Sensitive Detection Of L-cysteine Research Articles

Bioinspired 5-caffeoylquinic acid capped silver nanoparticles using Coffee arabica leaf extract for high-sensitive cysteine detection

Selection of plant extracts as bioactive phytochemical source to synthesize nanoparticles is highly demanding due to the biocompatibility, nontoxicity, and cost-effectiveness over other available physical and chemical methods. Here, for the first time, Coffee arabica leaf extracts (CAE) were used to produce highly stable silver nanoparticles (AgNPs) and the corresponding bio reduction, capping and stabilization mechanism mediated by dominant isomer 5-caffeoylquinic acid (5-CQA) is discussed. UV–Vis, FTIR, μRaman spectroscopy, TEM, DLS and Zeta potential analyzer measurements were employed to characterize these green synthesized NPs. The affinity of 5-CQA capped CAE–AgNPs to thiol moiety of amino acid is utilized for the selective as well as sensitive detection of L-cysteine (L-Cys) to a low detection limit of 0.1 nM, as obtained from its μRaman spectra. Hence, the proposed novel, simple, eco-friendly, and economically sustainable method can provide a promising nanoplatform in the field of biosensors compliant with large-scale industrial production of AgNPs without aid of further instrumentation.

A simple copper(ii) dppy-based receptor for sensing of l-cysteine and l-histidine in aqueous acetonitrile medium

A novel copper(ii)-dppy receptor enables rapid and sensitive detection of l-cysteine and l-histidine, exhibiting exceptional selectivity and early-stage identification potential.

SPR based gold nano-probe as optical sensor for cysteine detection via plasmonic enhancement in the presence of Cr3+

A selective and sensitive detection of L-cysteine (Cys) is an important tool for various biological studies. Here, Au nanoparticles (NPs) were prepared by chemical reduction technique. The probe was developed to detect and quantify Cys in the presence of Cr3+ ions which acts as a cross linker. The citrate capped Au NPs probe was analyzed by UV–visible spectrophotometry, TEM, EDAX, FTIR, DLS, XPS and zetasize. The zeta potential and effective size of Au NPs were −41.22 mV and 12 nm, respectively. The Cys interaction with Au NPs showed drastic colour variation from red to purple and colourless with rapid response time of 1 min. The limit of detection (LOD) of Au NPs probe was as low as 0.012 nM. The TEM image of Au NPs after Cys interaction verified the aggregation that resulted in colour change. The XPS core level scans of Au 4f showed 0.3 eV red shift when Cyswas interacted. The Au NPs sensor is highly selective for Cys with excellent reproducibility. Acidic pH slightly favored Cys detection. Further, the probe was applied to estimate Cys quantity from milk, urine, blood and environmental augmented samples in the presence of other amino acids . The study suggests that the proposed Au NPs could detect Cys with high accuracy from various biological samples.

Fe doped MoS2/polypyrrole microtubes towards efficient peroxidase mimicking and colorimetric sensing application.

Molybdenum disulfide (MoS2) nanosheets have been found to exhibit intrinsic peroxidase-like activity that could be applied in colorimetric sensing platforms. However, their poor conductivity and few exposed edge sites often lead to poor catalytic activity, impeding the application of MoS2 nanosheets in enzyme-like catalysis. Here, a novel strategy was developed to selectively deposit Fe-doped MoS2 nanosheets on polypyrrole microtubes to obtain Fe-MoS2@PPy microtubes to address these issues. In the synthesized Fe-MoS2@PPy microtubes, PPy microtubes can not only be used as a conductive support to promote the electron transfer, but also greatly alleviate the aggregations of MoS2 nanosheets, and thus improve the enzyme-like activity. Meanwhile, additional active sites, formed by Fe doping, also endow the catalyst with excellent activity in enzyme-like catalysis. Notably, in the process of sulfidation, the dissolution, redistribution and diffusion result in the disappearance of MoO3@FeOOH cores and the formation of Fe doped MoS2 nanosheets, which significantly facilitate the deposition of Fe-doped MoS2 nanosheets on PPy microtubes. On the basis of the high peroxidase-like catalytic efficiency of the Fe-MoS2@PPy microtubes, a simple and convenient colorimetric strategy for the rapid and sensitive detection of L-cysteine has been developed. This strategy introduces both the PPy layer and Fe doping to increase the conductivity and the density of active sites of MoS2 nanosheets, thus enhancing the catalytic activity and stability. More importantly, Fe-MoS2@PPy microtubes could be used as a good support for loading other materials such as Au and Ag nanoparticles (NPs), forming ternary Fe-MoS2/Ag, Au@PPy nanotubes. This work offers an opportunity to develop low-cost and highly active MoS2-based nanocomposites for promising potential applications in electrochemical energy conversion and medical diagnostics.

