Latest ArticlesThere is a close relationship between the biological functions of lipids and their structures, and various isomers greatly increases the complexity of lipid structures. The C=C bond location and sn-position are two of the essential attributes that determine the structures of unsaturated lipids. However, simultaneous identification of both attributes remains challenging. Here, we develop a visible-light-activated aziridination reaction system, which enables the dual-resolving of the C=C bond location and sn-position isomerism of in lipids when combines with liquid chromatography-mass spectrometry (LC-MS). Based on the derivatization of C=C bonds with PhI=NTs, their location in lipids could be easily identified by tandem MS. Especially, the sn-position isomers of unsaturated phosphatidylcholine (PC) can be separated and quantified by LC-MS after the derivatization. By using the proposed method, the significant changes of the sn-position isomers ratios of PC in mouse brain ischemia were revealed. This study offers a powerful tool for deep lipid structural biology.
Two 3d-4f-5d heterometallic cluster-containing polyoxometalates, formulated as Na22{(SbW9O33)4[La3W6MO18(H2O)8(CH3COO)4]2}·nH2O (abbreviated as La6M2, M = Co/Mn) were synthesized and structurally characterized. Single-crystal X-ray diffraction analyses reveal that the polyanions of La6Co2 and La6Mn2 consist of the uncommon 3d-4f-5d clusters {La6W12Co2} and {La6W12Mn2}, which are encapsulated by four trilacunary Keggin tungstoantimonates to form the parallelogram-shaped title compounds. Additionally, the polyanions can be extended into a two-dimensional (2D) frame by the linkage of peripheral Na+ ions. The inner space of the 2D layer was filled with water molecules and thus an H-bonded network was formed, which is expected to exhibit a fascinating proton conductivity. The study of water-assisted proton conduction demonstrated that La6Co2 and La6Mn2 were temperature- and humidity-dependent proton conductors, respectively, and the proton conductivities could reach 1.3 × 10−2 and 2.3 × 10−2 S/cm at 65 ℃ and 90% RH conditions.
Optical thermometry as an important local temperature-sensing technique, has received increasing attention in scientific and industrial areas. However, it is still a big challenge to develop luminescent materials with self-activated dual-wavelength emissions toward high-sensitivity optical thermometers. Herein, a novel ratiometric thermometric strategy of Bi3+-activated dual-wavelength emission band was realized in the same lattice position with two local electronic states of La3Sb1-xTaxO7:Bi3+(0 ≤ x ≤ 1.0) materials based on the different temperature-dependent emission behaviors, benefiting from the highly-sensitive and regulable emission to the coordination environment of Bi3+. The structural and spectral results demonstrate that the emission tremendously shifted from green to blue with 68 nm and the intensity was enhanced 2.6 times. Especially, the visual dual-wavelength emitting from two emission centers was presented by increasing the Ta5+substitution concentration to 20% or 25%, mainly originating from the two local electronic states around the Bi3+ emission center. Significantly, the dual-wavelength with different thermal-quenching performance provided high-temperature sensitivity and good discrimination signals for optical thermometry in the range between 303 and 493 K. The maximum relative sensitivity reached 2.64%/K (La3Sb0.8Ta0.2O7:0.04Bi3+@383 K) and 1.91%/K (La3Sb0.75Ta0.25O7:0.04Bi3+@388 K). This work reveals a rational design strategy of different local electronic states around the single-doping multiple emission centers towards practical applications, such as luminescence thermometry and white LED lighting.
Fibrosis occurs due to the excessive deposition of extracellular matrix caused by cell injury. After various types of tissue injury, the dysregulation of the internal response can eventually lead to the destruction of organ structure and dysfunction. There is increasing evidence that oxidative stress, which is characterized by excessive production of hydrogen peroxide (H2O2), is an important cause of fibrosis. Therefore, we synthesized a biosensitive and efficient electrochemical H2O2 sensor based on PtNi nanoparticle-doped N-reduced graphene oxide (PtNi-N-rGO) to detect H2O2 released from transforming growth factor β1 (TGFβ1)-induced myofibroblast. In addition, the sensor could easily detect changes in H2O2 in the lung and bronchoalveolar lavage fluid (BALF) of mice with pulmonary fibrosis. Furthermore, the sensor could also detect H2O2 in activated hepatic stellate cells and the liver of carbon tetrachloride (CCl4)-induced liver fibrosis. Moreover, the alterations in H2O2 detected by the sensor were consistent with nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) protein expression and the staining results of pathological sections. Taken together, these results highlight the use of H2O2 sensors for the rapid detection of fibrosis and facilitate the rapid evaluation of antifibrotic drug candidates.
