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Background: Nitrite has been involved in many food processing techniques and its excessive consumption is closely related to the development of different diseases. Therefore, highly sensitive detection of nitrite is significant to ensure food safety., Result: This study presents a simple and novel strategy for the highly sensitive detection of nitrite in food using paper-based analytical devices (PADs). In this proposed strategy, the nitrite present in the sample undergoes efficient diazotization when initially mixed with sulfanilamide solution before reacting with N-(1-naphthyl) ethylenediamine dihydrochloride (NED) coated on the detection region of the PAD, leading to the maximum production of colored azo compounds. Specifically, within the concentration range of 0.1-20 mg/L, the LOD and LOQ for the nitrite assay using the premixing strategy are determined as 0.053 mg/L and 0.18 mg/L, respectively which significantly surpass the corresponding values of 0.18 mg/L (LOD) and 0.61 mg/L (LOQ) achieved with the regular Griess reagent analysis., Significance: The study highlights the critical importance of the premixing strategy in nitrite detection. Under optimized conditions, the strategy demonstrates an excellent limit of detection (LOD) and limit of quantification (LOQ) for nitrite detection in eight different meat samples. In addition to its high precision, the strategy is applicable in the field of nitrite analysis. This strategy could facilitate rapid and cost-effective nitrite analysis in real food samples, ensuring food safety and quality analysis., Competing Interests: Declaration of competing interest The authors have no relevant financial or non-financial interests to disclose., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Carboxymethyl cellulose-based hydrogel coated Fe 3 O 4 magnetic nanoparticles were prepared using a coprecipitation combining graft copolymerization method, and characterized by various techniques to study their structure-property relationships. The nanocomposite was used as a heterogeneous Fenton-like catalyst for Acid Red 73 degradation. The effects of several key parameters, solution pH, H 2 O 2 concentration, catalyst dosage, and temperature of the reaction medium on the pseudo-first-order kinetics of dye degradation was evaluated. The results showed that the nanocomposite catalyst were highly effective in activating H 2 O 2 to produce reactive radicals for dye degradation, achieving complete decomposition under optimal conditions of 300 min at 25 °C and pH 3.5 with 100 mM H 2 O 2 and 200 mg·L -1 catalyst. The complexing hydrogel-Fe 2+ /Fe 3+ were the key factors that speed up the redox cycling between Fe 2+ and Fe 3+ species, thus accelerate the fast degradation rate of target pollutants. Scavenging experiments and electron paramagnetic resonance analyses revealed that Acid Red 73 was decomposed mainly by the attack of •OH radicals. Besides, reusability of the prepared nanocatalyst was also tested., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Magnetically retrievable formulations of laccase potentially promising for biomedical and environmental applications were constructed by immobilization of the enzyme on the surface of magnetic nanoparticles functionalized by siloxane layers with active amino and methacrylyol moieties. The functional magnetic particles were prepared using a hydrolytic polycondensation reaction of tetraethoxysilane with 3-methacryloxypropyltrimethoxysilane (MPS). The results indicated that the amounts of laccase loading on the methacrylyol functional magnetic particles were approximately 150mg/g under the optimum conditions. The stability of the immobilized laccase was highly enhanced against thermal treatments and provided better long-term storage. Compared to free laccase, the immobilized laccase exhibited significantly higher decolourisation efficiency in the decolorization of a representative dye, methyl red, which resulted from the magnetic particles adsorption and enzymatic catalysis. These results show its great potential for industrial applications., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Electrospun cellulose acetate (CA) membrane was employed as a support that provided sites for AgCl crystals in situ growth. The Ag@AgCl crystals on electrospun CA composites with exposed {100} and {111} facets were fabricated at room temperature by a double diffusion technique. The crystal structure, morphology, composition, and absorption light ability of CA supported Ag@AgCl were characterized utilizing X-ray powder diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflection-infrared intensity (ATR-IR), X-ray photoelectron spectroscopy measurements (XPS), energy dispersive spectrometer (EDS) and ultraviolet-visible (UV-vis) diffuse reflectance spectra, respectively. The photocatalytic activity of the catalysts was evaluated using methyl orange (MO) as a target. The CA supported cubic Ag@AgCl catalyst exhibited much higher catalytic activity than octahedral catalyst in terms of the degradation of MO under visible light. The 10mg CA based cubes could completely degrade MO (10 mg L(-1)) in 160 min. The photocatalyst still exhibited a good catalytic ability after three times., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

A novel photobioelectrochemical system (PBES) was developed by acclimating algal-bacterial biofilm in both anode and cathode using Chlorella vulgaris and indigenous wastewater bacteria as inoculums. The PBES was operated in polarity reversion mode depend on dark/light alternate reaction to achieve simultaneous pH self-neutralization, azo dye degradation (Congo red) and bioelectricity generation. The anodic accumulated acidity and cathodic accumulated alkalinity were self-neutralized after polarity reversion and hence eliminate the membrane pH gradient. The Congo red was first decolored in the dark anode and the resultant decolorization liquid was subsequently mineralized after the dark anode changing to the photo-biocathode. The presence of C. vulgaris significantly enhanced the two-stage degradation of Congo red, with 93% increases in decolorization rates and 8% increases in mineralization compared to the algae-free BES. The PBES continuously generated stable voltage output over four months under repeatedly reversion of polarity. The maximum power density produced before and after polarity reversion was 78 and 61 mW/m(2), respectively. The synergy between C. vulgaris and mixed bacteria was responsible for the successful operation of the PBES which can be potentially applied to treat wastewater containing azo dye with benefits of enhanced azo dye degradation, high net power output and buffer minimization., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Stimulus-responsive hydrogels, which can undergo significant physicochemical changes in response to various physical or chemical stimuli, have drawn wide attention in many fields. In this study, novel photoresponsive hydrogels prepared by free radical copolymerization of xylan-type hemicellulose methacrylate with 4-[(4-acryloyloxyphenyl)azo]benzoic acid (AOPAB) were investigated, which showed multiresponsive behaviors to pH, water/ethanol alternating solutions, and light. The swelling ratios of the prepared hydrogels in distilled water decreased from 9.8 to 2.2 g/g with AOPAB content increase from 2% to 16%. The hydrogel displayed rapid swelling and deswelling performance in water and ethanol alternating solutions. Additionally, under UV irradiation the trans-conformation of azobenzene in the hydrogel would generally convert into the cis-conformation and resulted in the hydrophilic/hydrophobic balance variation of the hydrogel. Therefore, the hydrogel loaded with vitamin B12 (VB12) showed a higher drug cumulative release rate under UV irradiation than that without UV irradiation.

Enhanced simultaneous decolorization of Congo red and bioelectricity generation with anthraquinone-2,6-disulphonic disodium salt (AQDS), riboflavin (RF) and humic acid (HA) as mediators in air-cathode microbial fuel cell (MFC) was demonstrated. Compared with mediator-free MFC, the MFC with added 0.005 mM AQDS, 0.005 mM RF or 1g/L HA showed 36%, 26% and 15% increase in maximum power density along with 394%, 450%, and 258% increases in decolorization rates of Congo red, respectively. Addition of mediators at higher concentration further increased power and Congo red decolorization but the increases were not proportional to the rise in mediator concentration. Based on decreases of anode charge transfer resistance and increases of Congo red decolorization, the mediators kinetically promote the extracellular electron transfer between bacteria, anode and Congo red. Microbial analysis showed that addition of mediators changed the composition of anodic microbial community and stimulated the growth of species belonging to Chlorobi, Endomicrobia and Firmicutes., (Copyright © 2013 Elsevier Ltd. All rights reserved.)