Latest ArticlesWhite light emitting systems of pure organic materials have attracted extensive research interest due to their better compatibility and functional scalability. The reported organic white light materials are mainly based on the multi-channel emission regulation of the compound itself or the mixing of multicolor luminescence materials, but studies on the dependence between multicolor luminescence and the external environment are lacking, which limits the application of these materials in areas such as identification and sensing. This paper reports that the 4- or 3‑hydroxyl-substituted naphthalimides NapH1 and NapH2 form intermolecular hydrogen bonds with adjacent molecules in the environment, and undergo excited-state intermolecular proton transfer under irradiation, resulting in blue-yellow or blue-red dual fluorescence emission, respectively. Since the two compounds have different two-color luminescence channels and the two-color intensity ratio is affected by the environment, and the intermolecular hydrogen bond is determined by the hydrogen bond receptor, polarity, and temperature in the environment, the full spectrum from blue to red light and white light emission can be obtained by adjusting the mixing ratio of the two dyes and the solvent polarity and the ambient temperature. This environmentally sensitive white emission is used to detect the alkalinity of different papers, and the dyed paper can be used as a test strip for acid-base vapor detection.
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.
Paper-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.
Exciton behavior is crucial to the exploitation of light-emitting conjugated polymer (LCPs) for optoelectronic devices. Singlet excitons are easily trapped by the intrinsically defect structures. Herein, we set a polyfluorenol (PPFOH) as an example to systematically investigate its photophysical behavior to check the role of defect structures in LCPs. According to time-resolved photoluminescence analysis, the feature emission peaks from individual chain of PPFOH in diluted DMF solution is effectively avoided the influence of fluorenone formation, but the residual green-band emission at 550 nm is easily observed in the PL spectra of PPFOH dilute toluene solution obtained delay 1.5 ns, confirmed the formation of "guest" physical aggregation-induced defect structure. Remarkably, efficient and ultrafast energy transfer from individual chain to defect structure is observed in PPFOH films. Interestingly, the efficient energy transfer happened for the film obtained from DMF solution (200 ps) than those of toluene ones (600 ps). Meanwhile, compared to relatively stable green-band emission in PPFOH film from toluene solution, red-shifted emission peak (11 nm) of PPFOH film from DMF solutions exposed to saturated DNT vapor also confirmed their different aggregation-induced green-band emission. Therefore, this aggregation defect structures are influenced on the photophysical property of LCPs in solid states.
The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in late 2019 has negatively affected people's lives and productivity. Because the mode of transmission of SARS-CoV-2 is of great concern, this review discusses the sources of virus aerosols and possible transmission routes. First, we discuss virus aerosol collection methods, including natural sedimentation, solid impact, liquid impact, centrifugal, cyclone and electrostatic adsorption methods. Then, we review common virus aerosol detection methods, including virus culture, metabolic detection, nucleic acid-based detection and immunology-based detection methods. Finally, possible solutions for the detection of SARS-CoV-2 aerosols are introduced. Point-of-care testing has long been a focus of attention. In the near future, the development of an instrument that integrates sampling and output results will enable the real-time, automatic monitoring of patients.
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.
The irregular defects and residual tumor tissue after surgery are challenges for effective breast cancer treatment. Herein, a smart hydrogel with self-adaptable size and dual responsive cargos release was fabricated to treat breast cancer via accurate tumor elimination, on-demand adipose tissue regeneration and effective infection inhibition. The hydrogel consisted of thiol groups ended polyethylene glycol (SH-PEG-SH) and doxorubicin encapsulated mesoporous silica nanocarriers (DOX@MSNs) double crosslinked hyaluronic acid (HA) after loading of antibacterial peptides (AP) and adipose-derived stem cells (ADSCs). A pH-cleavable unsaturated amide bond was pre-introduced between MSNs and HA frame to perform the tumor-specific acidic environment dependent DOX@MSNs release, meanwhile an esterase degradable glyceryl dimethacrylate cap was grafted on MSNs, which contributed to the selective chemotherapy in tumor cells with over-expressed esterase. The bond cleavage between MSNs and HA would also cause the swelling of the hydrogel, which not only provide sufficient space for the growth of ADSCs, but allows the hydrogel to fully fill the irregular defects generated by surgery and residual tumor atrophy, resulting in the on-demand regeneration of adipose tissue. Moreover, the sustained release of AP could be simultaneously triggered along with the size change of hydrogel, which further avoided bacterial infection to promote tissue regeneration.
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.
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