Latest ArticlesThe preparation of immobilized enzyme with excellent performance is one of the difficulties that restrict the application of enzyme catalysis technology. Here, Candida rugosa lipase (CRL) was firstly adsorbed on the surface of magnetic zeolitic imidazolate framework-8 (ZIF-8) nanospheres, which was further encapsulated with a mesoporous SiO2 nano-membrane formed by tetraethyl orthosilicate (TEOS) polycondensation. Consequently, lipase could be firmly immobilized on carrier surface by physical binding rather than chemical binding, which did not damage the active conformation of enzyme. There were mesopores on the silica nano-membrane, which could improve the accessibility of enzyme and its apparent catalytic activity. Moreover, silica membrane encapsulation could also improve the stability of enzyme, suggesting an effective enzyme immobilization strategy. It showed that TEOS amount and the encapsulation time had significant effects on the thickness of silica membrane and the enzyme activity. The analysis in enzyme activity and protein secondary structure showed that lipase encapsulated in silica membrane retained the active conformation to the greatest extent. Compared with the adsorbed lipase, the encapsulated lipase increased its thermostability by 3 times and resistance to chemical denaturants by 7 times. The relative enzyme activity remained around 80% after 8 repetitions, while the adsorbed lipase only remained at 7.3%.
Late-stage modification of complex molecules via site-selective hydrodefluorination is a challenging endeavor. The selective activation of carbon-fluorine (C–F) bonds in the presence of multiple C–F bonds is of importance in organic synthesis and drug discovery. Herein, we describe the activation of C-F bonds via multiphoton photoredox catalysis to selectively produces a series of hydrodefluorinated compounds by simply tuning the reaction conditions. Moreover, this protocol was successfully applied to the late-stage functionalization of different drug-derivatives and the corresponding mono-, di-, and tri-defluorinated products were obtained in good to excellent yields. A detailed mechanistic investigation provides insight into the unprecedented hydrodefluorination pathway.
The first synthesis of flavanostilbenes with a 2-cyclohepten-1-one core was carried out by applying an effective strategy in three steps from abundant polymerized flavanol resources. A key regio- and stereoselective Cu-mediated [5 + 2] cycloaddition/decarboxylation cascade was explored and applied without the use of protecting groups, and water as an environmentally friendly solvent contributed to the cascade. The intramolecular [5 + 2] cycloaddition mechanism, involving oxidation and dearomatization of the flavanol unit as a diene, was proposed and supported by the synthesis of the intermediate. The regioselectivity of the cyclization was found to be dependent on the substitution effects of the stilbene units by the exploration of substrate scope.
Dion–Jacobson (DJ) phase hybrid perovskites have been proven to improve the photovoltaic performance of the devices due to its unique structure. At present, some DJ hybrid perovskites have been reported and used for photodetection filed, but most of them are based on lead-bromide systems, which is not conducive to construct broadband photodetection devices due to the limitation of intrinsic absorption. Herein, we constructed a bilayered DJ hybrid perovskite (3AMPY)(EA)Pb2I7 (3AMPY2+ is 3-(aminomethyl)pyridinium, EA+ is ethylammonium) using an aromatic spacer, which exhibit large current on/off ratios of ~104 under 520 and 637 nm illumination. In particular, the single crystal device based on (3AMPY)(EA)Pb2I7 shows a distinguished detectivity of 7.4 × 1012 Jones and a high responsivity of 0.89 A/W under 637 nm illumination. Such finding not only enriches the quantities of DJ hybrid perovskites, but also provides useful assistance for constructing high-performance optoelectronic device in the future.
The extracellular vesicles show great potential as a noninvasive biomarker for the early detection of cancer. Hence, there is an urgent requirement to create biosensors that are time-saving, simple, and easily scalable in order to accomplish rapid, sensitive, and quantitative detection of extracellular vesicles. In this study, we present a self-propelled DNA walker powered by endonuclease Nt.BbvCI, which enables the development of a "signal on" sensing platform for the rapid and highly sensitive detection of extracellular vesicles. The DNA motor employed tracks made of streptavidin magnetic beads, which consisted of substrate strands labeled with fluorescein and motor strands locked by aptamers. The aptamer recognition of the target protein on extracellular vesicles unlocked the motor strand, initiating the DNA motor process. After replacing the optimal buffer solution containing the endonuclease Nt.BbvCI, the motor strands autonomously moved along the streptavidin magnetic beads track, continuously releasing fluorescent molecules and producing detectable fluorescence signals. Under optimal conditions, the detection range was from 2×104 particles/mL to 2×109 particles/mL, with a detection limit of 2.9×103 particles/mL, demonstrating excellent selectivity. This method has demonstrated good selectivity in different tumor-derived extracellular vesicles and performs well in complex biological samples. The ability to effectively analyze surface proteins of extracellular vesicles in a short period of time gives our DNA walker a tremendous potential for developing simple and cost-effective clinical diagnostic devices.
Photodynamic therapy (PDT) presents a promising avenue in cancer treatment. Erlotinib, an FDA-approved anticancer drug targeting epidermal growth factor receptor (EGFR), has shown effectiveness in normalizing tumor vasculature across various tumors, thereby promoting tumor oxygenation and facilitating PDT. In this work, erlotinib was conjugated with a near-infrared (NIR) photosensitizer, benzo[a]phenoselenazinium, yielding three EGFR-targeted PDT agents (NBSe-nC-Er). These newly synthesized photosensitizers demonstrate specificity in binding to EGFR, thereby enhancing their accumulation in cancer cells and tumors, and consequently improving the efficiency of both PDT and chemotherapy. Additionally, the NIR fluorescence emitted by the photosensitizer allows for imaging-guided therapy, offering a non-invasive means of monitoring treatment progress. The distinctive properties of the three-in-one photosensitizer render it an ideal candidate for precise tumor treatment, overcoming the limitations of conventional therapies.
The first total synthesis of (+)-taberdicatine B and (+)-tabernabovine B has been accomplished in 10 steps with 26.9% overall yield and 15 steps with 7.3% overall yield, respectively. The prominent features of this efficient synthetic strategy include the following: (1) (+)-Taberdicatine B and (+)-tabernabovine B were accessed from common advanced intermediates by varying the substituents; (2) A one-pot asymmetric bromocyclization/hydrolysis was explored to assemble HPI skeleton; (3) Dieckmann condensation to form β-keto ester for the assembly of seven-membered ring; (4) An ester reduction/amide semireduction/cyclization sequence was applied to form the cage-like framework.
Current research primarily focuses on emerging organic pollutants, with limited attention to emerging inorganic pollutants (EIPs). However, due to advances in detection technology and the escalating environmental and health challenges posed by pollution, there is a growing interest in treating waters contaminated with EIPs. This paper explores biochar characteristics and modification methods, encompassing physical, chemical, and biological approaches for adsorbing EIPs. It offers a comprehensive review of research advancements in employing biochar for EIPs remediation in water, outlines the adsorption mechanisms of EIPs by biochar, and presents an environmental and economic analysis. It can be concluded that using biochar for the adsorption of EIPs in wastewater exhibits promising potential. Nonetheless, it is noteworthy that certain EIPs like Au(Ⅲ), Rh(Ⅲ), Ir(Ⅲ), Ru(Ⅲ), Os(Ⅲ), Sc(Ⅲ), and Y(Ⅲ), have not been extensively investigated regarding their adsorption onto biochar. This comprehensive review will catalyze further inquiry into the biochar-based adsorption of EIPs, addressing current research deficiencies and advancing the practical implementation of biochar as a potent substrate for EIP removal from wastewater streams.
In this work, an effective catalyst of Cu/MnOOH has been successfully constructed for electrochemical nitrate reduction reaction (eNO3RR) for synthesis of ammonia (NH3) under ambient conditions. The substrate of MnOOH plays an important role on the size and electronic structure of Cu nanoparticles, where Cu has the ultrafine size of 2.2 nm and positive shift of its valence states, which in turn causes the increased number of Cu active sites and enhanced intrinsic activity of every active site. As a result, this catalyst realizes an excellent catalytic performance on eNO3RR with the maximal NH3 Faraday efficiency (FE) (96.8%) and the highest yield rate (55.51 mg h−1 cm−2) at a large NH3 partial current density of 700 mA/cm2, which could help to promote the industrialization of NH3 production under ambient conditions.
Nor-seco-cucurbit[10]uril (ns-CB[10]) is a kinetic product with unique structure. The single bridged methylene in its structure makes the molecular cavity of ns-CB[10] more deformable when compared to ordinary cucurbit[n]uril, reducing its structural stability. Repeated experiments showed that ns-CB[10] gradually cracks in an acidic solution and changes the specificity of cucurbit[5]uril (CB[5]) and cucurbit[8]uril (CB[8]) under more robust acidic solutions and when heated. A series of experiments were designed to study the transformation behavior of ns-CB[10]. It was found that the concentration of ns-CB[10] was correlated with the content distribution of CB[5] and CB[8]. This study explores the influencing factors and mechanisms of the transformation of ns-CB[10] to CB[5] and CB[8]. The results are of great significance for the application of ns-CB[10], understanding the formation mechanism of cucurbit[n]urils. Furthermore, it provides a new pathway for synthesizing new cucurbit[n]urils.
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