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Biosensors have tremendous revolutionary potential for the precise location and rapid detection of biomarkers for human disease. However, the minimization of nonspecific protein adsorption interactions and surface contamination is critical for their application in complex media. We report herein, the antifouling interface was constructed by electrochemical copolymerization of poly (3,4-ethylenedloxythlophene) (PEDOT) and glycyrrhiza polysaccharide (GPS). Hydrophilic PEDOT/GPS can reduce the interference and nonspecific adsorption of biological protein macromolecules, which has been verified by electrochemical and fluorescent characterization. Gold nanoparticles (AuNPs) were subsequently modified onto PEDOT/GPS surface to attach biomacromolecules containing thiol groups. MicroRNA, the promising biomarker of a large numbers of genetic diseases, was used as the testing model. Due to the robust antifouling capability of PEDOT/GPS as well as high biocompatibility of GPS/AuNPs, the fabricated biosensor based on PEDOT/GPS/AuNPs demonstrated excellent sensing performance, such as a wide detection range (0.01 nM–10 nM), a low detection limit (300 fM) and high reproducibility, showing great potential of medical applications.

Ultrasensitive and low-fouling microRNA electrochemical biosensors were successfully constructed by introducing thiol-terminated antifouling molecules (peptide sequence, polyethylene glycol, or mercapto alcohol) onto the surface of polyaniline-modified electrodes. For the three kinds of antifouling materials investigated, the newly designed and synthesized peptide exhibited superior antifouling ability to others, and it could effectively reduce the nonspecific adsorption of proteins and even prevent the fouling effect of serum. Compared with microRNA biosensors without antifouling capability, or those modified with polyethylene glycol or mercapto alcohol, the biosensor modified with the designed zwitterionic peptide showed the highest specificity for single-base mismatch, three-base mismatch, and completely complementary microRNAs. Most interestingly, the experimental results indicated that the introduction of antifouling molecules to the sensing interfaces did not significantly change the sensitivity of the biosensor. The strategy of constructing antifouling biosensors based on newly synthesized zwitterionic peptides and conducting polymers can be promisingly extended to the development of other electrochemical sensors and biosensors without encountering biofouling. Graphical abstract Ultrasensitive and low-fouling microRNA electrochemical biosensors were constructed by introducing thiol-terminated antifouling molecules (peptide sequence, polyethylene glycol, or mercapto alcohol) onto the surface of polyaniline-modified electrodes. The biosensor modified with the designed zwitterionic peptide showed the highest specificity amongst four kinds of biosensors.

A rapid, sensitive and low-fouling sensor for application to detect clinical biomarkers directly in biological media is highly desirable. Herein, we report a versatile strategy to prepare polyaniline (PANI) based conducting polymer hydrogel through the assembly of PANI and phytic acid (PA) by dynamic boronate bond. PANI/PA, a conductive hydrogel with high specific area and multiple pore structures have demonstrated excellent antifouling ability and electrochemical property. The electrochemical biosensors for microRNA can be developed by the immobilization of DNA probes onto PANI/PA interface (microRNA24 is used as a model case), and redox currents of PANI were utilized as the sensing signals to assay DNA/RNA hybridization reaction. Owing to the typical characteristics of PANI/PA hydrogel, the biosensor has shown excellent sensing performances with wide linear range (1.0 fM-1.0 pM), low sensing limit (0.34 fM) and efficient ability to detect microRNA mismatches. Given the facile processability, excellent stability and good antifouling property of the PANI/PA hydrogel, the proposed hydrogel-based biosensor may find broad applications in clinical diagnostics and biomedical devices.

C25H17N2O8, triclinic, P1̄ (no. 2), a = 9.6002(5) Å, b = 10.4192(5) Å, c = 11.0226(5) Å, α = 93.412(4)°, β = 98.094(4)°, γ = 98.787(4)°, V = 1075.04(9) Å3, Z = 2, R gt(F) = 0.0547, wR ref(F 2) = 0.1426, T = 293(2) K.

A simple electrochemical patterning strategy has been developed for the construction of ultrasensitive biosensors based on polyethylene glycol (PEG)-polypyrrole (PPy) nanowires substrate in order to supply improved antifouling performances. PPy nanowires array was produced through electrochemical polymerization of pyrrole at constant potential onto glassy carbon electrode (GCE) surface. PPy nanowires surfaces were decorated with 4-armed PEG molecules by electrochemical oxidation of amine groups offered by PEG end chains. The prepared PEG/PPy nanowires have integrated the excellent electrical conductivity of conducting polymer PPy nanowires with the good antifouling property of PEG. MicroRNAs (miRNAs) play very important roles in cancer development and a variety of diseases, which make them become promising biomarkers of the onset, prognosis and risk of diseases. Therefore the establishment of miRNA profiles for diseases and the detection of miRNAs in biological samples are critical milestones in diagnostics. An ultrasensitive electrochemical biosensor for miRNA can be effortlessly developed by the immobilization of DNA probes onto PEG/PPy nanowires. DNA/RNA hybridization was monitored by changes of methylene blue (MB) redox signal using differential pulse voltammetry (DPV) method. A wide linear range (0.10 pM ∼ 1.0 nM) to target miRNA was obtained by the fabricated biosensor, and miRNA mismatches can also be easily identified with satisfactory. Furthermore, the biosensor based on PEG/PPy nanowires can be extended to the development of any type of DNA-based biosensor.

