Latest ArticlesFe-N-C materials have received increasing attention, due to its distinctive catalytic activity. However, the Fe-N coordination number dependence of catalytic ability and mechanism for H2O2 activation remain elusive. Herein, a series of Fe-N-C heterogeneous Fenton-like catalysts with different Fe-N coordination number were prepared for tetracycline degradation. The results demonstrated that samples with Fe-N4 structure exhibited high activity. The excellent performance was mainly ascribed to the high adsorption capacity and the formation of superoxide radicals (•O2−) catalyzed by Fe linked to pyridinic nitrogen. The intermediates and degradation pathways of tetracycline degradation by Fe-N-C/H2O2 system were analyzed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Furthermore, we applied our Fe-N-C catalysts to treat simulated pharmaceutical wastewater with high tetracycline degradation capacity despite high concentrations of organic matter such as oxalic acid and various ionic interferences. Our work reveals the dependence of the activation H2O2 on the Fe-N coordination environment and the degradation mechanism of these catalysts. It provides insights into the prospects for tuning the catalyst in practical applications.
Hydrogen-bonded organic frameworks (HOFs) are a promising candidate for optical sensing, but the lack of effective design strategies poses significant challenges to the construction of HOFs for organic acid sensing. In this work, the first HOF for organic acid sensing is reported by constructing a multiple-pyridine carbazole-based dense HOF, namely HOF-FJU-206, from a tripyridine-carbazole molecular 3,6-bis(pyridin-4-yl)-9-(4-(pyridin-4-yl)phenyl)-9H-carbazole (CPPY) with carbazole center for luminescence, pyridyl sites for its responsive of hydrogen proton, and narrow channels in the dense framework for the diffusion of hydrogen protons. HOF-FJU-206 exhibits differential responsively fluorescence sensing and recovery properties to formic, acetic, and propionic acids with different molecular sizes and pKa value (acid dissociation constant). The dissociation degree of various acids can be determined by analyzing the slope of changes in both peak wavelength and intensity of in-situ fluorescence, which easily enables the dual-corrective recognition of different acids. The varying degree of protonation at pyridine sites is proved to be the reason for differential sensing of various acids, as demonstrated by 1H NMR spectra, X-ray photoelectron spectroscopy (XPS) characterization, and modeling studies.
Structural colors originated from Mie scattering of dielectric spheres can be regulated by the coupling effect between them and substrates. Here a rapid visual identification method of silver ornaments was proposed by the coupling effect of ZnO spheres with them. Both simulation and experimental results proved that, by coupling with different metal substrates, the Mie resonance scattering peaks of ZnO spheres with dimeter of 700 nm showed different degrees of redshift, which lead to different structural color appeared when ZnO spheres deposited on different metal surfaces with a similar appearance. A red structural color was displayed on the surface of the real silver ornament and a yellow-green structural color was shown on the surface of the cupronickel ornament. This method is quite simple and low-cost because it only needs to spray the dispersion of ZnO spheres on the ornament surface. Due to the mild chemical properties of the ZnO, covering and erasing ZnO spheres on the surface of silver would not corrode the silver ornament. Finally, an atomizer method was used for portable and daily testing. This work opens new perspectives on the visual identification of silver.
Two novel fungal metabolites, asperochones A and B, were obtained from an Aspergillus sp. Their structures were determined by 1D/2D nuclear magnetic resonance (NMR) spectroscopy, high resolution electrospray ionization mass spectroscopy (HRESIMS), and single-crystal X-ray diffraction analysis. Asperochone A possesses an intriguing skeleton bearing 5/6/6/6/7/5/5/5 octacyclic ring system, and asperochone B also exhibits an unusual carbon skeleton with five stereochiral centers. Their structures were proposed as heterotrimeric and heterodimeric products of aromatic polyketides. In addition, asperochone A exhibited a potential anti-tuberculosis effect since it showed a moderate potency against Mycobacterium smegmatis.
Membrane will inevitably reach the end of its lifespan due to the irrecoverable fouling accumulation in membrane bioreactors (MBRs) during long-term operation. Herein, we developed an eco-friendly membrane regeneration strategy with triethyl phosphate (TEP), which successfully prolonged the lifespan of end-of-life (EOL) polyvinylidene fluoride (PVDF) membranes in a large-scale MBR. The regenerated (Rg) membrane exhibited a water permeance of 534.8 ± 45.7 L m−2 h−1 bar−1, along with stable rejection rate, which was comparable with that of the new membrane. Furthermore, compared to the membrane subjected solely to preliminary cleaning, the Rg membrane presented a more hydrophilic surface due to the combination of preliminary cleaning and solvent-based processing. Besides, the Rg membrane presented less fouling propensity with the critical flux of 15.2 L m−2 h−1, significantly higher than that of the EOL membrane (4.0 L m−2 h−1). Importantly, the membrane regeneration strategy was capable of guaranteeing the effluent quality in MBR systems for treating real municipal wastewater. This study provides an eco-friendly membrane regeneration strategy for effectively removing the irrecoverable foulants, thereby promoting the advancement of sustainable membrane-based wastewater treatment technology.
