COLLOIDS AND SURFACES B-BIOINTERFACES
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2018
·
IF 3.997
Hai-Bo Wang,Li-Hong Ma,Bi-Yun Fang,Yuan-Di Zhao,Xue-Bin Hu
This study has reported that a GR-5 DNAzyme based lead ion strip biosensor could exhibit an enhanced specificity with the assistance of graphene oxide (GO). This enhancement results from the specific π-stacking interaction between the ribose rings of the nucleobases and the carbon hexagons in GO which can reduce the false positive interference by removing unhybridized ssDNA during the annealing of GR-5 DNAzyme. Meanwhile, conjugate pad was sprayed with two kinds of AuNP-DNA probes, and nitrocellulose membrane test zone and control zone were immobilized with two kinds of biotin-DNA probes, respectively. The limit of detection of this strip biosensor was estimated to be about 0.05 nM (S/N = 3) and 1 nM (with naked eyes) with a linear range from 0.01 to 100 μM. Furthermore, the strip biosensor exhibited excellent selectivity toward Pb 2+ in the presence of other divalent metal ions. For real soil samples, the obtained recoveries were in the range from 91.5% to 113.1%.
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Analytical Methods
·
2018
·Vol. 10
·期 29
·3654-3659
·
IF 2.073
Bao-Shan He,Dan-Dan Yan
The detection of nitrite is vital for environmental conservation and public health. In this study, high surface area nanoclusters of wavy graphene/Au composites (w-GN/Au) were synthesized by a one-step hydrothermal method and utilized for the detection of nitrite. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy were used to characterize the structure and constituents of 3D-GN/Au. The effectiveness of w-GN/Au composites as the accelerant for the determination of nitrite was assessed via Cyclic Voltammetry (CV). The results showed that the reaction current for nitrite detection obtained at the composite electrode had greatly improved compared to that obtained using the bare electrode. Within the optimal conditions, the oxidation peak currents of nitrite had an excellent linear correlation in the range of 1.0 × 10−7 to 5.0 × 10−3 mol L−1 with a detection limit of 6.0 × 10−8 mol L−1via differential pulse voltammetric (DPV). Based on these findings, we could draw the conclusion that these modified materials could be utilized for constituting an electrochemical sensor to develop an excellent method for the detection nitrite in real samples, namely, tap water and sausage, with acceptable recovery.
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ANALYTICAL AND BIOANALYTICAL CHEMISTRY
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2018
·Vol. 410
·期 29
·7671-7678
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IF 3.307
He Baoshan,Li Ming
In this paper, an electrochemical aptasensor based on gold electrode (AuE)-modified Ag@Au core-shell nanoparticles was prepared. The surface of AuE was modified with Ag@Au core-shell nanoparticles to elevate APT binding sites and accelerate electron transfer properties between the electrode and ferrocene (Fc). When SM 2 existed, the aptamer conformation would change and the response current intensity would increase because the Fc was pulled closer to the electrode surface. Subsequently, through a series of conditional optimization analysis, the optimal values of volume of Ag@Au core-shell, APT concentration, APT incubation time, and SM 2 incubation time were 9 μL, 0.2 μmol/L, 75 min, and 40 min, respectively. Under optimum conditions, the results of differential pulse voltammetry experiments showed that the linear relationship was good in the range of 0.1~50 ng/mL, Δ I ′ (μA) = 1.145 C (ng/mL) + 54.666, R 2 = 0.964, with a detection limit of 0.033 ng/mL. The spiked recovery for SM 2 in the pork samples was 92.6~101.0% and the relative standard deviation (RSD) was 2.7~4.1%, which indicated that the proposed aptasensor exhibited desirable performance in actual sample analysis.
An electrochemical aptasensor based on gold electrode-modified Ag@Au core-shell nanoparticles was prepared. The detection principle was on the basis of the change of current signal of DPV in Tris-HCl buffer solution before and after incubation of SM 2 . After the formation of APT-SM 2 complex, the ferrocene modified on the aptamer was pulled closer to the electrode surface and sped up the electron transfer rate.