A dual-sensing platform is proposed based on multi-walled carbon nanotubes/Prussian blue-functionalized polypyrrole nanowire array (PPY/MWCNTs/PB). Highly aligned PPY nanowire arrays were electrochemically prepared on the surface of glassy carbon electrodes, which were doped with MWCNTs/PB nanocomposites. The nanomaterial combines the characteristics of the PPY nanowires (high conductivity and large specific surface area) and MWCNTs/PB (excellent catalytic performance and intrinsic redox activity). Owing to the nanowire microstructure and outstanding electrical properties, the PPY/MWCNTs/PB nanowire arrays show excellent electrocatalysis of the reduction of hydrogen peroxide and facilitate the construction of a high-performance biosensing platform for microRNA (miRNA). A linear relationship between analytical signal and concentration of hydrogen peroxide and miRNA was obtained in the range 5 to 503 µM (1.4-5.1 mM) and 0.1 pM to 1 nM, and detection limits of 1.7 μM and 33.4 fM, respectively. This new supersensitive sensing platform has broad application prospects of biomolecule and other analyte determination in drug, biomedical, plant protection, and environmental analysis. Prussian blue/multi-walled carbon nanotubes functionalized polypyrrole nanowire arrays (PPY/MWCNTs/PB) were prepared by a facile one-step electrochemical method. PPY/MWCNTs/PB nanowire arrays show excellent electrocatalysis of the reduction of H

Nine undescribed (1–4, 6–10) sesquiterpene coumarins, together with a new natural one (5) and ten known ones (11–20), were isolated from the low polarity fraction of the 95% ethanol extract of the resin of Ferula sinkiangensis. Their structures were elucidated based on the comprehensive analysis of HRESIMS, 1D and 2D NMR data. The absolute configurations were determined by comparison of experimental and calculated ECD spectra. All the identified SCs were evaluated for their anti-neuroinflammatory activities in LPS-induced BV-2 cells. Ferusingensine G (8) displayed a significant inhibitory effect on nitric oxide (NO) production with an IC50 value of 1.2 μM. The results suggested that natural SCs might be served as potential neuroinflammatory inhibitors.

A nanocomposite consisting of phytic acid (PA) that was doped with poly(3,4-ethylenedioxy-thiophene) (PEDOT) and modified with copper nanoparticles (CuNPs) was placed on a glassy carbon electrode and then applied in an enzymeless glucose sensor. The undulating PEDOT/PA composite has good conductivity and a large surface area, which was suitable as substrate for the uniform growth of CuNPs. The modified electrode typically operated at a potential near 0.55 V (vs. Ag/AgCl) demonstrated remarkable catalytic activity towards direct oxidation of glucose in NaOH solution (the major limitation of this sensor). Figures of merit include (a) a wide analytical range (5 to 403 μM); (b) high sensitivity (79.27 μA·μM−1·cm−2), (c) a low detection limit (0.28 μM at a signal to noise ratio of 3), and (d) fast response (< 4 s).

Background Tamarix species are well known as the main host plants of Herba Cistanches, a valuable Traditional Chinese Medicine. They are also traditional medicinal plants themselves and are used to treat spleen problems, leucoderma and ocular conditions. Purpose The aim of the present study was to investigate the anti-inflammatory effect of Tamarix hohenackeri Bunge. Methods In the present study, BV-2 microglial cells were used and stimulated with lipopolysaccharide (LPS). Cell viability was tested using the MTT assay. The release of nitric oxide (NO) was determined using the Griess assay. The mRNA level of inducible nitric oxide synthase (iNOS), tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-6 were investigated by quantitative real-time PCR (qRT–PCR). The protein levels of phosphorylated of IκBα, ERK and MEK, as well as the cytoplasmic and nuclear NF-κB p65 were tested by Western blot analysis. The translocation of the NF-κB p65 subunit from the cytosol to the nucleus was investigated by immunofluorescence staining. Results Ethyl acetate (EtOAc) extract of Tamarix hohenackeri Bunge significantly inhibited the release of NO. Phytochemical research was performed to produce 13 main constituents. Among them, compounds 6, 7, 10 and 13 were identified to be the effective components with anti-inflammatory activity. These compounds significantly inhibited the production of NO by LPS-activated BV-2 microglial cells. qRT–PCR showed that compounds 6 and 7 significantly suppressed the LPS-induced transcription of genes encoding pro-inflammatory mediators, including iNOS, TNF-α, IL-1β and IL-6. Western blot analysis showed that compound 7 inhibited the LPS-induced phosphorylation of IκBα and antagonized the LPS-induced reduction of cytoplasmic NF-κB p65 and the increase of nuclear NF-κB p65. Immunofluorescence staining showed that nuclear translocation of NF-κB p65 was suppressed by compound 7. Western blot analysis showed that compound 7 inhibited the LPS-induced phosphorylation of ERK and MEK. Conclusion The present study revealed, for the first time, the effective anti-inflammatory agents from T. Hohenackeri. Compound 7 exerted potent anti-inflammatory effects and its underlying mechanism may be associated with its capacity to inhibit NF-κB signaling pathway and the MEK/ERK activation in activated microglia. The compound may be potential candidate therapeutic agent for neurodegenerative diseases.

