Broad-Specificity Screening of Pyrethroids Enabled by the Catalytic Function of Human Serum Albumin on Coumarin Hydrolysis.

Sensing systems based on cholinesterase and carboxylesterase coupled with different transduction technologies have emerged for pesticide screening owing to their simple operation, fast response, and suitability for on-site analysis. However, the broad spectrum and specificity screening of pyrethroids over organophosphates and carbamates remains an unmet challenge for current enzymatic sensors. Human serum albumin (HSA), a multifunctional protein, can promote various chemical transformations and show a high affinity for pyrethroids, which offer a route for specific and broad-spectrum pyrethroid screening. Herein, for the first time, we evaluated the catalytic hydrolysis function of human serum albumin (HSA) on the coumarin lactone bond and revealed that HSA can act as an enzyme to catalyze the hydrolysis of the coumarin lactone bond. Molecular docking and chemical modifications indicate that lysine 199 and tyrosine 411 serve as the catalytic general base and contribute to most of the catalytic activity. Utilizing this enzymatic activity, a broad specific ratiometric fluorescence pyrethroids sensing system was developed. The binding energetics and binding constants of pesticides and HSA show that pyrethroids bind to HSA more easily than organophosphates and carbamates, which is responsible for the specificity of the sensing system. This study provides a general sensor platform and strategy for screening pesticides and reveals the catalytic activity of HSA on the hydrolysis of the coumarin lactone bond, which may open innovative horizons for the chemical sensing and biomedical applications of HSA.

Rapid self-calibrating fluorescent detection of copper (II) ions in wine with high accuracy.

Excessive copper in wine can cause formation of oxidation reactions and affect the quality of wine. Herein, a rapid self-calibrating fluorescence sensing system for the detection of copper (II) ions in wine was developed. The sensing system has a dual-emission peak of 480 nm and 550 nm at the excitation wavelength of 390 nm. Only the yellow fluorescence can be selectively quenched by copper (II) ions. In contrast, the blue fluorescence stays almost constant, resulting in the apparent change of fluorescence image from yellow to blue. The reaction can be completed within 8 s. The sensing system showed a good linear relationship with copper (II) ions concentration in 0-4 µmol/L, with a detection limit of 46.5 nmol/L. Based on this sensing system, a fluorescent dual-tube detection bottle was designed to detect copper (II) ions more conveniently and was successfully applied to detect copper (II) ions in wine.

Low Polarity-Triggered Basic Hydrolysis of Coumarin as an AND Logic Gate for Broad-Spectrum Cancer Diagnosis.

The ability to accurately diagnose cancer is the cornerstone of early cancer treatment. The mitochondria in cancer cells maintain a higher pH and lower polarity relative to that in normal cells. A probe that reports signals only when both conditions are met may provide a reliable method for cancer detection with reduced false positives. Here, we construct an AND logic gate fluorescent probe using mitochondrial microenvironments as inputs. Utilizing the hydrolysis of a coumarin scaffold, the probe generates fluorescence signals ("ON") only when high pH (>7.0) and low polarity conditions exist simultaneously. Additionally, the higher mitochondrial membrane potential in cancer cells provides an additional level of selectivity because probe has increased affinity for cancer cell mitochondria. These capabilities endow the probe with a high contrast fluorescence diagnosis ability of cancer at cellular and tissue levels (as high as 51.9 fold), which is far exceeding the clinic threshold of 2.0 fold.

Simultaneous Detection of Human Serum Albumin and Sulfur Dioxide in Living Cells Based on a Catalyzed Michael Addition Reaction.

As vital important bioactive species, human serum albumin (HSA) and sulfur dioxide (SO2) are essential molecules in the organisms and act a pivotal part in many biological events. Although studies have shown that SO2-induced HSA radicals can cause oxidative damage, the underlying mechanism of the synergistic effect of HSA and SO2 in various diseases is obscure, mainly because of the lack of powerful tools that can simultaneously detect HSA and SO2 in living systems. In this work, we report a novel single-site, double-sensing fluorescent probe 1 for the simultaneous detection of HSA and SO2. The probe is based on our finding that HSA can catalyze a Michael addition reaction between the probe and SO2, which induces a change in fluorescence. Probe 1 can effectively entered the endoplasmic reticulum and can be used to image exogenously introduced and de novo synthesis of HSA in endoplasmic reticulum. Furthermore, the simultaneous detection of HSA and SO2 was realized for the first time with probe 1. More important, we observed that HSA still retains its activity to catalyze the Michael addition reaction of 1 and SO2 in living cells, which may provide a significant boost in the study of the role of HSA in medicine and pharmacy.