Latest ArticlesHerein, we report a semi-synthetic strategy affording a nitrophorin 2 (NP2) variant with a N,N′-bis(2-pyridylmethyl)amine (Dpa) ligand as sidechain selectively installed at position 27, which was assembled from a synthetic peptide thioester bearing the Dpa ligand and an expressed protein segment via native chemical ligation. The semi-synthetic NP2 was able to accept the natural heme b cofactor and the Dpa ligand was able to bind Cu(Ⅱ)/Fe(Ⅲ) ions, leading to heteronuclear active site.
Present research on the antimalarial mechanisms of artemisinin (ART) is mainly focused on covalent drug binding targets alkylated by free radicals, while non-covalent binding targets have rarely been reported. Here, we developed a novel photoaffinity probe of ART to globally capture and identify the antimalarial target proteins of ART through chemical proteomics. The results demonstrated that ART can bind to parasite proteins by both covalent and non-covalent modification, and these may jointly contribute to the antimalarial effects. Our work enriches the research on the antimalarial targets of ART, and provides a new perspective for further exploring the antimalarial mechanism of ART.
Following our previous work on human immunodeficiency virus-1 (HIV-1) non-nucleoside reverse transcriptase inhibitors (NNRTIs), a series of novel biphenyl-pyridone derivatives were synthesized and evaluated for their anti-HIV-1 activity to expand their structure–activity relationship. Some of them exhibited low nanomolar activity toward wild-type HIV-1 and clinically relevant single/double mutant strains. The most active compound B1 was 231-fold more potent (EC50 = 17 nmol/L) than the lead compound 2 (EC50 = 3.93 µmol/L) against wild-type (WT) HIV-1. This compound was approximately 3.5-fold less cytotoxic (CC50 = 100.58 µmol/L) than compound 2 (CC50 = 28.24 µmol/L), presenting a higher selectivity index (SI) value of 5923. Compared with 2, the antiviral potency of B1 was significantly increased against five single mutant strains (L100I, K103N, E138K, Y181C and Y188L) and two double mutant strains (F227L+V106A and K103N+Y181C). Especially, K103N, Y181C and K103N+Y181C were more sensitive to B1 than both 2 and doravirine. Besides, the enzymatic inhibitory activity of B1 against wild-type HIV-1 reverse transcriptase was approximately 32-fold higher (IC50 = 100 nmol/L) than 2 (IC50 = 3.21 µmol/L). Molecular docking studies and dynamic simulations were conducted to explain their potent activity. Taken together, this research represents an important step toward the discovery of novel biphenyl-pyridone drug candidates for HIV therapy.
Photo-catalytic oxidation of intracellular nicotinamide adenine dinucleotide (2′-phosphate) (NAD(P)H) has attracted much attention for cancer therapy. However, the general oxygen-dependent mechanism heavily depresses the efficacy in hypoxic tumors. To solve this problem, herein platinum nanoparticles (Pt NPs) with catalase-like (CAT-like) and catalytic H2 evolution activities were introduced as a powerful assistant to enhance the photo-catalytic NAD(P)H oxidation of Ru1 ([Ru(phen)2(PIP-OCH3)]2+, phen = 1,10-phenanthroline, PIP-OCH3 = 2-(4–methoxy phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline) under hypoxic and even oxygen-free conditions. Firstly, Pt NPs can transform the original and in situ formed H2O2 once again into O2 by the CAT-like activity, thus relieving tumor hypoxia and realizing cyclic utilization (at least in part) of the precious oxygen in hypoxia. Secondly, Pt NPs can also be served as H2 evolution catalysts while using Ru1 as the photosensitizer and NAD(P)H as the electron and proton donor. In this process, NAD(P)H is oxidized without the participation of oxygen, which can provide an effective way even under oxygen-free conditions. Via co-encapsulation of Ru1 and Pt NPs in bovine serum albumin (BSA) with tumor targeting ability, the resultant Ru/Pt@BSA could photo-catalyze intracellular NAD(P)H oxidation under hypoxic conditions (3% O2), and exhibited an efficient and selective anticancer activity both in vitro and in vivo. Our results may provide new sights for efficient and targeted cancer treatment under hypoxic conditions.
The trade-off between mass-loading and cycling stability is always a big challenge for iron oxide-based electrodes. Herein, α-Fe2O3 nanoparticles uniformly anchored on nitrogen-doped wood carbons with high mass-loading have been synthesized via a facile electrodeposition method accompanied by post-heating treatment. The resultant composite delivers a high specific capacitance of 603 F/g at 0.1 A/g and superior capacitance retention of 85.5% after 10,000 cycles at 10 A/g, indicating excellent long-term cycling stability. Such excellent electrochemical performance can be attributed to the synergistic effects of α-Fe2O3 nanoparticles and the conductive matrix as well as the formation of interfacial Fe-O-C bonding, which enables the composite electrode to provide plenty of accessible redox active sites, sufficient electron transport and electrolyte ions diffusion, and robust interfacial interaction. Consequently, the asymmetrical supercapacitor exhibits a high energy density of 30.3 Wh/kg at 125 W/kg, suggesting its great potential for practical applications.