In this study, we evaluated the effects of crude fucoidan on the physicochemical properties and biological activities of surimi gels. The gel strength and water holding capacity of surimi products significantly increased by adding 0.125% of fucoidan, and reduced with the further addition of fucoidan. Crude fucoidan exhibited little effect on the textural properties and protein content of surimi products. Moreover, the whiteness of surimi gels was inversely proportional to fucoidan concentrations. The scanning electron microscopy analysis suggested fucoidan at low concentration promoted the cross-linking of protein and the densification of gel network structure to improve the gel properties of surimi products, while excessive fucoidan hindered the cross-linking of proteins resulting in the formation of loose and inhomogeneous microstructure. Interestingly, the biological activities analysis revealed the homogenates from surimi gels containing fucoidan exhibited potent DPPH, ABTS, hydroxyl radical scavenging capacity, and reducing capacity, also displaying significant bacteriostatic effects on both Escherichia coli and Staphylococcus aureus in concentration-dependent manners.

Honeycomb-like cobalt nanostructures modified graphene oxide doped polypyrrole (CoNSs/RGO/PPy) nanocomposites were successfully prepared via a simple two-step electrochemical synthesis route. Firstly graphene oxide (GO) doped PPy nanocomposite was electrodeposited onto a pretreated glassy carbon electrode (GCE) to obtain GO/PPy nanocomposite; secondly honeycomb-like cobalt nanostructures were electrochemical reduced onto GO/PPy nanocomposite surface in a cobalt chloride solution at − 1.0 V. During the second reduction process, GO/PPy was reduced to a more conductive RGO/PPy nanocomposite simultaneously. The electrode modified with CoNSs/RGO/PPy nanocomposites exhibited outstanding electrocatalytic performance for enzymeless glucose sensing in alkaline media. Under optimum experimental conditions, the nonenzymatic glucose sensor displayed linear ranges from 0.5 μM to 2.667 mM, a high sensitivity of 297.73 μA mM − 1 cm − 2 , a very low detection limit of 29 nM (at S/N = 3) and a superfast response time of 1 s. The developed glucose sensor displayed favorable selectivity against common interferents, excellent stability and high reproducibility, and it has great potential to successfully detect glucose concentration in real biological samples.

A glassy carbon electrode (GCE) was modified with graphene oxide-doped polypyrrole (PPy), and flower-like cobalt nanostructures were then deposited on GCE by electrochemical reduction. The modified electrode shows improved catalytic behavior towards nitrite oxidation as the result of the nanoporous structure and the synergistic effect between cobalt nanostructures and GO/PPy. It is found that the amperometric oxidation current at 0.80 V (vs SCE) is about 2.5 times larger than that of a GCE modified with carbon nanotubes. Under optimum conditions, the modified electrode displays a linear range that extends over the 1.0 μM to 3.2 mM and 6.8 – 12 mM concentration ranges, a lower detection limit of 15 nM (at an S/N ratio of 3), and a response time of 1 s. The modified electrode is adequately selective, highly stable and highly reproducible. The method was successfully applied to the determination of nitrite in pickled radish.

A reagentless and label-free voltammetric modified electrode was developed for the carcinoembryonic antigen (CEA), an important biomarker for colorectal adenocarcinoma. It is based on the use of a reticular hybrid composite consisting of polyaniline (PANI) nanowires grown on the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) that was doped with an ionic liquid (IL). The composite features excellent electrical conductivity and a porous structure, a high specific surface and inherent redox activity. It was placed on a glassy carbon electrode (GCE) and antibody against CEA was immobilized on its surface. The redox current of PANI, measured typically at 0.16 V (vs. Ag/AgCl) serves as the analytical information. This electrode displays linear range that extends from 0.001 to 10 ng mL−1, with a detection limit as low as 0.7 pg mL−1. It also possesses excellent temporal stability and selectivity.

Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with bovine serum albumin-stabilized Au nanoclusters (AuNCs) was successfully synthesized through electrochemical polymerization in a solution containing EDOT monomer and AuNCs. The obtained PEDOT/AuNCs composite possessed a microstructure with AuNCs evenly distributed within the PEDOT film as dopants. The PEDOT/AuNCs modified electrode exhibited high electrocatalytic activity toward nitrite oxidation, and it was further developed into an amperometric sensor for nitrite. If operated at 0.80 V (vs. SCE), the linear range of the sensor was from 0.05 to 2600 μM, with a very low limit of detection of 17 nM (S/N = 3).

Ischemic stroke is a global disease with high disability and mortality rates. Cognitive impairment is one of the major clinical features of ischemic stroke, and microglia-mediated inflammation has been shown to be an important contributor to the pathogenesis of ischemic stroke. Kellerin, extracted from Ferula sinkiangensis, was previously shown to inhibit microglial activation and exert a strong anti-neuroinflammatory effect. However, there is no report of the potential therapeutic effect of kellerin on ischemic stroke by targeting microglial cells. In this study, we wanted to examine the effects of kellerin on ischemic stroke in the bilateral common carotid artery occlusion (BCCAO) model and the lipopolysaccharide (LPS)-activated microglia model. We found that kellerin alleviated cognitive impairment, decreased neuronal loss, suppressed microglial activation, and transformed microglia from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype in BCCAO mice. Moreover, in in vitro studies, we found that kellerin regulated microglial polarization and inhibited the NLRP3 and MAPK signaling pathways after LPS treatment. These findings provide a new understanding of the function of kellerin in ischemic stroke, and suggest that kellerin could be a potential therapeutic agent for the treatment of ischemic stroke.

