Latest ArticlesA label-free and sensitive electrochemical biosensing strategy for a hepatocellular carcinoma biomarker of miRNA-122 has been proposed based on hybridization induced ion-barrier effect on the electroactive sensing interface. First, a bifunctional electroactive electrode with the nanocomposite of Prussian blue (PB) and gold nanoparticles (AuNPs) was prepared through a two-step electrodeposition process. The PB endows the electrode excellent K+-dependent voltammetric signal and the AuNPs act as the matrix for the self-assembly immobilization of the thiolated probe DNA. Upon specific hybridization of probe DNA with the target miRNA-122, the formed double duplex induced the ion-barrier effect, which blocked the diffusion of the K + from the bulk solution to the electrode surface. As a result, the voltammetric signal of the PB on the electrode was surpressed, and thus the target miRNA-122 was monitored. The sensing assay showed that the miRNA-122 could be analyzed in the concentration range from 0.1 fmol/L to 1.0 nmol/L, with a detection limit of 0.021 fmol/L. The practical applicability of the biosensor was also verified by the spiking serum assay.
Photocatalysis technology has been proved to be a potential strategy for removal of organic dyes, however high-power light sources are generally necessary to initiate photocatalytic reaction. In this work, we employed an excellent photocatalyst of Bi2WO6 with visible light harvest and meanwhile an intrinsic ferroelectricity, which realized the efficient degradation of organic dye via the synergetic photopiezocatalysis. Through coupling the illumination by a low-power (9 W) LED and the ultrasonic vibration (120 W) by an ultrasonic cleaner, the nanoflower-like Bi2WO6 composed of ultrathin nanosheets showed a much more enhanced photopiezocatalysis performance for purification of organic dye than the individual photocatalysis and piezocatalysis. Furthermore, the high mineralization efficiency and the good durability of the Bi2WO6 catalyst were demonstrated. The possible mechanism of photopiezocatalysis was finally proposed, where the ultrasound-induced piezoelectric field in Bi2WO6 drove photo-generated electrons and holes to diffuse along opposite directions, consequently promoting the separation efficiency of charge carriers. This work indicates that the synergetic photopiezocatalysis by coupling irradiation and ultrasonic vibration is a promising strategy to purify organic pollutants in wastewater.
Nowadays, Cu-based materials have attracted extensive attention as electrocatalysts, while the inherent reason of the filling of high anti-bonding state of Cu d band (3d104s1) makes it difficult to hybridize with O 2p band of oxygen intermediates during the adsorption process of oxygen evolution reaction (OER). To increase the efficiency of Cu-based electrocatalysts, efforts have been made to optimize the electronic structures and to create surface defects and hierarchical nanostructures with more exposed accessible active sites. Herein, we report a facile method for preparing CuO electrocatalysts with hierarchical nanostructures using the Cu-alanine complex as a precursor through room-temperature chemical precipitation and subsequent calcination in air. Investigations of products obtained at different calcination temperatures reveal the relationship between OER activities and the material characteristics such as specific surface areas, crystal growth orientations, and element components. The product obtained at 500 ℃ exhibits the smallest overpotential of 290 mV in 1.0 mol/L KOH for electrocatalyzing OER. Combining with various characterizations of CuO electrocatalysts after OER activities, the possible catalytic mechanism and the influence factors of their OER performance are also discussed.
Water electrolysis technology holds the perfect promise of the hydrogen production, yet control of efficiency and rate of water electrolysis greatly relies on the availability of high-performance electrode materials for kinetic-sluggish oxygen evolution reaction (OER). Accordingly, substantial endeavors have been made to explore advanced electrode materials over the past decade. Recently, RuO2 and RuO2-based materials have been demonstrated to be promising for OER due to their remarkable electrocatalytic activity and pH-universal application. Herein, the great achievements and progresses of this flourishing spot are comprehensively reviewed, which are started by a general description of OER to understand the reaction mechanism in detail. Subsequently, the key advantages and issues of RuO2 towards OER are also introduced, followed by proposing many advanced strategies for further promoting the electrocatalytic OER performance of RuO2. Finally, the daunting challenges and future progresses of RuO2 electrocatalysts toward practical water oxidation are highlighted, aiming to provide guidance for the fabrication of desirable RuO2-based electrocatalysts toward OER.
Nanocomposites comprising flexible polymers and high dielectric constant inorganic nanoparticles are considered to be one of the promising candidates for electrostatic capacitor dielectrics. However, the effect of interfacial property on electrical energy storage of dielectric polymer nanocomposites is still not clear. Herein, the role of the polarity of the interfacial region is investigated. For this purpose, three polymers with different polarity, polymethyl methacrylate (PMMA), polyglycidyl methacrylate, and polymethylsulfonyl ethyl methacrylate (PMSEMA) are attached onto BaTiO3 (BT) nanoparticle surface via surface-initiated reversible addition-fragmentation chain transfer polymerization. It is found that the polarity of shell polymers shows an apparent effect on the dielectric and energy storage of dielectric polymer nanocomposites. For example, PMSEMA@BT (shell polymer possesses the highest polarity) increases dielectric loss and decreases the breakdown strength of the nanocomposites, leading to lower energy storage capability. However, PMMA@BT (shell polymer possesses the lowest polarity) can induce higher breakdown strength of the nanocomposites. As a result, the PMMA@BT nanocomposite exhibits the highest electrical energy storage capability among the three nanocomposites. This research provides new insight into the design of core-shell nanofillers for dielectric energy storage applications.
