Latest ArticlesMicroRNAs are a class of important biomarkers, and the simultaneous detection of multiple miRNAs can provide valuable information about many diseases and biological processes. Amplification-free determination has been developed for the analysis of multiple miRNAs because of its characteristic low cost and high fidelity. Herein, a method for the amplification-free analysis and simultaneous detection of multiple miRNAs based on a so-called pico-HPLC-LIF system is described. In this process, a bare open capillary with an inner diameter of 680 nm is used as a separation column for a sample volume of several hundreds of femtoliters (300 fL), followed by separation and detection. The technique has a zeptomolar limit of detection. The method was applied to detect cellular miRNA from adenocarcinomic human alveolar basal epithelial (A549) cell extracts, and the simultaneous detection of the mir-182, miR-155, and let-7a was achieved. The results showed that the expression of mir-182 and miR-155 was up-regulated and that of let-7a was down-regulated in A549 cells. This method for multiple miRNAs detection is expected to have broad applications in miRNA-based disease diagnosis, prognosis, treatment, and monitoring.
Noble-metal-free photocatalysts with high and stable performance provide an environmentally-friendly and cost-efficient route for green organic synthesis. In this work, CdS nanoparticles with small particle size and different amount were successfully deposited on the surface of covalent organic frameworks (COFs). The deposition of suitable content of CdS on COFs could not only modify the light adsorption ability and the intrinsic electronic properties, but also enhance the photocatalytic activity and cycling performance of CdS for the selective oxidation of aromatic alcohols under visible light. Especially, COF/CdS-3 exhibited the highest yield (97.1%) of benzaldehyde which is approximately 2.5 and 15.9 times as that of parental CdS and COF, respectively. The results show that the combination of CdS and COF can improve the utilization of visible light and the separation of photo-generated charge carriers, and COF with the π-conjugated system as supports for CdS nanoparticles could provide efficient electron transport channels and improve the photocatalytic performance. Therefore, this kind of COF-supported photocatalysts with accelerated photo-induced electrons and charge-carrier separation between semiconductors possesses great potentials in future green organic synthesis.
2D halide perovskites have emerged as promising materials because of their stability and passivation effect in perovskite solar cells (PSCs). However, the introduction of bulky organic ammonium cations from 2D halide perovskites would decrease the device performance generally compared to the traditional 3D MAPbI3. Incorporation of ultrathin 2D halide perovskite nanosheets (NSs) with 3D MAPbI3 could address this issue. Herein, we report a rationally designed PSCs with dimensional graded 3D/2D MAPbI3/(PEA)2PbI4 heterojunction, in which 2D (PEA)2PbI4 NSs were synthesized and incorporated between 3D MAPbI3 and hole-transporting layer. Besides the significantly improved stability, a notable increasement in power conversion efficiency (PCE) of 20% was obtained for the 3D/2D perovskite solar cells due to the favourable band alignment among (PEA)2PbI4 NSs and the other components. The graded structure of MAPbI3/(PEA)2PbI4 would upshift the energy level continuously, which enhances the hole extraction efficiency thus reduces the interface charge recombination, leading to the increasements of VOC from 1.04 V to 1.07 V, JSC from 21.81 mA/cm2 to 23.15 mA/cm2 and the fill factor from 67.89% to 74.78%, and therefore an overall PCE of 18.53%.
A 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.
Highly active and low-cost catalytic electrodes for urea oxidation reaction (UOR) are always crucial for exploration of urea fuel cells. Herein, novel york-shell-structural Ni2P/C nanosphere hybrids (Ni2P/C-YS) are rationally constructed via a hydrothermal method and subsequent phosphidation treatment under different temperature ranging from 250 ℃ to 450 ℃ for UOR applications. In the in-situ constructed hollow york-shell structure, the coupling of conductive carbon materials and active Ni2P allows numerous interfaces facilitating the electron transfer and thereby accelerating the catalytic kinetics. The results demonstrate that Ni2P/C-YS-350 nanocomposite can boost the UOR process with a low potential of 1.366 V vs. RHE at a current density of 50 mA/cm2 in alkaline electrolyte and afford the superior durability with negligible potential decay after 23 h. This study presents that the carbon coated Ni2P hybrid with the optimized crystallinities and hollow york-shell configurations can be a promising candidate for application in urea fuel cells.
Developing an excellent photocatalysis system to remove pesticides from water is an urgent problem in current environment purification field. Herein, a Z-scheme WO3/g-C3N4 photocatalyst was prepared by a facile in-situ calcination method, and the photocatalytic activity was investigated for degradation of nitenpyram (NTP) under visible light. The optimal Z-scheme WO3/g-C3N4 photocatalyst displayed the highest rate constant (0.036 min−1), which is about 1.7 and 25 times higher than that of pure g-C3N4 and WO3, respectively. The improvement of photocatalytic performance is attributed to fast transfer of photogenerated carriers in the Z-scheme structure, which are testified by electron spin resonance (ESR) experiments, photocurrent and electrochemical impedance spectra (EIS) measurements. Moreover, the effects of typical water environmental factors on the degradation NTP were systematically studied. And the possible degradation pathways of NTP were deduced by the intermediates detected by high-performance liquid chromatography-mass spectrometry (HPLC-MS). This work will not only contribute to understand the degradation mechanism of pesticides in real water environmental condition, but also promote the development of new technologies for pesticide pollution control as well as environmental remediation.
Overall water photo-splitting is a prospective ideal pathway to produce ultra-clean H2 energy by semiconductors. However, the band structure of many semiconductors cannot satisfy the requirement of H2 and O2 production at the same time. Herein, we illustrate that carbon dots (CDs)/Bi2WO6 photocatalyst with compensatory photo-electronic effect has enhanced activity for overall water photo-splitting without any sacrificial agent. In this complex photocatalytic system, the photo-potential provided by CDs makes the CDs/Bi2WO6 (C-BWO) composite could satisfy the band structure conditions for overall water photo-splitting. The C-BWO composite (3 wt% CDs content) exhibits optimized hydrogen evolution (oxygen evolution) of 0.28 μmol/h (0.12 μmol/h) with an approximate 2:1 (H2: O2) stoichiometry at normal pressure. We further employed the in-situ transient photovoltage (TPV) technique to study the photoelectron extraction and the interface charge transfer kinetics of this composite catalyst.
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.
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.
A novel route for tandem C–C/C–N formation, annulation and aromatization of hydrazones with 1, 2-dichloroethane to synthesize 1H-pyrazoles has been developed. Furthermore, the 1, 2-dichloroethane serves as alkylation reagent in good to excellent yields. This methodology features mild reaction conditions and good functional group tolerance, providing a direct approach for the preparation of 1H-pyrazoles.
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