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1.
J Appl Microbiol ; 130(6): 1883-1892, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32970915

RESUMO

AIMS: This study aimed to determine in vitro activity of copper nanoparticles and copper nanowires against Candida albicans strains and to assess their effects on morphology and submicron structure. METHODS AND RESULTS: The microdilution method determined the minimal inhibitory concentration (MIC) of copper nanoparticles (CuNPs) and copper nanowires (CuNWs) against three strains of C. albicans: ATCC 10231 and two clinical strains (C and E). Effects on the morphology and ultrastructure of C. albicans strains were examined by scanning electron microscopy and transmission electron microscopy. MIC for CuNPs was 129·7 µg ml-1 for strain ATCC 10231, 1037·5 µg ml-1 for strain C and 518·8 µg ml-1 for strain E. MIC for CuNWs was similar for all strains tested (260·3 µg ml-1 ). SEM and TEM studies showed alterations in morphology, cell wall and the complete collapse of the yeast after incubation with CuNPs. In contrast, most of the yeast cells maintained their structure with an intact cell wall, and only decreased the number and size of fimbriae when C. albicans was exposed to CuNWs. CuNPs and CuNWs formed hierarchical copper oxide nanostructures growing in situ in the culture medium. Results suggest a dual mechanism for antifungal activity: (i) free Cu2+ ions act as a biocide, (ii) sharp edges of marigold-like petal nanostructures could injure the cellular wall and membrane and cause the death of the yeast. CONCLUSIONS: CuNPs and CuNWs inhibited the growth of the three strains of C. albicans tested. Moreover, CuNPs disrupted cell wall with leakage of the cytoplasmic content. Each concentration of the series used for the determination of the activity of CuNPs and nanowires against C. albicans formed copper oxide marigold-like nanostructures. SIGNIFICANCE AND IMPACT OF THE STUDY: This study suggests that CuNPs and CuNWs are good candidates for formulating new therapeutic agents for candidiasis.


Assuntos
Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Cobre/farmacologia , Nanoestruturas/química , Nanofios/química , Antifúngicos/química , Candidíase/tratamento farmacológico , Cobre/química , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Nanoestruturas/ultraestrutura , Nanofios/ultraestrutura
2.
Curr Opin Chem Biol ; 59: 193-201, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33070100

RESUMO

Extracellular electron transfer via filamentous protein appendages called 'microbial nanowires' has long been studied in Geobacter and other bacteria because of their crucial role in globally-important environmental processes and their applications for bioenergy, biofuels, and bioelectronics. Thousands of papers thought these nanowires as pili without direct evidence. Here, we summarize recent discoveries that could help resolve two decades of confounding observations. Using cryo-electron microscopy with multimodal functional imaging and a suite of electrical, biochemical, and physiological studies, we find that rather than pili, nanowires are composed of cytochromes OmcS and OmcZ that transport electrons via seamless stacking of hemes over micrometers. We discuss the physiological need for two different nanowires and their potential applications for sensing, synthesis, and energy production.


Assuntos
Proteínas de Bactérias/metabolismo , Citocromos/metabolismo , Fímbrias Bacterianas/metabolismo , Bactérias Gram-Negativas/metabolismo , Proteínas de Bactérias/ultraestrutura , Citocromos/ultraestrutura , Transporte de Elétrons , Fímbrias Bacterianas/ultraestrutura , Geobacter/metabolismo , Geobacter/ultraestrutura , Bactérias Gram-Negativas/ultraestrutura , Modelos Moleculares , Nanofios/ultraestrutura
3.
Molecules ; 25(17)2020 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-32878143