Vertically aligned conducting polymer nanowire arrays had great potential applications in supercapacitor electrode material and exhibited enhanced electrocatalytic behavior towards the reduction of nitrite. In this paper, a facial template-free approach to synthesize large arrays of vertically aligned polyaniline (PANI) nanowires on electrochemically pretreated glassy carbon electrodes was reported by using a galvanostatic current method. The as-prepared large arrays of PANI nanowires had very narrow diameters and were oriented perpendicular to the substrate, which was a benefit to the ion diffusion when being used as the supercapacitor electrode. The highest specific capacitance of PANI nanowire arrays was measured and kept high at a large charge-discharge current density. Furthermore, it also can detect nitrite with ultrahigh sensitivity of 62.99 µA mM−1 cm−2 and a remarkable fast response time of less 1 s. The results indicated that the vertically aligned PANI nanowires could dramatically enhance the electrochemical performance.

Conducting polymer polyaniline (PANI) nanowire arrays were electrochemically in situ synthesized on the surface of glassy carbon electrodes, which were modified with self-assembled multi-walled carbon nanotubes (CNTs) networks. The ordered PANI nanowire arrays and CNTs networks were integrated to create 3D nanostructured PANI/CNTs composites. Owing to their unique microstructure and conductivity, the PANI/CNTs nanocomposite exhibited excellent electrical properties such as remarkable supercapacitor performance and catalytic activity toward nitrite electrochemical reduction. It was found that the PANI/CNTs nanocomposite was capable of delivering high specific capacitance and showed excellent cycling stability. Moreover, it could be utilized as an electrochemical sensor for the detection of nitrite, with an outstanding sensitivity, low detection limit (6.1 μM, a signal to noise ratio of 3) and a fast response time of less than 5 s.

Kellerin, a sesquiterpene coumarin derivative, has been identified as a major constituent of Ferula sinkiangensis K. M. Shen. It has been proved to be a potential natural therapeutic agent for Alzheimer's disease because of its inhibition of inflammatory cytokines nitric oxide (NO), tumor necrosis factor-α (IL-6) (TNF-α), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6) and interleukin-1β (IL-1β) in over-activated BV2 mouse microglial cells. Because of the multi chiral centers and the chemical instability of the sesquiterpene, coumarin, it is rather difficult to obtain this bioactive natural product by synthesis. Thus, biotransformation of kellerin was carried out to afford more novel derivatives using the callus of Angelica sinensis (Oliv.) Diels, which has an abundance of biosynthetic enzymes of phenylpropanoids. As a result, 14 products were obtained and identified, including four new sesquiterpene coumarin derivatives: 14′-hydroxy-(3′S,4′R,5′S,8′R,9′S,10′R)-kellerin (1), 5′,6′-ene-14′-hydroxy-(3′S,4′R,8′R,9′S,10′R)-kellerin (2), 5′,6′-ene-(3′R,8′R,9′S,10′R)-ferukrin (3), and 14′-hydroxy-(3′S,4′R,5′S,8′R,9′S,10′R)-deacetylkellerin (4), together with 10 other known compounds. Their structures were elucidated using comprehensive spectroscopic techniques and their possible biosynthetic pathways were proposed on the basis of the structural analyses. Furthermore, their anti-neuroinflammatory activities were assessed in BV2 cells by monitoring lipopolysaccharide-induced NO production, and the structure–activity relationships were discussed.

A facile two-step electrochemical strategy was reported to synthesize nanocomposite of reduced graphene oxide (RGO) doped conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) decorated with nickel nanoparticles (NiNPs) onto a glassy carbon electrode (GCE). Pure graphene oxide (GO) doped PEDOT composite was firstly electropolymerized onto the GCE through cyclic voltammetry, followed by electrochemical reduction in a solution containing nickel cations at a constant potential of −0.9 V. During the electrochemical reduction process, GO doped in the PEDOT composite would be reduced to a more conductive form of RGO, and at the same time, nickel cations could be reduced to form NiNPs and loaded on the composite surface. The prepared nanocomposite (NiNPs/PEDOT/RGO) modified electrode showed outstanding electrocatalytic activity toward the oxidation of glucose in alkaline media, and it could be developed into a nonenzymatic glucose sensor. Under optimum conditions, the glucose sensor exhibited a linear range from 1.0 μM to 5.1 mM and a detection limit of 0.8 μM (S/N = 3), associated with excellent stability, high reproducibility and favorable selectivity against common interferents. Furthermore, the nonenzymatic sensor was also successfully applied to the detection of glucose in human serum samples, showing promising potential in the clinical application.

