2S through an enzymatic reaction. Due to the adoption of the strategy of no fixation on the electrode, the generated H2S was easy to diffuse to the surface of the ITO electrode. The Bi2S3/Bi2MoO6 heterojunction was formed in situ through a chemical replacement reaction with Bi2MoO6, improving photoelectric conversion efficiency and realizing signal amplification. Based on this "signal on" mode, METTL3/METTL14 exhibited a wide linear range (0.00001-25 ng/µL) between protein concentration and photocurrent intensity with a limit of detection (LOD) of 7.8 fg/µL under optimal experimental conditions. The applicability of the developed method was evaluated by investigating the effect of four plasticizers on the activity of the METTL3/METTL14 protein, and the molecular modeling technique was employed to investigate the interaction between plasticizers and the protein.
Assuntos
Técnicas Biossensoriais , Bismuto , Técnicas Eletroquímicas , Metiltransferases , Molibdênio , Sulfetos , Metiltransferases/metabolismo , Metiltransferases/química , Bismuto/química , Sulfetos/química , Molibdênio/química , Processos Fotoquímicos , Humanos , Transistores Eletrônicos , Adenosina/análise , Adenosina/análogos & derivadosRESUMO
Organic electrochemical transistors with signal amplification and good stability are expected to play a more important role in the detection of environmental pollutants. However, the bias voltage at the gate may have an effect on the activity of vulnerable biomolecules. In this work, a novel organic photoelectrochemical transistor (OPECT) aptamer biosensor was developed for di(2-ethylhexyl) phthalate (DEHP) detection by combining photoelectrochemical analysis with an organic electrochemical transistor, where MXene/Bi2S3/CdIn2S4 was employed as a photoactive material, target-dependent DNA hybridization chain reaction was used as a signal amplification unit, and Ru(NH3)63+ was selected as a signal enhancement molecule. The poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-based OPECT biosensor modulated by the MXene/Bi2S3/CdIn2S4 photosensitive material achieved a high current gain of nearly a thousand times at zero bias voltage. The developed signal-on OPECT sensing platform realized sensitive and specific detection of DEHP, with a detection range of 1-200 pM and a minimum detection limit of 0.24 pM under optimized experimental conditions, and its application to real water samples was also evaluated with satisfactory results. Hence, the construction of this OPECT biosensing platform not only provides a promising tool for the detection of DEHP but also reveals the great potential of the OPECT application for the detection of other environmental toxins.
Assuntos
Técnicas Biossensoriais , Dietilexilftalato , Nitritos , Elementos de Transição , Técnicas Eletroquímicas/métodos , Técnicas Biossensoriais/métodos , Oligonucleotídeos , Limite de DetecçãoRESUMO
Oxygen vacancy defects (OVs) are one of the main strategies for nanomaterials modification to improve the photoactivity, but current methods for fabricating OVs are usually complicated and harsh. It is important to develop simple, rapid, safe, and mild methods to fabricate OVs. By studying the effects of different weak reducing agents, the concentration of the reducing agent and the reaction time on fabrication of OVs, it is found that L-ascorbic acid (AA) gently and rapidly induces the increase of OVs in Bi4O5Br2 at room temperature. The increased OVs not only improve the adsorption of visible light, but also enhance the photocurrent response. Based on this, the preparation of OVs in Bi4O5Br2 is employed to the development of a photoelectrochemical biosensor for the detection of DNA demethylase of methyl-CpG binding domain protein 2 (MBD2). The biosensor shows a wide linear range of 0.1-400 ng mL-1 and a detection limit as low as 0.03 ng mL-1 (3σ). In addition, the effect of plasticizers on MBD2 activity is evaluated using this sensor. This work not only provides a novel method to prepare OVs in bismuth rich materials, but also explores a new novel evaluation tool for studying the ecotoxicological effects of contaminants.
