A sandwich-type photoelectrochemical immunosensor for NT-pro BNP detection based on F-Bi2WO6/Ag2S and GO/PDA for signal amplification.

A sandwich-type photoelectrochemical (PEC) immunosensing platform was designed for detection of amino-terminal pro-B-type natriuretic peptide (NT-pro BNP). Thereinto, flower-like Bi2WO6/Ag2S nanoparticles (F-Bi2WO6/Ag2S) were employed as photoelectrochemical matrix, and graphene oxide and polydopamine composite (GO/PDA) were prepared as signal labels. In this proposal, Ag2S was in-situ growth on the surface of F-Bi2WO6 modified with thioglycolic acid (TGA). Specially, a cascade-like band-edge level between F-Bi2WO6 and Ag2S effectively improved the photocurrent conversion efficiency and enhanced the photocurrent response. Then, the conjugated GO/PDA aimed to further amplify signal because PDA as electron donor could sweep the holes and inhibit the recombination of photogenerated electron-hole pairs, while GO owned brilliant conductivity speeding up the electrons transfer. The photocurrent increased with the amount of GO/PDA conjugates which had positive correlation with the NT-pro BNP. Under optimal experimental conditions, the proposed sandwich-type PEC immunosensor presented a desirable linear relationship ranged from 0.1 pg/mL to 100 ng/mL for NT-pro BNP with the detection limit of 0.03 pg/mL (S/N = 3). The prepared PEC immunosensor exhibited high stability and selectivity, which offered an innovative idea for the detection of other biomolecules.

A novel sandwich-type photoelectrochemical immunosensor based on Ru(bpy)32+ and Ce-CdS co-sensitized hierarchical ZnO matrix and dual-inhibited polystyrene@CuS-Ab2 composites.

A novel and sensitive sandwich-type photoelectrochemical (PEC) immunosensor was developed for the quantitative detection of ß-amyloid protein (Aß). A ITO electrode was sequentially coated with hierarchical porous zinc oxide (ZnO) microspheres with a large specific area, sensitized with tris(bipyridine)ruthenium(II) ion (Ru(bpy)32+) to achieve high visible light absorption, and modified with cerium-doped cadmium sulfide (Ce-CdS) nanoparticles to enhance the PEC response. Under the stimulation of visible light and ascorbic acid as an efficient electron donor, the photoelectric signal of ZnO/Ru(bpy)32+/Ce-CdS was 70 times that of pure ZnO. The amino-functionalized polystyrene (PS) microspheres coated with copper sulfide (CuS) was linked with a secondary antibody (Ab2) for the first time for the Aß detection by the immunosensor. The good insulation and steric resistance of the as-prepared polystyrene@CuS-Ab2 (PS@CuS-Ab2) composite significantly weakened the photocurrent response of the immunosensor in the specific immune recognition. Under the optimal conditions, the quantitative detection of Aß was achieved within the range of 0.001-100 ng/mL with the detection limit of 0.37 pg/mL. In addition, the PEC immunosensor is easy to make, stable and selective, which has provided a good experimental platform for the detection of disease biomarkers.

Sandwich-type electrochemical immunosensor based on Au@Ag supported on functionalized phenolic resin microporous carbon spheres for ultrasensitive analysis of α-fetoprotein.

Signal amplification is crucial for obtaining low detection limits in electrochemical immunosensor. In this work, we developed a novel signal amplification strategy using Au@Ag nanoparticles loaded by polydopamine functionalized phenolic resin microporous carbon spheres (Au@Ag/PDA-PR-MCS). Phenolic resin microporous carbon spheres (PR-MCS) possesses uniform size and a large surface area (1656.8 m2 g-1). Polydopamine (PDA) functionalized phenolic resin microporous carbon spheres (PDA-PR-MCS) retains the advantages of PR-MCS and possesses strong adsorption ability. With the unique structure of PDA-PR-MCS, it not only improves the loading capacity and dispersity of Au@Ag nanoparticles (Au@Ag NPs), but also enhances the stability for the combination of the Au@Ag NPs by chemical absorption between Au@Ag NPs and -NH2 of PDA. The Au@Ag/PDA-PR-MCS exhibits extraordinary electrocatalytic activity towards reduction of hydrogen peroxide (H2O2) to make the electrochemical response more sensitive. Furthermore, Au NPs with good biocompatibility and excellent conductivity were electrodeposited on the surface of electrode, which was used as a sensing platform to immobilize primary antibody (Ab1) and accelerate the electron transfer on the electrode interface. Herein, the designed immunosensor provided a broad linear range from 20 fg/mL to 100 ng/mL for alpha fetoprotein (AFP) detection and a low detection limit of 6.7 fg/mL (signal-to-noise ratio of 3) under optimal experimental conditions. Moreover, the excellent performance in detection of human serum samples indicated that the proposed immunosensor will provide promising applications in clinical monitoring of AFP.

A constructed alkaline consortium and its dynamics in treating alkaline black liquor with very high pollution load.

BACKGROUND: Paper pulp wastewater resulting from alkaline extraction of wheat straw, known as black liquor, is very difficult to be treated and causes serious environmental problems due to its high pH value and chemical oxygen demand (COD) pollution load. Lignin, semicellulose and cellulose are the main contributors to the high COD values in black liquor. Very few microorganisms can survive in such harsh environments of the alkaline wheat straw black liquor. A naturally developed microbial community was found accidentally in a black liquor storing pool in a paper pulp mill of China. The community was effective in pH decreasing, color and COD removing from the high alkaline and high COD black liquor. FINDINGS: Thirty-eight strains of bacteria were isolated from the black liquor storing pool, and were grouped as eleven operational taxonomy units (OTUs) using random amplified polymorphic DNA-PCR profiles (RAPD). Eleven representative strains of each OTU, which were identified as genera of Halomonas and Bacillus, were used to construct a consortium to treat black liquor with a high pH value of 11.0 and very high COD pollution load of 142,600 mg l(-1). After treatment by the constructed consortium, about 35.4% of color and 39,000 mg l(-1) (27.3%) COD(cr) were removed and the pH decreased to 7.8. 16S rRNA gene polymerase chain reaction denaturant gradient gel electrophoresis (PCR-DGGE) and gas chromatography/mass spectrometry (GC/MS) analysis suggested a two-stage treatment mechanism to elucidate the interspecies collaboration: Halomonas isolates were important in the first stage to produce organic acids that contributed to the pH decline, while Bacillus isolates were involved in the degradation of lignin derivatives in the second stage under lower pH conditions. CONCLUSIONS/SIGNIFICANCE: Tolerance to the high alkaline environment and good controllability of the simple consortium suggested that the constructed consortium has good potential for black liquor treatment. Facilitating the treatment process by the constructed consortium would provide a promising opportunity to reduce the pollution, as well as to save forest resources and add value to a waste product.

The surfactant tween 80 enhances biodesulfurization.

In biocatalytic conversions, substrates and products may display inhibitory or toxic effects on the biocatalyst. Rhodococcus erythropolis 1awq could further remove sulfur from hydrodesulfurized diesel oil, and the biodesulfurization was enhanced by the surfactant Tween 80. Tween 80 was shown to decrease the product concentration associated with the cells, reducing product inhibition.