University Of Jinan

In this study, a highly sensitive biosensor for the detection of carcinoembryonic antigen (CEA) was developed by integrating the excellent properties of a near-infrared electrochemiluminescence (NIR ECL) substance and a double ECL signal quencher. Silver nanosheets (Ag-Cys) exhibiting NIR electrochemiluminescence were synthesized via a simple chemical reaction using AgNO₃ and l-cysteine (L-Cys) as precursors. The incorporation of L-Cys not only reduces photochemical damage but also preserved the antigen-binding activity, facilitating the construction of a high-performance immunosensor. In addition, copper-based metal-organic frameworks coated with sarcosine oxidase (Cu-MOFs/SOx) was synthesized and employed as a double quencher toward Ag-Cys based on electron transfer and resonance energy transfer mechanisms. The resulting sensor exhibited high sensitivity and selectivity, with a wide linear range of 0.00005-100 ng mL^-1 and a low detection limit of 43.65 fg mL^-1.

The fluctuation of cysteine (Cys) levels in living organisms can serve as an important indicator for early diagnosis and warning of various diseases. Excessive dietary intake of Cys-rich foods may also have potential health impacts. Therefore, it is crucial to develop methods to detect Cys in both organisms and food samples. Due to the structural similarities among biological thiol molecules, it is challenging to develop probes that can distinguish Cys from other biothiols. In this study, we designed and synthesized a novel fluorescent probe MI-Cys with a maleimide group for the specific detection of Cys. The response mechanism of the probe MI-Cys for Cys is the intramolecular cyclization amidation triggered by the Michael addition of Cys. The probe MI-Cys exhibits a good linear relationship for low-concentration Cys (0-1.0 μM) and has been applied in cellular imaging and food detection. This study not only offers an alternative recognition mechanism for constructing highly specific Cys fluorescent probes, but also provides a new approach for future bioimaging applications and food safety.

The strategy of constructing suitable surface heterojunctions for promoting the adsorption and carrier transport capacity can be really conducive to the enhanced gas-sensing properties of SnS₂-based sensors. In the current work, uniform spherical-like SnS₂/CoSnO₃ microflowers with the accelerated electrical conductivity have been fabricated by the modified solvothermal method for effectively detecting triethylamine (TEA) at low operating temperatures. It is found that the response of SnS₂ microflowers to 100 ppm TEA is 4.02 at 120 °C, and the one of SnS₂/CoSnO₃ composites is up to 33.30 at 90 °C. The employment of ultraviolet (UV) light excitation plays a critical role in the reduction of optimal operating temperatures of SnS₂-based samples. For example, pure SnS₂ and SnS₂/CoSnO₃-2(Co/Sn molar ratios of 10 %) display the responses of 5.45 and 53.71-100 ppm TEA at 80 and 60 °C, together with the superior gas selectivity and the rapid response/recovery times of 70/282 and 50/98 s, respectively. Significantly, high response of 13.72 and superior gas stability of SnS₂/CoSnO₃ composites are observed even at room temperature. According to density functional theory (DFT) calculation, CoSnO₃ has higher electrical conductivity, contributing to accelerating the electron transmission rate between materials. The enhanced gas-sensing mechanism is mainly attributed to the available construction of SnS₂-CoSnO₃ heterojunctions with the increased carrier density and adsorption capacity of the materials under UV light irradiation. Both the actual detection verification and gas-sensing devices suggest that the sensors have wide prospects in the practical application of seafood storage evaluation.