Biocompatible materials, such as zwitterionic poly(carboxybetaine methacrylate) (polyCBMA), are of extraordinary importance in growth of bioelectronics and biosensors, because they not only greatly suppress nonspecific protein adsorption, but also have rich functional groups to facilitate the fixation of biological molecules. A novel nanocomposite was synthesized herein through modification polyCBMA onto conducting polymer polyaniline (PANI) nanowire surface. The prepared polyCBMA/PANI composite, integrating the good conductivity of PANI nanowires with the excellent antifouling capability of polyCBMA, provided a wonderful matrix for the growth of ultrasensitive and low fouling biosensor. Carcinoembryonic antigen (CEA), an important biomarker for a variety of cancers, was utilized as a model test. Furthermore its antibody was fixed onto polyCBMA/PANI for the preparation of CEA biosensor. DPV was applied as a sensing principle with information at which peak potential and current the signals were recorded. The peak currents were in inverse proportion to the logarithm of CEA concentration in the range from 1.0 × 10−14 g mL−1 to 1.0 × 10−10 g mL−1, with a detect limit of 3.05 fg mL−1. Furthermore, this low fouling, label-free biosensor has been utilized for assaying in undiluted human serum samples with resisting serious nonspecific protein adsorption, demonstrating its feasible potential application in clinical analysis of CEA.

A non-fouling electrochemical immunosensor is described for determination of the tumor biomarker carcinoembryonic antigen (CEA). It is based on the use of composite wires made by chemical grafting of hyaluronic acid onto polyaniline nanowires. The modified nanowires possess excellent antifouling property both in single protein solutions and in dilute serum samples. The current of immunoelectrode exhibits a linear response in the 0.01 pg mL−1 to 10,000 pg mL−1 CEA concentration range and 0.0075 pg mL−1 detection limit. This work demonstrates that coating an electrode with hyaluronic acid can largely reduce unspecific adsorption of proteins on the electrode surface.

Oxidative stress and neuroinflammation are critical in the pathogenesis of neurodegenerative diseases. Extract of Coreopsis tinctoria Nutt. has been shown to ameliorate neurodegenerative diseases, potentially via inducing quinone oxidoreductase 1 (NQO1) and anti-neuroinflammation. The present study aimed to characterize the chemical profile and bioactive composition of the extract to identify the effective components responsible for the effects. Chromatography and spectra analysis yielded 26 constituents, including a new chalcone (compound 8 ). Bioassays showed that compounds 6 , 9 , 15 , 17 , 19 , 21 and 22 significantly inhibited production of nitric oxide (NO) in N9 cells induced by lipopolysaccharides (LPS). Meanwhile compounds 1 , 3 , 6 , 11 , 19 and 20 exhibited significant NQO1 inducing activities in Hepa 1c1c7 cells. These results suggest that extract of C. tinctoria Nutt. contains bioactive components attenuating the progress of neurodegenerative diseases, thus, a valuable functional food for the prevention of neurodegenerative diseases.

A highly stable and sensitive nonenzymatic glucose sensor was successfully constructed through a facile electrodeposition method. Graphene oxide (GO) doped poly(3,4-ethylenedioxythiophene) (PEDOT) was first electrodeposited onto a glass carbon electrode using cyclic voltammetry and copper nanoparticles were then electrodeposited onto the rough surface of the PEDOT/GO nanocomposite through electrochemical reduction in a solution containing copper cations. The modified electrode was used for reliable nonenzymatic electrochemical detection of glucose, and under optimized conditions, it exhibited a high sensitivity of up to 909.1 μA mM−1 cm−2 and a very fast response time of less than 1 s, with a wide linear range of 0.1 μM to 1.3 mM and a low detection limit of 47 nM. This nonenzymatic glucose sensor was, furthermore, highly stable and unresponsive to potentially interfering substances, and it could be used for the assay of glucose in real human serum samples. These enhanced sensing performances were ascribed to the close contact of copper nanoparticles onto the rough surface of the PEDOT/GO conducting polymer nanocomposite, which has good conductivity and very high surface area that can act as an excellent substrate for the growth and support of copper nanoparticles. All these results indicate that this electrochemical sensor is highly promising for nonenzymatic glucose detection.

By using the linear sweep voltammetric technique, a phenanthroline (Phen) and zinc(II) (Phen-Zn(II)) complex was used as the electrochemical probe for the determination of double-stranded (ds) DNA. In pH 9.0 Britton- -Robinson (B-R) buffer solution, Phen can interact with Zn(II) to form a stable electroactive [Phen-Zn(II)] complex, which had a sensitive second order derivative polarographic reductive peak at -1.300 V (vs. SCE). After the addition of dsDNA into a solution of Phen-Zn(II) complex, the reduction peak current decreased with a negative shift of the reduction peak potential and without the appearance of new peaks. The results showed that a new supramolecular complex was formed via interaction of the Phen-Zn(II) complex with dsDNA. The conditions of interaction and the electrochemical detection were carefully investigated. Under the optimum conditions, the decrease in the reduction peak current was directly proportional to the dsDNA concentration in the range of 0.4-18.0 mg L-1 with the linear regression equation: ?Ip?/nA = 349.48 + + 84.647(c/mg L-1) (n = 13, ? = 0.991) and a determination limit of 0.20 mg L-1 (3?). The relative standard deviation (RSD) for 10 parallel determinations of 10.0 mg L-1 dsDNA was found to be 2.03 %. The method was successfully applied to the detection of synthetic samples with satisfactory results.

