Latest ArticlesPaper-based biosensors are widely employed in point-of-care testing (POCT) due to their convenience, portability, low cost, and ease of use. This study reports an integrated distance-based paper biosensor fabricated with a mesoporous membrane coated with stimuli-responsive polymer. The detection of α-amylase (AMY) using amylopectin-coated mesoporous membrane is demonstrated as an example. After introducing the AMY solution, it is observed that the aqueous solution flows along the paper strip due to AMY-catalyzed hydrolysis of amylopectin. The flow distance is proportional to the concentration of AMY with a detection limit as low as 4 mU/mL. In addition, the detection of AMY is demonstrated in human serum. Furthermore, the inhibitory effect of acarbose on AMY is evaluated. This reagent-free and disposable biosensor allows single-step rapid detection of the analyte. This approach is very promising for the development of user-friendly, equipment-free, and cost-effective biosensors with remarkable sensitivity and excellent selectivity for disease diagnosis and hypoglycemic drug screening.
While enol-keto tautomerism has attracted great interest in Schiff bases and related compounds in solution and crystal states, the self-assembly of energy-unfavored keto form were scarcely investigated. Here, we report a keto-form directed self-assembly of a naphthalene-attached enantiomeric N-salicylideneanil analog L/DGG-Nap accompanied with a significantly amplified circularly polarized luminescence (CPL). It was found that LGG-Nap exists as a mixture of enol and keto form in monomer at a diluted toluene solution. The increment of the concentrations leads to the formation of predominated keto form, which subsequently triggers the self-assembly. Cryo-transmission electron microscopy (Cryo-TEM) revealed that a hierarchical assembly process happened upon increasing the concentration of LGG-Nap in toluene. Individual nanofibers formed at 1 × 10−4 mol/L and transferred into helical nanofiber bundles in 5 × 10−3 mol/L. Interestingly, while these is nearly no circular dichroism (CD) or CPL in the monomeric solution, the assembly showed strong CD and CPL. Remarkably, the dissymmetry factor (glum) was significantly amplified from zero in solution through the 0.005 in individual nanofiber to 0.1 in nanofiber bundles. This work demonstrates that the enol-keto tautomerism can be broken and trigger the self-assembly upon increasing the concentration, which can subsequently direct the chiral self-assembly and significantly amplify the dissymmetry factor of assembled CPL materials.
Talaroclauxins A and B (1 and 2), two novel duclauxin hybrids, were obtained from Talaromyces stipitatus, along with three new (3−5) and one known analogue (6). Their structures were determined by NMR spectroscopy, HRESIMS, single-crystal X-ray diffraction, and quantum chemical calculations. Compound 1 is the first example of duclauxin-ergosterol hybrid featuring an unprecedented dodecacyclic ring system formed via a [4 + 2] cycloaddition, while compound 2, bearing an unusual 6/6/6/5/6/6/6/6 ring system, is a new member of the rare duclauxin-polyketide hybrid class of natural products. Plausible biosynthetic pathways for 1−6 are proposed. Compound 5 displayed moderate neuroprotective effects in glutamate sodium-induced SH-SY5Y cells.
Carbon dots (CDs) with superior fluorescence properties have attracted a growing number of research interests in anti-counterfeiting. However, the preparation of CDs with thermally turn-on fluorescence and full-color-emitting in visible spectrum is still a big challenge due to the complicated reaction mechanism in the formation of CDs. Here, a simple precursor-oriented strategy for the preparation of multicolor CDs with heat-stimuli turn-on fluorescence is reported. Comprehensive experimental characterizations and theoretical calculations revealed that the emission wavelength of CDs can be readily tuned from 460 nm to 654 nm with selected precursors, which was ascribed to the extent of conjugated sp2-domains (core states) and the amount of oxygen- and nitrogen-containing groups bound to sp2-domains (surface states). After simply mixing two or three kinds of CDs, a full-color range of fluorescence emission was realized, and the CDs-based fluorescence inks were successfully fabricated. Particularly, all the printed patterns from the inkjet exhibited a thermal-induced enhancement in fluorescence. On this basis, combining CDs with heating-induced "turn-off" fluorescence materials can lead to multidimensional and multistage encryption. These results demonstrate that the thermochromic and photochromic CDs with much more enhanced security exhibit promising application in data storage and encryption.
In the process of electrocatalytic water splitting, the management of gaseous products is an important task. Timely detachment of gaseous products from the electrode surface and the electrolyte is beneficial to the reduction of energy consumption of the electrolytic cell. In the existing industrial electrolytic cells, the circulating pump drives the electrolyte flowing to discharge the gaseous products. Up to now, several much more advanced strategies have been explored to deal with the negative effects of bubbles. In this review, we summarized various strategies for bubble detachment, including electrode design, external field imposing and system upgrading. We also elaborated the principle, functional features, practicability, advantages and limitations of each method. Finally, challenges and perspectives are also provided for the further development of advanced bubbles detachment strategies for efficient hydrogen evolution.
