Search

A sensitive electrochemical sensor based on bovine serum albumin (BSA)/poly (diallyldimethylammonium chloride) (PDDA) functionalized graphene nanosheets (PDDA-G) composite film modified glassy carbon electrode (BSA/PDDA-G/GCE) had been developed to investigate the oxidative protein damage and protections of protein from damage by flavonoids. The performance of this sensor was remarkably improved due to excellent electrical conductivity, strong adsorptive ability, and large effective surface area of PDDA-G. The BSA/PDDA-G/GCE displayed the greatest degree of BSA oxidation damage at 40 min incubation time and in the pH 5.0 Fenton reagent system (12.5 mM FeSO 4 , 50 mM H 2 O 2 ). The antioxidant activities of four flavonoids had been compared by fabricated sensor based on the relative peak current ratio of SWV, because flavonoids prevented BSA damage caused by Fenton reagent and affected the BSA signal in a solution containing Co(bpy) 3 3 + . The sensor was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). UV–vis spectrophotometry and FTIR were also used to investigate the generation of hydroxyl radical and BSA damage, respectively. On the basis of results from electrochemical methods, the order of the antioxidant activities of flavonoids is as follows: (+)-catechin > kaempferol > apigenin > naringenin. A novel, direct SWV analytical method for detection of BSA damage and assessment of the antioxidant activities of four flavonoids was developed and this electrochemical method provided a simple, inexpensive and rapid detection of BSA damage and evaluation of the antioxidant activities of samples. [ABSTRACT FROM AUTHOR]

Abstract The porous graphene functionalized black phosphorus composite (PG-BP) was successfully synthesized via strong coherent coupling between porous graphene surface plasmons and anisotropic black phosphorus localized surface plasmons by the method of penetration of infrared ray using infrared drying. And it was used to fabricate a novel high-sensitive electrochemical sensor for determination of bisphenol A (BPA) in daily use and biological samples. The PG-BP had been characterized by infrared spectroscopy, Raman, X-ray photoelectron spectroscopic, scanning electron microscopy and energy dispersive spectrometer, indicating that PG-BP with the large specific surface area and good electrical conductivity was successfully prepared. In addition, electrochemical properties of the modified materials are comparably explored by means of impedance spectroscopy and cyclic voltammograms. Under the optimal conditions, BPA was determined quantitatively using differential pulse voltammetry. The results showed that the BPA detection current has a good linear relationship in the range of 4.3 × 10−8–5.5 × 10−5 mol/L with a detection limit of 7.8 × 10−9 mol/L (S/N = 3). Results from the present work illustrate the prominent performance of PG-BP as a sensing channel for BPA sensor application and the huge potential of PG-BP as an electrode material. Graphical abstract Schematic representation of PG-BP/GCE fabrication and electrochemical detection of BPA. Unlabelled Image Highlights • The PG-BP were successfully prepared based on the strong coupling between porous graphene and black phosphorus. • This is the first research on the electrochemical sensors based on PG -BP composite. • The proposed electrochemical sensor exhibited a broad detection range and low detection limit for BPA. • The electrochemical sensor can be used for the sensitive and efficient analysis of BPA in real samples. [ABSTRACT FROM AUTHOR]

In this study, polyaniline functionalized graphene quantum dots composite with excellent performance was successfully prepared by situ polymerized, and it was applied to fabricate electrochemical sensor for analysis of calycosin in the complex samples of traditional Chinese medicine. The polyaniline functionalized graphene quantum dots composite was characterized by Fourier transform infrared spectroscopy and Raman analysis, to indicate that polyaniline functionalized graphene quantum dots composite was successfully synthesized. The morphology and microstructure of the modified electrodes were characterized by Scanning electron microscope and Transmission electron microscope. According to the results of cyclic voltammetry and electrochemical impedance spectroscope, the glassy carbon electrode modified with polyaniline functionalized graphene quantum dots composite significantly increased the electron transfer rate on the surface of sensor. Under the optimized conditions, the fabricated sensor was used for the analysis of calycosin in Radix Hedysari and Radix Astragali by differential pulse voltammetry, which displayed acceptable reproducibility, long-term stability, good selectivity and sensitivity. The proposed sensor exhibited a wide detection range (1.1 × 10 −5 –3.52 × 10 −4  mol/L) with a detection limit of 9.8 × 10 −6  mol/L (S/N = 3). This study provided a novel and convenient method for rapid evaluation of the quality of Radix Hedysari and Radix Astragali . [ABSTRACT FROM AUTHOR]