Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 776
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Talanta ; 206: 120175, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514861

RESUMO

Detecting the interactions between small molecules and proteins was critical for disease theranostics and drug development. Here we propose a novel universal assay strategy for monitoring small molecule-protein interactions in solution using strand displacement amplification (SDA) mediated by protein binding to small molecule with DNAzyme-based chemiluminescence detection. The DNA polymerase and nicking enzyme assisted SDA could yield a great amount of peroxidase-mimicking DNAzyme sequences which cause significantly chemiluminescence signals, while protein binding to the small molecule label would prevent DNA polymerase from extending nick site and DNAzyme sequence, and thus the chemiluminescence signals would obviously decrease. This strategy was demonstrated using folate and its binding protein (folate receptor), and the results revealed that the developed strategy enable offer a label-free, homogeneous, and highly sensitive chemiluminescence detection of folate receptor with a detection limit of 1pM. At the same time, it has been successfully used for folate receptor detection in human serum. The proposed chemiluminescence sensing method might provide a generic, robust, and high-throughput platform for detecting various small molecule-protein interactions for biological applications.


Assuntos
DNA Catalítico/química , Receptores de Folato com Âncoras de GPI/metabolismo , Ácido Fólico/metabolismo , Nanoestruturas/química , Técnicas Biossensoriais/métodos , Desoxirribonuclease I/química , Receptores de Folato com Âncoras de GPI/sangue , Hemina/química , Humanos , Limite de Detecção , Medições Luminescentes/métodos , Luminol/química , Estudo de Prova de Conceito
2.
Anal Bioanal Chem ; 411(29): 7857-7868, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31705220

RESUMO

A novel colorimetric sensing platform based on the peroxidase activity of hemin regulated by oligonucleotide and pesticide was reported for the ultrasensitive and selective detection of isocarbophos. Oligonucleotides can accumulate on the surface of hemin in acid condition and temporarily inhibit its catalytic activity, which results in the loss of one electron of TMB molecule and produce the blue products. With the addition of isocarbophos, the pesticide molecules can interact with oligonucleotides to form some complexes, which relieve the inhibition of ssDNA to hemin and further enhance its catalytic activity. Thus, the TMB molecules are further oxidized to lose another electron and produce the yellow product in a few minutes, which has the characteristic absorption peak at 450 nm. The color change of the sensing system is related to the amount of isocarbophos, so this method can quickly discriminate whether the target pesticide exceeds the maximal residue limit just by naked eyes. To improve the performance of sensing platform, some important parameters like buffer condition and ssDNA have been investigated, and the peroxidase activity of hemin was further studied to verify the catalytic mechanism. The proposed sensing platform has a detection limit as low as 0.6 µg/L and displays good selectivity against other competitive pesticides. Moreover, the developed sensing platform also exhibits favorable accuracy and stability, indicating that it has potential applications in the detection of pesticide residues in agricultural products. Graphical abstract A novel colorimetric sensing platform based on oligonucleotides and pesticide regulation; the peroxidase catalytic activity of hemin was firstly reported for the ultrasensitive and selective detection of isocarbophos pesticide.


Assuntos
Colorimetria/métodos , Hemina/química , Malation/análogos & derivados , Oligonucleotídeos/farmacologia , Praguicidas/farmacologia , Verduras/química , Catálise , DNA de Cadeia Simples/química , Cinética , Limite de Detecção , Malation/análise
3.
Chem Commun (Camb) ; 55(80): 12040-12043, 2019 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-31531449

RESUMO

A visible light-induced self-powered sensor for the detection of tyrosinase activity was proposed. A tyrosinase-responsive photoelectrochemical-chemical redox cycling strategy was integrated with a photofuel cell for signal amplification.


