Chunxiao Yan

CuO Nanostructures As Quartz Crystal Microbalance Sensing Layers for Detection of Trace Hydrogen Cyanide Gas

In this work, quartz crystal microbalance (QCM) sensors for detection of trace hydrogen cyanide (HCN) gas were developed based on nanostructural (flower-like, boat-like, ellipsoid-like, plate-like) CuO. Responses of all the sensors to HCN were found to be in an opposite direction as compared with other common volatile substances, offering excellent selectivity for HCN detection. The sensitivity of these sensors is dependent on the morphology of CuO nanostructures, among which the plate-like CuO has the highest sensitivity (2.26 Hz/μg). Comparison of the specific surface areas of CuO nanostructures shows that CuO of higher surface area (9.3 m(2)/g) is more sensitive than that of lower surface area (1.5 m(2)/g), indicating that the specific surface area of these CuO nanostructures plays an important role in the sensitivity of related sensors. On the basis of experimental results, a sensing mechanism was proposed in which a surface redox reaction occurs between CuO and Cu(2)O on the CuO nanostructures reversibly upon contact with HCN and air, respectively. The CuO-functionalized QCM sensors are considered to be a promising candidate for trace HCN gas detection in practical applications.

Single crystal WO3 nanoflakes as quartz crystal microbalance sensing layer for ultrafast detection of trace sarin simulant

Tungsten oxide (WO(3)) nanoflakes were synthesized, and characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Thermogravimetry and X-ray photoelectron spectroscopy demonstrate the existence of strongly bound surface water molecules on the surface of tungsten oxide nanoflakes. WO(3) nanoflake functionalized quartz crystal microbalance sensors were fabricated, and firstly used for detection of trace sarin simulant, dimethyl methylphosphonate (DMMP). The sensors have better reproducibility and stability as well as much shorter response (30s) and recovery time (73s) than those functionalized by conventional hydrogen-bond acidic branched copolymers. The strongly bound surface water molecules on the surface of WO(3) nanoflakes are believed to play a key role in achieving such excellent DMMP sensing characteristics.

Hydrothermal synthesis of nanostructured flower-like Ni(OH)2 particles and their excellent sensing performance towards low concentration HCN gas

Hierarchically structured Ni(OH)2 particles with a well-defined flower-like morphology were synthesized via a hydrothermal route. The molar ratio of SDBS/Ni, hydrothermal temperature and reaction time were found to have a profound influence on the size and morphology of the resulting products. These hierarchically structured flower-like Ni(OH)2 were employed on quartz crystal microbalance resonators for HCN sensing. The flower-like Ni(OH)2 modified QCM resonators exhibited excellent sensing performance. The sensitivity of flower-like Ni(OH)2 modified QCM resonators has reached 5.14 Hz (μg ppm)−1, nearly 40-fold as high as previous reports. The high sensitivity is attributed to its high specific surface area (61 m2 g−1), special morphology and especially to its surface structure. A sensing mechanism that involves surface vacancy sites and their adsorption and activation of oxygen molecules was proposed on the basis of experimental results. Effects of relative humidity show high tolerance of the sensors to relative humidity. The prefect linear relationship between response signal (ΔF) and HCN concentration, and a fast and sensitive response to low concentration HCN coupled with high selectivity show a promising future for these Ni(OH)2 modified QCM resonators in the detection of trace gaseous HCN.

Functionalized photonic crystal for the sensing of Sarin agents

The indiscriminate use of nerve agents by terrorist groups has attracted attention of the scientific communities toward the development of novel sensor technique for these deadly chemicals. A photonic crystal (PhC) hydrogel immobilized with butyrylcholinesterase (BuChE) was firstly prepared for the sensing of Sarin agents. Periodic polystyrene colloidal (240nm) array was embedded inside an acrylamide hydrogel, and then BuChE was immobilized inside the hydrogel matrix via condensation with 3-(diethoxyphosphoryloxy)-1,2,3-benzotriazin-4(3h)-one (DEPBT). It indicated that a total of 3.7 units of BuChE were immobilized onto the PhC hydrogel. The functionalized hydrogel recognized the Sarin agent and then shrunk, thus the diffraction of PhC hydrogel blue shifted significantly, and a limit of detection (LOD) of 10(-15)molL(-1) was achieved.

