Latest Articles[2+2]-Type cyclobutane derivatives comprise a large family of natural products with diverse molecular architectures. However, the structure elucidation of the cyclobutane ring, including its connection mode and stereochemistry, presents a significant challenge. Plumerubradins A–C (1–3), three novel iridoid glycoside [2+2] dimers featuring a highly functionalized cyclobutane core and multiple stereogenic centers, were isolated from the flowers of Plumeria rubra. Through biomimetic semisynthesis and chemical degradation of compounds 1–3, synthesis of phenylpropanoid-derived [2+2] dimers 7–10, combined with extensive spectroscopic analysis, single-crystal X-ray crystallography, and microcrystal electron diffraction experiments, the structures with absolute configurations of 1–3 were unequivocally elucidated. Furthermore, quantum mechanics-based 1H NMR iterative full spin analysis successfully established the correlations between the signal patterns of cyclobutane protons and the structural information of the cyclobutane ring in phenylpropanoid-derived [2+2] dimers, providing a diagnostic tool for the rapid structural elucidation of [2+2]-type cyclobutane derivatives.
Early recognition is key to improving the prognosis of ischemic stroke (IS), while available imaging methods tend to target events that have already undergone ischemia. A new method to detect early IS is urgently needed, as well as further study of its mechanisms. Viscosity and cysteine (Cys) levels of mitochondria have been associated with ferroptosis and IS. It is possible to identify IS and ferroptosis accurately and early by monitoring changes in mitochondrial Cys and viscosity simultaneously. In this work, a viscosity/Cys dual-responsive mitochondrial-targeted near-infrared (NIR) fluorescent probe (NVCP) was constructed for the precise tracking of IS using a two-dimensional design strategy. NVCP consists of a chromophore dyad containing diethylaminostyrene quinolinium rotor and chloro-sulfonylbenzoxadiazole (SBD-Cl) derivative with two easily distinguished emission bands (λem = 592 and 670 nm). NVCP performs the way of killing two birds with one stone, that is, the probe exhibits excellent selectivity and sensitivity for detecting viscosity and Cys in living cells with excellent biocompatibility and accurate mitochondrial targeting capability by dual channel imaging mode. In addition, NVCP recognized that the viscosity increases and Cys level decreases in cells when undergoing ferroptosis and oxygen-glucose deprivation (OGD) stress by confocal imaging, flow cytometry, and Western blot experiments. Treatment of ferroptosis inhibitors (ferrostatin-1 (Fer-1) and deferoxamine (DFO)) could reverse the variation tendency of viscosity and Cys. This is the first time that the relationship between ferroptosis and IS was identified through an analysis of Cys and viscosity. More importantly, the ischemic area was also instantly distinguished from normal tissues through fluorescence imaging of NVCP in vivo. The developed NIR dual-responsive probe NVCP toward viscosity and Cys could serve as a sensitive and reliable tool for tracking ferroptosis-related pathological processes during IS.
Photodynamic therapy (PDT) has received much attention in recent years. However, traditional photosensitizers (PSs) applied in PDT usually suffer from aggregation-caused quenching (ACQ) effect in H2O, single and inefficient photochemical mechanism of action (MoA), poor cancer targeting ability, etc. In this work, two novel Ru(Ⅱ)-based aggregation-induced emission (AIE) agents (Ru1 and Ru2) were developed. Both complexes exhibited long triplet excited lifetimes and nearly 100% singlet oxygen quantum yields in H2O. In addition, Ru1 and Ru2 displayed potent photo-catalytic reduced nicotinamide adenine dinucleotide (NADH) oxidation activity with turnover frequency (TOF) values of about 1779 and 2000 h−1, respectively. Therefore, both Ru1 and Ru2 showed efficient PDT activity towards a series of cancer cells. Moreover, Ru2 was further loaded in bovine serum albumin (BSA) to enhance the tumor targeting ability in vivo, and the obtained Ru2@BSA could selectively accumulate in tumor tissues and effectively inhibit tumor growth on a 4T1 tumor-bearing mouse model. So far as we know, this work represents the first report about Ru(Ⅱ) AIE agents that possess high singlet oxygen quantum yields and also potent photo-catalytic NADH oxidation activity, and may provide new ideas for rational design of novel PSs with efficient PDT activity.
