A simple assay platform for sensitive detection of Sudan I-IV in chilli powder based on CsPbBr quantum dots.

Sudan dyes are phenyl-azoic derivatives widely used in industry. Classified as carcinogenic and are strictly forbidden in foodstuffs; however, some unscrupulous businessmen adopted it for coloring foodstuffs. Here, a simple and effective fluorescence (FL) assay platform has been developed for the detection of Sudan I-IV based on CsPbBr perovskite quantum dots (QDs).

Silver triangular nanoplates as an high efficiently FRET donor-acceptor of upconversion nanoparticles for ultrasensitive "Turn on-off" protamine and trypsin sensor.

Silver triangular nanoplates (STNPs) as a high efficient fluorescence quenching reagent of upconversion nanoparticles (UCNPs) was used to constract a novel label-free fluorescence nanosensor for ultrasensitive detection of protamine and trypsin based on fluorescence resonance energy transfer (FRET) between STNPs and UCNPs. In this assay, the negatively charged STNPs can bind with positively charged UCNPs through electrostatic interaction, and then quenched the fluorescence of UCNPs. When protamine was added to the mixture of UCNPs-STNPs, the STNPs interacted with protamine and then detached from the surface of UCNPs and aggregated, which result in the recovery of the fluorescence of UCNPs.

Sensitive fluorescent detection of HO and glucose in human serum based on inner filter effect of squaric acid-iron(III) on the fluorescence of upconversion nanoparticle.

Diabetes mellitus is an epidemic disease that it has became a worldwide public health problem. Thus, blood glucose monitoring has attracted extensive attention. Here, we report a nanosensor based on inner filter effect (IFE) between upconversion nanoparticles (UCNPs) and squaric acid (SQA)-iron(III) for the highly sensitive and selective detection of glucose levels in human serum.

Glutathione regulation-based dual-functional upconversion sensing-platform for acetylcholinesterase activity and cadmium ions.

A dual-functional platform for the sensing of acetylcholinesterase (AChE) activity and cadmium ions (Cd) was developed based on the fluorescence resonance energy transfer (FRET) between NaYF:Yb,Er upconversion nanoparticles (UCNPs) and gold nanoparticles (AuNPs) via glutathione regulation. The detection mechanism is based on the fact that AuNPs can quench the fluorescence of UCNPs. AChE catalyzes the hydrolysis of acetylthiocholine (ATC) into thiocholine which reacts with AuNPs by S-Au conjunction and results the aggregation of AuNPs and change in fluorescence of UCNPs.

Rapid and highly-sensitive uric acid sensing based on enzymatic catalysis-induced upconversion inner filter effect.

In this work, a novel and simple fluorescence method for detection of uric acid (UA) based on NaYF4:Yb(3+), Tm(3+) upconversion nanoparticles (UCNPs) is developed. The proposed method is based on the fact that uricase can oxidize uric acid to allantoin and hydrogen peroxide, which, on its turn, can oxidize o-phenylenediamine (OPD) to the oxidized OPD (oxOPD). The fluorescence of UCNPs can be significantly quenched by oxOPD through inner filter effects (IFE).