Latest ArticlesDue to the high local concentration of substrates in confined space, porous solid Brønsted acids have been extensively explored for efficient acid-catalyzed reaction. However, the porous structures with strong Brønsted acids lack long-term stability due to chemical hydrolysis. Moreover, the products inhibition effect in confined rigid cavities severely obstructs subsequent catalysis. Here, tubular Brønsted acid catalyst with unique recognition of protons was presented by self-assembly of pH-responsive aromatic amphiphiles. The responsive assembly could mechanically transfer hydrogen ions from low-concentration acidic solution into tubular defined pores, thereby producing effective catalytic activity for Mannich reactions in mildly acidic solution. Notably, the tubular catalyst unfolded into flat sheets upon addition of triethylamine for efficient release of products, which could be recovered by subsequent acidification and the catalytic activity still remained. Therefore, the porous Brønsted acid with reversible assembly provides a new strategy for mass synthesis through increasing conversion times.
In this work, we have designed and synthesized a cyano-substituted p-phenylenevinylene derivative (PPTA), which can self-assemble into positively charged nanoparticles in an aqueous solution with a deep green fluorescence. An anionic polyelectrolyte material guar gum modified by carboxylic acid (GP5A) was chosen to build an artificial light-harvesting system (LHS) through self-assembly with PPTA, in which two acceptors Eosin Y (EY) and Nile red (NiR) were loaded into the PPTA-GP5A assemblies through electrostatic interaction and Van der Waals force. By adjusting the molar ratio of PPTA-GP5A/EY at 1:0.004, the one-step artificial LHS can exhibit high energy transfer efficiency (38.9%) and antenna effect (AE) (4.6). Subsequently, with the addition of NiR, the and AE of the two-step sequential artificial LHS were calculated to be 71.9% and 13.5, respectively. Moreover, the two-step artificial LHS constructed by the polyelectrolyte material GP5A can be used as a nanoreactor to photocatalyst alkylation of C-H bonds of phenyl vinyl sulfone (PVS) and tetrahydrofuran (THF) in water with a yield of 42%. Therefore, we have constructed an artificial LHS with two-step energy transfer based on polyelectrolytes through the electrostatic interaction to improve energy transfer efficiency, which can also be used as a nanoreactor for photocatalysis.
Hydrazine hydrate (DH) is an important fine chemical intermediate and as fuel for rockets, however, it also has serious toxic for humans and environment. Developing novel materials and methods for sensitive detection of DH in water and air is an important task. In order to effectively detect DH, a novel conductive supramolecular polymer metallogel (PQ-Ag) has been constructed by the coordination of bis-5-hydroxyquinoline functionalized pillar[5]arene (PQ5) with Ag+. The metallogel PQ-Ag could realize the multi-channel sensitive detection of DH through naked-eye, fluorescence, and electrochemical methods. The lowest limit of detection (LOD) is 0.1 mg/m3 in air and 2.68 × 10−8 mol/L in water, which is lower than the standard of the US Environmental Protection Agency (EPA) for DH of maximum allowable concentration in drinking water. More importantly, an electronic device for DH detection based on the metallogel PQ-Ag was designed and prepared, which can realize conveniently and efficiently multi-channel detection and alert of DH through sound and light alarms not only in water but also in air.
Despite the 1,2-difunctionalization reactions of styrenes have been well developed, the 1,1-regioselective addition reaction remains challenging. We disclose herein a palladium-catalyzed, highly 1,1-regioselective alkenylboration of styrenes by using alkenyl triflates and a diboron reagent as the coupling partners. A wide scope of styrenes derivatives and alkenyl triflates participate this reaction to provide the corresponding allyl boronates with high regioisomeric ratios. The success of this reaction is ascribed to the application of 1,10-phenanthroline-derivated ligand and the addition of ammonium chloride salt. Moreover, acrylate esters can also selectively afford the 1,1-alkenylboration products under the same reaction conditions.
Synthesis and functionalization of novel macrocyclic host molecules are important topics in supramolecular chemistry. In this work, the first amphiphilic [2]biphenyl-extended pillar[6]arene (AM-[2]BP-ExP6) was designed and synthesized with poly(ethylene glycol) chains as the hydrophilic tails and a rigid cavity as the hydrophobic core. Due to its amphiphilic nature, AM-[2]BP-ExP6 could self-assemble to stable fibers in water. What's more, AM-[2]BP-ExP6 could associate with quaternary ammonium modified tetraphenylethylene guest (QTPE) to form a 2:1 host-guest complex, accompanied by significant enhanced fluorescence. Interestingly, different like AM-[2]BP-ExP6, AM-[2]BP-ExP6⊃QTPE host-guest complex self-assembled into fluorescent particles with diameter about 310 nm, the obtained fluorescent particles can be further employed in living cell imaging.