Chemodynamic therapy (CDT), using Fenton agents to generate highly cytotoxic •OH from H2O2 has been demonstrated as a powerful anticancer method. However, the insufficient endogenous H2O2 in tumor cells greatly limited its therapeutic effect. Herein, we prepared a pH-responsive β-lapachone-loaded iron-polyphenol nanocomplex (LIPN) through a one-pot method. β-Lapachone in LIPN selectively enhanced H2O2 concentration in tumor cells, and ferrous ions cascadely generated abundant cytotoxic •OH. Therefore, LIPN with cascade amplification of reactive oxygen species (ROS) showed high chemodynamic cytotoxicity in tumor cells, efficiently improving the expression of damage-associated molecular patterns (DAMPs), and exerting strong immunogenic cell death (ICD). As a result, LIPN exhibited efficient tumor inhibition ability in 4T1 subcutaneous tumor model in vivo with great biocompatibility. Additionally, the infiltration of cytotoxic CD8+ T lymphocytes and inhibition of regulatory CD4+ FoxP3+ T lymphocytes in tumors demonstrated the activation of immunosuppressive tumor microenvironment by LIPN-induced ICD. Therefore, this work provided a new approach to enhance ICD of chemodynamic therapy through selective cascade amplification of ROS in cancer cells.
The typical wastewater treatment is focused on the photocatalytic efficiency in the degradation of organic pollutants, with little attention to the involved selectivity which may correlate with toxicant residues. Herein, an electron localization strategy for specific O2 adsorption/activation enabled by photothermal/pyroelectric effect and in situ constructed active centers of single-atom Co and oxygen vacancy (Co-OV) on the Co/BiOCl-OV photocatalyst was developed for photocatalytic degradation of glyphosate (GLP) wastewater of high performance/selectivity. Under full-spectrum-light irradiation, a high GLP degradation rate of 99.8% with over 90% C‒P bond-breaking selectivity was achieved within 2 h, while effectively circumventing toxicant residues such as aminomethylphosphonic acid (AMPA). X-ray absorption spectroscopy and relevant characterizations expounded the tailored anchoring of Co single atoms onto the BiOCl-OV carrier and photothermal/pyroelectric effect. The oriented formation of more •O2− on Co/BiOCl-OV could be achieved with the Co-OV coupled center that had excellent O2 adsorption/activation capacity, as demonstrated by quantum calculations. The formed unique Co-OV active sites could largely decrease the C‒P bond-breaking energy barrier, thus greatly improving the selectivity toward the initial C‒P bond scission and the activity in subsequent conversion steps in the directional photocatalytic degradation of GLP. The electron localization strategy by in situ constructing the coupled active centers provides an efficient scheme and new insights for the low-toxic photodegradation of organic pollutants containing C‒X bonds.
Lipids serve as fundamental constituents of cell membranes and organelles. Recent studies have highlighted the significance of lipids as biomarkers in the diagnosis of breast cancer. Although liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) is widely employed for lipid analysis in complex samples, it suffers from limitations such as complexity and time-consuming procedures. In this study, we have developed dopamine-modified TiO2 nanoparticles (TiO2-DA) and applied the materials to assist the analysis of lipids by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The TiO2-DA can provide large specific surface area and acidic environment, well suited for lipid analysis. The method was initially validated using standard lipid molecules. Good sensitivity, reproducibility and quantification performance was observed. Then, the method was applied to the analysis of 90 serum samples from 30 patients with breast cancer, 30 patients with benign breast disease and 30 healthy controls. Five lipid molecules were identified as potential biomarkers for breast cancer. We constructed a classification model based on the MALDI-TOF MS signal of the 5 lipid molecules, and achieved high sensitivity, specificity and accuracy for the differentiation of breast cancer from benign breast disease and healthy control. We further collected another 60 serum samples from 20 healthy controls, 20 patients with benign breast disease and 20 patients with breast cancer for MALDI-TOF MS analysis to verify the accuracy of the classification model. This advancement holds great promise for the development of diagnostic models for other lipid metabolism-related diseases.