Selective and sensitive detection of L-Cysteine via fluorometric assay using gold nanoparticles and Rhodamine B in aqueous medium

An assay method based on fluorometric and colorimetric change was developed for selective sensing of important thiol containing amino acid L-Cysteine (L-Cys) by using gold nanoparticles (Au NPs) and Rhodamine B (RhB) in aqueous environment. This fluorometric assay is basically relies on the competitive binding between RhB and Au NPs via electrostatic interaction as well as strong thiol(-SH)-Au NPs bonding via chemisorption. Citrate stabilized Au NPs (diameter ∼27 nm) was synthesized by soft chemical method and characterized by UV–Vis absorption spectroscopy and Transmission electron microscopic (TEM) techniques. The change in non-radiative energy transfer between RhB and Au NPs are responsible for the observed drastic fluorescence quenching of RhB via FRET process. The recovery of fluorescence from the assay solution of RhB/Au NPs after addition of L-Cys was found linear over the concentration range 0.01 μM–1000 μM with experimental limit of detection (LOD) of 0.01 μM. The selective interaction of L-Cys with the mixed solution of RhB/Au NPs was reflected by the color change from wine to bluish-black of the final solution. The proposed fluorometric assay method accompanied with the observed colorimetric change could successfully differentiate other interfering amino acids including thiol (-SH) containing compounds namely L-Methionine, L-Homocysteine and antioxidant glutathione with the high degree of accuracy. Also the LOD is comparable to the concentration of L-Cys present in the blood plasma. The proposed sensing mechanism is also confirmed with pure human urine sample to detect the response of L-Cys in the urine. Therefore, this fluorometric assay technique for detection of L-Cys has great potential with the diagnostic impact for biomedical interest.

Fabrication of ternary MoS2-polypyrrole-Pd nanotubes as peroxidase mimics with a synergistic effect and their sensitive colorimetric detection of l-cysteine

Over the past few years, nanomaterials-based enzymatic mimics have attracted tremendous attention due to their excellent catalytic activity and environmental stability. In this work, ternary MoS2-polypyrrole (PPy)-Pd nanotubes have been prepared through a hydrothermal reaction and in situ redox polymerization process between pyrrole monomer and Na2PdCl4. The prepared MoS2-PPy-Pd nanotubes exhibited a higher peroxidase-like catalytic activity than individual MoS2, MoS2-PPy, PPy-Pd and MoS2-Pd nanocomposites due to the synergistic catalytic effect between the three components. The catalytic kinetic of MoS2-PPy-Pd nanotubes follows Michaelis-Menten behaviors, exhibiting a good affinity to both 3,3′,5,5′-tetramethylbenzidine (TMB) and H2O2 substrates. On the basis of high peroxidase-like catalytic efficiency of the MoS2-PPy-Pd nanotubes, a simple and convenient colorimetric strategy for the rapid and sensitive detection of l-cysteine with a detection limit of 0.08 μM has been developed. In addition, a high selectivity towards the detection of l-cysteine is achieved. This work present an opportunity of the prepared ternary MoS2-PPy-Pd nanotubes for promising potential applications in biosensing, environmental monitoring, and medical diagnostics.

Facile preparation of Prussian blue/polypyrrole hybrid nanofibers as robust peroxidase mimics for colorimetric detection ofl-cysteine

Prussian blue/polypyrrole hybrid nanofibers as efficient peroxidase mimics for the sensitive detection ofl-cysteine have been developed.