Letao Wang

Sensitive detection of acetaminophen based on Fe3O4 nanoparticles-coated poly(diallyldimethylammonium chloride)-functionalized graphene nanocomposite film

An electrochemical sensor based on Fe(3)O(4) nanoparticles (NPs)-coated poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (Fe(3)O(4)-PDDA-G) nanocomposite was fabricated for sensitive detection of acetaminophen. The nanocomposite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The electrochemical behaviors of acetaminophen on Fe(3)O(4)-PDDA-G composite film modified glassy carbon electrode (GCE) were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The experimental results indicated that the incorporation of Fe(3)O(4) NPs with PDDA-G greatly enhanced the electrochemical response of acetaminophen. This fabricated sensor displayed excellent analytical performance for acetaminophen detection over a range from 0.1 to 100 μ mol L(-1) with a detection limit of 3.7×10(-8) mol L(-1) (S/N=3). The redox peaks of acetaminophen, dopamine (DA) and ascorbic acid (AA) can be well separated on the Fe(3)O(4)-PDDA-G/GCE. Moreover, the proposed electrochemical sensor also exhibited good reproducibility and stability, and has been used to detect acetaminophen in tablets with satisfactory results.

Synthesis of PtAu bimetallic nanoparticles on graphene-carbon nanotube hybrid nanomaterials for nonenzymatic hydrogen peroxide sensor

PtAu bimetallic nanoparticles (NPs) were successfully synthesized on graphene sheets-multi walled carbon nanotubes (G-CNTs) hybrid nanomaterials via a simple one-step chemical co-reduction method in ethylene glycol (EG)-water system. The nanocomposites (PtAu/G-CNTs) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Then a sensitive nonenzymatic hydrogen peroxide (H2O2) sensor was fabricated based on PtAu/G-CNTs nanocomposites modified glassy carbon electrode (GCE). The results of electrochemical experiments demonstrated that the sensor exhibited excellent electrocatalytic activity to the reduction of H2O2. The sensor displayed a fast amperometric response time of less than 4s with linear detection range from 2.0 to 8561 μM and a relatively low detection limit of 0.6 μM (S/N=3). In addition, the sensor also showed good selectivity for H2O2 detection, long-term stability and reproducibility.

Sensitive determination of vanillin based on an arginine functionalized graphene film

An arginine (Arg) functionalized graphene (Arg-G) nanocomposite was produced successfully and the procedure was environment-friendly. An electrochemical sensor based on the Arg-G nanocomposite was developed for the determination of vanillin. The Arg-G modified glassy carbon electrode (GCE) showed excellent sensitivity properties by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under the optimized conditions, the oxidation peak current was proportional to vanillin concentration in the range of 2.0 × 10−6 to 7.0 × 10−5 mol L−1 with the correlation coefficient of 0.9986 and the detection limit of 1.0 × 10−6 mol L−1 (S/N = 3). Moreover, the sensor could be used for the detection of vanillin in real food samples with satisfactory results.

Point-of-Care Determination of Acetaminophen Levels with Multi-Hydrogen Bond Manipulated Single-Molecule Recognition (eMuHSiR)

This work aims to face the challenge of monitoring small molecule drugs accurately and rapidly for point-of-care (POC) diagnosis in current clinical settings. Overdose of acetaminophen (AP), a commonly used over the counter (OTC) analgesic drug, has been determined to be a major cause of acute liver failure in the US and the UK. However, there is no rapid and accurate detection method available for this drug in the emergency room. The present study examined an AP sensing strategy that relies on a previously unexplored strong interaction between AP and the arginine (Arg) molecule. It was found that as many as 4 hydrogen bonds can be formed between one Arg molecule and one AP molecule. By taking advantages of this structural selectivity and high tenability of hydrogen bonds, Arg, immobilized on a graphene surface via electrostatic interactions, was utilized to structurally capture AP. Interestingly, bonded AP still remained the perfect electrochemical activities. The extent of Arg-AP bonds was quantified using a newly designed electrochemical (EC) sensor. To verify the feasibility of this novel assay, based on multihydrogen bond manipulated single-molecule recognition (eMuHSiR), both pharmaceutical and serum sample were examined. In commercial tablet measurement, no significant difference was seen between the results of eMuHSiR and other standard methods. For measuring AP concentration in the mice blood, the substances in serum, such as sugars and fats, would not bring any interference to the eMuHSiR in a wide concentration range. This eMuHSiR method opens the way for future development of small molecule detection for the POC testing.