Efficient inner filter effect sensors based on CdTeS quantum dots and Ag nanoparticles for sensitive detection of l-cysteine

Abstract

In the design of new fluorescence sensors, exploration of new sensors with excellent performances and smart designs for the detection of ions and biomolecules is of continuing interest. Therefore, we designed an inner filter effect (IFE) based sensor by effectively combining between CdTeS quantum dots (QDs) and Ag nanoparticles (NPs). Ternary alloyed CdTeS QDs were synthesized by two steps and using 3-mercaptopropionic acid (MPA) as stabilizer, polyvinylpyrrolidone (PVP) stabilized Ag NPs were prepared by crystal-seed. The emission peak of CdTeS QDs and the absorption peak of Ag NPs could availably overlap by changing the Te/S molar ratios and l-ascorbic acid (AA) concentrations. The CdTeS QDs/Ag NPs (QNs) with an obviously emission at 580 nm were used as IFE-based sensors for l-cysteine (L-Cys). The QNs fluorescence was increasing with addition of l-Cysteine (L-Cys), the fluorescence (PL) intensity (F/F0) was linearly proportional to the L-Cys concentrations ranging from 20 μM to 400 μM with the correlation coefficient (R2) of 0.9942 and the detection limit was calculated to be 0.025 μM (S/N = 3), where F and F0 were the PL intensity in the presence and absence of L-Cys at 580 nm, respectively. Moreover, there was no interference to some potential interfering substances, which showed high sensitivity and selectivity for L-Cys.