Boron neutron capture therapy (BNCT) has emerged as a promising treatment for cancers, offering a unique approach to selectively target tumor cells while sparing healthy tissues. Despite its clinical utility, the widespread use of fructose-BPA (F-BPA) has been hampered by its limited ability to penetrate the blood-brain barrier (BBB) and potential risks for patients with certain complications such as diabetes, hyperuricemia, and gout, particularly with substantial dosages. Herein, a series of novel BPA derivatives were synthesized. After the primary screening, geniposide-BPA (G-BPA) and salidroside-BPA (S-BPA) exhibited high water solubility, low cytotoxicity and safe profiles for intravenous injection. Furthermore, both G-BPA and S-BPA had demonstrated superior efficacy in vitro against the 4T1 cell line compared with F-BPA. Notably, S-BPA displayed optimal BBB penetration capability, as evidenced by in vitro BBB models and glioblastoma models in vivo, surpassing all other BPA derivative candidates. Meanwhile, G-BPA also exhibited enhanced performance relative to the clinical drug F-BPA. In brief, G-BPA and S-BPA, as novel BPA derivatives, demonstrated notable safety profiles and remarkable boron delivery capabilities, thereby offering promising therapeutic options for BNCT in the clinic.
Gallstones are a common disease worldwide, often leading to obstruction and inflammatory complications, which seriously affect the quality of life of patients. Research has shown that gallstone disease is associated with ferroptosis, lipid droplets (LDs), and abnormal levels of nitric oxide (NO). Fluorescent probes provide a sensitive and convenient method for detecting important substances in life systems and diseases. However, so far, no fluorescent probes for NO and LDs in gallstone disease have been reported. In this work, an effective ratiometric fluorescent probe LR-NH was designed for the detection of NO in LDs. With an anthracimide fluorophore and a secondary amine as a response site for NO, LR-NH exhibits high selectivity, sensitivity, and attractive ratiometric capability in detecting NO. Importantly, it can target LDs and shows excellent imaging ability for NO in cells and ferroptosis. Moreover, LR-NH can target the gallbladder and image NO in gallstone disease models, providing a unique and unprecedented tool for studying NO in LDs and gallbladder.
Photocatalytic overall water splitting is a promising method for producing clean hydrogen energy, but faces challenges such as low light utilization efficiency and high charge carrier recombination rates. This study demonstrates that dielectric Mie resonance in TiO2 hollow nanoshells can enhance electric field intensity and increase light absorption through resonant energy transfer, compared to crushed TiO2 nanoparticles. The Mie resonance effect was confirmed through fluorescence spectra, photo-response current measurements, photocatalytic water splitting experiments, and Mie calculation. The incident electric-field amplitude was doubled in hollow nanoshells, allowing for increased light trapping. Additionally, the spatially separated Pt and RuO2 cocatalysts on the inner and outer surfaces facilitated the separation of photoinduced electrons and holes. Pt@TiO2@RuO2 hollow nanoshells exhibited superior photocatalytic water splitting performance, with a stable H2 generation rate of 50.1 µmol g−1 h−1 and O2 evolution rate of 25.1 µmol g−1 h−1, outperforming other nanostructures such as TiO2, Pt@TiO2, and TiO2@RuO2 hollow nanoshells. This study suggests that dielectric Mie resonance and spatially-separated cocatalysts offer a new approach to simultaneously enhance light absorption and charge carrier transfer in photocatalysis.
Traditional Pt/C electrode materials are prone to corrosion and detachment during H2S detection, leading to a decrease in fuel cell-type sensor performance. Here, a high-performance H2S sensor based on Pt loaded Ti3C2 electrode material with -O/-OH terminal groups was designed and prepared. Experimental tests showed that the Pt/Ti3C2 sensor has good sensitivity (0.162 µA/ppm) and a very low detection limit to H2S (10 ppb). After 90 days of stability testing, the response of the Pt/Ti3C2 sensor shows a smaller decrease of 2% compared to that of the Pt/C sensor (22.9%). Meanwhile, the sensor also has high selectivity and repeatability. The density functional theory (DFT) calculation combined with the experiment results revealed that the improved H2S sensing mechanism is attributed to the fact that the strong interaction between Pt and Ti3C2 via the Pt-O-Ti bonding can reduce the formation energy of Pt and Ti3C2, ultimately prolonging the sensor’s service life. Furthermore, the catalytic property of Pt can decrease the adsorption energy and dissociation barrier of H2S on Pt/Ti3C2 surface, greatly enhance the ability to generate protons and effectively transfer charges, realizing good sensitivity and high selectivity of the sensor. The sensor works at room temperature, making it very promising in the field of H2S detection in future.
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