Assuntos
Técnicas Biossensoriais/métodos , Monofenol Mono-Oxigenase/análise , Nanoestruturas/química , Técnicas Biossensoriais/instrumentação , Bismuto/química , Catálise , Catecóis/química , Fontes de Energia Elétrica , Técnicas Eletroquímicas/métodos , Eletrodos , Grafite/química , Hemina/química , Luz , Nitrilos/química , Oxirredução , Fosfinas/química , Sulfetos/química
4.
Mater Sci Eng C Mater Biol Appl ; 105: 110141, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31546407

RESUMO

Surface molecular imprinting for proteins, especially for the high molecular weight protein, are facing a great challenge today. We report a novel design to prepare molecular imprinting polymers (MIPs) on the surface of hemin-graphene nanosheets (H-GNs) for the recognition of thyroglobulin (Tg, 660 KD). H-GNs with an intrinsic peroxidase-like activity could effectively immobilize the protein template on its surface to improve the number of imprinted sites per unit surface area and then directly initiate free-radical polymerization to synthesize MIPs. The results indicated MIPs film could be prepared on the surface of H-GNs/filter paper, implying the advantages of surface imprinting, and exhibiting high adsorption capacity (400 mg g-1). The MIP composites clearly distinguished the proteins on the basis of the synergistic effect of shape complementarity and multiple interactions, not even anti-Tg antibodies and sample matrix. The gray intensity of the colorimetric paper-based sensor proved to be proportional to the concentration of Tg in the range of 5-100 ng mL-1 with a detection limit of 1 ng mL-1 (15 fM). The design and direct synthesis of MIPs on the H-GNs/filter paper provide a new perspective for the surface imprinting materials with potential in the recognition and detection of proteins.


Assuntos
Grafite/química , Hemina/química , Impressão Molecular/métodos , Polímeros/química , Proteínas/análise , Adsorção , Calibragem , Cinética , Peso Molecular , Nanopartículas/química , Nanopartículas/ultraestrutura , Propriedades de Superfície
5.
Anal Chim Acta ; 1079: 139-145, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31387704

RESUMO

A short G-rich sequence with three G-tracts can form a G-triplex (G3), a recently identified noncanonical DNA structure. Until now, very limited functional study and application of G3 is reported. Herein, we integrated G3 with isothermal exponential amplification reaction (EXPAR) for achieving simple and sensitive biosensing strategy. In this strategy, the cascade EXPAR cycles produces larger numbers of short G-rich sequences, which self-assemble into G3 structure and then bind hemin to form G3/hemin DNAzyme. This G3/hemin DNAzyme-based EXPAR strategy could detect as low as 4.7 fM target DNA with colorimetric detection, and the sensitivity of G3/hemin DNAzyme-based EXPAR strategy was much higher than that of the conventional G-quadruplex/hemin DNAzyme-based EXPAR strategy. We explored the reason for higher sensitivity of G3/hemin DNAzyme-based EXPAR strategy. The experimental results demonstrated that G3/hemin DNAzyme is an ideal signal generator for EXPAR-based biosensing platform. This work opens a new avenue to develop effective signal amplification strategy for ultrasensitive biosensing. This work is also helpful for a deeper understanding of G3 structure and the future application of G3.


Assuntos
Técnicas Biossensoriais/métodos , Colorimetria/métodos , DNA Catalítico/química , DNA Viral/análise , DNA/química , Hemina/química , Pareamento Incorreto de Bases , Benzotiazóis/química , DNA/genética , DNA Catalítico/genética , DNA Viral/genética , HIV/genética , Peróxido de Hidrogênio/química , Indicadores e Reagentes/química , Limite de Detecção , Técnicas de Amplificação de Ácido Nucleico/métodos , Conformação de Ácido Nucleico , Hibridização de Ácido Nucleico , Ácidos Sulfônicos/química
6.
Anal Chim Acta ; 1079: 207-211, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31387713

RESUMO

Signal amplification strategy have been the intensive direction for highly-sensitive microRNA (miRNA) detection, however, it is worth noting that signal quenching approach is rarely realized. Inspired by the unwinding of G-quadruplex with Klenow Fragment polymerase (KF), a simple and label-free signal quenching system for detection of miRNAs was developed. In the presence of target miRNA, miRNA was used as a primer to promote KF activity resulting in the disruption of G-quadruplex structure of probe and the biological catalysis inactivation of DNAzyme formed by G-quadruplex structure and hemin. As a result, the probe would be transformed from G-quadruplex to duplex and the obvious differential signal could be observed in most cases even with naked eyes. With the significant signal decreasing, the target miRNA can be rapidly analyzed by UV-vis spectra with a considerably low detection limit (4.5 nM). This method exhibits excellent selectivity and anti-interference ability by discriminating base-mismatched and other miRNA families from target miRNA. Meanwhile, a good recovery (90.7%∼102.4%) in 5% human serum was obtained and this strategy verified a high expression level of miR21 in total RNA of MCF-7 compared with 293T and HeLa. It implies that this assay is of great potential to be applied in biochemical research and clinical diagnosis.


