A sensitive chemiluminescence sensor for glutathione detection based on Au supported carbon nitride catalyst

Enhanced electrochemiluminescence of dual-defect graphite carbon nitride for ultrasensitive detection of CEA

Herein, a dual-defective graphite carbon nitride (DDCN) was prepared by polymerization under N2 atmosphere combined with oxidation treatment. The luminous intensity of dual-defect graphite phase carbon nitride based on defect state luminescence is significantly improved compared to CN-air. On this basis, a biosensor for CEA detection was constructed based on specific immunobinding of antigen-antibody. It is noted that the biosensor exhibits a wide linear range of 1 × 10-5 ∼ 1 × 102 ng•mL-1, a low detection limit of 3.3 × 10-4 pg•mL-1, a recovery of 94 %∼105 % and RSD less than 4.41 %. In addition, there was no significant difference to the clinical results, indicating that this work has good clinical application prospects.

O-Phthalaldehyde Derivatization for the Paper-Based Fluorometric Determination of Glutathione in Nutritional Supplements

Herein, a new, direct paper-based fluorimetric method is described for the quantitative determination of glutathione (GSH) molecules in nutritional supplements. Briefly, the proposed analytical method is based on the fluorescence emission resulting from the direct and selective chemical reaction of GSH molecules with the derivatization reagent that is o-phthalaldehyde (OPA) in acidic conditions at room temperature. The intensity of the emitted fluorescence on the surface of the analytical paper devices after irradiation with a lamp at 365 nm is proportional to the concentration of GSH and is measured using a smartphone as the detector. This methodology, which is suitable for measurements in laboratories with limited resources, does not require specialized instrumentation or trained personnel. The protocol governing the proposed method is simple and easily applicable. Essentially, the chemical analyst should adjust the value of pH on the surface of the paper by adding a minimal amount of buffer solution; then, after adding a few microliters of the derivatization reagent, wait for the surface of the paper to dry and, finally, add the analyte. Subsequently, the irradiation of the sensor and the measurement of the emitted fluorescence can be recorded with a mobile phone. In the present study, several parameters affecting the chemical reaction and the emitted fluorescence were optimized, the effect of interfering compounds that may be present in dietary supplements was examined, and the stability of these paper sensors under different storage conditions was evaluated. Additionally, the chemical stability of these paper devices in various maintenance conditions was studied, with satisfactory results. The detection limit calculated as 3.3 S/N was 20.5 μmol L-1, while the precision of the method was satisfactory, ranging from 3.1% (intra-day) to 7.3% (inter-day). Finally, the method was successfully applied to three different samples of dietary supplements.

A rod-like melem with high fluorescence quantum yield for sensitive detection of reduced glutathione

A rod-like melem with high fluorescence quantum yield of 71.3 % was prepared in this work to enhance the chemiluminescence (CL) intensity of Na₂SO₃-Ce (Ⅳ) system. The results showed that the CL intensity of Na₂SO₃-Ce (Ⅳ) system could be increased by 350 times based on chemiluminescence resonance energy transfer (CRET) mechanism. Furthermore, a CL sensor based on Na₂SO₃-Ce (Ⅳ)-melem system was designed to detect reduced glutathione (G-SH). It was indicated that the CL sensor exhibited excellent G-SH detection performance with a detection limit of 0.065 nM and a linear range from 0.32 to 650 μM. This study applied melem for CL detection and provided a new way for the detection of G-SH.

Integration detection of mercury(ii) and GSH with a fluorescent "on-off-on" switch sensor based on nitrogen, sulfur co-doped carbon dots

Using aurine and citric acid as precursors, we have synthesized stable blue-fluorescent nitrogen and sulfur co-doped carbon dots (NS-CDs), with a high quantum yield of up to 68.94% via a thermal lysis method. The fluorescent NS-CDs were employed as a sensitive sensor for the integration detection of Hg2+ and glutathione (GSH). This was attributed to Hg2+ effectively quenching the fluorescence of the NS-CDs by static quenching, and then GSH was able to recover the fluorescence owing to the stronger binding between Hg2+ and the sulfhydryl of GSH. Based on the "on-off-on" tactic, the detection limits of Hg2+ ions and GSH were 50 nM and 67 nM respectively. The fluorescence sensor was successfully applied to detect Hg2+ ions and GSH in actual samples (tap water and fetal bovine serum). Furthermore, we have proved that the sensor had good reversibility. Overall, our NS-CDs can serve as effective sensors for environmental and biological analysis in the future.