Assuntos
Técnicas Biossensoriais , Nanoestruturas , Ácido Ascórbico , Oxigênio , DNA , Luz , Técnicas Biossensoriais/métodosRESUMO
A photoelectrochemical (PEC) biosensor was established for histone deacetylase Sirt1 detection based on the polyaspartic acid (PASP)-mediated redox cycling amplification and Sirt1 catalysis deacetylation-triggered recognition of the deacetylated substrate peptide, using PASP as the recognition reagent. After BiVO4 was composited with gold nanoparticles and SnS2, the photoactivity of the composite was greatly enhanced due to the matched energy band structure. Under the catalysis of Sirt1 enzyme, the acetylated substrate peptide was deacetylated to obtain a positive peptide, which was recognized by negative PASP. In addition to the recognition function, PASP also played other triple roles. First, PASP interacted with the positive peptide to form a double-stranded structure, which led to the electrode interface changing from irregular to regular, resulting in an improved PEC response. Second, PASP was involved into redox cycle amplification due to its reduction to dehydroascorbic acid. Further, it was used for repeated preparation of ascorbic acid to provide electron donors. This process enhanced the PEC response. Third, based on the matched energy band with BiVO4, PASP effectively improved the photoactivity of BiVO4. With multiplex signal amplification, the PEC biosensor showed a wide linear range (1.83-1830 pM) and high detection sensitivity with a low detection limit of 0.732 pM (S/N = 3). The applicability of this method was evaluated by studying the effects of a known inhibitor of nicotinamide and the heavy metal ions of Cd2+ and Pb2+ on Sirt1 enzyme activity, and the results showed that this method not only provided a new platform for screening Sirt1 enzyme inhibitors but also provided new biomarkers for evaluating the ecotoxicological effects of environmental pollutants.
Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Técnicas Eletroquímicas/métodos , Ouro/química , Limite de Detecção , Nanopartículas Metálicas/química , Oxirredução , Peptídeos , Sirtuína 1RESUMO
A novel electrochemiluminescence (ECL) biosensor was fabricated for miRNA-162a detection by using silver nanoclusters/molybdenum disulfide (AgNCs@MoS2) as an ECL material, peroxodisulfate (S2O82-) as a co-reactant, and semicarbazide (Sem) as a co-reaction accelerator. Firstly, hairpin probe Ha modified on AgNCs@MoS2/GCE was unfolded based on its hybridization with target microRNA. Then, the unfolded Ha can further be hybridized with another hairpin DNA of Hb on (AuNPs-semicarbazide)@Cu-MOF, resulting in the release of target microRNA, which further causes a cyclic hybridization. This creates more (AuNPs-semicarbazide)@Cu-MOF on the electrode surface, achieving cyclic hybridization signal amplification. Strikingly, due to the presence of Sem, accelerating the reduction of S2O82- and resulting in the generation of more oxidant intermediates of SO42-, the amount of excited states of Agincreases to further amplify the ECL signal. The biosensor exhibited high sensitivity with a low LOD of 1.067 fM, indicating that the introduction of co-reaction accelerators can provide an effective method for signal amplification. The applicability of this method was assessed by investigating the effect of Pb(II) ion on miRNA-162a expression level in maize seedling leaves. A novel electrochemiluminescence biosensor was fabricated for miRNA-162a detection by using silver nanoclusters/molybdenum disulfide as an ECL material, peroxodisulfate as a co-reactant, and semicarbazide as a co-reaction accelerator.