Assuntos
DNA Catalítico/química , MicroRNAs/sangue , Técnicas Biossensoriais/métodos , Linhagem Celular Tumoral , Colorimetria/métodos , DNA Catalítico/genética , DNA Polimerase Dirigida por DNA/química , Quadruplex G , Células HEK293 , Hemina/química , Humanos , Limite de Detecção
7.
Biosens Bioelectron ; 142: 111554, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31382098

RESUMO

Maduramicin (MD) is a type of monoglycoside polyether ionophore antibiotic that can effectively treat coccidiosis and facilitate animal growth. However, its extensive and excessive use brings potential risk to human health. Herein, an electrochemical immunosensor based on indirect competitive format was fabricated for analysis of MD residue in eggs by a multiple signal amplification system. Initially, Au nanoparticles were deposited onto glassy carbon electrode surface to load the coating antigen MD-BSA and to improve conductivity. Then the signal amplification platform was constructed by encapsulating hemin into Fe-MIL-88 NH2 metal-organic frameworks (hemin@MOFs), and then the obtained composites were decorated with AuPt nanoparticles. The synthesized hemin@MOFs/AuPt was not only used as a signal amplification mediator, but also utilized as a carrier for immobilization of horseradish peroxidase-conjugated affinipure goat anti-mouse antibody (Ab2-HRP) and horseradish peroxidase (HRP). The constructed hemin@MOFs/AuPt-Ab2-HRP bioconjugates could effectively amplify the current signal since hemin@MOFs, AuPt and HRP all exhibited high catalytic activity towards the hydrogen peroxide. Moreover, the established immunosensor showed high sensitivity and stability during the detection procedure. With the synergistic catalytic effect of hemin@MOFs, AuPt and HRP, a wide detection range of 0.1-50 ng mL-1 and a low detection limit of 0.045 ng mL-1 were achieved (S/N = 3), respectively. Ultimately, the developed method displayed excellent performance in practical applications, providing a promising probability to detect other veterinary drug residues to guarantee food safety.


Assuntos
Antibacterianos/análise , Ouro/química , Hemina/química , Lactonas/análise , Estruturas Metalorgânicas/química , Drogas Veterinárias/análise , Animais , Anticorpos Imobilizados/química , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Análise de Alimentos/métodos , Humanos , Imunoensaio/métodos , Limite de Detecção , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Platina/química
8.
Biosens Bioelectron ; 142: 111574, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31408824

RESUMO

The monitoring of transcription factors (TFs) is critical for understanding the regulation of gene transcriptions. Here, by programming nucleic acid sequence-based and cascaded recycling amplifications, we developed a sensitive and non-label electrochemical biosensor for detecting TFs from tumor cell extracts. The binding of the target nuclear factor-kappa B p50 (NF-κB p50) with the dsDNA probes protects them from being digested by exonuclease III for subsequent initiation of three cascaded recycling cycles, which causes the generation of tremendous free G-quadruplex special sequences on the sensing electrode. Such G-quadruplexes can specifically bind and confine hemin within the vicinity of the sensor, generating substantially enhanced reduction current to achieve determination of NF-κB p50 within the range from 0.5 pM to 5 nM with the detection limit down to 0.13 pM. The proposed sensing system also has high selectivity and it can be used to interrogate the presence of NF-κB p50 in tumor cell extracts, demonstrating its potential for disease diagnosis and gene transcription-related studies.


Assuntos
Técnicas Biossensoriais/métodos , Subunidade p50 de NF-kappa B/análise , Sondas de DNA/química , DNA Catalítico/química , Técnicas Eletroquímicas/métodos , Exodesoxirribonucleases/química , Quadruplex G , Células HeLa , Hemina/química , Humanos , Neoplasias/patologia , Técnicas de Amplificação de Ácido Nucleico/métodos
9.
Analyst ; 144(20): 5959-5964, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31441909

