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1.
Chem Commun (Camb) ; 55(77): 11551-11554, 2019 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-31490470

RESUMO

A novel ratiometric electrochemiluminescence (ECL)-electrochemical (EC) hybrid biosensor with a high accuracy and reproducibility was fabricated for the ultrasensitive detection of miRNA-133a. With the help of a DNA tetrahedron nanostructure and hybridization chain reaction dual amplification strategy, the detection limit of 12.17 aM for miRNA-133a was obtained.


Assuntos
Técnicas Biossensoriais/métodos , DNA/química , MicroRNAs/análise , Nanoestruturas/química , 2,2'-Dipiridil/análogos & derivados , 2,2'-Dipiridil/química , Técnicas Biossensoriais/instrumentação , Técnicas Eletroquímicas , Corantes Fluorescentes/química , Humanos , Limite de Detecção , Medições Luminescentes , Azul de Metileno/química , Técnicas de Amplificação de Ácido Nucleico , Conformação de Ácido Nucleico , Hibridização de Ácido Nucleico , Compostos Organometálicos/química
2.
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
3.
J Agric Food Chem ; 67(35): 9942-9949, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31403785

RESUMO

We develop an ultrasensitive T2-mediated immunosensor based on the coordination chemistry and Cu(I)-catalyzed 1,3-dipolar cycloaddition of azide andalkyne (CuAAC) and apply it for the detection of pesticide residues. We functionalize polyglutamic acid (PGA) on polystyrene to form a brush-like nanostructure that has a large loading capacity of Cu(II) through the coordination chemistry between PGA and Cu(II). Such a brush-like nanostructure could be used to chelate Cu(II) to modulate the CuAAC between azide-functionalized 1000 nm polystyrene (PS1000) and alkyne-functionalized 30 nm magnetic nanoparticles (MNP30), and the MNP30-PS1000 conjugate as a product of CuAAC can act as a magnetic probe in this T2-based immunosensor. This click chemistry and coordination chemistry-mediated immunosensor allows for an ultrasensitive detection for chlorpyrifos residue (0.022 ng/mL), a 58-fold enhancement compared with that of enzyme-linked immunosorbent assay (1.28 ng/mL), providing a promising platform for detection of trace small molecules.


Assuntos
Técnicas Biossensoriais/métodos , Clorpirifos/análise , Nanoestruturas/química , Resíduos de Praguicidas/análise , Alquinos/química , Azidas/química , Técnicas Biossensoriais/instrumentação , Quelantes/química , Química Click , Cobre/química , Água Potável/análise , Lagos/análise , Ácido Poliglutâmico/química , Sensibilidade e Especificidade , Poluentes da Água/análise
4.
Chem Commun (Camb) ; 55(71): 10571-10574, 2019 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-31417999

RESUMO

A portable dual-mode sensing platform based on a self-standing TiO2 nanotube membrane is developed for simultaneously performing both qualitative analysis by the naked eye and quantitative analysis by ionic current. This dual-mode diagnosis strategy exhibits a high performance in telomerase detection in urine specimens from patients with bladder cancer.


Assuntos
Nanotubos/química , Telomerase/urina , Titânio/química , Neoplasias da Bexiga Urinária/diagnóstico , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Cor , Ouro/química , Humanos , Membranas Artificiais , Nanopartículas Metálicas/química , Prata/química , Neoplasias da Bexiga Urinária/urina
5.
Chem Commun (Camb) ; 55(67): 9959-9962, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31364996

RESUMO

On the basis of BSA stabilized tetraphenylethylene nanocrystals (BSA-TPE NCs) as aggregation-induced enhanced electrochemiluminescence (ECL) emitters with high ECL efficiency and good biocompatibility, as well as molecular recognition between ß-CD and ferrocene, an ultrasensitive and versatile ECL biosensing platform was constructed to achieve microRNA detection in cancer cells.


