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1.
Nanomaterials (Basel) ; 9(8)2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31408969

RESUMO

In this paper, a graphene/ITO nanorod metamaterial/U-bent-annealing (Gr/ITO-NM/U-bent-A)-based U-bent optical fiber local surface plasmon resonance (LSPR) sensor is presented and demonstrated for DNA detection. The proposed sensor, compared with other conventional sensors, exhibits higher sensitivity, lower cost, as well as better biological affinity and oxidize resistance. Besides, it has a structure of an original Indium Tin Oxides (ITO) nanocolumn array coated with graphene, allowing the sensor to exert significant bulk plasmon resonance effect. Moreover, for its discontinuous structure, a larger specific surface area is created to accommodate more biomolecules, thus maximizing the biological properties. The fabricated sensors exhibit great performance (690.7 nm/RIU) in alcohol solution testing. Furthermore, it also exhibits an excellent linear response (R2 = 0.998) to the target DNA with respective concentrations from 0.1 to 100 nM suggesting the promising medical applications of such sensors.

2.
Nanoscale Res Lett ; 14(1): 248, 2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31342195

RESUMO

Herein, a magnetic graphene field-effect transistor biosensor was prepared through the transfer of a chemical vapor deposition graphene film onto a glass substrate to produce a sensing film and conductive channel. By fixing 1-pyrenebutanoic acid succinimidyl ester onto graphene film as an anchor, a probe aptamer was immobilized on the graphene film in order to capture magnetically labeled complementary single-stranded DNA. Our experiments showed that, within a periodic magnetic field, the biosensor impedance exhibited a periodic oscillation, the amplitude of which was correlated to the complementary DNA concentration. Based on this principle, the magnetic graphene field-effect transistor was utilized to detect single-stranded DNA with detection limition of 1 pM. The results were rationalized using a model wherein the magnetic force causes the DNA strand to bend, thereby resulting in magnetic nanobeads/DNA modulation of the double conductive layer of graphene transistors. Furthermore, since a periodic magnetic field could be introduced to produce a periodic impedance changes of MGFETs, sampling integration could be used to improve the signal-to-noise ratio efficiently by increasing the number of periods of the external magnetic field. Therefore, a novel biosensor for DNA detection with high sensitivity has been presented in this work. Based on the detection principle, this system may also be a potential tool for detecting other bio-molecules, cells, etc.

3.
Materials (Basel) ; 11(11)2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30469387

RESUMO

The electronic structure and spin polarization properties of pentagonal structure PdSe2 doped with transition metal atoms are studied through first- principles calculations. The theoretical investigations show that the band gap of the PdSe2 monolayer decreases after introducing Cr, Mn, Fe and Co dopants. The projected densities of states show that p-d orbital couplings between the transition metal atoms and PdSe2 generate new spin nondegenerate states near the Fermi level which make the system spin polarized. The calculated magnetic moments, spin density distributions and charge transfer of the systems suggest that the spin polarization in Cr-doped PdSe2 will be the biggest. Our work shows that the properties of PdSe2 can be modified by doping transition metal atoms, which provides opportunity for the applications of PdSe2 in electronics and spintronics.

4.
Nanomaterials (Basel) ; 8(11)2018 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-30469395

RESUMO

The electronic structure and the optical properties of Graphene/MoS2 heterostructure (GM) are studied based on density functional theory. Compared with single-layer graphene, the bandgap will be opened; however, the bandgap will be reduced significantly when compared with single-layer MoS2. Redshifts of the absorption coefficient, refractive index, and the reflectance appear in the GM system; however, blueshift is found for the energy loss spectrum. Electronic structure and optical properties of single-layer graphene and MoS2 are changed after they are combined to form the heterostructure, which broadens the extensive developments of two-dimensional materials.

