Temperature- and pH-Sensitive Nitrogen and Sulfur Codoped Carbon Quantum Dots for Sequential Detection of Fe³⁺ and H₂S

Abstract

In this study, nitrogen and sulfur codoped carbon quantum dot (N,S-CQD) fluorescent nanoprobes were synthesized through a one-step hydrothermal method using l-cysteine and α-methacrylic acid as raw materials, and an “on–off–on” fluorescence mechanism was designed using N,S-CQDs for sequential determination of Fe3+ and H2S in human serum. The quenching process (on–off) and mechanism of N,S-CQDs by Fe3+ were studied via fluorescence spectroscopy, zeta potential, cyclic voltammetry, and orbital energy level simulation. Meanwhile, an “off–on” strategy for the N,S-CQD/Fe3+ fluorescence sensing platform was constructed for the determination of the H2S-based “on–off” mechanism. This study not only achieved highly selective detection of Fe3+ and H2S over a wide concentration range of 0–250, 250–500, and 2.5–900 μM, respectively, but also improved our understanding on the specific identifications between N,S-CQDs, Fe3+, and H2S. What is more, it was found that N,S-CQDs also possessed pH and temperature sensing performance. Finally, N,S-CQD fluorescent nanoprobes were successfully applied for the determination of Fe3+ and H2S in spiked serum samples, which also proved their potential application in medical diagnosis and biosensors.

Carbon quantum dots aqueous solution as electrolyte for H2O2 production based on photoelectrochemical water splitting

“…26,27 Another clear signal at ∼3689 cm −1 belonged to the stretching vibrations for the N-H bond in -NH-C or -CONH-. 35 Similar signals were observed in 4-CQDs (Fig. S3b †), although with slight shi.…”

Design of a Synthetic Strategy to Achieve Enhanced Fluorescent Carbon Dots with Sulfur and Nitrogen Codoping and Its Multifunctional Applications

“…[ 47 ] As shown in Figure 2d, the S 2p fitted bands could be divided into ≈162.2, 163.1, 164.4, and 167.8 eV, corresponding to S 2p 1/2 , S 2p 3/2 , CS, and SO. [ 56 ] After XPS and FT‐IR analysis, these results indicated the successful doping of S elements.…”

Rose Bengal‐Derived Carbon Quantum Dots as a Fluorescence Probe for the Highly Sensitive Detection of Fe3+ Ions

“…We have cited additional references within the Supporting Information [51–88] . The Supporting Information includes: 1.…”