Fabrication of l-cysteine-capped CdTe quantum dots based ratiometric fluorescence nanosensor for onsite visual determination of trace TNT explosive.

New strategies for onsite determination of trace 2,4,6-trinitrotoluene (TNT) explosives have become a research hotspot for homeland security needs against terrorism and environmental concerns. Herein, we designed a ratiometric fluorescence nanohybrid comprising 3-mercaptopropionic acid-capped green-emitting CdTe quantum dots (gQDs) encapsulated into SiO sphere and l-cysteine (Lcys)-capped red-emitting CdTe QDs (rQDs) conjugated onto SiO surface. The surface Lcys can be used as not only the stabilizer of the rQDs but also the primary amine provider which can react with TNT to form Meisenheimer complexes.

Nitrogen-Doped Graphene Quantum Dots@SiO2 Nanoparticles as Electrochemiluminescence and Fluorescence Signal Indicators for Magnetically Controlled Aptasensor with Dual Detection Channels.

We proposed a facile method to prepare the nitrogen-doped graphene quantum dots (NGQDs) doped silica (NGQDs@SiO2) nanoparticles (NPs). The NGQDs@SiO2 NPs were further explored as a versatile signal indicator for ochratoxin A (OTA) aptasensing by combination with electrochemiluminescence (ECL) and fluorescence (FL) detection. In this strategy, the core-shell Fe3O4@Au magnetic beads (MBs) acted as a nanocarrier to immobilize the thiolated aptamer specific for OTA, and the amino modified capture DNA (cDNA) was efficiently tagged with NGQDs@SiO2 NPs.

A FRET-based ratiometric fluorescent aptasensor for rapid and onsite visual detection of ochratoxin A.

A color change observable by the naked eye to indicate the content of an analyte is considered to be the most conceivable way of various sensing protocols. By taking advantage of the Förster resonance energy transfer (FRET) principles, we herein designed a dual-emission ratiometric fluorescent aptasensor for ochratoxin A (OTA) detection via a dual mode of fluorescent sensing and onsite visual screening. Amino group-modified OTA's aptamer was firstly labeled with the green-emitting CdTe quantum dots (gQDs) donor.

Preparation of graphene quantum dots based core-satellite hybrid spheres and their use as the ratiometric fluorescence probe for visual determination of mercury(II) ions.

We herein proposed a simple and effective strategy for preparing graphene quantum dots (GQDs)-based core-satellite hybrid spheres and further explored the feasibility of using such spheres as the ratiometric fluorescence probe for the visual determination of Hg(2+). The red-emitting CdTe QDs were firstly entrapped in the silica nanosphere to reduce their toxicity and improve their photo and chemical stabilities, thus providing a built-in correction for environmental effects, while the GQDs possessing good biocompatibility and low toxicity were electrostatic self-assembly on the silica surface acting as reaction sites. Upon exposure to the increasing contents of Hg(2+), the blue fluorescence of GQDs can be gradually quenched presumably due to facilitating nonradiative electron/hole recombination annihilation.