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MICROCHIMICA ACTA
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2018
·Vol. 185
·期 10
·1-10
·
IF 5.705
Huang Yan-Qin,Yang Li-Na,Wang Yong-Sheng,Xue Jin-Hua,Chen Si-Han
The authors report on a one-pot approach for synthesizing highly fluorescent protamine-stabilized gold nanoclusters. These are shown to be a viable nanoprobe for selective and sensitive fluorometric determination of lead(II) via quenching of fluorescence via Pb(II)-Au(I) interaction. Under optimized conditions, fluorescence measured at excitation/emission peaks of 300/599 nm drops in the 80 nM–15 μM lead(II) concentration range. The detection limit is 24 nM, and relative standard deviations (for n = 11) at concentrations of 0.10, 4.0 and 15 μM are 1.6, 2.5 and 1.9%, respectively. The relative recoveries of added lead(II) in the water samples ranged from 97.9 ± 2.29% to 101.2 ± 1.83%.
Lead(II) ions are found to be able to selectively and sensitively quench the fluorescence of the protamine-gold nanoclusters (PRT-AuNCs). Thereby, an inexpensive, selective and sensitive lead(II) assay was established.
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ANALYST
·
2018
·Vol. 143
·期 17
·4067-4073
·
IF 3.864
Chang Cheng,Lu Yang,Miao Zhong,Wenfang Deng,Yueming Tan,Qingji Xie,Shouzhuo Yao
Herein, Au nanocluster (AuNC)-embedded chitosan (CS) nanocapsules were prepared and used as a novel signal amplification system for the sensitive fluorescence immunoassay of Escherichia coli O157:H7 (E. coli O157:H7). AuNCs were embedded in CS to form AuNCs@CS nanocapsules, where a large number of AuNCs were embedded in each nanocapsule. A rapid, ultrasensitive, and selective method for the fluorescence detection of E. coli O157:H7 was developed by coupling the nanocapsule-amplification strategy with immunological recognition and magnetic separation. Compared with a conventional immunoassay using AuNCs as labels, the fluorescence signals of the proposed immunoassay were greatly amplified, because much more fluorescent AuNCs are linked to each bacterial cell. As a result, a linear range was obtained from 3 to 700 CFU mL−1, with a detection limit of 1 CFU mL−1. This method was successfully used to detect E. coli O157:H7 in drinking water and milk samples.
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ANALYTICAL CHEMISTRY
·
2018
·
IF 6.042
Na Li,Ting Zhong,Jia-liang Liu,Jun Zheng,Hu-cheng Deng,Wen Zhou,Ming Li,Ming-shi Feng,Qi-jun Liu,Chong-ying Li
Analysis and characterization of micro/nano-sized pore structure are critical issues in shale geology and engineering. Scanning electron microscopy (SEM) imaging is one of the most widespread methods for the analysis of the micro/nano-sized pores in shale, but precise identification of the ultrafine pore structure in shale is still a big challenge because shale is so complex that some components may have overlap with pores based on the simple discrimination of gray scale under SEM microscopy. Here, Fe3O4/Au nanocomposite with magnetic properties is synthesized, characterized, and introduced as a novel pore-marker to improve SEM identification and quantitation of micro/nano-sized pores in shale. Due to the superparamagnetic property, the nanomarker is conveniently controlled by an external magnetic field to fill into pores and offers a sharp contrast imaging between matrix of shale (various gray) and pores (bright), which makes the identification of micro/nano-sized pores in shale much more straightforward and reliable. Furthermore, because gold, as a noble metal, is particularly rare in shale, energy-dispersive X-ray spectroscopy mapping of Au is delicately used to precisely calculate area porosity in shale. Combining with the aforementioned merits of the nanomarker, a precise and practical technique is proposed to promote characterization of micro/nano-sized pores in shale.
