Latest ArticlesTo mitigate the water pollution problem by photocatalytic degradation of typical antibiotics of tetracycline (TC), we prepared defective Bi2Sn2O7 (BSO) quantum dots (QDs) with a full spectral response due to Bi metal deposition, using a one-pot hydrothermal method, labeled as Bi@BSO-OV. The optimized Bi@BSO-OV showed 73.4% removal of TC in 1 h under irradiation with a 50 W LED lamp in the wavelength band in the visible-near-infrared (vis-NIR) light, a rate that is substantially greater than that of pure BSO (14.7%). The synergistic interaction of Bi metal and oxygen vacancies (OVs) is crucial to boosting photocatalytic performance. The near-infrared region of the photo-response is extended by the surface plasmon resonance (SPR) effect of Bi metal, enhancing the photocatalytic performance and dramatically raising the efficiency of solar energy utilization. In addition to inducing defect levels in BSO, the OVs also activate the surface adsorbed O2 to promote the production of •O2− and 1O2. DFT calculations reveal that Bi metal and OVs can mutually tune the charge transfer pathways. On the one hand, Bi metal can act as both a charge transfer bridge and an electron donor to assist charge separation. On the other hand, OVs-induced defect levels allow electrons that leap to the conduction band (CB) to first leap from the valence band (VB) to the defect levels, notably improving interfacial charge separation and transfer. The concept of design executed in this study for altering the catalyst by introducing both OVs and Bi metal can provide a rational design idea and potential insight for improving the photocatalytic activity for environmental applications.
Development of hydrothermally stable, low-temperature catalysts for controlling nitrogen oxides emissions from mobile sources remains an urgent challenge. We have prepared a metal oxide-zeolite composite catalyst by depositing Mn active species on a mixture support of CeO2/Al2O3 and ZSM-5. This composite catalyst is hydrothermally stable and shows improved low-temperature SCR activity and significantly reduced N2O formation than the corresponding metal oxide catalyst. Comparing with a Cu-CHA catalyst, the composite catalyst has a faster response to NH3 injection and less NH3 slip. Our characterization results reveal that such an oxide-zeolite composite catalyst contains more acidic sites and Mn3+ species as a result of oxide-zeolite interaction, and this interaction leads to the generation of more NH4+ species bound to the Brønsted acid sites and more reactive NOx species absorbed on the Mn sites. Herein, we report our mechanistic understanding of the oxide-zeolite composite catalyst and its molecular pathway for improving the low-temperature activity and N2 selectivity for NH3-SCR reaction. Practically, this work may provide an alternative methodology for low-temperature NOx control from diesel vehicles.
Fluorescence Anisotropy (FA) is an effective biochemical detection method based on molecular rotations. Graphene oxide (GO) has been extensively used as an FA amplifier. However, the enhancement of FA by GO alone is limited and the strong scattering of GO will easily make the measurement of FA inaccurate. In order to address these problems, an octopus-like DNA nanostructure (ODN) was designed and coupled with GO to enhance the FA together in this work. By mimicking the multi-clawed structure of the octopus, the ODN can be adsorbed on GO tightly, which not only could improve the sensitivity because of the double FA enhancement abilities of GO and ODN, but also could improve the specificity due to the decrease of the nonspecific interaction in complex samples. Furthermore, ODN could maintain a certain distance between the fluorophore and GO to reduce the fluorescence quenching efficiency of GO, which could improve the accuracy. This method has been applied for the detection of hepatitis B virus DNA (HBV-DNA) in a range of 1–50nmol/L and the limit of detection (LOD) was 330pmol/L. In addition, the proposed method has been successfully utilized to detect HBV-DNA in human serum, indicating that this method has a great practical application prospect.
Dicarboxylic acids have a wide range of applications in the polymer industry to construct valuable materials. Photocatalysis has recently emerged as an efficient and sustainable strategy to generate dicarboxylic acids. However, photocatalytic dicarboxylation with CO2 is mainly limited to unsaturated bonds, and the dicarboxylation of C–C single bonds still remains a challenge. Herein, we report a photocatalytic dicarboxylation of C–C single bonds in strained rings with CO2 units via consecutive photo-induced electron transfer (ConPET). It is also the first photocatalytic reductive ring-opening reaction of cyclobutanes. Notably, this transition-metal-free protocol exhibits good functional group tolerance, broad substrate scope, facile scalability, and easy product derivatizations. Moreover, diacids can easily be derivatized to main-chain liquid crystalline polyesters.
In some industrial wastewater, heavy metals combine with organic complexing agents to form heavy metal complexes (HMCs). These HMCs can be difficult to decompose and remove through conventional techniques due to their higher stability than free heavy metal ions. In recent years, persulfate based advanced oxidation processes (PS-based AOPs) have been recognized as a viable technique for HMCs degradation. Nevertheless, a comprehensive and in-depth understanding of the relevant HMCs decomplexation mechanisms in PS-based AOPs is still lacking. This review delineates the current progress of HMCs decomplexation in PS-based AOPs. We discuss the distinctions between the two widely used oxidant types in PS-based AOPs techniques. Moreover, we summarize and highlight the decomplexation mechanisms based on electron and energy transfer, and degradation pathways of HMCs. We also emphasize the effects of environmental water constituents, namely pH, inorganic ions, and natural organic matter (NOM), on HMCs decomplexation. Ultimately, we identify the existing challenges and perspectives that will steer the direction of advancing PS-based AOPs to remove HMCs.