Assuntos
Materiais Biocompatíveis/química , Corantes Fluorescentes/química , MicroRNAs/análise , Nanopartículas/química , Soroalbumina Bovina/química , Estilbenos/química , Animais , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Bovinos , Linhagem Celular Tumoral , Técnicas Eletroquímicas , Compostos Ferrosos/química , Humanos , Limite de Detecção , Medições Luminescentes , Metalocenos/química , Sensibilidade e Especificidade , beta-Ciclodextrinas/química
6.
Anal Bioanal Chem ; 411(23): 6119-6128, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31388714

RESUMO

A new approach employing a microchip in combination with photothermal lens microscopy has been described for a DNA hybridization assay using gold nanoparticles. The difference in adsorption propensities of single- and double-stranded DNAs on gold nanoparticles was used for a highly sensitive DNA hybridization assay through a photothermal lens effect in a femtoliter scale of detection volume. Under the optimized conditions, the results showed that the variation of photothermal lens signal in the focal volume of 105 fL (10-15 L) was linearly proportional to the target DNA concentration over the range of 50-500 nM with detection limits of 30.7 nM and 27.3 nM for target DNA I and II, respectively. The lowest amount of target DNA that was measured using gold nanoparticles was 2.6 zepto mole. The assay was completed within 5 min and the relative standard deviations (n = 8) for both target DNAs were about 2.34%. The hybridization process was proved by two different common methods including gel electrophoresis and in situ fluorescence monitoring of DNA hybridization. The performance of this detection method was investigated in diluted human serum sample as a complex sample. The recovery values were between 98 and 104.9%. Graphical abstract.


Assuntos
DNA/análise , Ouro/química , Dispositivos Lab-On-A-Chip , Nanopartículas Metálicas/química , Hibridização de Ácido Nucleico , Técnicas Biossensoriais/instrumentação , DNA/genética , Desenho de Equipamento , Limite de Detecção , Nanopartículas Metálicas/ultraestrutura , Microscopia/instrumentação
7.
Chem Commun (Camb) ; 55(69): 10288-10291, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31396601

RESUMO

A simple nanopore modification and sensing strategy was developed for the detection of miRNAs. This preparation and sensing approach provides a quick, simple and facile tool for the detection of specific biomolecules with high sensitivity and selectivity, and may find a wide range of applications in bio-analysis.


Assuntos
Ouro/química , Ácidos Nucleicos Imobilizados/química , MicroRNAs/análise , Nanoporos/ultraestrutura , Técnicas Biossensoriais/instrumentação , Desenho de Equipamento , Hibridização de Ácido Nucleico
8.
Int J Nanomedicine ; 14: 4833-4847, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31308661

RESUMO

Background: The use of functionalized graphene oxide (fGO) has led to a new trend in the sensor field, owing to its high sensitivity with regards to sensing characteristics and easy synthesis procedures. Methods: In this study, we developed an ultra-sensitive carboxyl-graphene oxide (carboxyl-GO)-based surface plasmon resonance (SPR) aptasensor using peptides to detect human chorionic gonadotropin (hCG) in clinical serum samples. The carboxyl-GO based SPR aptasensor provided high affinity and stronger binding of peptides, which are great importance to allow for a non-immunological label-free mechanism. Also, it allows the detection of low concentrations of hCG, which are in turn considered to be important clinical parameters to diagnose ectopic pregnancies and paraneoplastic syndromes. Results: The high selectivity of the carboxyl-GO-based SPR aptasensor for hCG recombinant protein was verified by the addition of the interfering proteins bovine serum albumin (BSA) and human serum albumin (HSA), which did not affect the sensitivity of the sensor. The carboxyl-GO-based chip can enhance the assay efficacy of interactions between peptides and had a high affinity binding for a ka of 17×106 M-1S-1. The limit of detection for hCG in clinical serum samples was 1.15 pg/mL. Conclusion: The results of this study demonstrated that the carboxyl-GO-based SPR aptasensor had excellent sensitivity, affinity and selectivity, and thus the potential to be used as disease-related biomarker assay to allow for an early diagnosis, and possibly a new area in the field of biochemical sensing technology.


Assuntos
Técnicas Biossensoriais/instrumentação , Gonadotropina Coriônica/sangue , Grafite/química , Ressonância de Plasmônio de Superfície/instrumentação , Animais , Bovinos , Eletroquímica , Humanos , Peptídeos/química , Espectroscopia Fotoeletrônica , Soroalbumina Bovina/química
9.
J Agric Food Chem ; 67(32): 9104-9111, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31334655

