Strong enhancement of the chemiluminescence of the Cu(II)-H2O2 system on addition of carbon nitride quantum dots, and its application to the detection of H2O2 and glucose

The authors report that carbon nitride quantum dots (CN QDs) exert a strong enhancing effect on the Cu(II)/H2O2 chemilumi-nescent system. Chemiluminescence (CL) intensity is enhanced by CN QDs by a factor of similar to 75, while other carbon nanomaterials have a much weaker effect. The possible mechanism of the effect was evaluated by recording fluorescence and CL spectra and by examining the effect of various radical scavengers. Emitting species was found to be excited-state CNQDs that produce green CL peaking at 515 nm. The new CL system was applied to the sensitive detection of H2O2 and glucose (via glucose oxidase-catalyzed formation of H2O2) with detection limits (3 sigma) of 10 nM for H2O2 and 100 nM for glucose. The probe was employed for glucose determination in human plasma samples with satisfactory results

Facile synthesis of carbon quantum dot/silver nanocomposite and its application for colorimetric detection of methimazole

International audienc

Terbium–To–Quantum Dot Förster Resonance Energy Transfer for Homogeneous and Sensitive Detection of Histone Methyltransferase Activity

International audienceThe development of rapid, simple, and versatile biosensors for monitoring the activity of histone modifying enzymes (HMEs) is needed for the improvement of diagnostic assays, screening of HME inhibitors, and a better understanding of HME kinetics in different environments. Nanoparticles can play an important role in this regard by improving or complementing currently available enzyme detection technologies. Here, we present the development and application of a homogeneous methyltransferase (SET7/9) assay based on time-gated Förster resonance energy transfer (TG-FRET) between terbium complexes (Tb) and luminescent semiconductor quantum dots (QDs). Specific binding of a Tb-antibody conjugate to a SET7/9-methylated Lys4 on a histone H3(1–21) peptide substrate attached to the QD surface resulted in efficient FRET and provided the mechanism for monitoring the SET7/9 activity. Two common peptide-QD attachment strategies (biotin–streptavidin and polyhistidine-mediated self-assembly), two different QD colors (625 and 705 nm), and enzyme sensing with post- or pre-assembled QD–peptide conjugates demonstrated the broad applicability of this assay design. Limits of detection in the low picomolar concentration range, high selectivity tested against non-specific antibodies, enzymes, and co-factors, determination of the inhibition constants of the SET7/9 inhibitors SAH and (R)-PFI-2, and analysis of the co-factor (SAM) concentration-dependent enzyme kinetics of SET7/9 which followed the Michaelis–Menten model highlighted the excellent performance of this TG-FRET HME activity assay

Energy transfer with nanoparticles for in vitro diagnostics

International audienc