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A sensitively competitive electrochemical immunosensor for the detection of cortisol was successfully developed based on gold nanoparticles and magnetic functionalized reduced graphene oxide (AuNPs/MrGO). In order to construct the base of the immunosensor, the MrGO was initially fabricated by chemical cross-linking and used to modify the nafion pretreated glassy carbon electrode. Subsequently, the surface of electrode was modified by AuNPs via electrochemical deposition. A variety of cortisol (Cor) can be firmly loaded in the AuNPs/MrGO with large specific surface area and good bioactivity to construct the basic electrode (Cor/AuNPs/MrGO/Nafion@GCE), which was characterized by the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. Due to the cortisol on the surface of basic electrode and samples can competitively combine with the cortisol antibody labelled by horseradish peroxidase (HRP-Strept-Biotin-Ab). Finally, the detection signal of electrochemical immunosensor (HRP-Strept-Biotin-Ab-Cor/AuNPs/MrGO/Nafion@GCE) in the test liquid had negative correlations with the concentration of cortisol in samples. The AuNPs/MrGO with excellent electrical conductivity being applied, the electrochemical response of the immunosensor was immensely amplified. The immunosensor displayed excellent analytical performance for the detection of cortisol range from 0.1 to 1000 ng/mL with a detection limit of 0.05 ng/mL at 3σ. Moreover, compared the developed immunoassay with commercially available enzyme linked immunosorbent assay, the proposed method showed good precision, acceptable stability and reproducibility, indicating the immunosensor could be used for the sensitive, efficient and real-time detection of cortisol in real samples. Therefore, the present strategy provides a novel and convenient method for clinical determination of cortisol. [ABSTRACT FROM AUTHOR]

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]

Highlights: [•] A pectic polysaccharide (CPP1b) from Codonopsis pilosula was at first identified. [•] The chemical structure of CPP1b was elucidated. [•] The ultramicrostructure of CPP1b was described. [•] CPP1b presents potential anti-tumor and adjucant anti-tumor activity. [ABSTRACT FROM AUTHOR]

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]

Abstract: A conjugated polymer/ZnS complex was successfully synthesized and characterized by the methods of FTIR, UV–vis, ESR and TEM. The result showed that the conjugated polymer/ZnS complex could extend the absorption band to the visible region (190–700nm), whereas pure ZnS could be activated under ultraviolet light (<380nm) irradiation only. Photocatalytic experiment showed that the conjugated polymer/ZnS complex had extremely high photocatalytic activity for degradation of dyes. The conjugated polymer played an important role in the photocatalytic degradation of dyes. [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]

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, a novel electrochemical immunosensor for early screening of depression markers-heat shock protein 70 (HSP70) was successfully developed based on the porous graphene (PG) with huge specific surface area and excellent structure. Benefiting from the strong adsorption and good bioactivity of PG which was initially prepared via a simple pyrolysis process, a variety of heat shock protein70 (HSP70) can be firmly loaded on the PG to construct the basic electrode (HSP70/PG/GCE)，which was characterized by the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. Due to the HSP70 fixed on the surface of basic electrode and the HSP70 in the samples can competitively combine with the horseradish peroxidase labeled human HSP 70 antibody (HRP-Strept-Biotin-Ab). As a result, it presented a negative correlation between the concentration of HSP70 in samples and the detection signal of the proposed electrochemical immunosensor (HRP-Strept-Biotin-Ab-HSP70/PG/GCE) in the test liquid. The application of PG with excellent electrical conductivity in construction of immunosensor remarkably improved the sensitivity of the immunosensor for detection of HSP70. The proposed immunosensor demonstrated a wide linear range of 0.0448 ~ 100 ng/mL with a low detection limit of 0.02 ng/mL at 3σ. Moreover, the proposed immunosensor could be applied for the sensitive and efficient detection of HSP70 in real samples with good precision, acceptable stability, reproducibility and satisfactory results. Therefore, the HSP70 immunosensor provides a novel and convenient method for early clinical screening of depression markers-heat shock protein 70. [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]

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]

• ZIF-8@N-Gr with excellent performance was prepared. • ZIF-8@N-Gr can be used in immunosensor development for Apo-A4 detection. • Lower limit of detection and wider linear range than ELISA kit. • Determination of Apo-A4 in plasma with no need for sample treatment. The fabrication of electrochemical biosensors to directly, rapidly and ultrasensitively detect disease markers in urine or blood samples has become a new and competitive challenge in the field of sensor research. In this paper, a novel electrochemical immunosensor with high selectivity and sensitivity for the detection of the depression marker human apolipoprotein A4 (Apo-A4) was successfully constructed using zeolite imidazole ester metal organic skeleton-nitrogen doped graphene composites (ZIF-8@N-Gr). To this end, because of the higher surface area and biocompatibility, ZIF-8 with abundant biomolecular binding sites provided a good microenvironment for effectively immobilizing antigens. ZIF-8@N-Gr presented a flake structure, as the electrode displayed excellent electrical conductivity, which enhanced the electron transfer and significantly amplified the current signal of the immunosensor. More importantly, these immunosensors are capable of assaying human apolipoprotein A4 (Apo-A4) in 100% serum without suffering from any significant biological interference. Under optimized experimental conditions, the sensor was used for the analysis of whole serum samples and presented a wide linear range from 1.47 × 10−10 g/mL to 3.00 × 10−7 g/mL with a low detection limit of 8.33 × 10−11 g/mL (3σ, n = 15). The satisfactory results of human serum sample analysis indicated that the proposed immunosensor had promising potential in the clinical diagnosis of depression. [ABSTRACT FROM AUTHOR]

As a new type of conductive material, polyaniline functionalized graphene quantum dots (PAGD), which were prepared by in-situ polymerization had been used to construct a novel electrochemical immunosensor for early screening of depression markers-heat shock protein 70 (HSP70). Profiting from the huge specific surface area, good bioactivity and excellent structure of PAGD, a variety of heat shock protein 70 (HSP70) was firmly loaded on the surface of PAGD for successful construction of basic electrode (HSP70/PAGD/GCE), which was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. Due to the HSP70 fixed on the surface of basic electrode and the HSP70 in the samples can competitively combine with the horseradish peroxidase labeled human HSP70 antibody (HRP-Strept-Biotin-Ab). As a result, there is negative correlation between the concentration of HSP70 in samples and the detection signal of the proposed electrochemical immunosensor (HRP-Strept-Biotin-Ab-HSP70/PAGD/GCE) in the test liquid. Under conditions optimized for determining HSP70, wide linearity was obtained in the range of 0.0976–100 ng/mL, with a low detection limit of 0.05 ng/mL at 3σ. Moreover, the proposed electrochemical immunosensors was successfully applied to detect HSP70 in plasma samples, and exhibited good precision, acceptable stability and reproducibility. Therefore, this study provides a novel and convenient method for early clinical screening of depression markers, and also provides a reliable and objective analysis method for the diagnosis of depression at the molecular level. Unlabelled Image • The polyaniline functionalized graphene quantum dots (PAGD) was successfully prepared. • The HRP-Strept-Biotin-Ab-HSP70/PAGD/GCE immunosensor for determination of HSP70 was successfully fabricated. • The proposed immunosensor exhibited a broad detection range and low detection limit for HSP70. • It provides a novel and convenient method for early clinical screening of depression markers-HSP70 in real samples. [ABSTRACT FROM AUTHOR]