Artificial macrocycle with high binding selectivity in water is often challenging but urgently needed in various research and application areas. Herein, we report a new water-soluble biomimetic tetralactam macrocycle and realize the ultra-high selectivity to nucleosides over corresponding monophosphate nucleotides by rational modification. The introduction of charged groups at the periphery of endo-functionalized cavity makes the selectivity (guanosine to guanosine 5′-monophosphate) increase remarkably from 100 to 1119. Based on the ultra-high selectivity of biomimetic tetralactam macrocycle, the sensitive CD73 enzyme activity assay was then achieved through product-selective fluorescence indicator displacement assay. Furthermore, the capability of the proposed method for inhibitor screening was successfully displayed.
A novel asymmetric [4 + 2] cycloaddition of 2-methylidenetrimethylene carbonate with pyrrolidone-derived enones has been achieved to produce the functionalized tetrahydropyran-fused spirocyclic scaffolds via palladium-catalysis. An array of enantioenriched spiro-pyrrolidine-2,3-diones bearing adjacent quaternary and tertiary stereocenters are obtained in high yields with excellent enantioselectivities (up to 96% yield and 99% ee). The further transformation of the product has been accomplished for the construction of medical interesting β2,2-amino acids and β-lactams. Preliminary mechanistic research was well conducted.
Herein, a novel molecular tweezer based on 2,2′-bipyridine-bridged porphyrin subunits was constructed for efficient fullerenes recognition. The syn conformation of the molecule, which was obtained by Zn(Ⅱ) coordination, gives rise to a proper cavity to interact with fullerene guests to form a stable 1:1 complex in toluene solution. It exhibits distinct binding selectivity towards C60 over C70. Moreover, the fullerene recognition capacity can be adequately suppressed by importing H2PO4− to competitively capture Zn(Ⅱ) along with syn-anti conformational conversion. Subsequently, the molecular tweezer regenerated to bind the fullerene by introducing the Ca2+ into the system. Significantly, the association-disassociation process can be switched reversibly and repeatedly.
Macrocycle confinement induced guest near-infrared (NIR) luminescence was research hotspot currently. Here in, we reported a cucurbit[7]uril (CB[7]) confined 3,7-bis((E)-2-(pyridin-4-yl)vinyl)-10-H-phenothiazine bridged bis(4-(4-bromophenyl)pyridine) (G), which not only boosted its NIR luminescence but also realized detection of HClO/ClO− in living cells and lysosome imaging. Fluorescence spectroscopy experiments were performed to calculate the detection ability of probe G to HClO/ClO− up to 147 nmol/L. As compared with G, supramolecular probe G⊂CB[7] formed after encapsulated by CB[7], the detection ability towards HClO/ClO− was improved to 24 nmol/L which was ascribe to the macrocycle CB[7] confinement increasing the fluorescence intensity to 103 folds. Accompanying the excitation wavelength changing, the fluorescence red-shifted to 820 nm when excited by 570 nm light, which was used to NIR lysosome imaging. Meanwhile, the supramolecular assembly G⊂CB[7] was also successfully used to highly sense to exogenous HClO/ClO− in RAW 264.7 cells and live animal.
Lateral flow immunoassay (LFIA) has become popular in laboratories, at-home testing, and medical diagnostics due to its minimal cost and user-friendliness. Nevertheless, conventional test strips based on colloidal gold can only obtain qualitative or semi-quantitative results with low sensitivity. In this work, Au-Fe3O4 dumbbell-like nanoparticles were synthesized and used as the LFIA labelling marker for highly sensitive colorimetric-photothermal dual-mode detection of SARS-CoV-2 spike(S) protein. The unique dumbbell structure of Au-Fe3O4 NPs makes it possible to combine the best features of both Au NPs and Fe3O4 NPs. The increased surface area of these NPs enhances their LSPR effect and photothermal effect, which achieves signal amplification to increase sensitivity. The Au-Fe3O4 NPs modified with S protein antibody could identify S protein in samples, which were recognized and accumulated on T-line by another antibody, generating color band for qualitative colorimetric detection. The T-line was irradiated by laser to obtain temperature change for quantitative detection of photothermal. In optimized conditions, the detection limit was 1.22 pg/mL, three orders of magnitude more sensitive than colorimetric detection. Finally, the approach was performed on SARS-CoV-2 pseudovirus samples and outperformed traditional colloidal gold strips. This LFIA platform exhibits significant promise for practical implementation, as it can satisfy the need for low-cost, high-sensitivity, and home-based quantitative detection for respiratory infectious diseases.
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