Polystyrene resins (PS) have been practical ion exchangers for radionuclides removal from water. However, nonspecific effects of ion exchange groups continue to be a major obstacle for emergency treatment with coexisting ions of high concentrations. The selectivity for Cs+ enables zirconium phosphate (ZrP) to be the most promising inorganic sorbent for radioactive cesium extraction, despite being difficult to synthesize and causing excessive pressure loss in fixed-bed reactors due to fine powder. Herein, through facile confined crystallization in host macropores, we prepared PS confined α-ZrP nanocrystalline (ZrP-PS). Size-screen sorption of layered α-ZrP and sulfonic acid group preconcentration of PS synergistically enable a considerably higher Cs+ affinity of ZrP-PS than PS, as confirmed by X-ray photoelectron spectroscopy (XPS) analysis. ZrP-PS demonstrated remarkable cesium sequestration performance in both batch and continuous experiments, with a high adsorption capacity of 269.58 mg/g, a rapid equilibrium within 80 min, and a continuous effluent volume of 2300 L/kg sorbents. Given the excellent selectivity for Cs+ and flexibility to separate from treated water, ZrP-PS holds great promise as purification packages for the emergency treatment of radioactively contaminated water.
Mitochondrial damage is closely related to the occurrence of many diseases. However, accurate monitoring and reporting of mitochondrial damage are not easy. Here, we developed a small molecule fluorescent probe named CB-Cl, which has splendid spectral properties (large Stokes shift, strong affinity for RNA, etc.) and excellent targeting ability to intracellular mitochondria. After mitochondria were damaged by external stimuli, CB-Cl would light up the nucleolus as a signal reporter. The cascade imaging of mitochondria and nucleolus using CB-Cl can monitor and visualize the mitochondrial status in living cells in real-time. Based on the above advantages, the probe CB-Cl has reference significance for the related research of mitochondrial damage and the prevention and treatment of related diseases.
In this work, semirigid linkers of the alkyl-thiophene-alkyl structure are developed to construct double-cable polymers. Three alkyl units, propyl (C3H6), hexyl (C6H12), and dodecyl (C12H24), are applied as semirigid linkers, yielding three double-cable polymers: PBC6-T, PBC12-T, and PBC24-T, respectively. PBC12-T which uses C6H12-thiophene-C6H12 linkers is found to exhibit the best device efficiency of 5.56%, while PBC6-T and PBC24-T with shorter or longer linkers yield device efficiencies of only 2.65% and 1.09% in single-component organic solar cells (SCOSCs). Further studies reveal that PBC12-T exhibits higher crystallinity and improved charge transport, resulting in better efficiencies. Our work provides an approach to construct double-cable conjugated polymers with long alkyl linkers, and it shows the importance of the linker length for the photovoltaic performance of SCOSCs.
Metal-organic frameworks (MOFs) with inherent porosity and suspended acidic groups are promising proton conducting materials in water or aqua-ammonia media. Herein we report a new lanthanide phosphonate, namely, Dy2(amp2H2)2(mal)(H2O)2·5H2O (MDAF-6). It possesses a 3D open-framework structure, and shows a high NH3 adsorption capacity of 142.4 cm3/g at P/P0 = 0.98 at 298 K due to acid-base interaction. Interestingly, the proton conductivity of MDAF-6-NH3 is enhanced by five orders of magnitude compared to MDAF-6 after 8.5 h exposure in saturated NH3-H2O vapor, indicating the importance of coexistent conjugate acid-base pairs of H3O+-H2O and NH4+-NH3 in promoting proton conduction. Magnetic studies of MDAF-6 revealed slow magnetization relaxation under zero dc field, characteristic of single-molecule magnet behavior. This work provides not only a new multifunctional MOF material, but also a new strategy to improve proton conduction in aqua-ammonia medium.
Malignant tumors are the main diseases threatening human life. Using precise theranostics to diagnose and cure tumors has emerged as a new method to improve patient survival. Based on the current development of precise tumor imaging, image-guided tumor therapy has received widespread attention because it is beneficial for developing precise treatment of tumors, has the potential to improve the efficacy of tumor therapy and reduce the incidence of adverse side effects. Nanoprobes, which are nanomaterial functionalized with specific biomolecules, have intrigued intense interest due to their great potential in monitoring biorecognition and biodetection evens. Benefiting from the unique advantages of nanomaterials, including the easy surface functionalization, the unique imaging performances, and the high drug loading capacity, nanoprobes have become a powerful tool to simultaneously realize tumor precise imaging, diagnosis, and therapy. This review introduces the non-invasive tumor precise imaging and highlights the recent advances of image-guided oncotherapy mediated by nanoprobes in anti-tumor drug delivery, tumor precise surgical navigation, chemodynamic therapy, and phototherapy. Finally, a perspective on the challenge and future direction of nanoprobes in imaging-guided tumor theranostics is also discussed.