The deterioration of water caused by industrial production is a thorny problem. Solving the problem cogently through innovative coagulationstrategies has been recognized of important practical significance. In this work, a simple enhanced coagulation by using ferric chloride (FC) and poly-ferric chloride (PFC) coupled with polyamidine (PA) were tried to remove the toxic organics. The results shown that PA addition could obviously enhance coagulation performances of the iron-based coagulants. The synergic coagulation process and mechanism were studied and discussed in detail based on the coagulation behaviors, flocs properties, removal efficiency and zeta potentials. FC and PFC remove organics mainly through charge neutralization and adsorption-bridging, resulting in a good purification performance. While PA with a higher charge density showed better purification performance due to enhanced charge neutralization. It is worth mentioning that the addition of PA could make the coagulants adapt to a wider pH range, and remove the toxic organics more effectively. That is to say, the practical adaptability of the coagulant was enhanced. This work thus provides a simple strategy to effectively purify wastewater and further improve the water safety.
Researchers engrossed in enantioseparation keep seeking for versatile chiral separation selectors. This work proposes a concept of quasi-dual-chiral-channel (QDCC) enantioseparation platform, where the surface sequentially grafted quinine (QN) and functional cyclodextrin (CD) can imitate two independent chiral channels without mutual interference to achieve wide spectrum chiral resolution. Chiral separation results combined with molecular docking simulation indicates that the different interaction mode of QN and functional CD layer renders QDCC the wide separation capability. This work provides a valuable insight into the rational design of versatile enantioseparation materials.
Three isomorphic polytungstates, Cs9K18H10{[Sm2(H2O)4W4O10(AsW9O33)3]2(N(CH2PO3)2)}·46.5H2O (1), Cs10K9H18{[Eu2(H2O)4W4O10(AsW9O33)3]2(N(CH2PO3)2)}·41.5H2O (2), Cs10K9H18{[Gd2(H2O)4W4O10 (AsW9O33)3]2(N(CH2PO3)2)}·46H2O (3), have been successfully synthesized and characterized by routine methods, and demonstrated excellent catalytic activities in Knoevenagel condensation reaction as heterogeneous catalysts. Notably, catalyst 1 achieved higher reaction activity than catalysts 2 and 3, where a satisfactory reaction yield (95%) and high TON value (6380) could be obtained at moderate reaction condition. In addition, in the scale-up experiment, with the help of catalyst 1, 7.8 g benzaldehyde and 5.7 g ethyl cyanoacetate could transform into corresponding condensation product with a satisfactory yield (83%) and impressive TON value (13,883).
Bacterial infection of wounds is an escalating medical problem, issuing threats to both global public health and personal health. Photothermal antibacterial technology as a novel sterilization strategy has outstanding sterilization efficiency, high safety and low risk of emergence of drug-resistant bacteria. By combining inherent antibacterial activity and light-assisted antibacterial treatment, developing novel multifunctional dressings with synergistic high-efficiency antibacterial effects and also promoting wound healing possesses attractive advantages in the field of treating bacterial wound infections in clinical care. Herein, a multifunctional hydrogel formed by in situ photo-cross linking was designed and prepared by first grafting methacrylic anhydride as a photosensitizer onto chitosan, and then introducing oxidatively synthesized polydopamine (PDA). The physicochemical characterizations of the synthesized hydrogels demonstrated their tunability certainly associated with PDA concentration, including pore size, water swelling, rheological properties and in vitro degradability. In addition, the composite hydrogels exhibited good adhesion, anti-oxidation and photothermal properties due to the existence of PDA. Within 10 min upon exposure to 808 nm near-infrared (NIR) light irradiation, this hydrogel system displayed outstanding antibacterial activity against Staphylococcus aureus with almost 100% killing efficiency, of which rapid efficient sterilization plays a significant role in wound healing. Moreover, the hydrogel is capable of cytocompatibility and has low toxicity to murine fibroblasts (L929 and NIH/3T3). In the full-thickness wound defect infection model in mice, the wound closure ratio, inflammatory response, fibroblasts, neovascularization and epithelialization were measured. Animal experiments also reveal that the hydrogel assisted with NIR laser irradiation can inhibit effectively infection at an early stage and accelerate the wound healing process. In summary, this novel multifunctional injectable hydrogel exhibits excellent swelling capacity, bio-adhesion, antioxidant property, photothermal activity, efficient antibacterial property and facilitates skin healing, which has great promising application as a medical dressing biomaterial in infected wound care fields.
This work reported a facile approach to surface oxygen vacancy (OV)-enriched urchin-like TiO2 microparticles (U-TiO2), which were highly effective and durable in catalyzing selective nitrate reduction to ammonia (NO3RR). Specifically, the U-TiO2 delivered a mass activity of 1.15 min−1 mgcatalyst−1, a low yield of toxic NO2−-N intermediate (≤0.4 mg/L) and an exceptional high NH3-N selectivity of 98.1% in treating 22.5 mg/L of NO3−-N under a potential of -0.60 V vs. RHE, outperforming most of the reported oxide-based catalysts. When comparing the performance of U-TiO2 with that of the solid amorphous TiO2 counterpart (A-TiO2) that had close particle size but more OV on surfaces, we identified that the OV was the reactive sites, but rather than its content, the NO3RR kinetics were primarily limited by the electron and mass transfer at U-TiO2/water interfaces. Accordingly, the superior performance of U-TiO2 to A-TiO2 could be ascribed to the hierarchical urchin-like structure in U-TiO2. The in-situ DEMS test revealed that the NO3RR on U-TiO2 followed a pathway of *NO3− → *NO2−→ *NO → *N → *NH → *NH2 → *NH3. We also demonstrated that the U-TiO2 could keep its robust performance under a wide NO3−-N concentration range and in the presence of some co-existing ions (such as Ca2+, Cl−, Mg2+). However, the presence of humic acid and CO32− in water slowed down the NO3RR on U-TiO2. This work provides a more fundamental insight into the OV-driven NO3RR process on TiO2, which should benefit for the development of efficient TiO2-based catalysts.
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