Assuntos
Técnicas Biossensoriais/métodos , Dissulfetos/química , Substâncias Luminescentes/química , Nanopartículas Metálicas/química , MicroRNAs/análise , Molibdênio/química , Nanocompostos/química , Técnicas Biossensoriais/instrumentação , Cobre/química , DNA/química , DNA/genética , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Ouro/química , Ácidos Nucleicos Imobilizados/química , Ácidos Nucleicos Imobilizados/genética , Limite de Detecção , Luminescência , Medições Luminescentes , Estruturas Metalorgânicas/química , MicroRNAs/genética , Hibridização de Ácido Nucleico , Semicarbazidas/química , Prata/química , Zea mays/químicaRESUMO
A novel photoelectrochemical immunosensor has been constructed for the determination of methylated RNA. MoS2 nanosheets with large specific area were employed as photoactive material, gold nanoparticles were used as signal amplification unit and immobilization matrix of 4-mercaptophenylboronic acid, anti-m6A antibody was adopted as methylated RNA recognition reagent, and poly(U) polymerase-mediated RNA chain extension and Ru(NH3)63+ were used as assisted signal amplification unit. With the sensitization effect of Ru(NH3)63+, the photoactivity of WS2 nanosheets was improved greatly, which also improved the sensitivity. Using visible-light excitation and ascorbic acid as electron donor, the sensitive determination of methylated RNA was achieved by monitoring the photocurrent change with different concentrations of methylated RNA. This photoelectrochemical immunosensor has a wide linear relationship with methylated RNA concentration from 0.05 to 35 nM under optimal experimental conditions. The low detection limit of 14.5 pM was realized based on 3σ criterion. In addition to the good selectivity, this sensor also presents high reproducibility with a relative standard deviation of 1.4% for the photocurrent of seven electrodes. The applicability of the developed method was also investigated by detecting the level of methylated RNA in corn seedling leaves with and without sulfadiazine treatment. Graphical abstract A novel photoelectrochemical immunosensor was developed for methylated RNA detection using the photoactive material of MoS2 and poly(U) polymerase-mediated RNA chain extension.
Assuntos
RNA Polimerases Dirigidas por DNA/metabolismo , Técnicas Eletroquímicas/instrumentação , Imunoensaio/instrumentação , Imunoensaio/métodos , RNA/química , RNA Polimerases Dirigidas por DNA/química , Dissulfetos/química , Técnicas Eletroquímicas/métodos , Eletrodos , Ouro , Nanopartículas Metálicas , Metilação , Molibdênio/química , Nanoestruturas , Compostos de Rutênio/químicaRESUMO
A photoelectrochemical method was proposed for DNA hydroxymethylation determination using black TiO2 (B-TiO2) nanosphere as photoactive material and ZnO as photoactivity inhibitor. After hydroxymethylated DNA (5hmC-DNA) was captured on the probe modified B-TiO2/ITO electrode surface through hybridization, a glycosyl can be then transferred from uridine diphosphoglucose to 5hmC-DNA and formed a covalent structure with -CH2OH in the presence of T4 ß-glucosyltransferase (ß-GT). Afterwards, based on a series of covalent reaction, amino functionalized ZnO nanoparticles are further immobilized to the surface of the electrode. Due to the capacity to expend the irradiation light and the photogenerated electron of electron donor, the modified ZnO nanoparticles can result in a decreased photocurrent. The developed method shows wide linear ranges from 0.05-200 nM for hydroxymethylated DNA and 1-220 unit·mL-1 for T4-ß-glucosyltransferase. The corresponding determination limits were 0.013 nM and 0.24 unit·mL-1, respectively. The enzyme activity inhibited by 4-phenylimidazole was evaluated. This photoelectrochemical method shows high specificity for 5hmC-DNA (compared to 5fC, 5mC, m6A, control) and ß-GT (compared to ß-AGT, UGT2B7), and shows excellent stability for testing 5hmC (RSD = 2.75%). Graphical abstractSchematic representation of photoelectrochemical method for DNA hydroxymethylation and ß-glucosyltransferase detection based on the glycosylation reaction of -CH2OH in 5-hydroxymethylcytosine and the inhibition activity of ZnO to the photoactivity of black TiO2 nanospheres.
Assuntos
Técnicas Biossensoriais/métodos , Metilação de DNA/genética , DNA/química , Nanopartículas Metálicas/química , Titânio/química , Óxido de Zinco/química , Humanos , NanosferasRESUMO
A nanocomposite was prepared from ß-cyclodextrin (ß-CD) functionalized graphene oxide and magnetic nanoparticles (GO/Fe3O4/ß-CD). In parallel, a polyamidoamine dendrimer conjugated to avidinylated alkaline phosphatase (PAMAM-avidin-ALP) was prepared and exploited as a signal amplification unit in a voltammetric immunoassay for 5-methylcytosine (5mC) in genomic DNA. The GO/Fe3O4/ß-CD as a substrate material exhibited good solubility, electrical conductivity and large surface. This is beneficial for the further modification of antibodies (Ab) by host-guest interaction and amide bonds. By taking advantage of three-dimensional structure to capture avidin-ALP by amide linkages, PAMAM was used as a catalytic signal amplification element in this assay. Under the optimized condition and at a typical working potential of 0.94 V, the response to 5mC is linear in the 0.01-50 nM concentration range with a detection limit of 3.2 pM (at S/N = 3). The method is stable, selective and reproducible. It was applied to the determination of 5mC in genomic DNA of human tissue. Graphical abstract An electrochemical immunoassay was constructed for 5-methylcytosine detection based on nanocomposite of graphene oxide, magnetite nanoparticles and ß-cyclodextrin, and enzymatic signal amplification.
