Xiaojing Lu

Electrochemical sensor for paracetamol recognition and detection based on catalytic and imprinted composite film

A new strategy for a composite film based electrochemical sensor was developed in this work. A layer of conductive film of poly(p-aminobenzene sulfonic acid) (pABSA) was electropolymerized onto glassy carbon electrode surface and exhibited a high electrocatalytic active for paracetamol (PR) redox. The subsequent formation of a layer of molecular imprinted polymer (MIP) film on pABSA modified electrode endowed the sensor with plentiful imprinted cavities for PR specific adsorption. The advantages of the composite film made the prepared sensor display high sensitivity and good selectivity for PR detection and recognition. Under the optimal conditions, the sensor could recognize PR from its interferents. A linear ranging from 5.0 × 10(-8) to 1.0 × 10(-4)mol/L for PR detection was obtained with a detection limit of 4.3 × 10(-8)mol/L. The sensor has been applied to analyze PR in tablets and human urine samples with satisfactory results. The simple, low cost, and efficient strategy reported here can be further used to prepare electrochemical sensors for other compounds recognition and detection.

CD/AuNPs/MWCNTs based electrochemical sensor for quercetin dual-signal detection

A dual-signal strategy was developed in the present work for quercetin (QR) electrochemical recognition and detection. Mercapto-β-cyclodextrin (HS-β-CD) self-assembled on gold nanoparticles and multi-walled carbon nanotubes modified electrode surface to fabricate an electrochemical sensor. Scanning electron microscope, electrochemical impedance spectroscopy, and cyclic voltammetry were employed to characterize the preparation process of the sensor. Hydroquinone (HQ) was chosen as an electrochemical marker for QR detection due to its small molecular size for the formation of inclusion with HS-β-CD. The results of UV-vis and differential pulse voltammetry demonstrate that the added QR can replace the included HQ in CD cavities, resulting in the dual-signal in electrochemical experiments composed of the decrease of oxidized current of HQ and the increase of oxidized current of QR. Compared with the sensor for QR detection in the absence of HQ, the sensor based dual-signal strategy exhibited a higher sensitivity with a wider detection range from 5.0 × 10(-9) to 7.0 × 10(-6)mol/L. With good selectivity, reproducibility, and stability, the sensor was applied for real samples detection with satisfactory results. The proposed dual-signal strategy can be readily extended to the selective recognition and sensitive detection of other molecules.

“Sign-on/off” sensing interface design and fabrication for propyl gallate recognition and sensitive detection

A new strategy based on sign-on and sign-off was proposed for propyl gallate (PG) determination by an electrochemical sensor. The successively modified poly(thionine) (PTH) and molecular imprinted polymer (MIP) showed an obvious electrocatalysis and a good recognition toward PG, respectively. Furthermore, the rebound PG molecules in imprinted cavities not only were oxidized but also blocked the electron transmission channels for PTH redox. Thus, a sign-on from PG current and a sign-off from PTH current were combined as a dual-sign for PG detection. Meanwhile, the modified MIP endowed the sensor with recognition capacity. The electrochemical experimental results demonstrated that the prepared sensor possessed good selectivity and high sensitivity. A linear ranging from 5.0×10(-8) to 1.0×10(-4)mol/L for PG detection was obtained with a limit of detection of 2.4×10(-8)mol/L. And the sensor has been applied to analyze PG in real samples with satisfactory results. The simple, low cost, and effective strategy reported here can be further used to prepare electrochemical sensors for other compounds selective recognition and sensitive detection.