Zunzhong Ye

A portable electrochemical immunosensor for rapid detection of trace aflatoxin B1 in rice

To explore the possibility of achieving a rapid and in situ detection of aflatoxin B1 (AFB1), a portable biosensing instrument consisting of an impedance detector and a 3D-printed USB-compatible sensor chip was developed. In this study, we proposed an electrochemical biosensor based on screen-printed interdigitated microelectrodes (SPIMs) and a portable detector to achieve low-cost, highly selective and sensitive detection of AFB1 in rice. Under optimized conditions, the immunosensor provided a detection limit of 5 ng mL−1, which was below the allowable concentration. The total detection time including incubation was less than 1 h. The results obtained from this developed portable detection system were comparable to those from a commercial electrochemical station in the laboratory. Hence, the portable detector offers new tools for detection of a wide variety of analytes in clinical and environmental samples.

Solvent sensors based on amorphous ZnSnO thin-film transistors

Amorphous zinc–tin oxide (a-ZTO) thin-film transistors (TFTs) were prepared using a combustion solution method. The properties of the a-ZTO films and a-ZTO TFTs were studied in detail. For applications, a-ZTO TFTs are used as solvent sensors. The a-ZTO TFTs exhibited strong sensitivity and selectivity in detecting solvents (e.g., cyclohexane, ethanol, and deionized water). The electron donors in the ZTO channels were determinated by the polarity of the solvent, which affects the location of the Femi level (Ef). Moreover, a feasible mechanism model related to the electron transfer channel (ETC) was proposed to explain the sensor behaviours. This model can be applied to most of the amorphous oxide TFT sensors. This work is expected to not only provide an insight into the fundamental understanding of the behaviours of amorphous oxide TFT biosensors, but also to offer a basic design guideline for device fabrication in this system.

Design and Elementary Evaluation of a Highly-Automated Fluorescence-Based Instrument System for On-Site Detection of Food-Borne Pathogens

A simple, highly-automated instrument system used for on-site detection of foodborne pathogens based on fluorescence was designed, fabricated, and preliminarily tested in this paper. A corresponding method has been proved effective in our previous studies. This system utilizes a light-emitting diode (LED) to excite fluorescent labels and a spectrometer to record the fluorescence signal from samples. A rotation stage for positioning and switching samples was innovatively designed for high-throughput detection, ten at most in one single run. We also developed software based on LabVIEW for data receiving, processing, and the control of the whole system. In the test of using a pure quantum dot (QD) solution as a standard sample, detection results from this home-made system were highly-relevant with that from a well-commercialized product and even slightly better reproducibility was found. And in the test of three typical kinds of food-borne pathogens, fluorescence signals recorded by this system are highly proportional to the variation of the sample concentration, with a satisfied limit of detection (LOD) (nearly 102–103 CFU·mL−1 in food samples). Additionally, this instrument system is low-cost and easy-to-use, showing a promising potential for on-site rapid detection of food-borne pathogens.

Portable and amplicon contamination prevention cartridges for DNA amplification coupled to lateral flow detection

An appropriate amount of oil sealed on the solution surface does not affect lateral-flow dipstick (LFD) detection. With this property, three types of enclosed and portable cartridges for DNA amplification coupled to LFD detection were realized to detect DNA amplicons specifically.

A fast and visual method for duplex shrimp pathogens detection with high specificity using rapid PCR and molecular beacon

Molecular diagnosis of genome is one of the major methods for pathogens detection. The commonly used PCR method can realize an exponential amplification of the target gene but is time-consuming. In this work, we proposed a duplex and visual method using rapid PCR combined with molecular beacons to specifically detect two kinds of shrimp pathogens in one reaction tube. We only need to observe the fluorescence change of the reaction tube with naked eye to determine the result. A home-made automatic transfer equipment allows reaction tubes shuttling quickly between two water baths to achieve rapid PCR amplification. A simple device was also designed to present the detection results easily determined with naked eye. This duplex and visual detection method is fast, low-cost and of high specificity. From DNA extraction to results judgment, only 15 min was enough. Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV) and Vibrio parahaemolyticus (VP) are two common shrimp pathogens which were chosen as our detection objects. This method may give a possibility to conduct end-point visual duplex detection, which may make a positive influence on the pathogen prevention.

Detection of cephradine through the electrochemical study of the degradation product of cephradine

The degradation product of cephradine(CEP), a broad spectrum antibiotic, with NaOH was studied in solution by Cyclic Voltammetry and Differential Pulse Voltammetry at a three electrode system (Gold working electrode, Hg/HgCl reference electrode and Platinum counter electrode). Our experiment was based on that the R-SH in degradation product could cause a deoxidization peak at gold working electrode. The response was optimized with respect to accumulation time, ionic strength, drug concentration, reproducibility and other variables. We found that the degradation product of CEP in Na2HPO4-NaH2PO4 buffer could cause a sensitive deoxidization peak at -0.68V. A linear dependence of peak currents on the concentration was observed in the range of 10-7 - 10-6 mol/L, with a detection limit of 0.5*10-7mol/L. This method can achieve satisfactory results in the application of detecting human-made CEP.