Assuntos
5-Metilcitosina/análise , Técnicas Biossensoriais , 5-Metilcitosina/química , Fosfatase Alcalina/química , Avidina/química , Mama , Neoplasias da Mama/genética , DNA/química , Dendrímeros/química , Técnicas Eletroquímicas , Feminino , Grafite/química , Humanos , Imunoensaio , Nanopartículas de Magnetita/química , Nanocompostos/química , Estômago , Neoplasias Gástricas/genética , beta-Ciclodextrinas/químicaRESUMO
The enzyme histone acetyltransferase (HAT) catalyzes the acetylation of a substrate peptide, and acetyl coenzyme A is converted to coenzyme A (CoA). A photoelectrochemical method is described for the determination of the HAT activity by using exfoliated MoS2 nanosheets, phos-tag-biotin, and ß-galactosidase (ß-Gal) based signal amplification. The MoS2 nanosheets are employed as the photoactive material, graphene nanosheets as electron transfer promoter, gold nanoparticles as recognition and capture reagent for CoA, and phos-tag-biotin as the reagent to link CoA and ß-Gal. The enzyme ß-Gal catalyzes the hydrolysis of substrate O-galactosyl-4-aminophenol to generate free 4-aminophenol which is a photoelectrochemical electron donor. The photocurrent increases with the activity of HAT. Under optimal conditions, the response is linear in the 0.3 to 100 nM activity range, and the detection limit is 0.14 nM (at S/N = 3). The assay was applied to HAT inhibitor screening, specifically for the inhibitors C646 and anacardic acid. The IC50 values are 0.28 and 39 µM, respectively. The method is deemed to be a promising tool for epigenetic research and HAT-targeted cancer drug discovery. Graphical abstract Histone acetyltransferase was detected using a sensitive photoelectrochemical method using MoS2 nanosheets as photoactive material.
Assuntos
Técnicas Biossensoriais , Dissulfetos/química , Técnicas Eletroquímicas , Inibidores Enzimáticos/análise , Histona Acetiltransferases/antagonistas & inibidores , Histona Acetiltransferases/análise , Molibdênio/química , Nanopartículas/química , Ácidos Anacárdicos/análise , Ácidos Anacárdicos/farmacologia , Benzoatos/análise , Benzoatos/farmacologia , Avaliação Pré-Clínica de Medicamentos , Inibidores Enzimáticos/farmacologia , Histona Acetiltransferases/metabolismo , Humanos , Nitrobenzenos , Tamanho da Partícula , Processos Fotoquímicos , Pirazóis/análise , Pirazóis/farmacologia , Pirazolonas , Propriedades de SuperfícieRESUMO
A simple and sensitive electrochemical aptasensor was constructed for zeatin detection, where MoS2 nanosheets were used as the immobilization matrix for gold nanoparticles (AuNPs), and AuNPs were employed as the immobilization matrix to probe DNA. After the aptamer DNA and assist DNA hybridized with probe DNA, Y-type DNA can be formed with two biotins at the terminals of aptamer DNA. Then, avidin modified alkaline phosphatase (Avidin-ALP) can be further modified on the electrode surface through the biotin and avidin interaction. Under the catalytic effect of ALP, p-nitrophenylphosphate disodium (PNPP) can be hydrolyzed to produce p-nitrophenol (PNP). However, in the presence of zeatin, the formed Y-type DNA can be destroyed due to the formation of the zeatin-aptamer conjugate, which further reduces the amount of PNP and leads to the decrease of the oxidation signal of PNP. Under the optimum conditions, the change of the oxidation peak current of PNP was inversely proportional to the logarithm value of zeatin concentration in the range of 50 pM-50 nM. The detection limit was calculated to be 16.6 pM. This electrochemical method also showed good detection selectivity and stability. The potential applicability of this method was proved by detecting zeatin in real samples.
Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Sondas de DNA/química , Dissulfetos/química , Nanopartículas Metálicas/química , Molibdênio/química , Zeatina/análise , Fosfatase Alcalina/química , Sequência de Bases , Técnicas Eletroquímicas/métodos , Enzimas Imobilizadas/química , Ouro/química , Limite de Detecção , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
A sensitive and selective photoelectrochemical (PEC) method is described for the detection of protein kinase A (PKA) activity based on the use of graphite-like carbon nitride (g-C3N4) and the CdS quantum dots (QDs). Firstly, a complex was synthesized from g-C3N4 and gold nanoparticles (AuNPs). It was employed as both the PEC-active material and as a support for immobilization of peptides. The latter were assembled on an ITO electrode modified with g-C3N4-AuNPs and subsequently phosphorylated by PKA in the presence of adenosine 5'-[γ-thio]triphosphate (ATP-S). Finally, CdS quantum dots (QDs) were introduced on the ITO in order to increase the PEC response of g-C3N4 based on the Cd-S binding between the QDs and thiol groups. Under the optimal conditions and a typical working voltage of -0.3 V, the method has a dynamic range that extends from 0.05 to 50 unit·mL-1, with a 0.017 unit·mL-1 lower detection limit. The method was successfully applied to the quantification of the inhibitory effect of ellagic acid on the activity of PKA, and to monitor enzyme activity in cell lysates. Graphical abstract Schematic of a sensitive and selective photoelectrochemical biosensor for the detection of protein kinase A activity. It is based on the use of graphite-like carbon nitride and CdS quantum dots.
Assuntos
Compostos de Cádmio/química , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Ensaios Enzimáticos/métodos , Grafite/química , Nitrilas/química , Processos Fotoquímicos , Pontos Quânticos/química , Sulfetos/química , Proteínas Quinases Dependentes de AMP Cíclico/antagonistas & inibidores , Avaliação Pré-Clínica de Medicamentos , Eletroquímica , Eletrodos , Ouro/química , Nanopartículas Metálicas/química , Inibidores de Proteínas Quinases/farmacologia , Compostos de Estanho/químicaRESUMO
A photoelectrochemical biosensor is described for sensitive detection of microRNA-162a. A multiple amplification strategy is employed that involves (a) isothermal strand displacement polymerase reaction; (b) terminal deoxynucleotidyl transferase-mediated extension, (c) amplification of streptavidin-coated gold nanoparticles, and (d) biotin functionalized alkaline phosphatase. Graphite-like C3N4 (g-C3N4) nanosheets were used as photoactive material. By using these amplification strategies, the detection limit is as low as 0.18 fM of microRNA, and the photocurrent increases linearly with the concentration of microRNA-162a in the range from 0.5 fM to 1 pM. The method was successfully applied to quantify the expression level of microRNA-162a in total RNA extracted from the leaves of maize seedlings after incubation with the chemical mutagen ethyl methanesulfonate. The results confirmed the applicability of the method to the analysis of practical biological samples. Graphical Abstract Schematic of a photoelectrochemical microRNA assay based on a multiple amplification strategy involving (a) isothermal strand displacement polymerase reaction; (b) terminal deoxynucleotidyl transferase-mediated extension,
Assuntos
Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , MicroRNAs/análise , Técnicas de Amplificação de Ácido Nucleico/métodos , Limite de Detecção , MicroRNAs/genética , Hibridização de Ácido Nucleico , Folhas de Planta/genética , Zea mays/genéticaRESUMO
A method is described for photoelectrochemical determination of chloramphenicol (CLOA). It is based on the use of (a) aptamers protected with photoactive WS2 nanosheets, and (b) DNase I-assisted target recycling. The DNA aptamer without label was employed for recognition of CLOA. In the absence of CLOA, the aptamer is adsorbed on the surface of WS2. This leads to a decrease of photocurrent due to the steric-hindrance effect of aptamer DNA. The adsorption of WS2 also protects the aptamer from digestion by DNase. In the presence of CLOA, the aptamer will be desorbed from the WS2 surface due to formation of an aptamer/CLOA conjugate. This results in an increased photocurrent due to a decreased amount of aptamer DNA on the electrode surface. The increase of photocurrent can be further improved by applying DNase triggered catalytic recycling of CLOA. Under optimal experimental conditions, the response is linear 10 pM - 10 nM CLOA concentration range, with a 3.6 pM lower detection limit (at 3σ). This method is acceptably selective, accurate and stable. It was applied to the determination of CLOA in spiked milk samples and gave satisfactory results. Graphical abstract A simple and sensitive photoelectrochemical apta-biosensor was fabricated for chloramphenicol detection. In this work, WS2 nanosheets were employed as photoactive material, and DNase I catalytic chloramphenicol recycling strategy was adopted to amplify the detection signal.