RESUMO

It is of great importance to achieve facile and reliable detection of telomerase because it is an important cancer biomarker. The complex components of cell extracts and ultra-low concentration of telomerase makes it more difficult to realize a simple and sensitive visual detection of telomerase activity. Herein, a facile and sensitive visual strategy was developed for the detection of telomerase based on the telomerase-controlled in situ formation of a G-quadruplex-hemin DNAzyme. To avoid the influence of the complex components of cell extracts, a telomerase substrate (TS) was immobilized onto the surface of magnetic beads (MBs) to form a MB/TS complex. MB/TS incubated with telomerase can add several TTAGGG repeat units to the 3' terminal of TS. After magnetic separation and washing, these G-rich elongated DNA folded into numerous G-quadruplex-hemin DNAzymes under the aid of K+ and hemin, which efficiently catalysed the TMB/H2O2 reaction. Magnetic separation basically eliminated the non-specific background interference from other cell extracts and redundant hemin. Taking full advantage of the in situ formation of multiple catalysts, the telomerase activity could be sensitively evaluated by a color change of the TMB/H2O2 solution. The telomerase activity down to 1 HeLa cell per µL and 0.5 HeLa cell per µL can be measured by the naked eye and UV-vis spectroscopy, respectively. Due to the magnetic separation and enrichment, the sensitivity was obviously improved compared with the previous colorimetric assay. Meanwhile, the telomerase activity of 5 HeLa cells per µL in human serum can be visually detected. Therefore, this study provides a facile, cost-effective and robust colorimetric assay for the visual detection of telomerase activity, which holds great potential in telomerase-based cancer clinical diagnostics.


Assuntos
Técnicas Biossensoriais/métodos , DNA Catalítico/química , Ensaios Enzimáticos/métodos , Quadruplex G , Hemina/química , Neoplasias/metabolismo , Telomerase/metabolismo , Colorimetria , Humanos , Neoplasias/diagnóstico , Células Tumorais Cultivadas
10.
Biosens Bioelectron ; 143: 111602, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31442756

RESUMO

Herein, a novel biosensing platform for versatile electrochemiluminescence (ECL) "off" and fluorescence (FL) "on" detection of lipopolysaccharide (LPS) with multiple-amplification strategy is proposed. The specific recognition of target to aptamer on the magnetic beads (MB) firstly released abundant DNA sequences of three kinds. The sequences hybridized with multifunctional molecular beacon (MMB) and initiated numerous bidirectional polymerization and shearing reactions, generating a large number of DNA fragments (a1) by multiple cycling amplification. Then a1 was introduced to the triple-helix sensing system, opening the triple-helix structure. In ECL system, the G-rich chains S2 were exposed to form G-quadruplex-hemin complex in the presence of hemin, which could efficiently quench ECL for "off" detection of LPS. In FL system, the fluorophore FAM and quencher BHQ on S1 chain were separated with opening of triple-helix structure, achieving fluorescence "on" signal for LPS assay. So the versatile platform can achieve greatly amplified ECL and FL signal changes for sensitive assay of LPS, showing wide linear ranges (0.1 fg/mL-0.1 ng/mL by ECL and 10 fg/mL-1-1 µg/mL by FL) and low detection limits (0.012 fg/mL by ECL and 1.269 fg/mL by FL). Therefore, the present ECL "Off" and FL "On" dual-signal detection patterns for LPS displayed many advantages over other reported methods, which provided an outlook for future applications in clinical diagnosis.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Lipopolissacarídeos/isolamento & purificação , Medições Luminescentes , Aptâmeros de Nucleotídeos/química , DNA Catalítico/química , Fluorescência , Quadruplex G , Ouro/química , Hemina/química , Humanos , Lipopolissacarídeos/química , Nanopartículas Metálicas/química
11.
Anal Chim Acta ; 1081: 59-64, 2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31446964

RESUMO

Herein, a signal-on electrochemical aptasensor for highly sensitive detection of thrombin (TB) was constructed based on the DNAzyme-driven DNA walker strategy. We developed a new dual functional hairpin DNA (HP) containing a substrate sequence of the Mg2+-dependent DNAzyme (in the loop region) and the G-quadruplex forming segment (in the stem region). The DNA walker (TBA2-DWs), containing a TB aptamer and an enzymatic sequence, was introduced onto gold electrode (GE) by aptamers-target specific recognition, and thus initiated the enzymatic sequences to hybridize with the substrate sequence. Then, the DNA walker could repeatedly bind and cleave HP in the assistance of Mg2+, unlocking many active G-quadruplex forming sequences. Finally, hemin can further bind the G-quadruplex to form G-quadruplex/hemin complexes and generate enhanced current output. The aptasensor for TB assay showed a linear detection range from 1 pM to 60000 pM with a lower detection limit of 0.58 pM. And more, the proposed detection strategy was enzyme-free and label-free.