In this work, the phase-transitioned BSA (PTB) film using the mild and fast fabrication process adhered to the capillary inner wall uniformly, and the fabricated PTB film-coated capillary column was applied to realize open tubular capillary electrochromatography (OT-CEC) enantioseparation. The enantioseparation ability of PTB film-coated capillary was evaluated with eight pairs of chiral analytes including drugs and neurotransmitters, all achieving good resolution and symmetrical peak shape. For three consecutive runs, the relative standard deviations (RSD) of migration time for intra-day, inter-day, and column-to-column repeatability were in the range of 0.3%–3.5%, 0.2%–4.9% and 2.1%–7.7%, respectively. Moreover, the PTB film-coated capillary column ran continuously over 300 times with high separation efficiency. Therefore, the coating method based on BSA self-assembly supramolecular film can be extended to the preparation of other proteinaceous capillary columns.
Carbon dots (Cdots) has been proved to possess the catalytic decomposition of H2O2 in the photocatalytic system. It is a potential photo-Fenton catalyst. Since multiple emissive Cdots have different light response range. There is rarely investigation on the performance of Cdots based photo-Fenton on the light wavelength. Herein, blue, green and red emissive carbon dots were synthesized from the different ratio of o-phenylenediamine and catechol by the solvothermal method. They exhibit different light adsorption range from UV to visible light. Furthermore, the photo-Fenton reactivity of Cdots was studied for catalyzing the decomposition of H2O2 to generate free hydroxyl radicals and consequently applying for the removal of methyl blue. The results exhibit that Cdots with the broader light adsorption rang possess the stronger catalytic activity for the photo-Fenton reaction. The H2O2 decomposition rate of red emissive Cdots is 0.074 min−1, which is 2.64 and 1.46 times than the blue and green emissive Cdots, respectively. And the radical detection results confirm that the photo-Fenton happens in the reaction. In addition, the Cdots photo-Fenton can be carried out in the broad pH range from acidic to basic solution, which has a great potential to treat wastewater in the neutral system.
Injectable hydrogels have been considered as promising materials for bone regeneration, but their osteoinduction and mechanical performance are yet to be improved. In this study, a novel biocompatible injectable and self-healing nano hybrid hydrogel was on-demand prepared via a fast (within 30 s) and easy gelation approach by reversible Schiff base formed between −CH=O of oxidized sodium alginate (OSA) and −NH2 of glycol chitosan (GCS) mixed with calcium phosphate nanoparticles (CaP NPs). Its raw materials can be ready in large quantities by a simple synthesis process. The mechanical strength, degradation and swelling behavior of the hydrogel can be readily controlled by simply controlling the molar ratio of −CH=O and −NH2. This hydrogel exhibits pH responsiveness, good degradability and biocompatibility. The hydrogel used as the matrix for mesenchymal stem cells can significantly induce the proliferation, differentiation and osteoinduction in vitro. These results showed this novel hydrogel is an ideal candidate for applications in bone tissue regeneration and drug delivery.
A heterojunction of Sm-doped g-C3N4/Ti3C2 MXene (SCN/MX) was constructed via prepolymerization and solid mixture-calcination method. The modified g-C3N4 presented a hollow porous seaweed-like shape which can increase its specific area and active sites. In SCN/MX composite, the optical properties, no matter optical absorption ability or separation performance of photo-induced electrons and holes, were enhanced. Among them, Sm-doping may play an important role on transferring the photogenerated electrons to suppress their recombination, and Ti3C2 MXene would broaden light absorption and further improve the carrier migration efficiency. The SCN/MX presented higher photocatalytic degradation efficiency (> 99%) of ciprofloxacin under visible light irradiation. The quenching experiments and electron spin-resonance spectroscopy confirmed that the dominated active materials were superoxide radical and holes. The degradation mechanisms of ciprofloxacin (CIP) over the SCN/MX were attacking of the active materials on the piperazine ring and quinolone ring, and the final products were CO2, H2O and F−.
An improved ssDNA library immobilized systematic evolution of ligands by enrichment (SELEX) was applied to select aptamers against carbaryl. After nine selection rounds, a highly enriched ssDNA pool was obtained. The Apta3 was demonstrated as the optimal aptamer. In order to facilitate the modification of aptamer, the Apta3 was further truncated with the dissociation constant (Kd) of 0.364±0.055 μmol/L and a fluorescent aptasensor was developed. The linear range for carbaryl was from 100 nmol/L to 1500 nmol/L, with the limit of detection was as low as 15.23 nmol/L. Besides, the biosensor was validated for the carbaryl spiked real samples, and the recoveries were between 97.7% and 107.3%.
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