Biofouling arising from nonspecific adsorption is a substantial outstanding challenge in diagnostics and disease monitoring, and antifouling sensing interfaces capable of reducing the nonspecific adsorption of proteins from biological complex samples are highly desirable. We present herein the preparation of novel composite nanofibers through the grafting of polyethylene glycol (PEG) polymer onto polyaniline (PANI) nanofibers and their application in the development of antifouling electrochemical biosensors. The PEGylated PANI (PANI/PEG) nanofibers possessed large surface area and remained conductive and at the same time demonstrated excellent antifouling performances in single protein solutions as well as complex human serum samples. Sensitive and low fouling electrochemical biosensors for the breast cancer susceptibility gene (BRCA1) can be easily fabricated through the attachment of DNA probes to the PANI/PEG nanofibers. The biosensor showed a very high sensitivity to target BRCA1 with a linear range from 0.01 pM to 1 nM and was also efficient enough to detect DNA mismatches with satisfactory selectivity. Moreover, the DNA biosensor based on the PEGylated PANI nanofibers supported the quantification of BRCA1 in complex human serum, indicating great potential of this novel biomaterial for application in biosensors and bioelectronics.

An ultrasensitive biosensor for alpha-fetoprotein was developed based on electrochemically synthesized polyaniline (PANI) nanowires, which were functionalized with gold nanoparticles (AuNPs) and polyethylene glycols (PEG). The prepared PEG/AuNPs/PANI composite, combining the electrical conductivity of the AuNPs/PANI with the robust antifouling ability of PEG, offered an ideal substrate for the development of low fouling electrochemical biosensors. Alpha-fetoprotein (AFP), a well-known hepatocellular carcinoma biomarker, was used as a model analyte, and its antibody was immobilized on the PEG/AuNPs/PANI for the construction of the AFP immunosensor. Using the redox current of PANI as the sensing signal, in addition to the good biocompatibility of PEG/AuNPs and the anti-biofouling property of PEG, the developed immunosensor showed improved biosensing performances, such as wide linear range and ultralow detection limit (0.007 pg mL−1). More importantly, it is label-free, reagentless and low fouling, making it capable of assaying AFP in real serum samples without suffering from significant interference or biofouling.

A new electrochemical method for the sensitive detection of adenine was established on a chitosan (CTS)- and graphene (GR)-modified carbon ionic liquid electrode (CILE). CILE was prepared by mixing 1-butylpyridinium hexafluorophosphate (BPPF6) and paraffin with graphite powder. Due to the synergistic effects of GR, CILE, and the interaction of GR with IL on the electrode surface, the electrochemical performance of CTS/GR/CILE were greatly enhanced. Electrochemical behaviors of adenine on the modified electrode was investigated with a single well-defined oxidation peak appeared. The electrochemical reaction of adenine was an adsorption-controlled irreversible process, and the electrochemical parameters were further calculated. Under the optimal conditions, the oxidation peak current was proportional to adenine concentration in the range from 1.0 nmol L−1 to 70.0 μmol L−1 with a detection limit of 0.286 nmol L−1 (3σ) by differential pulse voltammetry. The established method showed the advantages such as good selectivity, stability, and repeatability.

In the presence of excess pyridine (py), Zn(OAc) 2 ·2H 2 O reacted with an equimolar amount of asymmetric salen-type Schiff base ligand, generated in situ from the condensation of 2,3-diaminophenol with o-vanillin or 5-bromo-3-methoxybenzaldehyde, to give the d-block "complex ligand" [Zn(HL 1 )(py)] or [Zn(HL 2 )(py)], respectively. Interaction of [Zn(HL 1 )(py)] or [Zn(HL 2 )(py)] with Ln(NO 3 ) 3 ·6H 2 O in a 1:1 molar ratio gave the cyclic hetero-tetranuclear complexes [Zn 2 (L 1 ) 2 (py) 2 Ln 2 (NO 3 ) 4 (dmf) 2 ]·3Et 2 O (Ln = Nd, 1; Yb, 2; Er, 3; and Gd, 4) or [Zn 2 (L 2 ) 2 Ln 2 (NO 3 ) 4 (dmf) 4 ] (Ln = Nd, 5; Yb, 6; Er, 7; and Gd, 8), respectively, in moderate yields. Photophysical studies of these cyclic Zn 2 Ln 2 tetranuclear complexes showed that, upon photoexcitation in the 200-550 nm range corresponding to the intraligand π→π* transition of the Schiff base, strong and characteristic NIR luminescence of Ln 3+ ions with emissive lifetimes in the microsecond ranges were observed, whereas the ligand-centered singlet ( 1 LC) visible fluorescence was mostly quenched as a result of effective intramolecular energy transfer from the 1 LC excited state to the Ln 3+ ions. In addition, the occupation of py groups at the axial position of Zn 2+ ions and the involvement of heavy atoms seem to help to enhance the NIR luminescence to some extent.

