synthesis-of-hierarchical-znocdsse-heterostructure-nanotrees

Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees

A two-step chemical vapor deposition procedure is here employed to prepare tree-like hierarchical ZnO/CdSSe hetero-nanostructures. The structures are ...

University of Delaware

A simple aptasensor for sensitive and selective detection of acetamiprid has been developed based on electrochemical impedance spectroscopy (EIS). To improve sensitivity of the aptasensor, gold nanoparticles (AuNPs) were electrodeposited on the bare gold electrode surface by cycle voltammetry (CV), which was employed as a platform for aptamer immobilization. With the addition of acetamiprid, the formation of acetamiprid-aptamer complex on the AuNPs-deposited electrode surface resulted in an increase of electron transfer resistance (Ret). The change of Ret strongly depends on acetamiprid concentration, which is applied for acetamiprid quantification. A wide linear range was obtained from 5 to 600nM with a low detection limit of 1nM. The control experiments performed by employing the pesticides that may coexist or have similar structure with acetamiprid demonstrate that the aptasensor has only specific recognition to acetamiprid, resulting in high selectivity of the aptasensor. The dissociation constant, Kd of 23.41nM for acetamiprid-aptamer complex has been determined from the differential capacitance (Cd) by assuming a Langmuir isotherm, which indicates strong interaction between acetamiprid and aptamer, further proving high selectivity of the aptasensor. Besides, the applicability of the developed aptasensor has been successfully evaluated by determining acetamiprid in the real samples, wastewater and tomatoes.

A highly selective electrochemical impedance spectroscopy-based aptasensor for sensitive detection of acetamiprid.

In this work, bi-functional SiO2-Pt@meso-SiO2 core-shell nanoparticles were designed to prepare a highly sensitive and selective electrochemical zinc(II) aptasensor. This core-shell structure boasts its SiO2 mesoporous shell and the inside Pt nanoparticles. SiO2 mesoporous shell can fix aptamer without affecting its configuration and can admit electrolyte through the shell. SiO2 core inside can be the substrate of larger amount of Pt nanoparticles that improve the conductivity of the modified electrode dramatically. Due to the application of such a special bi-functional structure and the aptamer's strong combination capacity with Zn(2+), Zn(2+) is pre-enriched onto the electrode effectively and specifically, so that it can be determined sensitively and selectively. Results have shown that the zinc(II) aptasensor can be utilized at a wide linear working range from 100 pM to 50 μM and a low detection limit of 65 pM, which makes it practical in both biological samples and environment monitoring. This method has been successfully applied in Zn(2+) monitoring in human blood and disrupted human cells (MCF-7).

A highly sensitive and wide-ranged electrochemical zinc(II) aptasensor fabricated on core-shell SiO2-Pt@meso-SiO2.

A new tree-like ZnO/CdSSe nanocomposite with CdSSe branches grown on ZnO nanowires prepared via a two-step chemical vapor deposition is presented. The nanotrees (NTs) are vertically aligned on a substrate. The CdSSe branches result in strong visible light absorption and form a type-II heterojunction with the ZnO stem that facilitates efficient electron transfer. A combination of photoluminescence spectroscopy and lifetime measurements indicates that the NTs are promising materials for applications that benefit from a Z-scheme charge transfer mechanism. Vertically aligned branched ZnO nanowires can provide direct electron transport pathways to substrates and allow for efficient charge separation. These advantages of nanoscale hierarchical heterostructures make ZnO/CdSSe NTs a promising semiconductor material for solar cells, and other opto-electronic devices.

Efficient Z-scheme charge separation in novel vertically aligned ZnO/CdSSe nanotrees.

A Kerr-gated microscope capable of imaging ultraviolet luminescence with femtosecond time resolution has been developed. The system allows the spatial, spectral, and temporal measurement of UV-emitting samples. The instrumentation was optimized for emission collection in the UV, resulting in sub 90 fs time resolution of gated signals. ZnO nanowires were used to demonstrate the performance of the instrument. The evolution of the emission from a single nanowire was tracked via ultrafast transient spectroscopy and through sequential imaging. Transient dynamics were extracted from a region of intense emission on a single ZnO nanowire. This technique is a powerful tool capable of contactless ultrafast measurements of charge carrier dynamics in single nanoparticles.

Article	Year
A highly selective electrochemical impedance spectroscopy-based aptasensor for sensitive detection of acetamiprid. Biosensors & bioelectronics\| PubMed ID: 23274191	2013
A highly sensitive and wide-ranged electrochemical zinc(II) aptasensor fabricated on core-shell SiO2-Pt@meso-SiO2. Biosensors & bioelectronics\| PubMed ID: 24077119	2014
Efficient Z-scheme charge separation in novel vertically aligned ZnO/CdSSe nanotrees. Nanotechnology\| PubMed ID: 26894995	2016
Ultraviolet femtosecond Kerr-gated wide-field fluorescence microscopy. Optics letters\| PubMed ID: 27244389	2016

Zhengxin Li

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