Luminescence Enhancement based Sensing of L‐Cysteine by Doped Quantum Dots

Abstract

The interaction of a presynthesized orange emitting Mn2+‐doped ZnS quantum dots (QDs) with L‐Cysteine (L−Cys) led to enhance emission intensity (at 596 nm) and quantum yield (QY). Importantly, the Mn2+‐doped ZnS QDs exhibited high sensitivity towards L−Cys, with a limit of detection of 0.4±0.02 μM (in the linear range of 3.3–13.3 μM) and high selectivity in presence of interfering amino acids and metal ions. The association constant of L−Cys was determined to be 0.36×105 M−1. The amplified passivation of the surface of Mn2+‐doped ZnS QDs following the incorporation and binding of L−Cys is accounted for the enhancement in their luminescence features. Moreover, the luminescence enhancement‐based detection will bring newer dimension towards sensing application.

Engineering Cytochrome C with Quantum Dots and Ionic Liquids: A Win-Win Strategy for Protein Packaging against Multiple Stresses

“…The X-ray diffraction peaks at 28.6°, 47.7°, and 56.5°for the synthesized Mn 2+ -doped ZnS QDs are the characteristic (111), (220), and (311) planes of cubic ZnS blende crystals (Figure 1a). 28 Upon addition of ILs to QD, there is no-much difference in the XRD profiles of the QDs and QD-IL composite which confirms that there is no change in the basic crystal structure of QD even after the treatment with ILs. It is worth mentioning that the zeta potential of particles is an important parameter, which measure their interactions in dispersed media.…”

α‐Acrylaldehyde 3‐Pyrrolyl BODIPY as a Specific Optical Sensor for Cysteine and Homocysteine

“…The association constant Ka for 3 with Cys was calculated from the plot of intensity of absorbance/fluorescence spectra of compound 3 against the concentration of Cys (ln [Cys]) for 1 : 1 stoichiometry of host-guest interaction, following the reported method. [32] The higher value K a (1.88 × 10 6 M À 1 ) for 3-Cys (Figure S20(a)), indicated the compound's higher affinity towards Cys which is comparably higher than the reported values [33][34][35] for the detection of Cys with other optical probes. The Stern-Volmer quenching constant of 3 with Hcy was determined by the Stern-Volmer equation, [36] which was observed to be 3469.08 � 0.8 M À 1 (Figure S21(b)).…”

Simple and Cost-Effective Quantum Dot Chemodosimeter for Visual Detection of Biothiols in Human Blood Serum

“…Various approaches for qualitative as well as quantitative analysis of these bioanalytes have been developed, mainly based on electroanalytical techniques, , high-performance liquid chromatography (HPLC), , capillary electrophoresis separation, immunoassays based on derivatization with fluorescent/phosphorescent reagents, spectrophotometric methods, etc. , Unfortunately, all of these methods require either expensive reagents or equipment or skilled manpower to ensure reproducibility. In this context, much attention is being paid to the development of simple and cheap fluorescent probes, without compromising selectivity and sensitivity. − Nanoparticles have been proven to be an efficient substitute for organic fluorophores, particularly for developing emission “turn on/off” sensors. − Among various nanoparticles, quantum dots (QDs) are of particular interest in developing novel biosensors owing to their unique properties such as broad absorption band, emission in the visible region, photostability, etc. − Moreover, the potential of QDs to transfer electrons or holes to biologically important molecules, interacting covalently or noncovalently with their surface, can be used to tune the QD emission intensity and thus generate charge transfer-based emission “on/off” signaling. − …”