Nanomaterials with enzyme mimetic activity have attracted extensive attention, especially in the regulation of their catalytic activities by biomolecules or other polymers. Here, a covalent organic ...framework (Tph‐BT COF) with excellent photocatalytic activity is constructed by Schiff base reaction, and its mimetic oxidase activity and peroxidase activity is inversely regulated via single‐stranded DNA (ssDNA). Under light‐emitting diode (LED) light irradiation, Tph‐BT exhibited outstanding oxidase activity, which efficiently catalyzed oxidation of 3,3′,5,5′‐tetramethylbenzidine (TMB) to produce blue oxTMB, and ssDNA, especially those with poly‐thymidine (T) sequences, can significantly inhibit its oxidase activity. On the contrary, Tph‐BT showed weak peroxidase activity, and the presence of ssDNA, particularly poly‐cytosine (C) sequences, can remarkably enhance the peroxidase activity. The influence of base type, base length, and other factors on the activities of two enzymes is also studied, and the results reveal that the adsorption of ssDNA on the surface of Tph‐BT prevented intersystem crossing (ISC) and energy transfer processes to reduce 1O2 generation, while the electrostatic interaction between ssDNA and TMB enhanced Tph‐BT's affinity for TMB to facilitate the electron transfer from TMB to •OH. This study investigates multitype mimetic enzyme activities of nonmetallic D‐A conjugated COFs and demonstrates their feasibility of regulation by ssDNA.
A D‐A covalent organic framework (Tph‐BT) with unique mimetic oxidase and peroxidase activities has been synthesized. The outstanding oxidase activity of Tph‐BT can be significantly inhibited by the adsorption of single‐stranded DNA (ssDNA), while the weak peroxidase activity of Tph‐BT can be remarkably enhanced upon the addition of ssDNA.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Meeting the demand for fresh water and energy is among the major challenges to the development of human civilization. Herein, we report the concept of a covalent organic framework hydrogel (named ...CPP) as a synergistic platform for seawater desalination and uranium extraction. In natural seawater, CPP shows an exceptional evaporation rate (0.744 kg m
−2
h
−1
) and uranium extraction capacity (4.15 mg g
−1
), which benefits from the hydrophilic 3D hydrogel network and capillary microporous channels of CPP providing adequate water transport, improving the mass transfer of uranyl ions, and increasing the binding sites of uranyl ions. In addition, CPP exploits interfacial solar heating to limit heat, increases solar energy utilization, and further accelerates the coordination between uranium and binding sites. The excellent photocatalytic effects endow CPP with high anti-biofouling activity, achieving long-term solar desalination and highly efficient uranium extraction. The connection between freshwater and nuclear energy is realized in a new material providing an opportunity to meet the growing needs of mankind.
CPP with capillary microporous channels for rapid diffusion of uranyl ions and adequate water transport, and good photothermal effect can realize synergistic freshwater collection and uranium extraction.
We reported here a method to enhance detection sensitivity in surface plasmon resonance (SPR) spectroscopy integrated with a surface molecular imprinting recognition system and employing magnetic ...molecular imprinting polymer nanoparticles for amplifying SPR response. The proposed magnetic molecular imprinting polymer was designed by self-polymerization of dopamine on the Fe3O4 NPs surface in weak base aqueous solution in the presence of template chlorpyrifos (CPF). The imprinted Fe3O4@polydopamine nanoparticles (Fe3O4@PDA NPs) were characterized by Fourier transform infrared spectroscopy, UV–vis absorption spectroscopy, and transmission electron microscopy. The biosensor showed a good linear relationship between the SPR angle shift and the chlorpyrifos concentration over a range from 0.001 to 10 μM with a detection limit of 0.76 nM. A significant increase in sensitivity was therefore afforded through the use of imprinted Fe3O4@PDA NPs as an amplifier, and meanwhile, the imprinted Fe3O4@PDA NPs had an excellent recognition capacity to chlorpyrifos over other pesticides. The excellent sensitivity and selectivity and high stability of the designed biosensor make this magnetic imprinted Fe3O4@PDA NP an attractive recognition element for various SPR sensors for detecting pesticide residuals and other environmentally deleterious chemicals.
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IJS, KILJ, NUK, PNG, UL, UM
In this work, a simple and rapid approach was developed for separation and detection of chiral compounds based on a magnetic molecularly imprinted polymer modified poly(dimethylsiloxane) (PDMS) ...microchip coupled with electrochemical detection. Molecularly imprinted polymers were prepared employing Fe3O4 nanoparticles (NPs) as the supporting substrate and norepinephrine as the functional monomer in the presence of template molecule in a weak alkaline solution. After extracting the embedded template molecules, Fe3O4@polynorepinephrine NPs (MIP–Fe3O4@PNE NPs) showed specific molecular recognition selectivity and high affinity towards the template molecule, which were then used as stationary phase of microchip capillary electrochromatography for chiral compounds separation. Mandelic acid and histidine enantiomers were used as model compounds to test the chiral stationary phase. By using R‐mandelic acid as the template molecule, mandelic acid enantiomer was effectively separated and detected on the MIP‐Fe3O4@PNE NPs modified PDMS microchip. Moreover, the successful separation of histidine enantiomers on the MIP–Fe3O4@PNE NPs modified microchip using L‐histidine as template molecule was also achieved.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A novel dual-emission fluorescence ratiometric probe of luminol-Tb-GMP CPNPs for highly sensitive and selective detection of ALP and As(v) has been constructed based on the stimulus responsivity of ...luminol. The introduction of luminol as a ligand for Tb
, combined with GMP, leads to a sensor which is more robust, sensitive, and efficient.