Hypercrosslinked polymers (HCPs) with large surface areas, high intrinsic porosities and low production costs may be available platforms for iodine capture. However, the lack of iodine-philicity binding sites limits their adsorption capacity. Here we use vapor-phase postsynthetic amination strategy to introduce electron-donating amino groups into the prefabricated HCPs for enhancing their iodine capture performance. Through simple vapor-phase exposure, the halogen-containing HCPs can be grafted by amines through nucleophilic substitution toward chloro groups. Combining with the abundant amino groups and high porosities, the amino-functionalized porous polymers show substantially increased iodine adsorption capacity, about 221% as that of original one, accompanied by excellent recyclability. Mechanism investigations reveal the key roles of the electron-donor amino groups and π-conjugated benzene rings along with structure characteristics of porous polymer frameworks in iodine capture. Moreover, this vapor-phase amination strategy shows good generality and can be extended to various amines, e.g., ethylenediamine, 1,3-diaminopropane and diethylenetriamine. Our work proves that this simple vapor-phase postsynthetic functionalization strategy may be applied in other porous polymers with wide application prospects in adsorption, separation and storage.
Understanding the luminescence mechanisms and regulating the emission centers of carbon dots (CDs) are important for advancing their related applications. In this work, we systematically investigate the formation processes of multi-emission centers in CDs synthesized through a bottom-up approach by controlling the solvothermal reaction temperature. CDs synthesized at a lower temperature (140 ℃, 140-CDs) exhibit smaller particle sizes (3–4 nm) with dominant green–yellow emission, while CDs synthesized at a higher temperature (180 ℃, 180-CDs) exhibit larger particle sizes (8–9 nm) with enhanced red emission and emerging near-infrared (NIR) emission. The green–yellow emission and red emission originate from the core state and the surface-related state, respectively, and the emissions could be regulated by temperature-controlled dehydration and carbonization processes. The clear NIR emission center in 180-CDs is attributable to the increased content of radical defects in the cores during the increased dehydration and carbonization processes during higher-temperature solvothermal treatment.
The research of long persistent luminescence (LPL) materials has yield brilliant results in many fields. However, the efforts are still needed for the regulation of the LPL performance. In this work, a series of LPL metal organic halides with rich halogen-bond interactions, Py-CdX2 (X = Cl, Br, I) were synthesized through self-assembly by CdX2 and pyridine solvent. The steady-state emission redshifted and phosphorescence lifetime declined as the halogen atoms are aggravated. Three halides exhibit adjustable emission from blue to green and multiple phosphorescence from green to yellow at room temperature by changing the excitation wavelengths. Surprisingly, Py-CdX2 can emit the visible color-tunable LPL from green to yellow after removing different excitation sources at ambient conditions. Combing the results of theoretical calculation and experimental analysis, it is found that heavy atom effect and the rich intermolecular halogen bond help realize LPL and multiple triplet states originated from the pyridine ring and the halogens.
Natural enzymes, such as horseradish peroxidase (HRP), are a class of important biocatalysts with the high specificity, but their catalytic efficiency is usually unsatisfactory. Thus, the higher catalytic efficiency induced by the confinement effect is promising in optical sensing systems. In this work, a dark-field light scattering sensing platform was fabricated by the confinement effect of HRP from hybridization chain reaction (HCR) and then released to solution by the toehold-mediated strand displacement reaction (TSDR). Then, HRP catalyzed the 3,3′, 5,5′-tetramethylbenzidine (TMB) to TMB2+ with the assistance of hydrogen peroxide, which etched the gold nanorods (AuNRs) with the weakened light scattering. The single-particle assay was established based on the decreased light scattering intensity of AuNRs under dark-field microscope. The proposed assay revealed excellent analytical performance within a linear range from 25 pmol/L to 600 pmol/L, and a low limit of detection of 3.12 pmol/L. Additionally, it also manifested satisfactory recovery of miRNA-21 in human serum samples. The high sensitivity, excellent specificity, and universal applicability make this sensing platform promising for disease diagnosis.
Dry powder inhalation represents a promising approach for the treatment of lung cancer, offering several advantages such as enhanced targeting, improved bioavailability, and reduced toxicity. However, traditional dry powder formulations suffer from limitations, notably low pulmonary delivery efficiency and inadequate penetration into tumor tissues, thereby limiting their therapeutic efficacy. In response to these challenges, we have developed an innovative trojan horse strategy, harnessing an inhalable nanoparticle-in-microsphere system characterized by tunable size, reversible charge, and mucus-penetrating capabilities. The inhalable nanoparticle-in-microsphere system exhibit stable structural properties, excellent environmental responsiveness and high biocompatibility. More importantly, the therapeutic effect of MTX@PAMAM@HA@Gel (MPHG) was demonstrated in vitro and in vivo. This system offers improved pulmonary delivery efficiency, enhanced drug retention within tumor tissues, and effective penetration, thus representing a promising strategy in lung cancer treatment.
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