RESUMO

Gold nanoflowers (GNFs) exhibit stronger light scattering ability than gold nanospheres (GNSs) with the same diameter, thereby contributing to enhancing the sensitivity of the scattering-based sensing method. However, the application of GNFs in biosensors based on dynamic light scattering (DLS) has not been yet reported. Herein, we describe for the first time an improved no-wash immunosensor based on dynamic light scattering for the detection of Escherichia coli O157:H7 (E. coli O157:H7) in milk using GNFs for sensitive signal transduction. To achieve this goal, a thiolated amphiphilic carboxyl ligand was introduced to modify the GNF surface and improve solution stability and antibody functionalization. Several key factors that affect the detection sensitivity of our developed GNF_DLS immunosensor were systematically investigated. Under the optimal conditions, our proposed GNF_DLS immunosensor provided an excellent linear detection for E. coli O157:H7 within the range from 6 × 100 to 6 × 104 colony-forming units (CFU)/mL, with a limit of detection of 2.7 CFU/mL. Combined with our previously reported two-step large-volume immunomagnetic separation (IMS) method, the designed GNF_DLS immunosensor can sensitively, selectively, and accurately detect the presence of E. coli O157:H7 in pasteurized milk. The potential of our GNF_DLS method for monitoring the presence of a single bacterial cell in 1 mL of sample solution was also demonstrated. Overall, the developed GNF_DLS immunosensor can be used for the rapid and high-sensitivity determination of pathogenic bacteria and can be extended for the ultrasensitive no-wash detection of other trace analytes.


Assuntos
Técnicas Biossensoriais/métodos , Difusão Dinâmica da Luz/métodos , Escherichia coli O157/isolamento & purificação , Leite/microbiologia , Animais , Técnicas Biossensoriais/instrumentação , Bovinos , Difusão Dinâmica da Luz/instrumentação , Escherichia coli O157/crescimento & desenvolvimento , Contaminação de Alimentos/análise , Ouro/química , Leite/química , Nanoestruturas/química , Sensibilidade e Especificidade
10.
Phys Chem Chem Phys ; 21(28): 15787-15797, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31282520

RESUMO

With the aim of improving the reproducibility of capacitive immunosensors, we performed a comparative study of four different insulating/immobilization chemistries. Each chemistry targeted different areas of an interdigitated electrode including an alkyl thiol monolayer on the electrode surface, an amino silane monolayer on the gaps between electrodes, and conformal coatings via passive adsorption of the probe and a spin-coated layer of poly(methyl methacrylate) (PMMA). We analyzed the dielectric properties of these chemistries by comparing their capacitive behavior through equivalent circuit modeling and correlate the observed behavior with their surface characteristics by using atomic force microscopy and finite element modeling. We found that surface binding events occurring in the interdigitated electrode gaps play a major role in the overall change in capacitance. This was confirmed via finite element modeling showing an increased electric field intensity in the electrode gaps by 14%, compared to directly above the electrodes. Among the investigated surface chemistries, PMMA conformal coating produced a smooth surface (Rq roughness = 0.21 ± 0.02 nm) providing the most reproducible and stable capacitance change (15.6 ± 0.4%) in response to specific antigen-antibody binding.


Assuntos
Técnicas Biossensoriais/instrumentação , Eletrodos , Imunoensaio/instrumentação , Capacitância Elétrica , Microscopia de Força Atômica , Modelos Químicos , Ligação Proteica
12.
Anal Bioanal Chem ; 411(23): 6165-6172, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31312882

RESUMO

The copper(II) ion (Cu2+) has played an indispensable role in diverse kinds of functional physiological processes of organisms, which has become of growing interest. Despite the fact that numerous Cu2+ test papers using fluorescent probes have been fabricated, sensors featuring the ratiometric property that integrates quenched probes and an inner standard dye are rarely reported. Herein, a two-component ratiometric sensor in a paper-based device is proposed to realize highly selective Cu2+ detection. To overcome shortcomings such as low signal-to-noise ratio and incorrect response of the quenching probe, a novel BODIPY-based turn-off probe (P2017) is designed and introduced into the paper-based device with better water solubility and selectivity for Cu2+ detection. Furthermore, a reference dye (B001), exhibiting an emission at 690 nm when the excitation wavelength is 480 nm, is also introduced into the paper-based device. These two components can enhance the quality of the signal as P2017 is sensitively quenched by Cu2+, while B001 with a photostable property, serving as an internal benchmark, is unable to react with Cu2+. The results indicated that the two components provided a new concept for optimizing paper-based device fabrication and developing accurate, simple, and inexpensive Cu2+ detection methods, which could be potentially applied to monitor human health and the environment in remote areas. Graphical abstract.


