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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]

sCPP1b is a selenized derivative of pectic polysaccharide (CPP1b) that is isolated from Wen-Codonopsis pilosula. In this study, A549 cells were used for in vitro studies on cytotoxicity, cell morphology, cell migration, cycle distribution, apoptosis, and expression of apoptosis-associated proteins after treatment with CPP1b and sCPP1b. Results show that sCPP1b and CPP1b could change cell morphology, suppress cell migration, induce cell apoptosis, and block the cell cycle. CPP1b and sCPP1b induced apoptosis on A549 cells through upregulation of caspase-3 and Bax and downregulation of Bcl-2 proteins. sCPP1b possessed stronger antitumor activity than CPP1b. [ABSTRACT FROM PUBLISHER]

Abstract: A simple and environmentally friendly synthetic route for the preparation of gelatin functionalized graphene nanosheets (gelatin-GNS) was reported by using exfoliated graphene oxide as a precursor, in which gelatin acted as not only a reducing reagent but also a functionalization reagent to guarantee good dispersibility and stability of the GNS in distilled water and various physiological solutions. The obtained biocompatible gelatin-GNS attaching methotrexate (MTX) via strong π-π stacking interaction, exhibited a high drug loading capacity of MTX and excellent ability for controlled drug release. The pH-dependent release behavior of MTX from MTX@gelatin-GNS showed that the release amount under acid conditions is much higher than that under neutral conditions, which experienced a gelatin-mediated sustained release process. From the cytotoxicity assay, we can see that the MTX@gelatin-GNS showed remarkable toxicity while the gelatin-GNS showed nontoxic at appropriate concentration, both of them might be taken up by A549 cells through a nonspecific endocytosis process. The prepared nanohybrids system offers a novel formulation that combines the unique properties of a biodegradable material, gelatin, and graphene for biomedical applications. Therefore, the gelatin-GNS with good stability and biocompatibility can be selected as an ideal drug carrier to be applied in biomedicine studies. [Copyright &y& Elsevier]

Preparation methods and catalysis activity of the photocatalyst of nanometer TiO2/conjugated polymer complex were studied in the present research. The target catalyst could be activated by absorbing both ultraviolet and visible light (190–700 nm), whereas pure TiO2 absorbs ultraviolet rays (<380 nm) only. Furthermore, studies showed that the photocatalyst employed in this paper could depigmentize methyl orange solution in a few minutes under visible light. TiO2/conjugated polymer complex was a photocatalyst with high catalytical activity. The temperature of calcination plays an important role in depigmentation. The effect is summarized as—520≥560≫600>480≫440≫400 °C. The effect contributed to the TiO2 structure form changes and the increase of the degree of polymer conjugation. [Copyright &y& Elsevier]

CPP1b is a pectic polysaccharide isolated from Codonopsis pilosula , and it possesses potent antitumor activity. In this study, a HNO 3 –Na 2 SeO 3 method was performed to synthesize selenium–CPP1b (sCPP1b). The effects of BaCl 2 usage amount and HNO 3 concentration on the yield and selenium content of sCPP1b were investigated by single-factor experiments. Reaction time, reaction temperature and the ratio of polysaccharide to Na 2 SeO 3 were optimized by orthogonal experimental design at three levels of each of the three factors (L 9 (3) 4 ) based on antitumor activity, selenium content and yield of sCPP1b. Our results showed that 5 h of reaction time, 60 °C of reaction temperature, and 2:2 ratio of polysaccharide to Na 2 SeO 3 were the optimal selenylation modification conditions. The validation experiments completed under the optimal conditions gave the mean selenium content and yield of sCPP1b were 478.17 μg/g (RSD = 5.7%) and 595 mg/g (RSD = 1.6%), respectively. Selenylation modification can significantly increase the antitumor activity of CPP1b in vitro . The structural characterization of sCPP1b was further characterized by Fourier-transform infrared spectroscopy, thermogravimetric analysis, and high-performance gel permeation chromatography coupled with multi-angle laser light scattering. These structure analysis results indicated that sCPP1b has been successfully selenylation modified with similar structure to polysaccharide of CPP1b. [ABSTRACT FROM AUTHOR]

An electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE) was used as a new voltammetric sensor for the determination of ferulic acid (FA). The morphology and microstructure of the modified electrodes were characterized by scanning electron microscopy (SEM) and Raman spectroscopy analysis, and the electrochemical effective surface areas of the modified electrodes were also calculated by chronocoulometry method. Sensing properties of the electrochemical sensor were investigated by means of cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that ERGO was electrodeposited on the surface of GCE by using potentiostatic method. The proposed electrode exhibited electrocatalytic activity to the redox of FA because of excellent electrochemical properties of ERGO. The transfer electron number (n), electrode reaction rate constant (ks) and electron-transfer coefficient (α) were calculated as 1.12, 1.24s(-1), and 0.40, respectively. Under the optimized conditions, the oxidation peak current was proportional to FA concentration at 8.49 × 10(-8)mol L(-1) to 3.89 × 10(-5)mol L(-1) with detection limit of 2.06 × 10(-8)mol L(-1). This fabricated sensor also displayed acceptable reproducibility, long-term stability, and high selectivity with negligible interferences from common interfering species. The voltammetric sensor was successfully applied to detect FA in A. sinensis and biological samples with recovery values in the range of 99.91%-101.91%., (Copyright © 2014 Elsevier B.V. All rights reserved.)