Au@Ag Core/Shell Nanorods Based Colorimetric Assay for the Rapid and Selective Detection of Cyanide Anions

2019 ◽  
Vol 11 (12) ◽  
pp. 1739-1744
Author(s):  
Rui-Ling Zhang ◽  
Shi-Liang Jia ◽  
Kai-Ming Wang
Keyword(s):  
High Selectivity ◽  
Color Change ◽  
Colorimetric Assay ◽  
Water Solution ◽  
Blue Shift ◽  
Core Shell ◽  
Optimal Conditions ◽  
Sample Analysis ◽  
Aspect Ratios ◽  
Naked Eye Detection

A colorimetric assay based on Au@Ag core/shell nanorods was developed to rapidly determine cyanide in aqueous solution. The aspect ratios of Au@Ag core/shell nanorods were changed with the dissolution of metals in cyanide solution, which led to the decrease of Ag shell absorption spectra and the blue shift of longitudinal plasmon absorption band of Au core, as well as the color change of Au@Ag core/shell nanorods. In contrast to spherical Au@Ag nanoparticles with less sample analysis time (1 min per sample), the distinguish ability of this assay was proven to be higher. Under optimal conditions, the developed colorimetric assay gave a linear range of 1–200 μM for cyanide in water solution and a naked-eye detection limit of 0.5 μM. On the side, the colorimetric assay exhibited high selectivity towards cyanide over other common anions. The developed Au@Ag nanorods probes have been successfully applied to determine the level of cyanide in local lake, river and industrial water samples.

scholarly journals Nile-Red-Based Fluorescence Probe for Selective Detection of Biothiols, Computational Study, and Application in Cell Imaging

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4718
Author(s):  
Xiang Rong ◽  
Zhong-Yong Xu ◽  
Jin-Wu Yan ◽  
Zhi-Zhong Meng ◽  
Bin Zhu ◽  
...  
Keyword(s):  
Cell Imaging ◽  
High Selectivity ◽  
Fluorescence Enhancement ◽  
Fluorescence Probe ◽  
Color Change ◽  
Computational Study ◽  
Theoretical Calculations ◽  
Nile Red ◽  
Blue Shift ◽  
Selective Detection

A new colorimetric and fluorescence probe NRSH based on Nile-red chromophore for the detection of biothiols has been developed, exhibiting high selectivity towards biothiols over other interfering species. NRSH shows a blue shift in absorption peak upon reacting with biothiols, from 587 nm to 567 nm, which induces an obvious color change from blue to pink and exhibits a 35-fold fluorescence enhancement at 645 nm in red emission range. NRSH displays rapid (<1 min) response for H2S, which is faster than other biothiols (>5 min). The detection limits of probe NRSH towards biothiols are very low (22.05 nM for H2S, 34.04 nM for Cys, 107.28 nM for GSH and 113.65 nM for Hcy). Furthermore, NRSH is low cytotoxic and can be successfully applied as a bioimaging tool for real-time monitoring biothiols in HeLa cells. In addition, fluorescence mechanism of probe NRSH is further understood by theoretical calculations.

A fluorescent probe for the specific detection of cysteine in human serum samples

2019 ◽  
Vol 11 (26) ◽  
pp. 3280-3285 ◽  
Author(s):  
Zhen Huang ◽  
Cuiyan Wu ◽  
Yaqian Li ◽  
Zile Zhou ◽  
Ruihua Xie ◽  
...  
Keyword(s):  
Human Serum ◽  
Fluorescent Probe ◽  
High Selectivity ◽  
Color Change ◽  
Eye Detection ◽  
Specific Detection ◽  
Serum Samples ◽  
Naked Eye ◽  
Turn On ◽  
Naked Eye Detection

A turn-on fluorescent probe for cysteine with high selectivity was designed and synthetized. The probe can be used for “naked-eye” detection of Cys with an obvious color change from yellow to colorless. The probe could be applied for Cys detection in real human serum.

scholarly journals Competitive HRP-Linked Colorimetric Aptasensor for the Detection of Fumonisin B1 in Food based on Dual Biotin-Streptavidin Interaction

Biosensors ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 31 ◽  
Author(s):  
Zui Tao ◽  
You Zhou ◽  
Xiang Li ◽  
Zhouping Wang
Keyword(s):  
Reliable Method ◽  
Visual Detection ◽  
Color Change ◽  
Colorimetric Assay ◽  
Fusarium Species ◽  
Fumonisin B1 ◽  
Food Samples ◽  
Optimal Conditions ◽  
Complementary Strand ◽  
Streptavidin Binding