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COMPOSITES SCIENCE AND TECHNOLOGY
·
2018
·
IF 5.16
Rongjin Zhang,Bo Peng,Yan Yuan
Wearable and flexible humidity-sensing devices are essential for the real-time monitoring of air humidity in health and environmental applications. We propose a flexible sensor based on a conductive polymer comprising poly(3,4-ethylenedioxythiophene) (PEDOT) and reduced graphene oxide(rGO) to monitor changes in humidity. GO was used as a hard template for the in situ polymerization of EDOT to obtain PEDOT:rGO. Then, PEDOT:rGO-PEI/Au nanoparticles (NPs) ink was prepared through the in situ reduction of Au NPs modified with polyethylenimine (PEI). The ink was printed on the surface of a hydrophilic modified polyethylene terephthalate (PET) substrate using an ink-jet printer to form a specific pattern. After assembly, a PET-based PEDOT:rGO-PEI/Au NPs (PrGANPs) sensor device with high electrical performance, transparency, and sensitivity was obtained for testing at a variety of RH levels. The prepared PET-based PrGANPs sensor printed with 50 layers had a transmittance up to 61% at 500 nm. And the response and recovery times were approximately 20 and 35 s at 98% RH, respectively. Stability was maintained even after bending 200 times, and the sensor could respond within the humidity range of 11%–98% RH, while in response to a wide resistance range of 7.41%–51.60%.
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ELECTROANALYSIS
·
2018
·Vol. 31
·期 3
·422-427
·
IF 2.851
Xue Lou,Li-quan Zhang,Qing-hui Liu,Ying-hui Wang,Lian-Fei Yao,Yan-ting Wang,Zhi-hui Kang,Qiang Zhou,Han-Zhuang Zhang
The performance of nano-sensor based on MoS 2 nanosheet mixed with Au particle is tested based electrochemical test involving cyclic voltammogram and impedance spectroscopy, where the Fe III (CN) 6 3− /Fe II (CN) 6 4− and dopamine (DA) are chosen as research object to verify the role of layer number of MoS 2 nanosheet and the temperature. The electrochemical test shows the Au nanoparticle would improve the electron exchange reaction occurring on the electrode. In the solution of Fe III (CN) 6 3− /Fe II (CN) 6 4− , the electrode reaction follows , where increasing the layer number of MoS 2 nanosheet would restrict the reaction. In the DA system, the reaction of occurs on the electrode and increasing the layer number of MoS 2 nanosheet would facilitate the reaction. The difference as mentioned above is assigned to the energy level shift originated from variance of layer number of MoS 2 nanosheet and the changing of reaction mechanism. In addition, temperature would mainly facilitate the kinetics of electron exchange reaction, which is assigned to the diffusion acceleration of DA molecule. Simultaneously, the desorption process of reactant in the electrolyte would enhance. The role of layer number of MoS 2 nanosheet and the temperature is clarified with the thermodynamic and kinetic properties of electron exchange reaction based on MoS 2 nanosheet, which would improve the understanding of nano-sensor based on MoS 2 nanosheet.
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BIOSENSORS & BIOELECTRONICS
·
2018
·
IF 8.173
Danni Wang,Rui Guo,Yunyun Wei,Yingzhi Zhang,Xiayu Zhao,Zhangrun Xu
Detection of telomerase activity is crucial for the telomerase-related early diagnosis of cancer and drug screening. Herein, a multicolor visual telomerase detection method with high sensitivity was developed based on the etching of hexadecyl trimethyl ammonium bromide-stablized Au nanorods (Au NRs) by the oxidation state 3,3′,5,5′-tetramethylbenzidine sulfate (TMB 2+ ). In order to meet the demand of bare-eye inspection, an enzyme-free signal amplification strategy of catalytic hairpin assembly (CHA) was incorporated. After the introduction of telomerase, telomerase extension products specifically triggered cyclic CHA and led to the successive formation of G-quadruplex/hemin DNAzyme, which catalyzed the H 2 O 2 -mediated oxidation of TMB. The Au NRs were gradually etched as the concentration of catalysate TMB 2+ increased, resulting in the decrease of aspect ratio of the Au NRs. Correspondingly, the longitudinal localized surface plasmon resonance peak of Au NRs was blue-shifted, with the concomitant generation of a series of color transition. Under optimal conditions, a highly sensitive detection toward telomerase was realized down to 15 HeLa cells . Compared to previous colorimetric method for telomerase determination, multiple colors corresponding to telomerase activity was the most attractive virtue of our approach. More strikingly, telomerase-induced cyclic CHA significantly enhanced the accumulation of G-quadruplex/hemin DNAzyme, thus the signal amplification was effectively realized. Our approach exhibited excellent sensitivity and convenient signal readout, which is expected to provide great potential application in cancer diagnosis and therapy.