RESUMO

Most previous studies of perovskite core/shell structures have been based on ZnO/TiO2 nanowires (NWs), which are not suitable for high photoelectric conversion efficiency. Here, core/shell ZnO/TiO2 NWs with AgCl-doped CdSe quantum dots were fabricated as an electron transport layer (ETL) for perovskite solar cells, based on ZnO/TiO2 arrays. We designed CdSe with AgCl dopants that were synthesized by a colloidal process. An improvement of the recombination barrier (Rct1), due to shell supplementation with AgCl-doped CdSe quantum dots, improved the open circuit voltage, the fill factor, and the adsorption capacity of CH3NH3PbI3 perovskite with NWs. The enhanced cell steady state was attributable to TiO2 with AgCl-doped CdSe QD supplementation. A maximum power conversion efficiency of 15.12% was attained in an atmospheric environment. The mechanism of the recombination and electron transport in the perovskite solar cells becoming the basis of ZnO/TiO2 core/shell arrays was investigated to represent the merit of ZnO/TiO2 core/shell arrays as an electron transport layer in effective devices. These results showed an uncomplicated approach for restraining non-radiative recombination loss in hetero-structure core/shell arrays to significantly improve perovskite solar cell performance and increase the effectiveness of photovoltaics.


Assuntos
Nanofios/química , Pontos Quânticos , Compostos de Selênio/química , Compostos de Prata/química , Titânio/química , Óxido de Zinco/química , Fontes de Energia Elétrica , Transporte de Elétrons , Nanofios/ultraestrutura , Análise Espectral
4.
J Bacteriol ; 202(20)2020 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-32747429

RESUMO

Electrically conductive protein nanowires appear to be widespread in the microbial world and are a revolutionary "green" material for the fabrication of electronic devices. Electrically conductive pili (e-pili) assembled from type IV pilin monomers have independently evolved multiple times in microbial history as have electrically conductive archaella (e-archaella) assembled from homologous archaellin monomers. A role for e-pili in long-range (micrometer) extracellular electron transport has been demonstrated in some microbes. The surprising finding of e-pili in syntrophic bacteria and the role of e-pili as conduits for direct interspecies electron transfer have necessitated a reassessment of routes for electron flux in important methanogenic environments, such as anaerobic digesters and terrestrial wetlands. Pilin monomers similar to those found in e-pili may also be a major building block of the conductive "cables" that transport electrons over centimeter distances through continuous filaments of cable bacteria consisting of a thousand cells or more. Protein nanowires harvested from microbes have many functional and sustainability advantages over traditional nanowire materials and have already yielded novel electronic devices for sustainable electricity production, neuromorphic memory, and sensing. e-pili can be mass produced with an Escherichia coli chassis, providing a ready source of material for electronics as well as for studies on the basic mechanisms for long-range electron transport along protein nanowires. Continued exploration is required to better understand the electrification of microbial communities with microbial nanowires and to expand the "green toolbox" of sustainable materials for wiring and powering the emerging "Internet of things."


Assuntos
Transporte de Elétrons , Fímbrias Bacterianas/metabolismo , Geobacter/metabolismo , Nanofios/ultraestrutura , Engenharia de Proteínas/métodos , Condutividade Elétrica , Proteínas de Fímbrias/metabolismo , Microscopia Eletrônica
5.
Anal Bioanal Chem ; 412(27): 7515-7524, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32862271

RESUMO

Multi-walled carbon nanotubes (MWCNT) play a synergistic role with conducting polymer in practical applications such as biological sensing. In this paper, multi-walled carbon nanotube and polypyrrole (PPy) composites were prepared on a fiber surface for the first time, and their morphology and electrical properties were characterized. Compared with PPy-coated fiber, the presence of carbon nanotubes induced the growth of large areas of PPy nanowires. In addition, fiber organic electrochemical transistors (FECTs) based on PPy and MWCNT were assembled, showing a higher on/off ratio, better stability, and greater flexibility. The lactate biosensor based on FECTs exhibits high sensitivity, with a correlation coefficient of R = 0.9889, quick response time of 0.6-0.8 s, a wide linear response range of 1 nM-1 mM, and excellent selectivity for lactate. Furthermore, the lactate concentration in human sweat was successfully detected by a FECT-based sensor. The hybrid fibers can be easily woven and placed on fabric simply by stitching. This favorable performance of the FECT-based sensor makes it suitable for noninvasive sensing of lactate. Therefore, it provides a promising platform for future use in healthcare and detection applications. Graphical abstract.


