A ratiometric fluorescent probe for pH detection based on Ag ₂ S quantum dots–carbon dots nanohybrids

Abstract

In this study, a novel ratiometric fluorescent nanoprobe for pH monitoring has been developed by synthesizing red fluorescent Ag 2 S quantum dots (Ag 2 S QDs) and green fluorescent carbon dots (CDs) nanohybrids (Ag 2 S CDs) in one pot using CDs as templates. The nanoprobe exhibits dual-emission peaks at 500 and 670 nm under a single-excitation wavelength of 450 nm. The red fluorescence can be selectively quenched by increasing pH, while the green fluorescence is an internal reference. Therefore, the change of the relative fluorescence intensity (I 500 /I 670 ) in the ratiometric Ag 2 S CDs probes can be used for pH sensing. The results revealed that I 500 /I 670 of Ag 2 S CDs probes was linearly related to pH variation between pH 5.4 and 6.8. Meanwhile, the Ag 2 S CDs probes possessed a good reversibility along with pH changing between 5.0 and 7.0 without any interruption from common metal ions, proteins and other interferences.

Carbon dot/inorganic nanomaterial composites

“…The gas sensor prepared by CDs–WO 3 has excellent cycling stability and anti-interference ability. Lei et al 122 constructed a proportional fluorescent nanoprobe for pH detection (Fig. 9c).…”

Carbon dots-based fluorescent films to act as a potential antioxidant agent and pH ratiometric sensor for skin applications

“…It can also be seen from the CIE chromaticity diagram that the emission region of CD-oPD remained in the green region (Figure 4D). Therefore, from these results, it was shown that individual CDs are unable to monitor wound healing efficiently, due to the difficult detection of color and/or fluorescence variations (Song et al, 2017;Lei et al, 2020;Xu et al, 2020;Li et al, 2021).…”

“…In light of the limitations of single-channel nanoparticles, researchers are developing ratiometric sensors to improve the sensitivity of CDs to pH. (Song et al, 2017;Lei et al, 2020;Xu et al, 2020;Li et al, 2021;Silva et al, 2022). Ratiometric fluorescent sensors typically exhibit dual emission bands at different wavelengths (Silva et al, 2022).…”

“…In addition, ratiometric sensors enable rapid detection due to the response of the sample, which can also be seen with the naked eye. From this perspective, they can be applied to the detection of ions, pH, temperature, diseases, etc (Lei et al, 2020;Xu et al, 2020;Li et al, 2021). The advantages of these sensors, combined with the unique properties of CDs, allow the development of new platforms for in situ pH detection in biological systems with high efficiency.…”

Fluorometric assay of cyanophoric pyrethroids based on benzothiazole modified carbon quantum dots

“…Quantum dots (QDs) belong to the family of semiconductor nanocrystals, which are widely used as emerging fluorescent probes. 8 QDs have the advantages of a broad absorption spectrum, size-dependent emission, high quantum yield and high optical stability. [9][10][11] The main disadvantages of traditional QDs with CdSe as the core are their high biotoxicity, low biocompatibility and a complex synthetic pathway.…”