Surface Of CdS Quantum Dots Research Articles

Ultrasensitive electrochemiluminescence biosensor based on dual quenching effects of silver nanoclusters and multiple cycling amplification for detection of ATP

In this work, an electrochemiluminescence (ECL) biosensor based on dual ECL quenching effects of silver nanoclusters (Ag NCs) and multiple cycling amplification was designed to achieve ultrasensitive detection of ATP. The specific recognition of target ATP to aptamer initiated multiple cycling amplification, and a small amount of target was converted into a large number of DNA product chains (S1) by amplification. After S1 opened hairpin DNA 2 (HP2), Ag NCs approached the surface of CdS quantum dots (QDs) modified-electrode by complementary DNA, resulting in a significant decrease of ECL intensity from CdS QDs. The quenching principle is as follows. Firstly, the absorption spectrum of Ag NCs overlaps well with the ECL emission spectrum of CdS QDs, leading to effective ECL resonance energy transfer (ECL-RET); Secondly, Ag NCs could catalyze electrochemical reduction of K2S2O8, leading to consumption of ECL co-reactant and reducing ECL of QDs. The double-ECL quenching achieved ultrasensitive biosensing detection of ATP with a wide range from 1 aM to 1 pM. This present work reported new principle of double-quenching QDs ECL by Ag NCs, and developed a novel ECL biosensor by combining with multiple cycle amplification technique, which has great contribution to the development of QDs ECL and biosensing applications.

In-suit photodeposition of MoS2 onto CdS quantum dots for efficient photocatalytic H2 evolution

Photocatalytic hydrogen (H2) production from water is an appealing approach to alleviate the ever-increasing fossil fuel crisis. The development of visible-light-driven photocatalytic system is an essential task for H2 generation. CdS quantum dots (QDs) are excellent candidate for photocatalytic H2 generation. However, the photocatalytic performance of CdS QDs is largely limited by serious charge recombination and photocorrison problems. Herein, we developed a facile method for photodeposition of MoS2 onto CdS QDs. The in-suit photodeposition approach enables thin-layered MoS2 to be intimately decorated onto the CdS QD surface. The intimate contact favors the formation of junctions between CdS and MoS2, thus promoting charge separation in CdS/MoS2. Furthermore, the MoS2 catalysts can provide highly active catalytic sites for H2 evolution and serve as protective layer for CdS to restrict photocorrison. The resulted CdS/MoS2 photocatalysts exhibit excellent catalytic activity: the H2 generation rate reaches 13129 μmol h−1 g−1, which is 7.2 times higher than that of the pristine CdS-S QDs. The CdS/MoS2 photocatalysts also possess superior photocatalytic durability under visible light. This work provides a novel method for in-suit growth of MoS2 onto QDs. The surface modification strategy presented here offers new opportunities for developing new-types of photocatalysts based on QDs.

Enhanced Photocatalytic H2 -Production Activity of CdS Quantum Dots Using Sn2+ as Cocatalyst under Visible Light Irradiation.

Herein, oil-soluble CdS quantum dots (QDs) are first prepared through a solvent-thermal process. Then, oil-soluble CdS QDs are changed into water-soluble QDs via ligand exchange using mercaptopropionic acid as capping agent at pH 13. The photocatalytic performance is investigated under the visible light irradiation using glycerol as sacrificial agent and Sn2+ as cocatalyst. No H2 -production activity is observed for oil-soluble CdS QDs. Water-soluble CdS QDs exhibit significantly enhanced hydrogen evolution rate. When the concentration of cocatalyst Sn2+ increases to 0.2 × 10-3 m, the rate of hydrogen evolution reaches 1.61 mmol g-1 h-1 , which is 24 times higher than that of the pristine water-soluble CdS QDs. The enhanced H2 -production efficiency is attributed to the adsorption of Sn2+ ions on the surface of CdS QDs that are further reduced to Sn atoms by photogenerated electrons. The in situ generated Sn atoms serve as photocatalytic cocatalyst for efficient hydrogen generation.

Preparation of photoactive multilayer films with high photocurrent response and detection of thrombin

The CdS quantum dots (QDs) multilayers with high photoelectric conversion efficiency are firstly assembled based on the electrostatic layer-by-layer (LbL) self-assembly between the sequentially adsorbed positively charged Poly(diallyldimethylammonium chloride) (PDDA) and negatively charged CdS quantum dots. The electrodes we fabricated have high photocurrent intensity, which is 8–10 times of the traditional method. Based on CdS QDs multilayers, a sensitive and selective photoelectrochemical (PEC) sensor for thrombin was fabricated by using aptamer (ONS2)-labeled Pt nanoparticles (NPs) as novel energy transfer nanoprobes and thrombin as a ‘protective agent’. In the absence of thrombin, ONS2-labeled Pt NPs could be captured on CdS QDs surface by DNA hybridization between the thrombin aptamer (ONS1) and ONS2 and result in photocurrent quenching of sensing system. After the specific binding of thrombin aptamer and thrombin, however, the Pt NPs could not be captured on CdS QDs surface. The thrombin aptasensor displayed a linear range from 10−10mol/L to 10−15mol/L and a detection limit of 10−16mol/L. Fabrication of QDs multilayers with high photoelectric conversion efficiency is of great significance for the future development of PEC biosensor.