Fumonisin B1 (FB1) is the most prevalent and toxic form among fumonisin homologues which are produced by fusarium species and it contaminates various types of food products, posing serious health hazards for humans and animals. In this work, a colorimetric assay for the detection of FB1 has been developed based on competitive horseradish peroxidase (HRP)-linked aptamer and dual biotin-streptavidin interaction. In short, a biotinylated aptamer of FB1 was immobilized on the microplate by biotin-streptavidin binding; the complementary strand (csDNA) of the aptamer was ligated with HRP by biotin-streptavidin binding again to form a csDNA-HRP sensing probe, competing with FB1 to bind to the aptamer. The color change can be observed after the addition of chromogenic and stop solution, thereby realizing the visual detection of FB1. Under optimal conditions, good linearity was observed within the concentration range of 0.5 to 300 ng/mL, with a detection of limit of 0.3 ng/mL. This assay is further validated by spike recovery tests towards beer and corn samples, it provides a simple, sensitive and reliable method for the screening of FB1 in food samples and may be potentially used as an alternative to conventional assays.

scholarly journals A Reversible Colorimetric and Fluorescence “Turn-Off” Chemosensor for Detection of Cu2+ and Its Application in Living Cell Imaging

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4283 ◽  
Author(s):  
Yun Hu ◽  
Aiqian Chen ◽  
Zhuo Kong ◽  
Demeng Sun
Keyword(s):  
Cell Imaging ◽  
High Selectivity ◽  
Color Change ◽  
Dual Function ◽  
Biological Applications ◽  
Sensing System ◽  
Neutral Aqueous Solution ◽  
Intracellular Changes ◽  
Living Cell Imaging ◽  
Naked Eye Detection

Dual-function chemosensors that combine the capability of colorimetric and fluorimetric detection of Cu2+ are still relatively rare. Herein, we report that a 3-hydroxyflavone derivative (E)-2-(4-(dimethylamino)styryl)-3-hydroxy-4H-chromen-4-one (4), which is a red-emitting fluorophore, could serve as a reversible colorimetric and fluorescence “turn-off” chemosensor for the detection of Cu2+. Upon addition of Cu2+ to 4 in neutral aqueous solution, a dramatic color change from yellow to purple-red was clearly observed, and its fluorescence was markedly quenched, which was attributed to the complexation between the chemosensor and Cu2+. Conditions of the sensing process had been optimized, and the sensing studies were performed in a solution of ethanol/phosphate buffer saline (v/v = 3:7, pH = 7.0). The sensing system exhibited high selectivity towards Cu2+. The limit of naked eye detection of Cu2+ was determined at 8 × 10−6 mol/L, whereas the fluorescence titration experiment showed a detection limit at 5.7 × 10−7 mol/L. The complexation between 4 and Cu2+ was reversible, and the binding constant was found to be 3.2 × 104 M−1. Moreover, bioimaging experiments showed that 4 could penetrate the cell membrane and respond to the intracellular changes of Cu2+ within living cells, which indicated its potential for biological applications.

scholarly journals Dual Detection Highly Selective Colorimetric Chemosensors for Fluoride and Copper(II) Ions Based on Imine-Phenol Derivative

2020 ◽  
Vol 32 (4) ◽  
pp. 803-809
Author(s):  
Phoomirut Nusuwan ◽  
Piyada Jittangprasert ◽  
Mayuso Kuno ◽  
Kem Pumsa-ard ◽  
Pan Tongraung
Keyword(s):  
High Selectivity ◽  
Water Solution ◽  
High Yield ◽  
Visible Spectroscopy ◽  
Phenol Derivative ◽  
Qualitative Detection ◽  
Test Kit ◽  
Dual Detection ◽  
Uv Visible ◽  
Naked Eye Detection

A simple dual detection using colorimetric chemosensor, imine-phenol derivative L (bearing a 2-iminephenol group as a binding unit and a-nitrophenylazo group as a signaling unit), were synthesized for a high yield in two simple steps. Complexations of chemosensor L with various anions in acetonitrile solvent and other metal ions in DMSO/H2O solvent were monitored by UV-visible spectroscopy. The results indicated that the chemosensor L showed high selectivity for F− and Cu2+ ions. Furthermore, the complexes for L-F− and L-Cu2+ were evaluated by computational chemistry using a B3LYP/6-31G (d,p) and a B3LYP/6-311G (d,p) level of calculation. The complexes between L with F− and Cu2+ were magenta and yellow colored, respectively. Chemosensor L can be applied for the analysis of F− and Cu2+ ions with naked-eye detection making colour comparisons between the standard and the real sample. Most importantly, semi-qualitative detection of Cu2+ in water solution were successfully carried out with the developed test kit using chemosensor L.