Assuntos
Aptâmeros de Nucleotídeos/química , DNA Catalítico/química , DNA/química , Aptâmeros de Nucleotídeos/genética , Técnicas Biossensoriais/métodos , DNA/genética , DNA Catalítico/genética , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Quadruplex G , Ouro/química , Hemina/química , Sequências Repetidas Invertidas , Limite de Detecção , Hibridização de Ácido Nucleico , Trombina/análise
12.
Biosens Bioelectron ; 142: 111572, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31400730

RESUMO

We propose herein an immobilization-free, split-mode cathodic photoelectrochemical (PEC) strategy coupled with a cascaded amplification for versatile biosensing. Taking DNA and microRNA (miRNA) as the model targets, the hybridization between the targets and the hairpin probe triggers the digestion of the probe DNA by T7 exonuclease (T7 Exo), thus to generate G-quadruplex (G4) forming sequences, and then the released targets (DNA or miRNA) initiate the subsequent cycling processes and generate a large amount of G4 forming sequences. Subsequently, the formed G4 sequences associate with hemin to form the G4/hemin DNAzyme, which catalytically produces 1,4-bezoquinone (BQ) for conjugating onto the surface of the chitosan (CS) deposited BiOI/ITO photocathode via the quinone-chitosan conjugation chemistry (QCCC). Under photo excitation, the covalently attached quinones can act as electron acceptors of bismuth oxyiodine (BiOI), promoting the photocurrent generation and thus allowing the elegant and "signal-on" mode for probing targets of interest. Highly sensitive and selective PEC bioassays are readily realized, with the detection limits down to 2.2 fM (for DNA) and 0.2 fM (for miRNA). Since no labeling and no electrode modification processes are needed, this split-mode PEC biosensing strategy is amenable to convenient, time/labor saving, and high-throughput detections. More significantly, it provides a novel concept to design immobilization-free and label-free cathodic PEC biosensing systems, and showcases promise in general and versatile bioanalysis research.


Assuntos
Técnicas Biossensoriais/instrumentação , DNA/análise , MicroRNAs/análise , Hibridização de Ácido Nucleico , Benzoquinonas/química , Sondas de DNA/química , DNA Catalítico/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Desenho de Equipamento , Quadruplex G , Hemina/química
13.
Biosens Bioelectron ; 142: 111578, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31422223

RESUMO

The sensitive and accurate detection of cardiac troponin I (cTnI) is critical for myocardial infarction diagnosis. In this work, a dual-aptamer-based electrochemical (EC) biosensor was designed for cTnI detection based on the DNA nanotetrahedron (NTH) capture probes and multifunctional hybrid nanoprobes. First, the NTH-based Tro4 aptamer probes were anchored on a screen printed gold electrode (SPGE) surface through the Au-S bond, providing an enhanced spatial dimension and accessibility for capturing cTnI. Then, the hybrid nanoprobes were fabricated by using magnetic Fe3O4 nanoparticles as nanocarriers to load a large amount of cTnI-specific Tro6 aptamer, natural horseradish peroxidase (HRP), HRP-mimicking Au@Pt nanozymes and G-quadruplex/hemin DNAzyme. This signaling nanoprobes are capable of specifically recognizing the target cTnI based on the Tro6 aptamer and amplifying the signals to improve the detection sensitivity via enzymatic processes. We found the remarkable enhanced effect of EC signal to be attributed to the co-catalysis effect of hybrid nanozymes, HRP and DNAzyme. The target cTnI was sandwiched between the two types of aptamers (Tro4 and Tro6) on the electrode interface. Finally, this EC aptasensing platform exhibited great analytical performance with a wide dynamic range of 0.01-100 ng mL-1 and a low detection limit of 7.5 pg mL-1 for cTnI. The high selectivity, sensitivity and reliability of EC aptasensor can provide great potential in the clinic disease diagnostics.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Ácidos Nucleicos Imobilizados/química , Troponina I/sangue , Catálise , Sondas de DNA/química , DNA Catalítico/química , Técnicas Eletroquímicas/métodos , Quadruplex G , Ouro/química , Hemina/química , Peroxidase do Rábano Silvestre/química , Humanos , Limite de Detecção , Platina/química , Reprodutibilidade dos Testes , Troponina I/análise
14.
Analyst ; 144(15): 4472-4476, 2019 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-31257395

