Pb2+ Responsive Cu-In-Zn-S Quantum Dots With Low Cytotoxicity

Abstract

Water-soluble Cu-In-Zn-S quantum dots (CIZS QDs) with orange fluorescence have been synthesized with a glutathione (GSH) as stabilizer via facile a one-step hydrothermal method. The optimal reaction conditions of CIZS QDs including temperature, time, pH, and the molar ratios of precursors were studied. TEM results indicate that the aqueous-dispersible CIZS QDs are quasi-spherical, and the average diameters are 3.76 nm with excellent fluorescent stability. Furthermore, the cytotoxicity of CIZS QDs was investigated by the microcalorimetry combining with TEM and the IC50 was 10.2 μM. CIZS QDs showed a promising perspective in applications such as a fluorescent probe for bioimaging and biolabeling due to the low cytotoxicity and good biocompatibility. Moreover, the CIZS QDs can distinguish Pb2+ ion from other ions, offering great potentials in lead ion determination in drinking water. According to the results of UV, XRD, FL, PL, and ITC methods, the mechanism of CIZS QDs-Pb2+ assay is due to hydrogen bonding or van der Waals forces in the formation of Pb2+ and CIZS QDs.

Green Synthesis of Carboxymethyl Chitosan-Based CuInS2 QDs with Luminescent Response toward Pb2+ Ion and Its Application in Bioimaging

“…The decay of the fluorescence lifetime is related to the nonradiative leaps of the surface defects, which can act as trap states for charge carriers since the QD surface contains a large number of dangling bonds . When Pb 2+ comes into contact with the QD surface, the empty orbitals of Pb 2+ can interact with the outer electrons of S 2– , which are captured by a large number of “trap states”, leading to the enhancement of structural defects and thus suppressing the nonradiative jump . The higher surface defects lead to a decrease in the bandgap energy of CMC-CuInS 2 QDs, which is characterized by a rapid decay.…”

“…39 When Pb 2+ comes into contact with the QD surface, the empty orbitals of Pb 2+ can interact with the outer electrons of S 2− , which are captured by a large number of "trap states", leading to the enhancement of structural defects and thus suppressing the nonradiative jump. 40 The higher surface defects lead to a decrease in the bandgap energy of CMC-CuInS 2 QDs, which is characterized by a rapid decay. τ 1 and τ 2 are the fitted lifetimes; QY is the fluorescence quantum yields.…”

Review of the detection of metal ions using fluorescent probes

“…The probe is CIZS-QDs. Quantum dots are semiconductor nano-crystals which have strong quantum confinement effect and unique optoelectronic properties [15]. Due to their high photoluminescence efficiency and their large stokes shift, it is a great source for synthesizing fluorescent probes [15].…”

“…Quantum dots are semiconductor nano-crystals which have strong quantum confinement effect and unique optoelectronic properties [15]. Due to their high photoluminescence efficiency and their large stokes shift, it is a great source for synthesizing fluorescent probes [15]. Quaternary structure of quantum dots are mostly investigated and used in bioimaging and sensors because of their great optical properties.…”

“…Quaternary structure of quantum dots are mostly investigated and used in bioimaging and sensors because of their great optical properties. This probe is synthesized by a single hydrothermal reaction [15]. Optimum conditions of the reaction conditions are investigated by measuring fluorescence intensity.…”