Assuntos
Aptâmeros de Nucleotídeos/metabolismo , Técnicas Biossensoriais/métodos , Cloranfenicol/análise , Nanoestruturas/química , Processos Fotoquímicos , Sulfetos/química , Compostos de Tungstênio/química , Técnicas Biossensoriais/instrumentação , Cloranfenicol/química , Cloranfenicol/metabolismo , Eletroquímica , Eletrodos , Estudos de Viabilidade , Propriedades de SuperfícieRESUMO
A novel photoelectrochemical (PEC) assay is developed for sensitive detection of protein kinase A (PKA) activity based on PKA-catalyzed phosphorylation reaction in solution and signal amplification strategy triggered by PAMAM dendrimer and alkaline phosphatase (ALP). In this strategy, it is noteworthy at this point that PKA phosphorylation was achieved in solution instead of on the surface of the electrode, which has advantages of the good contact in reactants and simple experimental procedure. For immobilizing the phosphorylated peptide (P-peptide) on electrode surface, graphite-like carbon nitride (g-C3N4) and titanium dioxide (TiO2) complex is synthesized and characterized, which plays a significant role for TiO2 conjugating phosphate groups and g-C3N4 providing PEC signal. Subsequently, PAMAM dendrimer and ALP can be captured on P-peptide and TiO2/g-C3N4 modified ITO electrode via interaction between the -COOH groups on the surface of PAMAM dendrimer and the -NH2 groups of peptide and ALP, which can lead to the increase of ALP amount on the modified electrode surface assisted with the PAMAM dendrimer. As a result, the amount of ALP catalyzes of L-ascorbic acid 2-phosphate trisodium salt (AAP) to produce electron donor of ascorbic acid (AA), resulting in an increased photocurrent. The proposed detection assay displays high selectivity and low detection limit of 0.048 U/mL (S/N = 3) for PKA activity. This biosensor can also be applied for the evaluation of PKA inhibition and PKA activity assay in cell samples. Therefore, the fabricated PEC biosensor is potentionally well in PKA activity detection and inhibitor screening.
Assuntos
Fosfatase Alcalina/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/análise , Dendrímeros/química , Técnicas Eletroquímicas/métodos , Nitrilas/química , Titânio/química , Fosfatase Alcalina/química , Ácido Ascórbico/química , Biocatálise , Técnicas Biossensoriais , Linhagem Celular , Proteínas Quinases Dependentes de AMP Cíclico/química , Eletrodos , Grafite/química , Humanos , Limite de Detecção , Nanopartículas/química , Fosforilação , Compostos de Estanho/químicaRESUMO
It is extremely important for quantifying trace microRNAs in the biomedical applications. In this study, an ultrasensitive, rapid and efficient label-free fluorescence method was proposed and applied for detecting microRNA-21 in serum of gastric cancer patients based on DNA hybridization chain reaction (HCR). DNA H1 and DNA H2 were designed and used as hairpin probes, the HCR was proceeded in the presence of target microRNAs. Amounts of SYBR Green Ð dyes were used as signal molecules to intercalate long DNA concatemers from HCR, which guaranteed the model of label-free fluorescence and strong fluorescence density. The detection method showed a wide linear region from 1 fM to 105 fM, and the limit of detection was 0.2554 fM (at S/N = 3) for microRNAs. The results showed that this method had an excellent specificity and reproducibility. Furthermore, the label-free fluorescence strategy exhibited a sensitive response to microRNA-21 in real serum samples of gastric cancer patients and the results obtained were in accordance with reference method (R2 = 0.994). Overall, the proposed strategy could be satisfactory for rapid, ultrasensitive and efficient detection of microRNA-21, and held great potentials in clinic diagnosis of gastric cancer.
Assuntos
Técnicas Biossensoriais/métodos , MicroRNAs/sangue , Compostos Orgânicos/química , Espectrometria de Fluorescência , Benzotiazóis , Diaminas , Humanos , Limite de Detecção , MicroRNAs/química , Hibridização de Ácido Nucleico , Quinolinas , Reação em Cadeia da Polimerase em Tempo Real , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Neoplasias Gástricas/sangue , Neoplasias Gástricas/diagnóstico , Neoplasias Gástricas/genéticaRESUMO
An aptamer based method is described for the electrochemical determination of ampicillin. It is based on the use of DNA aptamer, DNA functionalized gold nanoparticles (DNA-AuNPs), and single-stranded DNA binding protein (ssDNA-BP). When the aptamer hybridizes with the target DNA on the AuNPs, the ssDNA-BP is captured on the electrode surface via its specific interaction with ss-DNA. This results in a decreased electrochemical signal of the redox probe Fe(CN)63- which is measured best at a voltage of 0.188 mV (vs. reference electrode). In the presence of ampicillin, the formation of aptamer-ampicillin conjugate blocks the further immobilization of DNA-AuNPs and ssDNA-BP, and this leads to an increased response. The method has a linear reposne that convers the 1 pM to 5 nM ampicillin concentration range, with a 0.38 pM detection limit (at an S/N ratio of 3). The assay is selective, stable and reproducible. It was applied to the determination of ampicillin in spiked milk samples where it gave recoveries ranging from 95.5 to 105.5%. Graphical abstract Schematic of a simple and sensitive electrochemical apta-biosensor for ampicillin detection. It is based on the use of gold nanoparticles (AuNPs), DNA aptamer, DNA functionalized AuNPs (DNA-AuNPs), and single-strand DNA binding protein (SSBP).
Assuntos
Ampicilina/análise , Nanopartículas Metálicas/química , Animais , Antibacterianos/análise , Aptâmeros de Nucleotídeos , DNA/química , Proteínas de Ligação a DNA/química , Técnicas Eletroquímicas/métodos , Ouro , Leite/químicaRESUMO
Taking advantage of the special exodeoxyribonuclease activity of T7 exonuclease, a simple, sensitive, selective, and label-free microRNA biosensor based on the cyclic enzymatic amplification method (CEAM) has been proposed. First, thiol functionalized DNA probes were assembled onto a gold nanoparticles modified gold electrode surface through a Au-S bond, followed by hybridizing with target miRNA. Subsequently, DNA in RNA/DNA duplexes was digested by T7 exonuclease, which can release the microRNA molecules from the electrode surface and return into the buffer solution. Meanwhile, the released microRNA can further hybridize with the unhybridized DNA probes on the modified electrode surface. On the basis of it, an isothermal amplification cycle is realized. The T7 exonuclease-assisted CEAM achieved a low detection limit of 0.17 fM. Moreover, this assay presents excellent specificity with discriminating only a single-base mismatched microRNA sequence. Furthermore, this work can also be applied to detect avian leukemia based on the decreased expression level of microRNA-21.