Assuntos
Ácido Láctico/análise , Nanotubos de Carbono/química , Nanofios/química , Polímeros/química , Pirróis/química , Suor/química , Técnicas Biossensoriais/instrumentação , Técnicas Eletroquímicas/instrumentação , Humanos , Limite de Detecção , Nanotubos de Carbono/ultraestrutura , Nanofios/ultraestrutura , Transistores Eletrônicos
6.
Molecules ; 25(14)2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32679654

RESUMO

Structural design is often investigated to decrease the electron transfer depletion in/on the pseudocapacitive electrode for excellent capacitance performance. However, a simple way to improve the internal and external electron transfer efficiency is still challenging. In this work, we prepared a novel structure composed of cobalt (Co) nanoparticles (NPs) embedded MnO nanowires (NWs) with an N-doped carbon (NC) coating on carbon cloth (CC) by in situ thermal treatment of polydopamine (PDA) coated MnCo2O4.5 NWs in an inert atmosphere. The PDA coating was carbonized into the NC shell and simultaneously reduced the MnCo2O4.5 to Co NPs and MnO NWs, which greatly improve the surface and internal electron transfer ability on/in MnO boding well supercapacitive properties. The hybrid electrode shows a high specific capacitance of 747 F g-1 at 1 A g-1 and good cycling stability with 93% capacitance retention after 5,000 cycles at 10 A g-1. By coupling with vanadium nitride with an N-doped carbon coating (VN@NC) negative electrode, the asymmetric supercapacitor delivers a high energy density of 48.15 Wh kg-1 for a power density of 0.96 kW kg-1 as well as outstanding cycling performance with 82% retention after 2000 cycles at 10 A g-1. The electrode design and synthesis suggests large potential in the production of high-performance energy storage devices.


Assuntos
Carbono/química , Cobalto/química , Capacitância Elétrica , Nanofios/química , Algoritmos , Técnicas de Química Sintética , Condutividade Elétrica , Compostos de Manganês/química , Modelos Teóricos , Nanofios/ultraestrutura , Óxidos/química , Análise Espectral
7.
Nanotechnology ; 31(43): 433001, 2020 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-32610303

RESUMO

Magnetic nanostructures and nanomaterials play essential roles in modern bio medicine and technology. Proper surface functionalization of nanoparticles (NPs) allows the selective bonding thus application of magnetic forces to a vast range of cellular structures and biomolecules. However, the spherical geometry of NPs poises a series of limitations in various potential applications. Mostly, typical spherical core shell structure consists of magnetic and non-magnetic layers have little tunability in terms of magnetic responses, and their single surface functionality also limits chemical activity and selectivity. In comparison to spherical NPs, nanowires (NWs) possess more degrees of freedom in achieving magnetic and surface chemical tenability. In addition to adjustment of magnetic anisotropy and inter-layer interactions, another important feature of NWs is their ability to combine different components along their length, which can result in diverse bio-magnetic applications. Magnetic NWs have become the candidate material for biomedical applications owing to their high magnetization, cheapness and cost effective synthesis. With large magnetic moment, anisotropy, biocompatibility and low toxicity, magnetic NWs have been recently used in living cell manipulation, magnetic cell separation and magnetic hyperthermia. In this review, the basic concepts of magnetic characteristics of nanoscale objects and the influences of aspect ratio, composition and diameter on magnetic properties of NWs are addressed. Some underpinning physical principles of magnetic hyperthermia (MH), magnetic resonance imaging (MRI) and magnetic separation (MS) have been discussed. Finally, recent studies on magnetic NWs for the applications in MH, MRI and MS were discussed in detail.