Assuntos
Técnicas Biossensoriais/instrumentação , Compostos de Boro/química , Cobre/análise , Corantes Fluorescentes/química , Papel , Cátions Bivalentes/análise , Desenho de Equipamento , Células Hep G2 , Humanos
13.
Anal Bioanal Chem ; 411(23): 5929-5935, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31338538

RESUMO

Because cerebral species involve rapid events, increasing the temporal resolution to realize in vivo near-real-time measurements is desirable. Here, we aimed to improve the low resolution of our previous on-line electroanalytical system by decreasing the dead volume and reducing molecular dispersion. This updated system has advantages of elevated time resolution and accelerated analysis for on-line monitoring of glucose versus the previous system. Finally, this new system was successfully applied to continuous measurement of cerebral glucose in vivo during global ischemia/reperfusion events. This study is expected to offer a reliable on-line analytical platform for continuous monitoring of important species associated with fast physiological and pathological events in vivo. Graphical abstract.


Assuntos
Encéfalo/metabolismo , Técnicas Eletroquímicas/instrumentação , Glucose/metabolismo , Microdiálise/instrumentação , Animais , Técnicas Biossensoriais/instrumentação , Química Encefálica , Desenho de Equipamento , Glucose/análise , Masculino , Ratos Sprague-Dawley
14.
Anal Chim Acta ; 1078: 125-134, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31358210

RESUMO

We synthesized three kinds of nitrogen-doped nanoporous carbon nanomaterials (represented by N-mC) through a cost-effective method, that is, pyrolysis of plant biomasses (grass, flower, and peanut shells). We further explored their potential as sensitive bioplatforms for electrochemical label-free aptasensors to facilitate the early detection of alpha-fetoprotein (AFP). Chemical structure characterizations revealed that rich functional groups coexisted in as-synthesized N-mC nanomaterials, such as C-C, C-O, C=O, C-N, and COOH. Among the three kinds of N-mC nanomaterials, the one derived from grass (N-mCg) exhibited the lowest carbon defect degree, the highest ID/IG ratio in the Raman spectra, and the largest specific surface area (186.2 m2 g-1). Consequently, N-mCg displayed excellent electrochemical activity and strong affinity toward aptamer strands, further endowing the corresponding aptasensor with sensitive detection ability for AFP. Electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) were used to investigate the whole detection procedure for AFP. The EIS and DPV results showed that the fabricated N-mCg-based aptasensor possessed an extremely low limit of detection of 60.8 and 61.8 fg·mL-1 (s/n = 3), respectively, for detecting AFP within a wide linear range from 0.1 pg mL-1 to 100 ng mL-1. Moreover, the aptasensor displayed acceptable selectivity and applicability, high reproducibility, and excellent stability in serum samples of cancer patients. Therefore, the proposed cost-effective and label-free strategy based on the nitrogen-doped nanoporous carbon derived from plant biomass is a promising approach for the early detection of various tumor markers.


Assuntos
Biomassa , Técnicas Biossensoriais/métodos , Carbono/química , Técnicas Eletroquímicas/métodos , Nanoestruturas/química , alfa-Fetoproteínas/análise , Adolescente , Adulto , Idoso , Aptâmeros de Nucleotídeos/química , Sequência de Bases , Técnicas Biossensoriais/instrumentação , DNA/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Feminino , Humanos , Limite de Detecção , Masculino , Pessoa de Meia-Idade , Nitrogênio/química , Plantas/química , Porosidade , Reprodutibilidade dos Testes , Adulto Jovem
15.
Anal Chim Acta ; 1078: 161-167, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31358215

RESUMO

Sarcosine is a recently identified biomarker for prostate cancer. However, the rapid detection methods for sarcosine are relatively lack because of the low concentration and the presence of complicated interfering substances in serum or urine. In this manuscript, hollow nanospheres of Fe3O4 was synthesized and used as carrier to disperse Pt (Pt) nanoparticles. In order to achieve excellent electron transfer ability, we use polyaniline to coat Pt-Fe3O4 nanoparticles, and pyrolyze the polyaniline to carbon (C). Thus, hollow magnetic Pt-Fe3O4@C nanocomposites with good electron transfer ability are formed. The Pt-Fe3O4@C nanocomposites have high catalytic activity and stability. The nanocomposites were immobilized on glassy carbon electrode (GCE) to construct a nonenzyme hydrogen peroxide (H2O2) sensor (Pt-Fe3O4@C/GCE). We further construct a sensitive sarcosine biosensor by immobilizing sarcosine oxidase (SOx) on the Pt-Fe3O4@C/GCE. The high catalytic activity and good biocompatibility of Pt-Fe3O4@C nanocomposites greatly retained the bioactivity of immobilized SOx, and the prepared sarcosine biosensor has good electrocatalytic performance towards sarcosine. It has a linear detection range between 0.5 and 60 µM with a limit of detection (LOD) of 0.43 µM (the signal to noise ratio is 3), and the sensitivity is 3.45 nA µM-1 (48.8 nA µM-1 cm-2), which has the potential to be used for rapid screening of prostate cancer.