RESUMO

RNA G-quadruplexes (rG4s) are important RNA secondary structures considering their significance in regulating numerous cellular processes. Described herein is an rG4 detecting and isolation method, which exploits the complex of rG4 and hemin to mimic peroxidase. In the presence of biotin tyramide and hydrogen peroxide, rG4s can be selectively self-biotinylated and easily isolated from a complex RNA mixture using streptavidin magnetic beads.


Assuntos
Quadruplex G , RNA Catalítico/isolamento & purificação , Materiais Biomiméticos/química , Materiais Biomiméticos/isolamento & purificação , Biotina/análogos & derivados , Biotina/química , Biotinilação , Catálise , Hemina/química , Peróxido de Hidrogênio/química , Fenômenos Magnéticos , Mutação , Oxirredução , Peroxidase/química , RNA Catalítico/química , RNA Catalítico/genética , Estreptavidina/química , Tiramina/análogos & derivados , Tiramina/química
15.
Anal Sci ; 35(10): 1135-1140, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31281131

RESUMO

In the present study, we synthesized a water-soluble substance (Hemin-mPEG) at room temperature by using hemin and poly(ethylene glycol) methyl ether (mPEG). It was found that the Hemin-mPEG maintained the excellent catalytic activity inherited from hemin, and was first used to catalyze a luminol-H2O2 chemiluminescence (CL) system to generate an intense and slow CL signal. The results of a mechanism research showed that the presence of Hemin-mPEG could promote the production of oxygen-relative radicals from H2O2 and dissolved oxygen in solution. Based on this mechanism, an ultra-sensitive, cheap and simply practical sensor for detecting glucose and H2O2 was developed. Under the most optimal experimental conditions, H2O2 and glucose detection results exhibited a good linear range from 0.002 to 3 µM and from 0.02 to 4 µM, respectively, and the detection limits were 1.8 and 10 nM, respectively. This approach has been successfully used to detect glucose in actual biological samples, and achieved good results.


Assuntos
Glucose/análise , Hemina/química , Peróxido de Hidrogênio/análise , Luminescência , Luminol/química , Polietilenoglicóis/química , Água/química , Catálise , Glucose/química , Peróxido de Hidrogênio/química , Limite de Detecção , Solubilidade
16.
Analyst ; 144(16): 4995-5002, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31328736

RESUMO

Herein, a split G-quadruplex DNAzyme as a signal reporter was integrated into an electrochemical sensing platform for the detection of antibiotics with specificity and sensitivity. To improve the signal-to-noise ratio, two G-rich oligonucleotide sequences (G1 and G2) were blocked into two different hairpin probes, preventing the two segments from assembling into a spilt G-quadruplex structure. Moreover, we designed a double-arch probe, consisting of an aptamer as the recognition element and two-step enzymatic signal amplification. Concretely, the first is the Nt.BbvCI-assisted nicking cyclic reaction activated by target-aptamer binding, and the second is exonuclease III-aided cyclic amplification for generating abundant G1 and G2. The modified capture probe on the electrode was used to combine G1 and G2 to form the spilt G-quadruplex/hemin when K+ and hemin were present. This complex plays the role of DNAzyme with superior horseradish peroxidase activity in catalyzing the decomposition of H2O2. Under optimal conditions, this biosensor showed an excellent performance for sensing kanamycin with a detection limit of 83 fM for kanamycin concentrations ranging from 100 fM to 1 nM. Hence, the proposed strategy has potential as an efficient and actual platform for small molecule analysis.