Assuntos
Hipertermia Induzida/métodos , Imageamento por Ressonância Magnética/métodos , Imãs/análise , Nanotecnologia/métodos , Nanofios/análise , Animais , Meios de Contraste/análise , Desenho de Equipamento , Humanos , Hipertermia Induzida/instrumentação , Imageamento por Ressonância Magnética/instrumentação , Magnetismo/instrumentação , Magnetismo/métodos , Nanotecnologia/instrumentação , Nanofios/ultraestrutura
8.
Anal Bioanal Chem ; 412(24): 6509-6517, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32388579

RESUMO

A new facile and fast approach to the synthesis of polyaniline (PANi) molecularly imprinted polymers (MIPs) based on aniline oxidative chemical polymerization was proposed for protein recognition. For the first time, a surface imprinting strategy was implemented for the synthesis of PANi MIPs on the inner surface of soft glass polycapillaries (PC) with a large (2237) number of individual microcapillaries. Two different PANi layers-(i) PANi film and (ii) protein imprinted PANi nanowires-were synthesized sequentially. Uniform and highly stable PANi film was synthesized by oxidative polymerization at pH< 1. The synthesis of PANi MIPs on the PANi film pre-coated surface improved the reproducibility of PANi MIP formation. PANi MIP nanowires were synthesized at "mild" conditions (pH > 4.5) to preserve the protein template activity. The binding of horseradish peroxidase (HRP) molecules on the PANi MIP selective sites was confirmed by photometry (TMB chromogenic reaction), SEM images, and FTIR spectroscopy. The developed PANi MIPs enable HRP determination with a limit of detection (LOD) as low as 1.00 and 0.07 ng mL-1 on the glass slips and PC, respectively. The PANi MIPs are characterized by high stability; they are reversible and selective to HRP. The proposed approach allows PANi MIPs to be obtained for proteins on different supports and to create new materials for separation and sensing. Graphical abstract.


Assuntos
Compostos de Anilina/química , Peroxidase do Rábano Silvestre/isolamento & purificação , Polímeros Molecularmente Impressos/química , Peroxidase do Rábano Silvestre/análise , Limite de Detecção , Impressão Molecular , Nanofios/química , Nanofios/ultraestrutura , Fotometria , Espectroscopia de Infravermelho com Transformada de Fourier
9.
Biosens Bioelectron ; 162: 112234, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32392153

RESUMO

A new organic-inorganic heterostructure was prepared by the hydrothermal deposition of poly (3,4-dioxoethylthiophene) (PEDOT) on TiO2 nanowire arrays (TiONWs) to construct a biosensor that can simultaneously function as photoelectrochemical (PEC) and electrochemical (EC) sensor to detect lactate. In both cases, the PEDOT-TiONWs heterostructure not only acted as an immobilization platform for lactate dehydrogenase (LDH) and coenzyme NAD+, but also generated current signals, which were further amplified by the cyclic catalytic mechanism. Specifically, LDH catalytically converted lactate to pyruvate, meanwhile NAD+ was transformed to NADH. For PEC sensing, the photo-generated holes from PEDOT-TiONWs could oxidize NADH back to NAD+, fulfilling a catalytic cycle. Herein, PEDOT significantly promoted the separation of electron-hole pairs and enhanced PEC signals due to its well-matched energy levels with TiONWs, high conductivity and strong visible light absorption. A dynamic range of 0.5-300 µM was observed between the PEC signals and lactate concentration, based on which a sensitivity of 0.1386 ± 0.0053 µA µM-1 and a detection limit of 0.08 ± 0.0032 µM were estimated. For EC sensing, PEDOT-TiONWs could directly oxidize NADH to NAD+ at ~0.54 V to realize the cyclic amplification due to the high conductivity and strong electrocatalytic capability of the heterostructure. The EC biosensor displayed a similar performance upon PEC mode of operation, except the relatively poor selectivity due to the possible oxidation of the interferences at the potentials > 0.54 V.