Assuntos
Técnicas Eletroquímicas , Exodesoxirribonucleases/química , MicroRNAs/análise , Técnicas Biossensoriais , Limite de DetecçãoRESUMO
Piezoelectric materials can generate the built-in electric field under ultrasound assistance, which is beneficial to the separation of the photogenerated electron-hole pairs in photocatalysis. Meanwhile, the ultrasound stress usually leads to accelerate electron transfer and enhance catalytic activity. Thus, piezo-photocatalysis technique is believed to be one of the effective techniques for organic pollutant degradation. In this work, a binary piezoelectric integrated piezo-photocatalytic Z-Scheme heterojunction with bismuth ferrite (BFO) and bismuth oxycarbonate (Bi2O2CO3, BOC) based on the in situ production of Bi2O2CO3 on Bi25FeO40 surface in dichloromethane, where Bi25FeO40 was employed as piezoelectric materials and Bi source, CO2 dissolved in dichloromethane was used as carbon source. Under 60 min ultrasound and visible light irradiation, the optimal BFO/BOC presented a higher piezo-photocatalytic tetracycline (TC) degradation rate (95 %) than Bi25FeO40 (30 %) and Bi2O2CO3 (17 %). Moreover, the optimal BFO/BOC illustrated higher piezo-photocatalytic TC degradation rate under ultrasound and visible light irradiation than that under visible light condition and ultrasound condition, respectively. These results strongly demonstrated the synergistically piezo-photocatalytic degradation of TC by BFO and BOC. This work not only provides a novel piezo-photocatalyst for pollutant degradation, but also provides a novel method to prepare Bi2O2CO3-based piezo-photocatalytic composite catalyst.
RESUMO
Bi/BiOI/BiOCl composite photocatalyst was constructed by one-step stirring approach at ambient environment to remove of tetracycline (TC) antibiotics via photodegradation in aqueous medium. A systematic discussion of the architecture, composition, formation, photochemical performance and photocatalytic activity of Bi/BiOI/BiOCl was carried out. By adjusting the experimental conditions, it was found that the Bi/BiOI/BiOCl photocatalyst obtained by using 0.7 mmol NaBH4, I/Cl = 5% and reacting for 6 h had the greatest removal performance. Under visible light irradiation, the photocatalytic degradation efficiency of TC reached 90.3% within 60 min, surpassing that of single BiOCl and BiOI. Through the active species removal experiment, it was determined that â¢O2- made a primary contribution to the photocatalytic degradation process. Moreover, the formation of Z-scheme heterojunction in Bi/BiOI/BiOCl was discussed, analyzing the photocatalytic mechanism and TC degradation pathway. The ecological toxicity of TC solution before and after degradation to rice seedlings was preliminarily tested. This study provides an idea for one-step synthesis of bismuth-based composite photocatalysts, with potential applications in the photocatalytic degradation of antibiotics.
Assuntos
Antibacterianos , Tetraciclina , Catálise , Antibacterianos/química , Tetraciclina/química , Luz , FotóliseRESUMO
Oxygen vacancy-rich ß-Bi2O3/Bi2O2SiO3 (BO/BOS) Z-Scheme heterojunction was prepared by hydrothermal method-assisted calcination. Under visible light, ß-Bi2O3/Bi2O2SiO3 photocatalyst demonstrated superior photocatalytic efficacy in degrading antibiotics and antibiotic-resistant Escherichia coli (AR E. coli) compared to individual ß-Bi2O3 and Bi2O2SiO3. The experimental results showed that BO/BOS-450 sample possessed the best photocatalytic activity against tetracycline (2 h, 80.8%), amoxicillin (4 h, 57.9%) and AR E. coli (3 h, 107.43 CFU·mL-1). BO/BOS-450 sample showed 91.8% electrostatic capture of AR E. coli in the bacterial capture experiment. In the antibiotic-resistant genes (ARGs) degradation experiment, BO/BOS-450 sample was able to bring the log10 (Ct/C0) value of tetA to -3.49 after 2 h. Oxygen vacancies (OVs) were verified through HR-TEM, XPS and EPR analyses. ESR experiments aligned with the quenching experiment results, confirming that the crucial active species were â§O2- and h+ during photocatalytic sterilization. A small-scale sewage treatment equipment was designed for the effective removal of ARB from real water samples.