Assuntos
Nanopartículas de Magnetita/química , Nanocompostos/química , Sarcosina/sangue , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Carbono/química , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Enzimas Imobilizadas/química , Humanos , Limite de Detecção , Platina/química , Sarcosina Oxidase/química
16.
Anal Chim Acta ; 1078: 42-52, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31358227

RESUMO

Hemoglobin A1c (HbA1c) is a standard biomarker to measure long-term average glucose concentration for diagnosis and monitoring of diabetes. Various methods have been reported for measuring HbA1c, however, portable and precise determination is still challenging. Herein, a new highly sensitive electrochemical nanobiosensor is developed for the specific determination of HbA1c. A nanocomposite of reduced graphene oxide (rGO) and gold with hierarchical architecture structure was electrochemically deposited on a cheap and flexible graphite sheet (GS) electrode. The nanocomposite increased the surface area, improved the electron transfer on the electrode surface and augmented the signal. It also provided a suitable substrate for linkage of thiolated DNA aptamer as a bioreceptor on the electrode surface by strong covalent bonding. The quantitative label free detection was carried out by differential pulse voltammetry (DPV) in a phosphate-buffered saline (PBS) solution containing redox probe Fe(CN)63-/4-. The detection is based on insulating the surface in presence of HbA1c and decreasing the current, which is directly related to the HbA1c concentration. The nanobiosensor demonstrated high sensitivity of 269.2 µA. cm-2, wide linear range of 1 nM-13.83 µM with a low detection limit of 1 nM. The biosensor was successfully used for measuring HbA1c in blood real sample. Furthermore, it is promising to use it as a part of a point of care device for low-invasive screening and management of diabetes.


Assuntos
Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Hemoglobina A Glicada/análise , Grafite/química , Nanopartículas Metálicas/química , Papel , Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/genética , Sequência de Bases , Técnicas Biossensoriais/instrumentação , DNA/química , DNA/genética , Técnicas Eletroquímicas/instrumentação , Eletrodos , Ouro/química , Humanos , Limite de Detecção , Nanocompostos/química , Reprodutibilidade dos Testes
17.
Anal Chim Acta ; 1075: 91-97, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31196427

RESUMO

Antioxidants are important to protect and maintain biological barriers, such as the skin. Antioxidant effects are often assessed using clinical trials, however these tests are costly and time consuming. In this work we introduce a skin membrane-covered oxygen electrode (SCOE) as an in vitro tool for monitoring H2O2 and antioxidant reactions in skin. The SCOE gives amperometric response to H2O2 concentrations down to 0.05 mM. More importantly, the electrode allows measurements of polyphenol penetration and reaction with H2O2 in skin. Measurements with SCOE show that lipophilic polyphenols such as quercetin, piceatannol, resveratrol, and plant extract from Plantago major impose their antioxidant effect in skin within 2-20 min. Rutin is however too hydrophilic to penetrate into stratum corneum and therefore cannot deliver its antioxidant effect during similar time interval. The measurements are interpreted considering polyphenol partition-penetration through stratum corneum and the reaction with the H2O2-catalase system in the skin. The contribution of other enzymes will be addressed in the future.


Assuntos
Antioxidantes/metabolismo , Peróxido de Hidrogênio/análise , Inflamação/metabolismo , Polifenóis/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Pele/metabolismo , Animais , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Catalase/metabolismo , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Peróxido de Hidrogênio/metabolismo , Hidroquinonas/metabolismo , Limite de Detecção , Oxigênio/química , Extratos Vegetais/química , Plantago/química , Pele/enzimologia , Suínos
18.
Naturwissenschaften ; 106(7-8): 40, 2019 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-31250116

RESUMO

Tandem oviposition, where males guide females in contact, requires quite a substantial muscle activity from males and, therefore, stronger heat production within the male thorax compared to the female thorax. In the present study, an infrared camera equipped with a macrolens was applied in the field, in order to estimate temperature in different body regions of male and female dragonflies Sympetrum vulgatum laying eggs in tandems. In both sexes, the thorax was considerably warmer than other body parts. The male thorax was on average 3-4 °C warmer than that of the female. These observations support previous data that Sympetrum males have a stronger muscular activity and heat production in tandem during the egg-laying process compared to females. The data provide additional evidence that this kind of contact guarding behavior during oviposition is rather costly for males. The tip of the male abdomen was much warmer than its own abdomen in the middle region. This result might be explained by possible heat transfer from the female head to the male abdomen through the contact between male abdominal appendages and the female head. An alternative explanation might be strong activity of the muscles controlling male anal appendages. Finally, this study also demonstrated a strong potential of IR cameras in field studies of dragonfly behavioral physiology.


