L-Cysteine-capped CdTe Quantum Dots as a Fluorescence Probe for Determination of Cardiolipin

This paper described the investigation of surface-modified quantum dots (QDs) as a fluorescence probe for the detection of cardiolipin. A single-step method for preparation of non-toxic and photo-stable cadmium telluride (CdTe) QDs capped by L-cysteine in aqueous solution was developed. The prepared QDs were characterized by high-resolution transmission electron microscopy, X-ray diffraction spectrometry, Fourier transform infrared spectrometry and spectrofluorometry. These functional QDs were used as a fluorescence probe for cardiolipin determination based on the fluorescence quenching. The optimum fluorescence intensity was found to be at pH 7.4 with QDs concentration of 4 × 10−5 mol L−1. The effect of other phospholipids on the intensity of CdTe QDs showed a low interference response. Under optimized conditions, the quenched fluorescence intensity was linear with the concentration of cardiolipin in the range of 1.33 × 10−7 − 10.4 × 10−7 mol L−1 (r = 0.9976) and a detection limit (S/N = 3) of 18.5 nmol L−1. The proposed method was applied to the determination of cardiolipin content of HepG2 cell samples before and after oxidative stress with satisfactory results.