5.
Analyst ; 143(7): 1670-1678, 2018 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-29512669

RESUMO

Sensitive detection of cancer biomarkers is valuable for clinical diagnosis and treatment assessment of cancers. Herein, we report a simple smartphone-based double-channel fluorescence setup for immunoassay. Not including the smartphone, the total cost of the detection device itself is about 80 $, including a laser pointer, a twinning measurement cell, a collective lens, and an outside box. The fluorescence images of the sample and reference areas were captured by the camera in the smartphone and the brightness ratio was calculated using a user-edited smartphone app. By using 2,3-diaminophenazine (DAP) as the model luminophore, the influence of exposure time and photosensitivity on the sensitivity was tested. The brightness ratio offers high stability of the fluorescence signal, which is helpful to improve the sensitivity. The applicability of this device was demonstrated by a catalytic fluorimetric method for Cu2+ determination, which is based on the oxidation of o-phenylenediamine (non-fluorescent) to DAP (strong fluorescent) by dissolved oxygen using Cu2+ as the catalyst. Accordingly, by using a CuS nanoparticle-conjugated second antibody as the signal tag, the immunoassay for a carcinoembryonic antigen was performed with the detection limit of 0.05 pg mL-1. This smartphone-based double-channel fluorescence device offers the advantages of high sensitivity, inexpensive and miniaturization.


Assuntos
Antígeno Carcinoembrionário/análise , Cobre/química , Imunoensaio , Nanopartículas Metálicas , Smartphone , Biomarcadores Tumorais/análise , Fluorescência , Humanos
6.
Nat Commun ; 8: 14902, 2017 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-28322227

RESUMO

Reliable determination of binding kinetics and affinity of DNA hybridization and single-base mismatches plays an essential role in systems biology, personalized and precision medicine. The standard tools are optical-based sensors that are difficult to operate in low cost and to miniaturize for high-throughput measurement. Biosensors based on nanowire field-effect transistors have been developed, but reliable and cost-effective fabrication remains a challenge. Here, we demonstrate that a graphene single-crystal domain patterned into multiple channels can measure time- and concentration-dependent DNA hybridization kinetics and affinity reliably and sensitively, with a detection limit of 10 pM for DNA. It can distinguish single-base mutations quantitatively in real time. An analytical model is developed to estimate probe density, efficiency of hybridization and the maximum sensor response. The results suggest a promising future for cost-effective, high-throughput screening of drug candidates, genetic variations and disease biomarkers by using an integrated, miniaturized, all-electrical multiplexed, graphene-based DNA array.


Assuntos
Técnicas Biossensoriais , DNA/química , Grafite/química , Ensaios de Triagem em Larga Escala/instrumentação , Hibridização de Ácido Nucleico , Análise Custo-Benefício , Sondas de DNA/química , Ensaios de Triagem em Larga Escala/economia , Cinética , Limite de Detecção , Miniaturização , Modelos Químicos , Reprodutibilidade dos Testes
7.
J Phys Chem A ; 120(50): 9932-9940, 2016 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-27936705

RESUMO

C 1s X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectra for three C66 fullerene isomers and related chlorinated species have been calculated by density functional theory (DFT) method. The XPS spectra show isomer dependence for the three pristine C66 isomers but not for the chlorinated species. The NEXAFS spectra exhibit strong dependence on the structures of all the investigated molecules and thus can be well employed to identify the three C66 fullerene isomers and related chlorinated species. Both XPS and NEXAFS spectra of the chlorinated species present significant variations compared with the pristine fullerenes. The spectral components for carbon atoms of different local environments have been explored as well. The spectra for the carbon atoms connecting to chlorine atoms exhibit a significant blue shift compared to the others.