Assuntos
Antibacterianos/análise , Técnicas Biossensoriais/métodos , DNA Catalítico/química , Canamicina/análise , Antibacterianos/química , Aptâmeros de Nucleotídeos/química , Sondas de DNA/química , DNA Catalítico/genética , Técnicas Eletroquímicas/métodos , Quadruplex G , Hemina/química , Peróxido de Hidrogênio/química , Canamicina/química , Limite de Detecção , Técnicas de Amplificação de Ácido Nucleico/métodos , Sensibilidade e Especificidade
17.
Chemistry ; 25(54): 12576-12582, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31314132

RESUMO

Nature has evolved enzymes with exquisite active sites that catalyze biotransformations with high efficiency. However, the exploitation of natural enzymes is often hampered by poor stability, and natural enzyme production and purification are costly. Supramolecular self-assembly allows the construction of biomimetic active sites, although it is challenging to produce such artificial enzymes with catalytic activity and stability that rival those of natural enzymes. We report herein a strategy to produce a horseradish peroxidase (HRP) mimic based on the assembly of chitosan with a G-quadruplex DNA (G-DNA)/hemin complex. A network-like morphology of the assembled nanomaterial was observed together with a remarkable enhancement of peroxidase activity induced by the chitosan and G-DNA components. The turnover frequency and catalytic efficiency of the enzyme-mimicking material reached or even surpassed those of HRP. Moreover, the catalytic complex exhibited higher tolerance than HRP to harsh environments, such as extremely low pH or high temperatures. In accord with the experimental and simulated results, it is concluded that the spatial distribution of the G-DNA and chitosan components and the exposure of the catalytic center may facilitate the coordination of substrates by the hemin iron, leading to the superior activity of the material. Our work provides a simple and affordable avenue to produce highly active and robust enzyme-mimicking catalytic nanomaterials.


Assuntos
Materiais Biomiméticos/química , Quitosana/química , Quadruplex G , Hemina/química , Peroxidase do Rábano Silvestre/química , Nanoestruturas/química , Catálise , Domínio Catalítico , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Cinética , Simulação de Dinâmica Molecular , Oxirredução , Conformação Proteica , Temperatura Ambiente , Termodinâmica
19.
Spectrochim Acta A Mol Biomol Spectrosc ; 222: 117228, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31212194

RESUMO

A sensitive and visible colorimetric strategy was proposed for Hg2+ detection by thymine-Hg2+-thymine (T-Hg2+-T) coordination chemistry and entropy driven catalytic reaction. The entropy driven catalytic reaction is induced by T-Hg2+-T coordination chemistry, resulting the releasing of G-riched sequence. Hemin/G-quadruplex-HRP-mimicking DNAzyme can be formed with the help of hemin, catalyzing TMB to TMB+ with a color change from colorless to blue. The sensitivity of this strategy can be reached to 2 pM, which is significantly improved by entropy driven catalytic reaction. In addition, entropy driven catalytic reaction provides a more reliable and accurate results. This method shows great promise for on-site analysis and in-house diagnosis of Hg2+ in water.


Assuntos
Quadruplex G , Hemina/química , Mercúrio/análise , Timina/análogos & derivados , Poluentes Químicos da Água/análise , Benzidinas/química , Técnicas Biossensoriais/métodos , Catálise , Compostos Cromogênicos/química , Colorimetria/métodos , Complexos de Coordenação/química , DNA Catalítico/química , Entropia , Limite de Detecção , Água/química
20.
Nanoscale ; 11(26): 12603-12609, 2019 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-31232410

RESUMO

Although various nanomaterials have been found to exhibit intrinsic enzyme-like activity, to date, there is no general strategy for designing nanozymes, and their catalytic mechanism has not been studied in depth. To realize the desired enzymatic properties, imitating the structure of natural enzymes is a commendable way to develop effective nanozymes. Inspired by the structure of natural horseradish peroxidase (HRP), we loaded hemin onto amino-modified single-walled carbon nanotubes (SWNT-NH2) to prepare an effective peroxidase-like nanozyme (SWNT-NH2@hemin). The peroxidase-like activity of hemin was enhanced by SWNT through π-π interactions, and the positively charged -NH2 groups played a similar role to arginine in HRP and stabilized the intermediate during catalysis and facilitated the cleavage of the O-O bond. This is instructive for the development of a variety of highly efficient nanozymes by simulating the adjacent environment of the active center in natural enzymes. In addition, dual sensor platforms consisting of a colorimetric method and electrochemical method were developed based on SWNT-NH2@hemin.


Assuntos
Materiais Biomiméticos/química , Hemina/química , Nanotubos de Carbono/química , Peroxidase/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA