Latest ArticlesUnderstanding the dynamic assembly process of DNA nanostructures is important for developing novel strategy to design and construct functional devices. In this work, temperature-controlled dynamic light scattering (DLS) strategy has been applied to study the global assembly process of DNA origami and DNA bricks. Through the temperature dependent size and intensity profiles, the self-assembly process of various DNA nanostructures with different morphologies have been well-studied and the temperature transition ranges could be observed. Taking advantage of the DLS information, rapid preparation of the DNA origami and the brick assembly has been realized through a constant temperature annealing. Our results demonstrate that the DLS-based strategy provides a convenient and robust tool to study the dynamic process of forming hieratical DNA structures, which will benefit understanding the mechanism of self-assembly of DNA nanostructures.
Human Notum (hNotum) inhibitors could be used for treating Wnt signalling-associated diseases including colorectal cancer. Herein, two series of chalcone derivatives were designed and synthesized aiming to find selective and potent hNotum inhibitors. Structure–activity relationship (SAR) studies showed that 2-methoxyl and 5-bromine substitutions on A-ring significantly enhanced anti-hNotum effect, while 4′-ethoxyl and 3′-alkyl substitutions on B-ring were beneficial for hNotum inhibition. Among all tested chalcones, B11 displayed the most potent anti-Notum effect (IC50 = 3.6 nmol/L), good selectivity, excellent chemical stability and suitable metabolic stability. Further investigations showed that B11 acted as a competitive inhibitor of hNotum, while this agent (5 µmol/L) significantly weaken the migration abilities of colorectal cancer cells. Collectively, this study deciphers the SARs of chalcones as hNotum inhibitors and reports a novel and potent hNotum inhibitor with the anti-migration effect on colorectal cancer cells, which offers a promising lead compound to develop novel anti-cancer agents.
Thermocatalytic nonoxidative ethane dehydrogenation (EDH) is a promising strategy for ethene production but suffers from intense energy consumption and poor catalyst durability; exploring technology that permits efficient EDH by solar energy remains a giant challenge. Herein, we present that an oxygen vacancy (Ov)-rich LaVO4 (LaVO4-Ov) catalyst is highly active and stable for photocatalytic EDH, through a dynamic lattice oxygen (Olatt.) and Ov co-mediated mechanism. Irradiated by simulated sunlight at mild conditions, LaVO4-Ov effectively dehydrogenates undiluted ethane to produce C2H4 and CO with a conversion of 2.3%. By loading a small amount of Pt cocatalyst, the evolution and selectivity of C2H4 are enhanced to 275 µmol h−1 g−1 and 96.8%. Of note, LaVO4-Ov appears nearly no carbon deposition after the reaction. The isotope tracked reactions reveal that the consumed Olatt. recuperates by exposing the used catalyst with O2, thus establishing a dynamic cycle of Olatt. and achieving a facile catalyst regeneration to preserve its intrinsic activity. The refreshed LaVO4-Ov exhibits superior reusability and delivers a turnover number of about 305. The Ov promotes photo absorption, boosts ethane adsorption/activation, and accelerates charge separation/transfer, thus improving the photocatalytic efficiency. The possible photocatalytic EDH mechanism is proposed, considering the key intermediates predicted by density functional theory (DFT) and monitored by in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS).
There are urgent needs of volatile amine gas sensors with high-performance in food quality control, disease monitoring and environmental pollution. Thin-film fluorescent probe is suitable for amine vapour sensing due to its high sensitivity, high selectivity, and no polluting analyte. Herein, a novel fluorescent probe based on indacenodithiophene structure with π conjugated system was designed and synthesized. The experimental results show that the films prepared by this material exhibit rapid and distinct fluorescence quenching after being exposed to saturated vapours of primary amine, secondary amine and tertiary amine represented by n-propylamine, diethylamine and trimethylamine, respectively. The quenching of fluorescence is 84%, 87% and 96%, respectively, within 10 s. The detection mechanism of probe for primary amine is based on specific chemical reaction, while the detection mechanism for secondary amine and tertiary amine is intramolecular charge transfer. Further experiments show that the detection limit of the fluorescent probe for trimethylamine, an important marker of food spoilage, could reach 4.610 ppt. On-site detection based on spoilage of small yellow croaker suggests the material possesses the potential for food freshness detection. This simple fluorogenic probe is an original approach to simplify real-time visual monitoring of volatile amine vapour.
It remains a big challenge to develop solid-state stimuli-responsive materials for time-dependent information encryption and inkless erasable printing with long retention times. Herein, a 2D Cu2I2-based MOF with photoresponsive spiropyran (SP) groups orderly installed on its skeleton is developed. The structural isomerization from SP to colored merocyanine (MC) form can be triggered by removing the CH3CN guests. Besides, the degree of structural isomerization and the retention time can be adjusted by controlling the amount of CH3CN guests, exhibiting dynamic photochromic behavior with multicolor states and tunable retention time. Based on these advantages, time-dependent information encryption is successfully achieved. Furthermore, the long retention time (> 72 h) of the MC form under daylight conditions in the CH3CN-removed Cu2I2-based MOF and good repeatability make it promising in various applications, such as temporary calendars, price-cards, billboards, and reusable identity cards. This work provides a novel design strategy to fabricate multi-functional MOF-based smart materials for challenging applications of time-dependent information encryption and inkless erasable printing.
