Peini Zhao

Determination of glyphosate in foodstuff by one novel chemiluminescence-molecular imprinting sensor.

A novel chemiluminescence (CL) sensor for the determination of glyphosate (GLY) was made up based on molecularly imprinted polymer (MIP). The molecularly imprinted microspheres (MIMs) with a small dimension which possess extremely high surface-to-volume ratio were synthesized using precipitation polymerization with GLY as template. And then the MIMs were modified on glass sheets, which were placed at the bottom of wells of microplate as the recognizer. Subsequently, a highly selective and high throughput chemiluminescence (CL)-molecular imprinting (MI) sensor for detection of GLY was achieved. Influencing factors were investigated and optimized in detail. The method can perform 96 independent measurements sequentially in 10 min and the limit of detection (LOD) for GLY was 0.046 μg mL(-1). The relative standard deviation (RSD) for 11 parallel measurements of GLY was 4.68%. The results show that CL-MI sensor can become a useful analytical technology for quick molecular recognition.

A novel high selectivity chemiluminescence sensor for fenvalerate based on double-sided hollow molecularly imprinted materials

Novel fenvalerate double-sided hollow molecularly imprinted microspheres (fenvalerate-DHMIMs) were fabricated by in situ polymerization with the help of mesoporous silica microspheres (MSMs) in this paper for the very first time. Scanning electron microscope was employed to characterize the surface morphology of the fenvalerate-DHMIMs. Taking advantage of the quenching effect of fenvalerate on the luminol-H(2)O(2)-NaOH chemiluminescence system, a new model was established to determine fenvalerate by a highly selective flow injection chemiluminescence method. The traditional flow-through cell was replaced by a novel Y-shaped column. The chemiluminescence intensity was linear with fenvalerate concentration over the range of 5.0 × 10(-8) to 2.0 × 10(-5) g mL(-1) and the detection limit was 2.2 × 10(-8) g mL(-1). The relative standard deviation (RSD) for the determination of 2.0 × 10(-6) g mL(-1) fenvalerate was 1.4% (n = 11). The proposed method was applied to the determination of fenvalerate in real samples with satisfactory results.

Multi-branch chemiluminescence–molecular imprinting sensor for sequential determination of carbofuran and omethoate in foodstuff

A novel chemiluminescence-molecular imprinting (CL–MI) sensor was developed for the sequential determination of two pesticide residue components. One “X” shaped multi-branch flow cell was used to pack two kinds of molecularly imprinted microspheres (MIMs) as the recognition device. The MIMs were synthesized by precipitation polymerization with carbofuran and omethoate as templates, acrylamide as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. The simple operation of the method enhanced the analysis efficiency and the combination of CL and MI resulted in good sensitivity and high selectivity. The application of the CL-MI sensor has very wide prospects. Calibration graphs were obtained over the concentration ranges 4.0 × 10−8 to 9.0 × 10−6 g mL−1 and 1.0 × 10−7 to 9.0 × 10−6 g mL−1 for carbofuran and omethoate, respectively. The limits of detection were 2.5 × 10−8 g mL−1 for carbofuran and 4.2 × 10−8 g mL−1 for omethoate. The proposed method was successfully applied to the sequential determination of both compounds in foodstuff.

A novel high selectivity sensor for tetradifon residues based on double-side hollow molecularly imprinted materials

A sensitive and rapid technique for high selectivity detection of tetradifon has been developed. This method is based on a new kind of hollow shell molecularly imprinted (MI) polymer. In this method, the new hollow shell MI polymer has bigger specific surface areas compared with the traditional one based on the double-sides hollow microspheres structure. The proposed method has the advantage of wider linear range and lower limit of detection compared with the traditional one. The change in chemiluminescence (CL) intensity is linearly proportional with the concentration of tetradifon in the range 0.1∼12 μg mL−1 and the detection limit has reached 0.0483 μg mL−1. The new MI-CL sensor has been successfully applied to the determination of residual tetradifon in food and the results obtained compare well with those by other methods.

Double signal amplification based on palladium nanoclusters and nucleic acid cycles on a μPAD for dual-model detection of microRNAs

MicroRNAs (miRNAs) are a class of significant biomarkers; however, it is still a huge challenge to express them accurately. Herein, a fluorescent/colorimetric dual-model biosensor based upon the quenching effect of graphitic carbon nitride on palladium nanoclusters (Pd NCs) on the platform of a microfluidic paper-based analytical device was built for the detection of miRNAs. On the one hand, Pd NCs could catalyze a chromogenic reaction so that preliminary detection was achieved by the naked eye. On the other hand, the fluorescence analysis combined with nucleic acid cycle signal amplification was required to get precise result and the detection limit is 3 fM, which was superior to the previous method. Whats more, this biosensor could be designed to detect other miRNAs via changing the corresponding aptamer sequences. Therefore, the as-constructed biosensor supplies a versatile platform to conduct point-of-care detection of miRNAs with outstanding performance.