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ANALYTICA CHIMICA ACTA
·
2018
·
IF 5.123
Yuting Zhang,Dongmei Deng,Xiaoli Zhu,Shuai Liu,Yan Zhu,Long Han,Liqiang Luo
Bimetallic Au-Ag/Co 3 O 4 nanofibers (Au-Ag/Co 3 O 4 NFs) were synthesized by an electrospinning method and calcination treatment. Due to the admirable synergic effect of electrocatalytic ability of Au and Ag, and the large surface-to-volume ratio of Co 3 O 4 nanofibers caused by their rough surface, the synthesized Au-Ag/Co 3 O 4 NFs were applied to a sensing platform for hydrogen peroxide oxidation . Using electrochemical techniques, the novel sensing platform based on Au-Ag/Co 3 O 4 NFs shows a wide linear concentration range with high detection sensitivity of 1241.1 μA mM −1 cm −2 . This sensitive sensor was also applied to determine H 2 O 2 from human breast cancer cells, indicating its great potential application in physiology and pathology.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2018
·
IF 5.667
Shiyu Xu,Xuejiao Dong,Siqi Chen,Yangyang Zhao,Guiye Shan,Yingchun Sun,Yanwei Chen,Yichun Liu
Creating high-index facet gold nanorods (Au NRs) is important for catalytic application. The high-index facet exhibits tremendously catalytic activity comparing with low-index facet. Herein, Cu 2+ ions were chosen to induce Au NRs to form high-index {200} facet. Firstly, Au/Cu NRs with high-index facets induce high-density charge distribution at local position, which led to the surface enhanced Raman scattering enhancement. Furthermore, the active electrons transfer from Au/Cu NRs to H 2 O 2 make them show peroxidase-like properties. The catalytic activity of Au/Cu NRs was confirmed by the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxidized TMB (oxTMB) by H 2 O 2 . According to Michaelis-Menten equation, the catalytic activity of Au/Cu was higher than Au NRs by 4.5 times. Meanwhile, the oxTMB molecules may be deoxidized to TMB molecules by the antioxidant of ascorbic acids. On the basis of this phenomenon, the colorimetric determination of ascorbic acid in real samples (vitamin drink) was developed with a detection limit of 25 μM.
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ACS Applied Materials & Interfaces
·
2018
·
IF 8.097
Ling-Yan Zhai,Min-Xiang Li,Wei-Lun Pan,Yun Chen,Min-Min Li,Jian-Xin Pang,Lei Zheng,Jin-Xiang Chen,Wen-Jun Duan
Breast cancer is the second cause of cancer mortality in women globally. Early detection, treatment, and metastasis monitoring are of great importance to favorable prognosis. Although conventional diagnostic methods, such as breast X-ray mammography and image positioning biopsy, are accurate, they could cause radioactive or invasive damage to patients. Liquid biopsy as a noninvasive method is convenient for repeated sampling in clinical cancer prognostic, metastatic evaluation, and relapse monitoring. MicroRNAs encased in exosomes circulating in biofluids are promising candidate cancer biomarkers because of their cancer-specific expression profiles. Here, we report an in situ detection of microRNA-1246 (miR-1246) in human plasma exosomes as breast cancer biomarker by a nucleic acid functionalized Au nanoflare probe. Needing neither time-consuming and costly isolation of exosomes from the plasma sample nor transfection means, the Au nanoflare probe can directly enter the plasma exosomes to generate fluorescent signal quantitatively by specifically targeting miR-1246. Only 40 μL of plasma is needed to incubate 4 h with the probe, giving signal sensitive enough to distinguish samples of breast cancer to normal control. Using plasma miR-1246 level detected by our assay as a marker, we differentiated 46 breast cancer patients from 28 healthy controls with 100% sensitivity and 92.9% specificity at the best cutoff. This simple, accurate, sensitive, and cost-effective liquid biopsy by the Au nanoflare probe is potent to be developed as a noninvasive breast cancer diagnostic assay for clinical adaption.
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