The sense of it: A new type of rapid, sensitive, and specific photoluminescence (PL)‐based assay has been proposed for the detection of phosphate (Pi) based on the competition of oxygen‐donor atoms ...from Pi with those from the carboxylate groups on a graphene‐quantum‐dot (GQD) surface for Eu3+ ions (see scheme). The graphene‐like structures combined with QD‐like optical properties suggest the promising nature of the GQDs as versatile tools in the fields of analytical science and biotechnology.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We demonstrate for the first time an interfacial polymerization method for the synthesis of high‐quality polyaniline‐modified graphene nanosheets (PANI/GNs), which represents a novel type of ...graphene/polymer heterostructure. The interfacial polymerization at a liquid–liquid interface allows PANI to grow uniformly on the surface of the GNs. An ultra‐high loading of Pt nanoparticles was then controllably deposited on the surface of the PANI/GNs to form a Pt/PANI/GNs hybrid. The obtained composites were characterized by scanning electron microscopy, transmission electron microscopy, energy‐dispersive spectrometry, X‐ray diffraction, X‐ray photoelectron spectroscopy, and thermogravimetric analysis. The Pt/PANI/GNs hybrid shows excellent electrocatalytic activity toward methanol oxidation and oxygen reduction. H2O2 and glucose were used as two representative analytes to demonstrate the sensing performance of a Pt/PANI/GNs‐modified electrode. It is found that this sensing element shows high sensitivity and a low detection limit for H2O2 and glucose. The results demonstrate that the Pt/PANI/GNs hybrid may be an attractive and advanced electrode material with potential applications in the construction of electrochemical sensors and biosensors.
Hybrids make sensors! High‐quality polyaniline‐modified graphene nanosheets (PANI/GNs) were prepared by using an interfacial polymerization method, then an ultra‐high loading of Pt nanoparticles (Pt NPs) was controllably deposited on the surface of PANI/GNs to form a Pt/PANI/GNs hybrid (see figure). The resultant hybrid shows high electrocatalytic activity toward the electrooxidation of methanol and reduction of oxygen.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Platinum nanoparticles (Pt NPs) with uniform size and high dispersion have been successfully assembled on poly(diallyldimethylammonium chloride) functionalized graphene oxide via a sodium borohydride ...reduction process. The loading concentration of Pt NPs on graphene can be adjusted in the range of 18–78 wt %. The obtained Pt/graphene nanocomposites are characterized by transmission electron microscopy, high resolution transmission electron microscopy, energy dispersive spectrometry, X-ray diffraction, and thermogravimetric analysis. The results show that the Pt NPs with sizes of approximate 4.6 nm uniformly disperse on graphene surface for all Pt loading densities. Electrochemical studies reveal that the Pt/graphene nanocomposites with electrochemically active surface area of 141.6 m2/g show excellent electrocatalytic activity toward methanol oxidation and oxygen reduction. The present method is promising for the synthesis of high performance catalysts for fuel cells, gas phase catalysis, and sensors.
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IJS, KILJ, NUK, PNG, UL, UM
Uranium is a key element in the nuclear industry and also a global environmental contaminant with combined highly toxic and radioactive. Currently, the materials based on post-modification of ...amidoxime have been developed for uranium detection and adsorption. However, the affinity of amidoxime group for vanadium is stronger than that of uranium, which is the main challenge hindering the practical application of amidoxime-based adsorbents. Herein, we synthesized a fluorescent covalent organic framework (TFPPy-BDOH) through integrating biphenyl diamine and pyrene unit into the π-conjugated framework. TFPPy-BDOH has an excellent selectivity to uranium due to the synergistic effect of nitrogen atom in the imine bond and hydroxyl groups in conjugated framework. It can achieve ultra-fast fluorescence response time (2 s) and ultra-low detection limit (8.8 nM), which may be attributed to its intrinsic regular porous channel structures and excellent hydrophilicity. More excitingly, TFPPy-BDOH can chemically reduce soluble U (VI) to insoluble U (IV), and release the binding site to adsorb additional U (VI), achieving high adsorption capacity of 982.6 ± 49.1 mg g−1. Therefore, TFPPy-BDOH can overcome the challenges faced by current amidoxime-based adsorbents, making it as a potential adsorbent in practical applications.
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•A fluorescent COF (TFPPy-BDOH) is synthesized by a one-step method.•TFPPy-BDOH has ultra-fast fluorescence response time for UO22+.•TFPPy-BDOH can selectively chemically reduce soluble U(VI) to insoluble U(IV).•TFPPy-BDOH achieves high sensitivity and selectivity for detecting and capturing UO22+ in harsh environments.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