A nine cyclic peptide (TCP-1) showed excellent specificity for colon cancer. TCP-1 binds with human tumor tissues at early stages and mice tumor with diameters of 1-4 mm, suggesting that TCP-1 may be used for early diagnosis of colon cancer. The mechanism of the targeted binding of TCP-1 to colon cancer was also studied using immunoprecipitation, LC-MS and bioinformatics. After screening and identifying of the possible binding target proteins of TCP-1, keratin, type Ⅱ cytoskeletal 5 was speculated to be the specific binding target protein of TCP-1 in human tumor tissue. Pharmacokinetics studies were conducted to investigate the target-mediated drug disposition of the new tumor-specific peptide by LC-MS/MS. The tissue distribution study showed that TCP-1 was found only in colon tumors (the target site) in tumor mice did not bind to any other tissues. Conjugating TCP-1 to tumor markedly increased its removal rate from blood circulation but mildly extended its staying time in vivo. In tumor mice, a lower AUC of TCP-1 (reduced by almost 35%) and 2-fold higher clearance were found compared to that of normal mice. The proposed metabolic pathway of TCP-1 in the kidney was also determined using LC-MSn-IT-TOF. The high specificity and low toxicity of the peptide may be caused by its extremely tight binding to the targets. Potential applications for future clinical use, including MRI and PET/CT were also explored, and this research may promote the development of colon cancer diagnostic technology research and provide new ideas and technical routes for tumor diagnostic technology.
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.
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.
The lithium (Li) metal batteries (LMBs) are considered one of the most promising next-generation batteries due to its extremely high theoretical specific capacity. However, there are a couple of issues, e.g., the serious side reactions that occurred at the solid-liquid interface between the electrolyte and Li metal anode, hindering the broad commercialization of LMBs. Thus, a comprehensive understanding of the mechanisms underlying the decomposition of electrolytes is crucial to the design of LMBs. Herein, we utilize density functional theory simulations to explore the decomposition mechanism of electrolytes. The most commonly used ether electrolyte solvents, i.e., 1,2-dimethoxyethane (DME) and 1,3-dioxalane (DOL), based on suitable lithium salts, namely bis(trifluoromethanesulfonyl)imide (LiTFSI), are chosen to model the actual situations. We explicitly demonstrate that an electron-rich environment near the interface accelerates the decomposition of electrolytes. For ether electrolytes, we show that the LiTFSI degradation path is depending on the ratio of DOL to DME. In addition, the solvation structures of lithium-ion undergo a series of transformations upon electrolyte degradation, becoming thermodynamically more favorable and having a higher reduction potential in an electron-rich environment. Our finding provides new insights into the decomposition mechanisms of electrolytes and paves the way for the rational design of high-performance LMBs.
Traditional photosensitizers show limited singlet oxygen generation in hypoxic infection lesions, which greatly suppress their performance in antibacterial therapy. Meanwhile, there still is lack of feasible design strategy for developing hypoxia-overcoming photosensitizers agents. Herein, radical generation of π-conjugated small molecules is efficiently manipulated by an individual selenium (Se) substituent. With this strategy, the first proof-of-concept study of a Se-anchored oligo (thienyl ethynylene) (OT-Se) with high-performance superoxide radical (O2•−) and hydroxyl radical (•OH) generation capability is present, and achieves efficient antibacterial activities towards the clinically extracted multidrug-resistant bacteria methicillin-resistant S. aureus (MRSA) and carbapenem-resistant E. coli (CREC) at sub-micromolar concentration under a low white light irradiation (30 mW/cm2). The water-dispersible OT-Se shows a good bacteria-anchoring capability, biocompatibility, and complete elimination of multidrug-resistant bacteria wound infection in vivo. This work offers a strategy to boost type-Ⅰ photodynamic therapy (PDT) performance for efficient antibacterial treatments, advancing the development of antibacterial agents.
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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