Assuntos
Técnicas Biossensoriais/instrumentação , Compostos Bicíclicos Heterocíclicos com Pontes/química , Nanofios/química , Polímeros/química , Titânio/química , Técnicas Eletroquímicas/instrumentação , Enzimas Imobilizadas/química , Desenho de Equipamento , L-Lactato Desidrogenase/química , Ácido Láctico/análise , Nanofios/ultraestrutura , Transdutores
10.
Nat Commun ; 11(1): 1861, 2020 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-32313096

RESUMO

Memristive devices are promising candidates to emulate biological computing. However, the typical switching voltages (0.2-2 V) in previously described devices are much higher than the amplitude in biological counterparts. Here we demonstrate a type of diffusive memristor, fabricated from the protein nanowires harvested from the bacterium Geobacter sulfurreducens, that functions at the biological voltages of 40-100 mV. Memristive function at biological voltages is possible because the protein nanowires catalyze metallization. Artificial neurons built from these memristors not only function at biological action potentials (e.g., 100 mV, 1 ms) but also exhibit temporal integration close to that in biological neurons. The potential of using the memristor to directly process biosensing signals is also demonstrated.


Assuntos
Potenciais de Ação , Eletrônica/instrumentação , Geobacter/metabolismo , Nanofios/química , Neurônios , Técnicas Biossensoriais , Eletricidade , Desenho de Equipamento , Humanos , Simulação de Dinâmica Molecular , Nanotecnologia/instrumentação , Nanofios/ultraestrutura , Redes Neurais de Computação , Sinapses/metabolismo , Dispositivos Eletrônicos Vestíveis
11.
Nano Lett ; 20(4): 2478-2485, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32142295

RESUMO

Miniaturized stretchable strain sensors are key components in E-skins for applications such as personalized health-monitoring, body motion perception, and human-machine interfaces. However, it remains a big challenge to fabricate miniaturized stretchable strain sensors with high imperceptibility. Here, we reported for the first time novel ultraminiaturized stretchable strain sensors based on single centimeter-long silicon nanowires (cm-SiNWs). With the diameter of the active materials even smaller than that of spider silks, these sensors are highly imperceptible. They exhibit a large strain sensing range (>45%) and a high durability (>10 000 cycles). Their optimum strain sensing ranges could be modulated by controlling the prestrains of the stretchable cm-SiNWs. On the basis of this capability, sensors with appropriate sensing ranges were chosen to respectively monitor large and subtle human motions including joint motion, swallow, and touch. The strategy of applying single cm-SiNWs in stretchable sensors would open new doors to fabricate ultraminiaturized stretchable devices.


Assuntos
Nanofios/química , Silício/química , Dispositivos Eletrônicos Vestíveis , Técnicas Biossensoriais/instrumentação , Desenho de Equipamento , Humanos , Nanotecnologia , Nanofios/ultraestrutura
12.
Nano Lett ; 20(4): 2359-2369, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32191041

RESUMO

We describe an optical transduction mechanism to measure the flexural mode vibrations of vertically aligned nanowires on a flat substrate with high sensitivity, linearity, and ease of implementation. We demonstrate that the light reflected from the substrate when a laser beam strikes it parallel to the nanowires is modulated proportionally to their vibration, so that measuring such modulation provides a highly efficient resonance readout. This mechanism is applicable to single nanowires or arrays without specific requirements regarding their geometry or array pattern, and no fabrication process besides the nanowire generation is required. We show how to optimize the performance of this mechanism by characterizing the split flexural modes of vertical silicon nanowires in their full dynamic range and up to the fifth mode order. The presented transduction approach is relevant for any application of nanowire resonators, particularly for integrating nanomechanical sensing in functional substrates based on vertical nanowires for biological applications.