8.
Nanotechnology ; 25(16): 165702, 2014 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-24671026

RESUMO

We demonstrate that continuous, uniform graphene films can be directly synthesized on quartz substrates using a two-temperature-zone chemical vapor deposition system and that their layers can be controlled by adjusting the precursor partial pressure. Raman spectroscopy and transmission electron microscopy confirm the formation of monolayer graphene with a grain size of ∼100 nm. Hall measurements show a room-temperature carrier mobility above 1500 cm2 V(-1) s(-1). The optical transmittance and conductance of the graphene films are comparable to those of transferred metal-catalyzed graphene. The method avoids the complicated and skilled post-growth transfer process and allows the graphene to be directly incorporated into a fully functional biosensor for label-free detection of adenosine triphosphate (ATP). This device shows a fast response time of a few milliseconds and achieves a high sensitivity to ATP molecules over a very wide range from 0.002 to 5 mM.


Assuntos
Trifosfato de Adenosina/química , Grafite/química , Quartzo/química , Técnicas Biossensoriais/métodos , Tamanho da Partícula , Propriedades de Superfície , Temperatura Ambiente
9.
Zhonghua Nan Ke Xue ; 18(1): 67-9, 2012 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-22295853

RESUMO

OBJECTIVE: To explore the correlation of the testosterone level with circulated endothelial progenitor cells in patients with Klinefelter's syndrome (KS) and its clinical significance. METHODS: This study included 36 patients affected by non-mosaic 47, XXY KS, each with one or more cardiovascular risk factors. Serum hormone levels and the content of circulated endothelial progenitor cells were determined by radioimmunology and cell culture methods, respectively, and the measurement was repeated after 6 months of testosterone replacement therapy. RESULTS: After testosterone replacement therapy, the testosterone level was increased from (8 +/- 3) to (24 +/- 10) nmol/L, while the content of endothelial progenitor cells ([41 +/- 48] cells/ml) showed no significant rise. CONCLUSION: There is no obvious correlation between the testosterone level and the content of endothelial progenitor cells in KS patients.


Assuntos
Células Endoteliais/citologia , Síndrome de Klinefelter/sangue , Células-Tronco/citologia , Testosterona/sangue , Adulto , Contagem de Células , Terapia de Reposição Hormonal , Humanos , Infertilidade Masculina/sangue , Síndrome de Klinefelter/tratamento farmacológico , Masculino , Testosterona/uso terapêutico
10.
Anal Biochem ; 394(1): 1-6, 2009 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-19464252

RESUMO

A biosensor for rapid detection of bacterial count based on adenosine 5'-triphosphate (ATP) bioluminescence has been developed. The biosensor is composed of a key sensitive element and a photomultiplier tube used as a detector element. The disposable sensitive element consists of a sampler, a cartridge where intracellular ATP is chemically extracted from bacteria, and a microtube where the extracted ATP reacts with the luciferin-luciferase reagent to produce bioluminescence. The bioluminescence signal is transformed into relevant electrical signal by the detector and further measured with a homemade luminometer. Parameters affecting the amount of the extracted ATP, including the types of ATP extractants, the concentrations of ATP extractant, and the relevant neutralizing reagent, were optimized. Under the optimal experimental conditions, the biosensor showed a linear response to standard bacteria in a concentration range from 10(3) to 10(8) colony-forming units (CFU) per milliliter with a correlation coefficient of 0.925 (n=22) within 5min. Moreover, the bacterial count of real food samples obtained by the biosensor correlated well with those by the conventional plate count method. The proposed biosensor, with characteristics of low cost, easy operation, and fast response, provides potential application to rapid evaluation of bacterial contamination in the food industry, environment monitoring, and other fields.


Assuntos
Bactérias/isolamento & purificação , Técnicas Biossensoriais/instrumentação , Equipamentos Descartáveis , Microbiologia de Alimentos , Trifosfato de Adenosina/análise , Trifosfato de Adenosina/isolamento & purificação , Animais , Bactérias/química , Técnicas Biossensoriais/métodos , Calibragem , Contagem de Colônia Microbiana , Análise de Alimentos , Medições Luminescentes , Reprodutibilidade dos Testes , Fatores de Tempo
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