Peptide drugs are known for their high biological safety. However, compared with small molecule drugs, peptide drugs are easily oxidized and hydrolyzed as well as short in half-life. Herein, inspired by the long circulation of albumin in blood, we screened albumin binding peptides (ABPs) from a one-bead one-compound (OBOC) peptide library to increase the half-life of peptide drugs. Beads displaying random peptides were screened using fluorescent labeled human serum albumin. Fluorescent beads with specific binding to albumin were isolated for sequencing. The selected ABPs can effectively bind to albumin, thus possessing the long circulation of albumin. The dissociation constant (KD) of ABPs to albumin is up to 1 × 10−8 mol/L. Once one of ABPs (ABP2) was coupled to triptorelin, the circulation half-life of triptorelin in mice was significantly prolonged to 263.50 h much longer than that of triptorelin alone (179.07 h). In addition, the combination therapy using ABP-conjugated triptorelin and doxorubicin (DOX) can effectively inhibit the proliferation of tumor cells in mice. The OBOC screening strategy and resulting ABPs showed great potential for enhancing the delivery efficiency of peptide drugs.
The intricate correlation between multiple degrees of freedom and physical properties is a fascinating area in solid state chemistry and condensed matter physics. Here, we report a quantum-magnetic system BaNi2V2O8 (BNVO), in which the spin correlation was modulated by unusual oxidation state, leading to different magnetic behavior. The BNVO was modified with topochemical reduction (TR) to yield TR-BNVO with partially reduced valance state of Ni+ in the two-dimensional NiO6-honeycomb lattice. Accordingly, the antiferromagnetic order is suppressed by the introduction of locally interposed Ni+ and oxygen vacancies, resulting in a ferromagnetic ground state with the transition temperature up to 710 K. A positive magnetoresistance (7.5%) was observed in the TR-BNVO at 40 K under 7 T. These findings show that topological reduction is a powerful approach to engineer low-dimensional materials and accelerate the discovery of new quantum magnetism.
Construction of proton transport channels in metal-organic frameworks (MOFs) with simple synthesis processes, high proton conductivities and good performance stabilities has been of great interest for proton exchange membrane fuel cell (PEMFC). Herein, we mimic the proton transport behavior of amino acid residues in bacteriorhodopsin, select UiO-66-COOH as the host, glycine and aspartic acid as the functional guest molecules, and then functionalize the MOF framework with amino acids to obtain biomimetic proton transport channels. This strategy endows UiO-66-COOH-Asp a high proton conductivity of 1.19 × 10−2 S/cm at 70 ℃ and 98% RH, excellent cycle stability of performances and performance durability, which can be comparable to the reported MOFs-based proton conductors. Moreover, the proton conduction mechanism in UiO-66-COOH-Asp is elaborated in detail due to its visual structure, which is also one of the advantages of adopting MOFs as research platform, making it possible to optimize the structure-activity relationship of advanced materials. Notably, this strategy has clear objectives and simple synthesis, which has made certain contributions to both theoretical research and future industrial production of proton conductors.
Lead-free double perovskite nanocrystals (NCs) have emerged as a promising candidate in the optical field, owing to their non-toxic, good moist heat and chemical stability. However, their poor optical properties limited their application. To improve the optical properties of lead-free double perovskite NCs, metal ion doping or alloying had been suggested as a promising strategy. Here, we prepared monodisperse, uniformly sized, cubic morphology of Cs2AgBiCl6 NCs with different Na+ incorporation amounts via a simple hot-injection method. The Na+ incorporation broke the parity-forbidden transition by reducing the inversion symmetry of the electron wave function at the Ag site, which changed the parity of the self-trapped exciton wave function and thus allowed radiative recombination. As a result, the photoluminescence quantum yield (PLQY) of Na+-alloyed Cs2AgBiCl6 NCs (12.1%) was higher than that of Cs2AgBiCl6 NCs (2.4%), and the exciton lifetime of Na+-alloyed Cs2AgBiCl6 NCs increased to 36.98 ns from 17.58 ns for Cs2AgBiCl6 NCs. By adjusting the amount of Na+ incorporation, the band gap of Cs2AgBiCl6 NCs can be significantly tuned from ~2.90 eV to ~3.50 eV. Furthermore, the temperature-dependent photoluminescence spectra indicated that the Na+-alloyed Cs2AgBiCl6 NCs possessed higher longitudinal optical phonon energy and exciton binding energy compared to Cs2AgBiCl6 NCs. This suggested that there were strong exciton-phonon interactions during exciton recombination, a reduced probability of non-radiative processes, and excellent thermal stability. It offers a promising strategy for improving the optical properties of lead-free double perovskite NCs, and have the potential to replace traditional lead halide perovskite NCs in future optoelectronic applications.
Developing fluorescence probes with multiple responses has vital significance but remains challenging. Herein, for the first time, we present a mitochondrial DNA (mtDNA)-triggered pH response signal-amplified fluorescent probe (QCY-DBT) for multiple cell detection. The probe exhibited a large stokes shift (229 nm), excellent DNA selectivity over RNA, and ultrasensitivity of detection limit (DL; 74.0 ng/mL). Thus, QCY-DBT was successfully applied to analyze multiple human peripheral blood cells and visualize mtDNA in healthy and apoptotic cells. In the tumor acidic environment (pH 6.0–7.0), the absorbance of QCY-DBT at 436 nm increased, and the fluorescence signal (665 nm) was amplified by mtDNA, which enabled the direct observation of tumor cells. Our study provides help in designing smart probes with multiple responses for efficient abnormal cell detection.
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