Assuntos
Nanofios/química , Silício/química , Transdutores , Luz , Nanotecnologia , Nanofios/ultraestrutura , Dispositivos Ópticos
13.
Nano Lett ; 20(4): 2576-2584, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32207951

RESUMO

Surface-enhanced Raman spectroscopy (SERS)-based protein analysis is a promising alternative to existing early stage diagnoses. However, SERS research conducted thus far accompanies challenges such as nonuniformity of plasmonic nanostructures, irregular coating of analytes, and denaturation of proteins, which seriously limit the practicability of suggested approaches. Here, we introduce a carboxylic acid-functionalized and graphitic nanolayer-coated three-dimensional SERS substrate (CGSS) fabricated by sequential nanotransfer printing. The substrate consists of well-defined, uniform gold nanowire arrays for effective Raman signal enhancement and a strong protein-immobilization layer. With an enhancement factor (EF) of 5.5 × 105, on par with the highest ever reported values, the CGSS allows the detection of protein conformational changes and the determination of protein concentration via Raman measurements. Exploiting the CGSS, we successfully measured the SERS spectra of Alzheimer's biomarkers, tau protein and amyloid ß, based on which secondary structural changes were analyzed quantitatively.


Assuntos
Doença de Alzheimer/diagnóstico , Peptídeos beta-Amiloides/análise , Grafite/química , Nanoestruturas/química , Análise Espectral Raman/métodos , Proteínas tau/análise , Biomarcadores/análise , Ácidos Carboxílicos/química , Desenho de Equipamento , Ouro/química , Humanos , Nanoestruturas/ultraestrutura , Nanofios/química , Nanofios/ultraestrutura , Análise Espectral Raman/instrumentação
14.
Nano Lett ; 20(4): 2460-2467, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32155085

RESUMO

Silver nanowires have attracted considerable attention as subdiffraction limited diameter waveguides in a variety of applications including cell endoscopy and photonic integrated circuitry. Optical signal transport occurs by coupling light into propagating surface plasmons, which scatter back into light further along the wire. However, these interconversions only occur efficiently at wire ends, or at defects along the wire, which are not controlled during synthesis. Here, we overcome this limitation, demonstrating the visible laser light-induced fabrication of gold nanostructures at desired positions on silver nanowires, and their utility as efficient in/out coupling points for light. The gold nanostructures grow via plasmon-induced reduction of Au(III) and are shown to be excellent "hotspots" for surface-enhanced Raman scattering.


Assuntos
Ouro/química , Nanoestruturas/química , Nanofios/química , Prata/química , Análise Espectral Raman/instrumentação , Desenho de Equipamento , Luz , Nanoestruturas/ultraestrutura , Nanofios/ultraestrutura , Ressonância de Plasmônio de Superfície/instrumentação , Propriedades de Superfície
15.
Sci Adv ; 6(7): eaay2760, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32110728

RESUMO

Bacterial response to transient physical stress is critical to their homeostasis and survival in the dynamic natural environment. Because of the lack of biophysical tools capable of delivering precise and localized physical perturbations to a bacterial community, the underlying mechanism of microbial signal transduction has remained unexplored. Here, we developed multiscale and structured silicon (Si) materials as nongenetic optical transducers capable of modulating the activities of both single bacterial cells and biofilms at high spatiotemporal resolution. Upon optical stimulation, we capture a previously unidentified form of rapid, photothermal gradient-dependent, intercellular calcium signaling within the biofilm. We also found an unexpected coupling between calcium dynamics and biofilm mechanics, which could be of importance for biofilm resistance. Our results suggest that functional integration of Si materials and bacteria, and associated control of signal transduction, may lead to hybrid living matter toward future synthetic biology and adaptable materials.