A new electrochemical method was proposed for the determination of trace amounts of proteins based on the cupferron (Cup) and cadmium(II) complex [Cup-Cd(II)] as the voltammetric probe. In the selected pH 6.5 Britton–Robinson (B–R) buffer solution, Cup can interact with Cd(II) to form a stable complex of [Cup-Cd(II)], which had a sensitive linear sweep voltammetric reductive peak at −0.654 V (vs. SCE). The addition of human serum albumin (HSA) into [Cup-Cd(II)] complex solution could greatly decrease the reductive peak current without the change of the reductive peak potential, which indicated that HSA could interact with [Cup-Cd(II)] complex to form a supramolecular biocomplex. The interaction mechanism was discussed and the decrease of reductive peak current was proportional to the concentration of HSA, which could be further used for the proteins determination. The optimal conditions of the binding reaction and the electrochemical detection were carefully investigated. Under the optimal conditions a new quantitative determination method for different kinds of proteins such as HSA, bovine serum albumin (BSA) and bovine hemoglobin (BHb) etc. was developed. The proposed method was simple, practical and relatively free from the interferences of coexisting substances, and it was further applied to the samples determination with satisfactory results. The binding constant (βs) and the binding number (m) of HSA with [Cup-Cd(II)] complex were calculated by the voltammetric data with the results as βs=1.12×106 and m=1.

A nanobiocompatible composite containing hemoglobin (Hb), ZnO nanoparticles (nano-ZnO) and ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF 6 ) was fabricated and further modified on the glassy carbon electrode (GCE). The electrochemical behaviours of Hb in the composite film were carefully studied and a pair of quasi-reversible redox peaks appeared in pH 7.0 phosphate buffer solution, which was attributed to the electrode reaction of Hb heme Fe(III)/Fe(II) redox couple. The presences ofnano-ZnO and BMIMPF 6 in the film can retain the bioactivity of Hb and greatly enhance the direct electron transfer of Hb. The immobilized Hb showed high stability and good electrocatalytic ability to the reduction of hydrogen peroxide and O 2 .

The electrochemical behaviors of the interaction of chromotrope 2R (CH2R) with human serum albumin (HSA) are investigated on the hanging mercury drop electrode with linear sweep voltammetry. In the acidic buffer solution (pH 2.5) CH2R has a well-defined voltammetric reductive wave at -0.34 V (SCE). On the addition of HSA into the CH2R solution, the reductive peak current of CH2R decreases with little movement of the peak potential. The voltammetric study shows that the electrochemical parameters of interaction solution do not change and a new electrochemically non-active complex is formed via interaction of CH2R with HSA, which cannot be reduced on the Hg electrode and results in the decrease of the free concentration of CH2R. The decrease of reductive peak current is proportional to HSA concentration and further used for protein detection. The binding ratio and the binding constant are further calculated with the experimental voltammetric data.

The interaction ofphenosafranine (PSF) with a glycosaminoglycan of heparin (Hep) in aqueous solution was characterized by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) in this paper and further used for Hep detection. In pH 1.5 Britton-Robinson (B-R) buffer solution PSF had a well-defined voltammetric reductive peak at -0.256 V (vs SCE), and the electrochemical response was faded by the addition of Hep. Cyclic voltammetric experiments indicated that the electrochemical behaviors of free PSF didn't change no matter whether Hep was presented in PSF solution or not. Based on the decrease of the peak current, a second order derivative linear sweep voltammetry was used to establish a sensitive electroanalytical method for Hep. The peak current was proportional to the concentration of Hep in the range of 0.7∼20.0 mg L -1 , demonstrating that this method was suitable for routine Hep detection. Under optimal conditions, the linear regression equation for the Hep determination was ΔIp"(nA) = 46.30 C (mg L -1 ) + 343.31 (n = 11, γ = 0.991) with a detection limit of 0.08 mg L -1 (3σ). The established method was further successfully applied to heparin sodium injection samples determination. The interaction mechanism was discussed based on the electrostatic attraction of the negatively charged Hep with the positively charged PSF, and the stoichiometry of Hep-PSF was calculated by the voltammetric method.

The tenderization effect of a new elastase from Bacillus sp. EL31410 was investigated on beef meat. Meat tenderization was done by dipping the meat cut in a solution containing proteolytic enzymes after freeze-dehydration. It was found that a marination time of 4 h was enough for enzyme adsorption. The samples were treated for 4 h in different enzyme solutions and then was stored at 4 °C for 24, 48, 72 h, and subjected to texture measurement, sensory evaluations, biochemical analysis and histological observations. A marked decrease in hardness, by texture measurements, was observed in the meats with papain and elastase and higher sensory scores for tenderness were observed in the meats treated with enzymes than in the control. The papain-treated beef meat received the highest score for tenderness, but the scores given for juiciness and taste were lower than that of the control. Rapid increases of fragmentation of myofibrils from the enzyme-treated meat were observed in the first 24 h of storage, especially for papain-treated meat. Meantime, elastin of myofibrilar structure was selectively degraded by elastase compared with the control when stored at 4 °C for 48 h as shown by electron microscopy. These findings suggest that Bacillus elastase (EL31410) is a promising substitute for papain as a favourable meat tenderizer.