Electrochemical oxidation of aqueous tris(1,3-dichloro-2-propyl) phosphate (TDCPP) by using Ti/SnO2-Sb/La-PbO2 as anode was investigated for the first time, and the degradation mechanisms and toxicity changes of the degradation intermediates were further determined. Results suggested that electrochemical degradation of TDCPP followed pseudo-first-order kinetics, and the reaction rate constant (k) was 0.0332 min−1 at the applied current density of 10 mA/cm2 and Na2SO4 concentration of 10 mmol/L. There was better TDCPP degradation performance at higher current density. Free hydroxy radical (·OH) was proved to play dominant role in TDCPP oxidation via quenching experiment, with a relative contribution rate of 60.1%. A total of five intermediates (M1, C6H11Cl4O4P; M2, C3H7Cl2O4P; M3, C9H16Cl5O5P; M4, C9H14Cl5O6P; M5, C6H10Cl3O6P) were identified, and the intermediates were further degraded prolonging with the reaction time. Flow cytometer results suggested that the toxicity of TDCPP and degradation intermediates significantly reduced, and the detoxification efficiency was achieved at 78.1% at 180 min. ECOSAR predictive model was used to assess the relative toxicity of TDCPP and the degradation intermediates. The EC50 to green algae was 3.59 mg/L for TDCPP, and the values raised to 84, 574, 54.6, 391, and 8920 mg/L for M1, M2, M3, M4, and M5, respectively, indicating that the degradation intermediates are less toxic or not toxic. Electrochemical advanced oxidation process is a valid technology to degrade TDCPP and pose a good detoxification effect.
Nucleic acid detection (NAD) based on real-time polymerase chain reaction (real-time PCR) is gold standard for infectious disease detection. Magnetic nanoparticles (MNPs) are widely used for nucleic acid extraction (NAE) because of their excellent properties. Microfluidic technology makes automated NAD possible. However, most of the NAD microfluidic chips are too complex to be applied to point-of-care (POC) testing. In this paper, a simple-structure cartridge was developed for POC detection of infectious diseases. This self-contained cartridge can be divided into a magnetic-controlled NAE part, a valve-piston combined fluidic control part and a PCR chip, which is able to extract nucleic acid from up to 500 µL of liquid samples by MNPs and finish the detection process from “sample in” to “answer out” automatically. Performance tests of the cartridges show that it met the demands of automated NAD. Results of on-cartridge detection of hepatitis B virus (HBV) demonstrated that this system has good uniformity and no cross-contamination between different cartridges, and the limit of detection (LOD) of this system for HBV in serum is 50 IU/mL. Multiplex detections of severe acute respiratory syndrome coronaviruses 2 (SARS-CoV-2) with a concentration of 500 copies/mL were carried out on the system and 100% positive detection rate was achieved.
Adenosine triphosphate (ATP) plays an important role in various biological processes and the ATP level is closely associated with many diseases. Herein, we designed a novel dual-emissive fluorescence nanoplatform for ATP sensing based on red emissive europium metal-organic framework (Eu-MOF) and blue emissive gold nanoclusters (AuNCs). The presence of ATP causes the decomposition of Eu-MOF owing to strong affinity of Eu3+ with ATP. As a result, the red emission of Eu-MOF decreases while the blue emission of AuNCs remains unchanged. The distinct red/blue emission intensity change enables the establishment of a ratiometric fluorescent and visual sensor of ATP. Moreover, a fluorescent paper-based sensor was fabricated with the ratiometric ATP probes, which enabled easy-to-use and visual detection of ATP in serum samples with a smartphone.
Cancer immunotherapy harnesses the immune system to attack tumors and has received extensive attention in recent years. Cancer vaccines as an important branch of immunotherapy are designed for delivering tumor antigens to antigen-presenting cells (APCs) to stimulate a strong immune response to against tumors, representing a potentially therapeutic and prophylactic effect with the long-term anti-cancer benefits. Nevertheless, the disappointing outcomes of their clinical use might be attributed to dilemma in antigen selection, immunogenicity, lymph nodes (LNs) targeting ability, lysosomal escape ability, immune evasion, etc. Nanotechnology, aiming to overcome these barriers, has been utilized in cancer vaccine development for decades. Numerous preclinical and clinical studies demonstrate positive results in nanomaterials-based cancer vaccines with considerable improvement in the vaccine efficacy. In this review, we systematically introduced the characteristics of nanovaccines and highlighted the different types of nanomaterials used for cancer vaccine design. In addition, the opportunities and challenges of the emerging nanotechnology-based cancer vaccines were discussed.
Rosmarinic acid (RA) is promising as a natural and nontoxic food additive. However, many analysis methods for RA generally depend on large instruments and single signals for quantitative detection. A new up-conversion fluorescence, colorimetric and photothermal multi-modal sensing strategy is developed for the quantification of RA. β-cyclodextrin (CD) modified citric acid (Cit) wrapped NaYF4:Yb/Er-Cit-CD (Y:Yb/Er-Cit-CD) up-conversion nanocomposite has been synthesized, which emits green fluorescence at 550 nm under 980 nm near-infrared (NIR) excitation. In the presence of oxidized 3, 3′, 5, 5′-tetramethylbenzidine (oxTMB), the green fluorescence is significantly quenched attributed to the fluorescence inner filter effect (IFE) between oxTMB and Y:Yb/Er-Cit-CD. When RA is intervened, blue oxTMB is reduced to colorless 3, 3′, 5, 5′-tetramethylbenzidine (TMB) inducing the recovery of up-conversion fluorescence. At the same time, colorimetric and photothermal signals readout can be easily achieved thanks to the color indication and photothermal effect of the oxTMB. The constructed Y:Yb/Er-Cit-CD/oxTMB sensor displays high sensitivity, visibility and simplicity for RA, and the limits of detection (LOD) for fluorescence, colorimetric and photothermal were 0.004 µmol/L, 0.036 µmol/L and 0.043 µmol/L, respectively. This sensing system is successfully performed for the detection of RA in food samples.
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