Reversible colorimetric and NIR fluorescent probe for sensing SO2/H2O2 in living cells and food samples

Preservative sulfur dioxide (SO₂) and bleach hydrogen peroxide (H₂O₂) were widely used in the food industry, at the same time, they were also a redox pair in biological systems. Therefore, the reversible sensing SO₂/H₂O₂ was of great significance in food safety and biology. In this paper, a colorimetric and NIR fluorescent dual channels response probe (DCA-Bba) for SO₂/H₂O₂ based on chromene-barbiturate was developed. DCA-Bba exhibited a rapid and sensitive recognition of SO₂, and the adduct DCA-Bba-HSO₃^- could detect H₂O₂ in PBS (with 10 % DMSO, v/v, pH 7.4) solution. The reversible response of DCA-Bba was implemented by HSO₃^- involved 1,4-addition and H₂O₂ induced elimination reaction. DCA-Bba showed a strong red fluorescence based on the intramolecular charge transfer (ICT) process, after the recognition of SO₂, the fluorescence of the adduct was quenched based on the photoinduced electron transfer (PET) process. And importantly, DCA-Bba had been applied for imaging SO₂/H₂O₂ redox cycles in living cells, as well as could detect the levels of SO₂ in white sugar, biscuit, Chinese liquor and red wine samples.

High-Efficiency CdSe Quantum Dots/Fe3O4@MoS2/S2O82- Electrochemiluminescence System Based on a Microfluidic Analysis Platform for the Sensitive Detection of Neuron-Specific Enolase

In this work, based on electrochemiluminescence (ECL) technology and self-assembled portable disease detection chips, a bioactivity-maintained sensing platform was developed for the quantitative detection of neuron-specific enolase. First, we prepared Fe₃O₄@MoS₂ nanocomposites as an efficient catalyst to accelerate the reduction of persulfate (S₂O₈^2-). Specifically, abundant sulfate radicals (SO₄^•-) were generated because of cyclic conversion between Fe²⁺ and Fe³⁺. Meanwhile, MoS₂ nanoflowers with a high specific surface area could not only load more Fe₃O₄ but also solve its agglomeration problem, which greatly improved the catalytic efficiency. Moreover, a biosensor chip was constructed by standard lithography processes for disease detection, which had good sensitivity and portability. According to the above strategies, the developed portable sensing platform played the part of promoting the practical application of bioanalysis in early tumor screening and clinical diagnosis. In addition, we developed a short peptide ligand (NARKFYKG, NAR) to avoid the occupation of antigen binding sites by specifically connecting to Fc fragments in antibodies. Thus, the binding efficiency of antibodies and the activity of biosensors were improved due to the introduction of NAR.

Enzyme Encapsulation by Facile Self-Assembly Silica-Modified Magnetic Nanoparticles for Glucose Monitoring in Urine

Silica nanoparticles hold tremendous potential for the encapsulation of enzymes. However, aqueous alcohol solutions and catalysts are prerequisites for the production of silica nanoparticles, which are too harsh for maintaining the enzyme activity. Herein, a procedure without any organic solvents and catalysts (acidic or alkaline) is developed for the synthesis of silica-encapsulated glucose-oxidase-coated magnetic nanoparticles by a facile self-assembly route, avoiding damage of the enzyme structure in the reaction system. The encapsulated enzyme was characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometry, and a vibrating sample magnetometer. Finally, a colorimetric sensing method was developed for the detection of glucose in urine samples based on the encapsulated glucose oxidase and a hydrogen peroxide test strip. The method exhibited a good linear performance in the concentration range of 20~160 μg mL⁻¹ and good recoveries ranging from 94.3 to 118.0%. This work proves that the self-assembly method could be employed to encapsulate glucose oxidase into silica-coated magnetic particles. The developed colorimetric sensing method shows high sensitivity, which will provide a promising tool for the detection of glucose and the monitoring of diabetes.

Nanoreactor of sarcosine oxidase-embedded ZIFs activates fluorescent response for diagnosis of prostate cancer

A fluorometric method was developed to detect sarcosine based on SOX@ZIF-8, which possessed great linearity, specificity, and easy operation.