Assuntos
Temperatura Corporal , Temperatura Alta , Odonatos/fisiologia , Oviposição/fisiologia , Animais , Técnicas Biossensoriais/instrumentação , Feminino , Raios Infravermelhos , Masculino , Fotografação/instrumentação
19.
Bioelectrochemistry ; 129: 116-123, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31153126

RESUMO

In this study, (1→3)(1→6)-ß-D-glucan (botryosphaeran) from Botryosphaeria rhodina MAMB-05 was used, for the first time, to immobilize laccase on a carbon black paste electrode modified with gold nanoparticles. The physicochemical characterization of the proposed laccase-biosensor was performed using transmission electron microscopy and electrochemical impedance spectroscopy. The performance of this novel bio-device was evaluated by choosing hydroquinone as a typical model of a phenolic compound. For hydroquinone determination, experimental variables such as enzyme concentration, pH and operational parameters of the electroanalytical technique were optimized. From square-wave voltammograms, a linear dependence between the cathodic current peak and the hydroquinone concentration was observed within the range 2.00-56.5µmolL-1, with a theoretical detection limit of 0.474µmolL-1. The proposed method was successfully applied to determine hydroquinone in dermatological cream, and samples from biological and environmental niches. The proposed biosensor device presented good selectivity in the presence of uric acid, various inorganic ions, as well as other phenolic compounds, demonstrating the potential application of this biosensing platform in complex matrices. Operational and analytical stability of the laccase biosensor were evaluated, and demonstrated good intra-day (SD=0.3%) and inter-day (SD=3.4%) repeatability and long storage stability (SD=4.9%).


Assuntos
Ascomicetos/enzimologia , Técnicas Biossensoriais/métodos , Enzimas Imobilizadas/química , Glucanos/química , Hidroquinonas/análise , Lacase/química , Fuligem/química , Técnicas Biossensoriais/instrumentação , Estabilidade Enzimática , Desenho de Equipamento , Ouro/química , Limite de Detecção , Nanopartículas Metálicas/química
20.
Anal Chim Acta ; 1076: 55-63, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31203964

RESUMO

In this work, an implantable and minimally invasive micro-aptasensor for adenosine monitoring in vivo, based on flexible integrated electrodes, was developed. Firstly the sensor was made by the modification of a needle-type electrode with reduced graphene oxide and gold nanoclusters (rGO-AuNCs) using two-step electrodeposition. Secondly Sulfhydryl-terminated capture probe (ssDNA1) was immobilized on rGO-AuNCs modified electrode surface by self-assembly, and then it was hybridized with adenosine aptamer (ssDNA2). Lastly methylene blue (MB) as an electrochemical indicator was adsorbed on the aptamer through specific interaction of MB with guanine base. The peak current of MB decreased linearly with increasing adenosine concentration due to the formation of aptamer-adenosine complex and displacement of the aptamer from the modified electrode surface. The sensor showed a low detection limit of 0.1 nM with signal-to-noise ratio equal to 3 as well as a wide linear response range (0.1 nM-1 mM) in vitro. Also, a high selectivity was demonstrated for adenosine in relation to uridine, guanosine, and cytidine. Experiments in vivo demonstrated fast responses for a range of adenosine concentrations. This work demonstrates a promising path for implantable devices for the determination of biomolecules in vivo, thus allowing for health tests, detection of infectious diseases, and other medical conditions.


Assuntos
Adenosina/análise , Aptâmeros de Nucleotídeos/química , DNA/química , Animais , Aptâmeros de Nucleotídeos/genética , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , DNA/genética , Sondas de DNA/química , Sondas de DNA/genética , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Ouro/química , Grafite/química , Indicadores e Reagentes/química , Limite de Detecção , Masculino , Nanopartículas Metálicas/química , Azul de Metileno/química , Hibridização de Ácido Nucleico , Ratos Wistar
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