Background: Tamarix hohenackeri Bunge is a salt cedar that grows widespread in the desert mountains in Xinjiang. T. hohenackeri has not been investigated earlier, although there are many reports of phytochemical work on other Tamarix species. Materials and Methods: To find out natural angiotensin-converting enzyme (ACE) inhibitor and platelet aggregation inhibitors, the bioactive extract (ethyl acetate [EtOAc] fraction) from the dried aerial parts of T. hohenackeri were investigated. The active fraction was purified by repeated column chromatography, including silica gel, Sephadex LH-20 column, medium-pressure liquid chromatography (MPLC) (polyamide column) and high-performance liquid chromatography (HPLC). The isolated major constituents were tested for their anti-platelet aggregation activity. Results: Bioassay-directed separation of the EtOAc fraction of the 70% ethanol extract from the air-dried aerial parts of T. hohenackeri led to the isolation of a new triterpenoid lactone (1), together with 13 known compounds (2-14). It was the first time to focus on screening bioactive constituents for this plant. The chemical structures were established on the basis of spectral data (ESI-MS and NMR). The results showed that the flavonoid compounds (7 and 8) and phenolic compounds (9, 10, 11, and 14) were potential ACE inhibitors. And the flavonoid compounds (5 and 7) showed significant anti-platelet aggregation activities. Conclusion: On the basis of the chemical and biological data, the material basis of ACE inhibitory activity for the active part was the phenolic constituents. However, the flavonoid compounds were responsible for the anti-platelet aggregation. The primary structure and activity relationship were also discussed respectively.

In this paper room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluoro-phosphate (BMIMPF6) was used as binder to fabricate a carbon ionic liquid electrode (CILE). Hemoglobin (Hb) was immobilized on the surface of CILE with clay and polyvinyl alcohol (PVA) composite film by layer to layer method. UV-Vis and FT-IR spectra showed that Hb in the film retained the essential features of its native structure. Electrochemical experiments indicated that a pair of well-defined quasi-reversible redox peak was obtained in pH 7.0 Britton-Robinson (B-R) buffer solution. The reduction and oxidation peak potentials were located at -0.405 V and -0.274 V (vs. SCE) with the formal potential as -0.340 V, which was contributed to the electrochemical reaction of heme Fe(III)/Fe(II) redox couples. The results suggested that the direct electron transfer of Hb in the PVA/Clay film with the CILE was accomplished. The direct electrochemical behaviors of Hb were carefully studied with the electrochemical parameters calculated. The PVA/Clay/Hb modified CILE gave excellent electrocatalytic ability to the reduction of H2O2 and the apparent Michaelis-Menten constant (K Mapp) value of Hb in the PVA/Clay film was calculated as 56.26 µmol L-1. Neste trabalho, líquido iônico hexaflúor-fosfato de 1-butil-3-metilimidazólio (BMIMPF6), em temperatura ambiente, foi usado como ligante na fabricação de um eletrodo líquido iônico de carbono (CILE). Hemoglobina (Hb) foi imobilizada na superfície de CILE com argila e um filme composto por polivinil álcool (PVA) pelo método camada por camada. Espectros de UV-Vis e FT-IR mostraram que Hb no filme reteve as características essenciais de sua estrutura original. Experimentos eletroquímicos indicaram que um par de picos redox quase-reversíveis bem definidos foi obtido em solução tampão Britton-Robinson (B-R), pH 7,0. Os potenciais dos picos de oxidação e redução foram localizados em -0,405 V e -0,274 V (vs. SCE), com potencial formal de -0,340 V, o qual contribuiu para a reação eletroquímica do par redox heme Fe(III)/Fe(II). Os resultados sugeriram que a tranferência de elétron direta de Hb no filme PVA/argila com CILE foi realizada.Os comportamentos eletroquímicos diretos de Hb foram estudados cuidadosamente com os parâmetros eletroquímicos calculados. O eletrodo CILE modificado, PVA/argila/Hb, apresentou excelente habilidade eletrocatalítica na redução de H2O2 e o valor para a constante de Michaelis-Menten aparente, (K Mapp), de Hb no filme PVA/argila foi calculado como 56,26 µmol L-1.

The property of carvedilol in acid-alkaline medium was studied by spectrofluorimetry. Effects of organic solvents on carvedilol fluorescence spectra were examined and the reason was discussed. A simple, rapid and high sensitive fluorimetric method for the determination of carvedilol in medicine is developed. The measurement of relative fluorescence intensity was carried out at 356 nm with excitation at 254 nm. Effects of pH, standing time and foreign ions on the determination of carvedilol have been examined. A linear relationship was obtained between the relative fluorescence intensity and concentration of carvedilol in the range of 0.50-270 ng ml(-1). The linear regression equation of the calibration graph is C = 0.000543F - 0.002 (C is concentration (microg ml(-1)) and F is relative fluorescence intensity in the equation), with a correlation coefficient of linear regression of 0.9998 and relative standard deviation of 2.31%. The detection limit of this method is 0.19 ng ml(-1), and recovery is from 98.70 to 102.1%. This method can be used for determination of carvedilol in tablet. The results obtained by this method agreed with those by the official method.

Suaeda physophora Pall. is a kind of desert plant mostly growing in saline habitats in Xinjiang Uygur Autonomous Region. In order to have a better utilization of halophytes, a screening for ACE inhibitors from halophytes growing in Xinjiang was carried out. The result showed that the 70% EtOH extract and n -BuOH extract of S. physophora Pall. possessed significant ACE inhibitory activities. So we focused on its biochemical constituents firstly. One new quinazoline alkaloid, namely Suaedine ( 1 ), along with six known compounds ( 2 – 7 ) was isolated from the aerial parts of S. physophora Pall. The structure of the new quinazoline alkaloid was established by one- and two-dimensional nuclear magnetic resonance, optical rotation and mass spectrometry analysis. The flavonoid compounds ( 2–4 ) and phenolic compound ( 5 ) exhibited significant ACE activities. It was the first time to focus on the chemical constituents and bioactivities of this plant.