Assuntos
Bactérias/metabolismo , Transdução de Sinais , Silício/química , Bactérias/ultraestrutura , Biofilmes , Sinalização do Cálcio , Nanofios/ultraestrutura
16.
Mater Sci Eng C Mater Biol Appl ; 108: 110371, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31924004

RESUMO

The objective of this paper is to demonstrate the potential of nanostructured polypyrrole formed by template free as platform for amperometric detection of DNA. The nanowires of polypyrrole (nw-PPy) are formed through electrochemical polymerization and chemically modified by electrochemical oxidation of ethylene diamine or dendrimers PAMAM to obtain aminated surface. The DNA probe and ferrocenyl group, as redox reporter, were covalently linked to the surface of nw-PPy. The chemical structure of nanostructured platform was characterized through SEM, FT-IR and XPS and the electrochemical properties through cyclic voltammetry and electrochemical impedance spectroscopy (EIS). We show that the properties of nw-PPy such as, hydrophilic character and large surface area have large effect on the electronic properties. Thus, the electrochemical performance is increased compared to others nanomaterials considering the obtained value of the rate of electron transfer of 18 s-1. These properties allow enhanced DNA sensing where detection limit of 0.36 atomolar without any amplification step. The biosensor can be applied in detection of genomic DNA of Mycobacterium tuberculosis and the mutated one which present the resistance to rifampicin and large selectivity was demonstrated. We believe that nw-PPy modified with redox marker is a promising platform for electrochemical biosensors and can be applied for various diagnosis prospects.


Assuntos
Técnicas Biossensoriais , DNA Bacteriano/análise , Técnicas Eletroquímicas/métodos , Mycobacterium tuberculosis/genética , Nanoestruturas/química , Polímeros/química , Pirróis/química , Dendrímeros/química , Eletrólitos/química , Compostos Ferrosos/química , Ouro/química , Cinética , Metalocenos/química , Mycobacterium tuberculosis/isolamento & purificação , Nanoestruturas/ultraestrutura , Nanofios/química , Nanofios/ultraestrutura , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier
17.
Methods Enzymol ; 630: 1-24, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31931981

RESUMO

Various approaches to magneto-controlled biocatalytic enzyme reactions are discussed with specific example systems. Magnetic nano- and micro-size particles functionalized with enzymes or cofactors/electron transfer mediators have been used to translocate the components of the biocatalytic processes and to activate/inhibit their reactions. Magneto-induced deposition of the functionalized particles on an electrode surface resulted in activation of bioelectrocatalytic reactions. On the other hand, magneto-induced removal of the particles from the electrode surface resulted in the inhibition of the electrochemical reactions. Aggregation/disaggregation of enzyme-modified magnetic nanoparticles resulted in different mechanisms of biocatalytic cascades, changing them reversibly between substrate diffusion and substrate channeling processes. Magnetohydrodynamic activation of bioelectrocatalytic processes allowed enhancement of a biofuel cell operation. Overall, a large variety of possible magneto-controlled enzyme reactions is briefly discussed, particularly emphasizing their applications in different bioelectronic systems.


Assuntos
Fontes de Energia Bioelétrica , Técnicas Biossensoriais , Enzimas Imobilizadas/química , Nanopartículas de Magnetita/química , Imãs/química , Animais , Biocatálise , Técnicas Biossensoriais/métodos , Condutividade Elétrica , Eletrodos , Humanos , Hidrodinâmica , Campos Magnéticos , Magnetismo/métodos , Modelos Moleculares , Nanofios/química , Nanofios/ultraestrutura
18.
Nanotechnology ; 31(16): 165501, 2020 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-31770731

RESUMO

Cyclodextrin (CD) is a conical compound used in food and pharmaceutical industry to complexation of hydrophobic substances. It is a product of microbial enzymes which converts starch into CD during their activity. We aim to detect CD using active-electrode biosensor of SnO2. They were grown on active electrode by the VLS method. The CD consists of several glucose units which have hydroxyl groups which tend to bind to interface states present in nanowires changing their conductivity. Experimental results of electrical conductivity at different CD concentrations are presented. A model that describes the influence of adsorbed glucose on nanowires and its electrical properties is also presented. Some general observations are performed on the applicability of the CD adsorption method by the nanowire-based biosensor.


