Papers by Author: Ju Lan Zeng

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Authors: Yu Cao, Zhong Cao, Jiao Yun Xia, Ju Lan Zeng, Li Xian Sun
Abstract: Four calixarene supramolecular compounds, RCT, PCT, MRCT, and TBCA as active materials, were immobilized on gold substrates of quartz crystal microbalance (QCM) sensors by using L-cysteine self-assembled monolayer (SAM) as a linker. The RCT immobilized QCM sensor possessed the best response characteristics for methanol molecule when the assembling concentration of RCT reached 1.0 mg/mL. The frequency shift response value of the RCT immobilized QCM sensor was in direct proportion to the concentration of methanol vapor with a range of 0 ~ 6000 ppm. Comparing with a gas chromatography, the proposed QCM sensor could be well used for the determination of methanol vapor with a recovery rate of 98.01 ~ 103.9 %, and the two methods showed a well consistent examination result. Also, the sensor possessed good reproducibility and stability, showing that the RCT immobilized QCM sensor can be applied for the detection of the methanol vapor of atmospheric polutants in our living environment.
Authors: Rui Fen Zou, Zhong Cao, Ju Lan Zeng, Yun Lin Dai, Li Xian Sun
Abstract: The adsorption characteristics of four calixarene supramolecular compounds, like RCT, PCT, MRCT, and TBCA, as coating materials of quartz crystal microbalance sensors responding to isopropanol vapor have been investigated in this paper. The results showed that the RCT was the best coating material for isopropanol vapor when the coating mass reached 20.41 μg. The frequency shift of RCT coated QCM and the concentration of isopropanol vapor had a good linear relationship and sensitivity. Comparing with the gas chromatography, the QCM sensor could be well used for the determination of isopropanol vapor with a recovery rate of 95.22~108.1 %, and the two methods showed a well consistent examination result. Also, the sensor possessed good reversibility, reproducibility and stability, indicating that the RCT coated QCM sensor can be applied for the detection of the atmospheric polutant of isopropanol vapor in practice. The mechanism of the calixarene derivative for recognition of the isopropanol molecule has been preliminarily discussed.
Authors: Zhong Cao, Shu Long, Xiang Shi, Ju Lan Zeng, Li Xian Sun, Rong Hua Yang
Abstract: The electrochemical behaviors and sensing application of 100nm-gold plate electrode based on 6-amino-1-hexanethiol (6-AHT) self-assembled monolayer (SAM) have been investigated in this paper. The 6-AHT assembled nano gold plate electrode exhibited a nice linear potential performance of responding to Hg2+ in the range of 1.0×10-8—1.0×10-6 mol/L with a slope of 42.57 mV/-pC (25°C) in Tris-HCl buffer solution (pH=5.0). No obvious interferences were observed from Na+, K+, Ba2+, Mg2+, Ca2+, and Cr3+. The detection limit can be evaluated to 8.0×10-9 mol/L. In addition, the electrode possessed good stability and reproducibility with a recovery rate of 96.50-103.67%, indicating that it can be used for the determination of Hg2+ content in environmental waste water samples. The sensing mechanism of 6-AHT monolayer has also been discussed by the formation of coordination structure between amino groups of the thiol molecules and the mercury ions.
Authors: Yun Lin Dai, Zhong Cao, Yi Min Dai, Ju Lan Zeng, Wei Gang Huang, Jing Ling Hu, De Liang He, Katsuyuki Aoki
Abstract: Coating with a calixarene derivative on gold surface of AT-cut quartz crystal, a piezoelectric quartz crystal (PQC) sensing device was successfully fabricated in this paper. Among four calixarene materials, the compound of MRCT was the most efficient actively coating material for recognizing ethanol molecule based on a host-guest recognition mechanism with C—H•••π interaction. In comparison with gas-chromatography (GC) method, the calixarene based PQC device can be well used for on-line detection of the ethanol vapor in the range of 0 ~ 3000 ppm around our environment with a recovery of 92.33~105.76 %. The detection limit can be evaluated to be 3.53 ppm. Furthermore, the proposed TSM sensor possessed good selectivity, reproducibility, reversibility and high stability for practical purpose.
Authors: Xi Xi Huang, Zhong Cao, Yong Le Liu, Yi Min Dai, Ju Lan Zeng, Rong Hua Yang, Hiroyuki Takei
Abstract: An novel optical nano biosensor based on gold capped nano-particles for detecting binding events between ligands and receptor molecules as well as interactions among proteins without use of labels has been presented in this paper. The optical properties of nano-sized gold particles exhibiting pronounced adsorption in the visible region which called as localized surface plasmon resonance (LSPR) have been exploited, whose peak wavelengths depended exquisitely on the refractive index of the surrounding. In comparison with surface plasmon resonance (SPR) technology, the optical nano biosensor possessed high sensitivity, surprisingly low “bulk effect”, ease of preparation, and low-cost polymer based fabrication, which opened a promising bioanalytical application in practice.
Authors: Zhong Cao, Li Xian Sun, Ting Zhou, Yong Feng Luo, Ju Lan Zeng, Shu Long, Ji Shan Li
Abstract: An electronic detection method for DNA molecules based on an extended gate field effect transistor (EGFET) sensing chip has been presented in this paper, which consists of one gold plate electrode for molecule recognition and FET part for signal transduction. The DNA probe was prepared by first immobilization of a thiolated single-stranded oligonucleotide (T1) and then an alkanethiol such as 6-hydroxy-1-hexanethiol (6-HHT) on the gold plate. A fast cyclic voltammetry (FCV) was applied to quantification of DNA molecules by using a cathodic peak around -1.3 V at a electrode reaction, corresponding to reductive desorption in strong alkali solution. By using a 70.7 mV DC voltage onto a Ag/AgCl reference electrode, the electronic signals of EGFET were applied to detection of DNA molecules and its hybridization, and the corresponding hybridization efficient was estimated to be about 37.5%. About 1 ~ 4 DNA molecules per 100 nm2 on the Au substrate of EGFET could be counted, showing a promising sensing technique for bio-molecule.
Authors: Zhong Cao, Ju Lan Zeng, Yi Min Dai, Xun Li, Dong Mei Luo
Abstract: The frequency domain power spectra of acoustic emission (AE) signals from different metal-acid reaction processes such as 6111 Al-alloy-hydrochloric acid (HCl) and 7070 Al-alloy-HCl for evolving hydrogen gases were obtained by fast Fourier transform (FFT) program and used for chemical analysis of different metal materials. Averaged power spectra from these processes and their corresponding characteristics were extracted. The characteristic AE frequency signals could be used for chemical pattern recognition of different metal materials like 6111 and 7050 aluminum alloys from the metal-acid reaction processes, that the principal component analysis (PCA) with appropriate frequency selection procedure gave a satisfactory classification with a correct rate of 78.1%. The back-propagation (BP) algorithm of artificial neural network (ANN) could give better recognition of AE signals for 6111 and 7050 alloys with a correct rate of 100%. Moreover, the AE energetic parameters are linearly correlated with the pH value of the acidic buffer solution, which opens a new possibility for quantitatively analytical application of AE signals on metal materials.
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