Core-shell Cu@C@ZIF-8 composite: a high-performance electrode material for electrochemical sensing of nitrite with high selectivity and sensitivity

2021 ◽  
Author(s):  
Feng Gao ◽  
Xiaolong Tu ◽  
Yongfang Yu ◽  
Yansha Gao ◽  
Jin Zou ◽  
...  
Keyword(s):  
High Performance ◽  
High Selectivity ◽  
Limit Of Detection ◽  
Metal Organic Framework ◽  
High Sensitivity ◽  
Electrochemical Sensing ◽  
Core Shell ◽  
Zeolitic Imidazolate Framework ◽  
Sensing Platform ◽  
The Difference

Abstract Herein, an efficient electrochemical sensing platform is proposed for selective and sensitive detection of nitrite on the basis of Cu@C@Zeolitic imidazolate framework-8 (Cu@C@ZIF-8) heterostructure. Core-shell Cu@C@ZIF-8 composite was synthesized by pyrolysis of Cu-metal-organic framework@ZIF-8 (Cu-MOF@ZIF-8) in Ar atmosphere on account of the difference of thermal stability between Cu-MOF and ZIF-8. For the sensing system of Cu@C@ZIF-8, ZIF-8 with proper pore size allows nitrite diffuse through the shell, while big molecules cannot, which ensures high selectivity of the sensor. On the other hand, Cu@C as electrocatalyst promotes the oxidation of nitrite, thereby resulting high sensitivity of the sensor. Accordingly, the Cu@C@ZIF-8 based sensor presents excellent performance for nitrite detection, which achieves a wide linear response range of 0.1 µM to 300.0 µM, and a low limit of detection (LOD) of 0.033 µM. In addition, the Cu@C@ZIF-8 sensor possesses excellent stability and reproducibility, and was employed to quantify nitrite in sausage samples with recoveries of 95.45-104.80%.

Conformality of PVD shell layers on vertical arrays of rods with different aspect ratios investigated by Monte Carlo simulations

MRS Advances ◽  
2017 ◽  
Vol 2 (8) ◽  
pp. 465-470 ◽  
Author(s):  
M. Yurukcu ◽  
H. Cansizoglu ◽  
M. F. Cansizoglu ◽  
T. Karabacak
Keyword(s):  
High Pressure ◽  
Monte Carlo ◽  
Flux Distribution ◽  
Thermal Evaporation ◽  
Sputter Deposition ◽  
Core Shell ◽  
Nanorod Arrays ◽  
Aspect Ratios ◽  
Normal Angle ◽  
Angle Deposition

AbstractApplications such as batteries, fuel cells, solar cells, and sensors, can benefit from high surface-to-volume ratio core/shell arrays of nanorods. The fabrication of the conformal shell layers on nanorod arrays has been a formidable task. In order to assess the deposition conditions for the production of conformal shell coatings by physical vapor deposition (PVD) techniques, we employed Monte Carlo (MC) simulations that involved shell depositions under different flux distributions and angles on arrays of rods. We investigated the conformality of PVD shell layers on nanorod arrays of different aspect ratios, which is defined to be the ratio of rod height to the gaps between nearest-neighbor rods. MC simulated core/shell structures were analyzed for the thickness uniformity of the shell layer across the sidewalls of rods. Our results show that a small angle deposition approach involving a uniform oblique flux (U-SAD) with a small incidence angle ≤ 30o can generate a fairly conformal shell coating around small aspect-ratio rods. However, normal angle deposition with an angular flux distribution (A-NAD) achieves superior conformality both on small and high-aspect-ratio structures compared to U-SAD, conventional uniform normal angle deposition (U-NAD), and SAD with an angular flux distribution (A-SAD). A-NAD can be realized in a PVD system such as by high pressure sputter deposition; while U-SAD can be achieved in thermal evaporation system with a small angle incident flux. In addition, U-NAD and A-SAD can correspond to film growth by normal incidence thermal evaporation and SAD-high pressure sputter deposition, respectively.

Statistical Modeling, Optimization and Kinetics of Mn2+ Adsorption in Aqueous Solution Using a Biosorbent

2019 ◽  
Vol 233 (8) ◽  
pp. 1201-1214 ◽  
Author(s):  
Elaheh Tajari ◽  
Narges Samadani Langeroodi ◽  
Mahnaz Khalafi
Keyword(s):  
Wheat Bran ◽  
Low Cost ◽  
Weight Ratio ◽  
P Value ◽  
Core Shell ◽  
Optimal Conditions ◽  
Solution Ph ◽  
Shell Weight ◽  
Removal Ratio ◽  
Kinetics Of