Photonic crystal hydrogel sensor for detection of nerve agent

Nowadays the photonic crystal hydrogel materials have shown great promise in the detection of different chemical analytes, including creatinine, glucose, metal ions and so on. In this paper, we developed a novel three-dimensional photonic crystal hydrogel, which was hydrolyzed by sodium hydroxide (NaOH) and immobilized with butyrylcholinesterase (BuChE) by 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride(EDC). They are demonstrated to be excellent in response to sarin and a limit of detection(LOD) of 1×10−9 mg mL−1 was achieved.

Acetylcholinesterase-functionalized two-dimensional photonic crystals for the detection of organophosphates

Due to the indiscriminate usage of organophosphates in military and agriculture, there is an increasing demand to develop sensors for monitoring organophosphorus nerve agents and pesticides. Herein, a sensitive two-dimensional photonic crystal (2D-PC) biosensor as a part of a portable device for the detection of Dipterex is presented. The 2D-PC array was self-organized on the water–air interface using 600 nm polystyrene (PS) colloidal particles, and it was further embedded into a polyacrylamide-acrylic acid (PAM-AA) hydrogel. After condensation between the amine groups of acetylcholinesterase (AChE) and the carboxyl groups of the hydrogel, a novel sensing platform of 2D-PC hydrogel with AChE as the recognition agent was constructed. The lattice spacing of AChE-functionalized 2D-PC was inversely proportional to the logarithm of the Dipterex concentration from 10−14 mol L−1 to 10−4 mol L−1 with estimated limit of detection (LOD) of 7.7 × 10−15 mol L−1. Simultaneously, the structural color of AChE-functionalized 2D-PC varied from yellow to blue. The biosensor achieved “naked-eye” detection due to which the use of AChE-functionalized 2D-PC is a promising technique for onsite and fast screening of organophosphates.

Study on a Photonic Crystal Hydrogel Material for Chemical Sensing

There is intense interest in the applications of photonic crystal hydrogel materials for the detection of glucose, metal ions, organophosphates and so on. In this paper, monodisperse polystyrene spheres with diameters between 100 ~ 440 nm were synthesized by emulsion polymerization. Highly charged polystyrene spheres readily self-assembled into crystalline colloidal array because of electrostatic interactions. Photonic crystal hydrogel materials were formed by polymerization of acrylamide hydrogel around the crystalline colloidal arrays of polystyrene spheres. After chemical modification of hydrogel backbone with carboxyl groups, our photonic crystals hydrogel materials are demonstrated to be excellent in response to pH and ionic strength changes.

2-Allylhexafluoroisopropanol Treated Photonic Crystal Material for DMMP Detection

Some photonic crystal materials are developed as chemical detection materials. Varies of sensitive chemical group can be used for varies of chemical detection. In this paper, Polystyrene particles in 240 nm size were prepared firstly. The polystyrene particles were self-assembled into crystalline colloidal arrays. A kind of fluoride-bearing chemical, 2-Allylhexafluoroisopropanol, were induced to the Polystyrene crystalline colloidal arrays. Then the diffraction properties were test. After treated by 2-Allylhexafluoroisopropanol, the Polystyrene crystalline colloidal arrays get a change of diffraction in both the wavelength and the intensity. When exposed to saturated vapor of DMMP.

Carbon Dioxide Adsorption Behavior of Modified HKUST-1

A kind of typical metal-organic frameworks (MOFs) material, HKUST-1 was prepared by hydrothermal method and characterized by XRD and SEM. The results of characterizations manifested that HKUST-1 showed a regular octahedral crystal structure. The as-prepared HKUST-1 was modified by several kinds of organic base materials and the CO2 adsorption behaviors of modified HKUST-1 materials were evaluated. The CO2 adsorption capacities of different base modified HKUST-1 varied with the base intensity of modified organic base materials.