Assuntos
Técnicas Biossensoriais , Ciclodextrinas/análise , Glucosiltransferases/metabolismo , Nanofios/química , Compostos de Estanho/química , Bacillus/enzimologia , Eletricidade , Eletrodos , Nanofios/ultraestrutura , Fatores de Tempo
19.
Microsc Res Tech ; 83(3): 268-275, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31729094

RESUMO

In this study, a ternary nanocomposite consisting of gold nanoparticles (AuNPs), hydroxyapatite (HAP) nanowires, and reduced graphene oxide (rGO) is synthesized by a simple one-step hydrothermal method, which is used to modify glassy carbon electrode (GCE) for detecting uric acid. The nanocomposite is characterized through various methods such as scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Electrochemical measurements of the modified GCE are performed in a conventional three-electrode system. Experimental results show that the obtained HAP nanowire and rGO are mixed homogeneously, and the AuNPs are deposited into this matrix. The GCE modified by the nanocomposites have superior electrocatalytic activities for uric acid. The peak current intensities of UAO (uricase)/HAP-rGO/AuNPs sensing system linearly increase as the uric acid concentration increases substantially in a range of 1.95 × 10-5 to 6.0 × 10-3 M (R2 = .9943), with a detection limit of 3.9 × 10-6 M (S/N = 3) and analytical sensitivity of 13.86 mA/M. The biosensor performs well in determining uric acid concentration in human urine samples.


Assuntos
Técnicas Biossensoriais/métodos , Durapatita/química , Ouro/química , Grafite/química , Nanopartículas Metálicas/química , Nanocompostos/química , Ácido Úrico/análise , Técnicas Biossensoriais/instrumentação , Técnicas Eletroquímicas , Humanos , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Nanocompostos/ultraestrutura , Nanofios/ultraestrutura , Urina/química , Difração de Raios X
20.
Spectrochim Acta A Mol Biomol Spectrosc ; 227: 117669, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31698154

RESUMO

Copper nanoparticles are explored significantly for their antimicrobial activity, especially for antibiotic-resistant strain infections. However, copper has severe toxic responses and mostly it is due to its generation capability of reactive oxygen species (ROS) molecules while interacting with in vitro or in vivo systems. In the current study, wire shaped copper nanostructures were synthesized via microwave irradiation with single step doping of carbon nanodots (CDs). The synthesized material (CuCs) was characterized by UV-Vis spectroscopy, fluorescence spectroscopy, FTIR, TEM, FESEM, XRD, DLS, and XPS. The fluorescence spectroscopy, microscopy and Raman spectroscopy results suggested CuCs to work well as a bi-modal imaging nanoprobe (fluorescence/SERS). The cell culture studies prove significant cytocompatibility and ROS scavenging property of the samples with respect to control. Further, CuCs-gelatin nanocomposite thin films were prepared and implanted into rodent deep wound model. The histological study has showed enhanced angiogenesis in the subcutaneous region. The results were validated by immuno-histochemistry. The ROS scavenging and enhanced angiogenesis were validated via gene expression studies and a HIF-α induced enhanced angiogenesis mechanism was also proposed for better wound healing.


Assuntos
Anti-Infecciosos/farmacologia , Carbono/química , Cobre/química , Imageamento Tridimensional , Nanopartículas Metálicas/química , Nanofios/química , Neovascularização Fisiológica , Análise Espectral Raman , Animais , Escherichia coli/efeitos dos fármacos , Feminino , Sequestradores de Radicais Livres/química , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Imagem Multimodal , Nanofios/ultraestrutura , Neovascularização Fisiológica/efeitos dos fármacos , Espectroscopia Fotoeletrônica , Molécula-1 de Adesão Celular Endotelial a Plaquetas/metabolismo , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Espectrometria de Fluorescência , Staphylococcus aureus/efeitos dos fármacos
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