Abstract This paper describes the adsorption of Mn2+ ions from water with a mixture of wheat bran and Japanese medlar core shell (weight ratio of 30–70 wheat bran to Japanese medlar core shell) as low-cost adsorbent. Scanning Electron Microscope was used to characterize the adsorbent. The response surface methodology (RSM) that is usually approximated by a second-order regression model was employed to evaluate the effects of solution pH, initial Mn2+ concentration, adsorbent weight and contact time on the removal ratio of the Mn2+ ions. In this regard, the significant variables initial Mn2+ ions concentration, pH, adsorbent weight and square pH were found based on the small P-value for the model coefficients. The predicted optimal conditions were also performed. In the process optimization, maximal value of the removal ratio of Mn2+ was achieved as 96.91%. Additionally, this paper discusses the kinetic of adsorption in optimal conditions.

scholarly journals A Novel Design Combining Isothermal Exponential Amplification and Gold-Nanoparticles Visualization for Rapid Detection of miRNAs

2018 ◽  
Vol 19 (11) ◽  
pp. 3374 ◽  
Author(s):  
Jiquan Jiang ◽  
Bin Zhang ◽  
Chi Zhang ◽  
Yifu Guan
Keyword(s):  
Early Phase ◽  
Color Change ◽  
Direct Detection ◽  
Colorimetric Assay ◽  
Disease Diagnosis ◽  
Dna Probes ◽  
Time Saving ◽  
Promising Alternative ◽  
Sandwich Hybridization ◽  
Wide Range

MicroRNAs (miRNAs) play important roles in a wide range of biological processes, and their aberrant expressions are associated with various diseases. The levels of miRNAs can be useful biomarkers for cellular events or disease diagnosis; thus, sensitive and selective detection of microRNAs is of great significance in understanding biological functions of miRNAs, early-phase diagnosis of cancers, and discovery of new targets for drugs. However, traditional approaches for the detection of miRNAs are usually laborious and time-consuming, with a low sensitivity. Here, we develop a simple, rapid, ultrasensitive colorimetric assay based on the combination of isothermal Exponential Amplification Reaction (EXPAR) and AuNP-labeled DNA probes for the detection of miRNAs (taking let-7a as a model analyte). In this assay, the presence of let-7a is converted to the reporter Y through EXPAR under isothermal conditions. The subsequent sandwich hybridization of the reporter Y with the AuNP-labeled DNA probes generates a red-to-purple color change. In other words, if the reporter Y is complementary to the AuNP-labeled DNA probes, the DNA-functionalized AuNPs will be aggregated, resulting in the change of solution color from red to purple/blue, while when the AuNP-labeled DNA probes are mismatched to the reporter Y, the solution remains red. This assay represents a simple, time-saving technique, and its results can be visually detected with the naked eye due to the colorimetric change. The method provides superior sensitivity, with a detection limit of 4.176 aM over a wide range from 1 nM to 1 aM under optimal conditions. The method also shows high selectivity for discriminating even single-nucleotide differences between let-7 miRNA family members. Notably, it is comparable to the most sensitive method reported to date, thus providing a promising alternative to standard approaches for the direct detection of let-7a miRNA. Importantly, through combination with specific templates, different miRNAs can be converted to the same reporter Y, which can hybridize with the same set of AuNP-labeled DNA probes to form sandwich hybrids. The color change of the solution can be observed in the presence of the target miRNA. This technique has potential as a routine method for assessing the levels of miRNAs, not only for let-7, but also for various miRNAs in the early phase of cancers. In addition, it can be a useful tool in biomedical research and clinical diagnosis, as well as diagnosis or surveillance programs in field conditions.

scholarly journals Spectral properties of coumarin derivatives in various environments

2013 ◽  
Vol 11 (4) ◽  
pp. 492-501 ◽  
Author(s):  
Alzbeta Holubekova ◽  
Pavel Mach ◽  
Jan Urban
Keyword(s):  
Gas Phase ◽  
Absorption Spectra ◽  
Spectral Properties ◽  
Density Functional ◽  
Water Solution ◽  
Blue Shift ◽  
Coumarin Derivatives ◽  
Complex Environments ◽  
Td Dft ◽  
Solvent Environment

AbstractThe structural and spectral properties of coumarin derivatives in complex environments were investigated within the time-dependent density functional theory (TD DFT). Absorption spectra calculations were obtained at TD PBE0/6-31+G(d,p) level of theory for coumarin47 in the gas-phase and in various polar and non-polar organic solvents. The geometries of coumarins 6, 30, 47 and 522 in the gas phase and in inclusion complexes with the β-cyclodextrin (βCD) were determined by PM3 and DFT (HCTH/6-31G) calculations. Encapsulation of coumarin in βCD and associated changes in electronic structure produced either a red or blue shift in the absorption spectra of coumarins. A proposed cavity model for βCD-coumarin complex in water solution allowed identification of various contributions to the overall shift in the absorption spectra of coumarin upon complex formation in a solvent environment

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