Excellent adsorption performance of dibenzothiophene on functionalized low-cost activated carbons with different oxidation methods

<p>Low-cost activated carbon (KAC) was functionalized by HNO₃, (NH₄)₂S₂O₈ and air oxidation, respectively, to remove dibenzothiophene (DBT) from model fuel. The changes in physical and chemical properties of these activated carbons were characterized by thermal analysis, elemental analysis, nitrogen adsorption apparatus, Raman spectra, scanning electron microscope and Boehm’s titration method. HNO₃ and (NH₄)₂S₂O₈ oxidation result in a significant decrease in pore structure, while air oxidation only causes slight pore reduction due to the re-activation by O₂. The oxygen-containing functional groups (OFGs) increase markedly after oxidative modification, in which (NH₄)₂S₂O₈ oxidation is considered as the most efficient method with respect to the introduction of OFGs. HNO₃ and (NH₄)₂S₂O₈ oxidation are more selective to generate carboxyls and lactones, whereas air oxidation creates more phenols, carbonyls and ethers. The DBT adsorption capacity follows the order: NAC (HNO₃-oxidized KAC) > OAC (air-oxidized KAC) > KAC > SAC ((NH₄)₂S₂O₈-oxidized KAC), implying the introduction of OFGs is beneficial for the DBT adsorption process, especially for selectivity, but excessive OFGs have a negative effect on the removal of DBT. Thus, to achieve high DBT adsorption performance, there should be a trade-off between the micropore volume and the OFGs amount.</p

Study of High-Aluminum-Content Sulfated Zirconia: Influence of Aluminum Content and Washing

A high-aluminum-content sulfated zirconia was prepared by the kneading method, and the washing process was considered as a key factor. Catalysts were characterized by XRD, BET analysis, SEM, TG, FT-IR spectroscopy, pyridine IR spectroscopy, NH₃ TPD, H₂ TPR, and ²⁷Al NMR spectroscopy, and the reactivity was evaluated by <i>n</i>-hexane isomerization. The results showed that the high-aluminum-content sulfated zirconia has a high activity after being washed with water. Moreover, the aluminum content was found to strongly influence the crystal form, catalyst structure, and acidity, as well as the anchoring effect on the labile sulfates. Actually, the higher the aluminum content was, the more sulfates were left in the catalyst samples after washing. The OH and SO stretching vibrations were shifted in the presence of aluminum or water. With the support of the aluminum coordination state, a hydrolysis model was deduced for different aluminum contents in the catalysts, and it can explain the formation of more Brønsted acid sites and AlOS bonds

Bioinspired Coordination Micelles Integrating High Stability, Triggered Cargo Release, and Magnetic Resonance Imaging

Catechol-Fe³⁺ coordinated micelles show the potential for achieving on-demand drug delivery and magnetic resonance imaging in a single nanoplatform. Herein, we developed bioinspired coordination-cross-linked amphiphilic polymeric micelles loaded with a model anticancer agent, doxorubicin (Dox). The nanoscale micelles could tolerate substantial dilution to a condition below the critical micelle concentration (9.4 ± 0.3 μg/mL) without sacrificing the nanocarrier integrity due to the catechol-Fe³⁺ coordinated core cross-linking. Under acidic conditions (pH 5.0), the release rate of Dox was significantly faster compared to that at pH 7.4 as a consequence of coordination collapse and particle de-cross-linking. The cell viability study in 4T1 cells showed no toxicity regarding placebo cross-linked micelles. The micelles with improved stability showed a dramatically increased Dox accumulation in tumors and hence the enhanced suppression of tumor growth in a 4T1 tumor-bearing mouse model. The presence of Fe³⁺ endowed the micelles <i>T</i>₁-weighted MRI capability both in vitro and in vivo without the incorporation of traditional toxic paramagnetic contrast agents. The current work presented a simple “three birds with one stone” approach to engineer the robust theranostic nanomedicine platform

Filling Chlorine Vacancy with Bromine: A Two-Step Hot-Injection Approach Achieving Defect-Free Hybrid Halogen Perovskite Nanocrystals

Mixed-halide (Cl and Br) perovskite nanocrystals (NCs) are of particular interest because they hold great potential for use in high-efficiency blue light-emitting diodes (LEDs). Generally, mixed-halide compounds are obtained by either a one-step synthesis with simultaneous addition of both halide precursors or a postsynthetic anion exchange using the opposite halogen. However, both strategies fail to prevent the formation of deep-level Cl vacancy defects, rendering the photoluminescence quantum yields (PLQYs) typically lower than 30%. Here, by optimizing both thermodynamic and kinetic processes, we devise a two-step hot-injection approach, which simultaneously realizes Cl vacancy filling and efficient anion exchange between Cl– and Br–. Both the identity of Br precursors and their injection temperature are revealed to be critical in transforming those highly defective CsPbCl3 NCs to defect-free CsPb(Cl/Br)3. The optimally synthesized NCs exhibit a saturated blue emission at ∼460 nm with a near-unity PLQY and a narrow emission bandwidth of 18 nm, which represents one of the most efficient blue emitters reported so far. The turn-on voltage of the ensuing LEDs is ∼4.0 V, which is lower than those of most other mixed-halide perovskites. In addition, LEDs exhibit a stable electroluminescence peak at 460 nm under a high bias voltage of 8.0 V. We anticipate that our findings will provide new insights into the materials design strategies for producing high-optoelectronic-quality Cl-containing perovskites

Multifunctional Micelles Dually Responsive to Hypoxia and Singlet Oxygen: Enhanced Photodynamic Therapy via Interactively Triggered Photosensitizer Delivery

Nanoparticulate antitumor photodynamic therapy (PDT) has been suffering from the limited dose accumulation in tumor. Herein, we report dually hypoxia- and singlet oxygen-responsive polymeric micelles to efficiently utilize the photosensitizer deposited in the disease site and hence facilely improve PDT’s antitumor efficacy. Tailored methoxy poly­(ethylene glycol)-azobenzene-poly­(aspartic acid) copolymer conjugate with imidazole as the side chains was synthesized. The conjugate micelles (189 ± 19 nm) obtained by self-assembly could efficiently load a model photosensitizer, chlorin e6 (Ce6) with a loading of 4.1 ± 0.5% (w/w). The facilitated cellular uptake of micelles was achieved by the triggered azobenzene collapse that provoked poly­(ethylene glycol) shedding; rapid Ce6 release was enabled by imidazole oxidation that induced micelle disassembly. In addition, the singlet oxygen-mediated cargo release not only addressed the limited diffusion range and short half-life of singlet oxygen but also decreased the oxygen level, which could in turn enhance internalization and increase the intracellular Ce6 concentration. The hypoxia-induced dePEGylation and singlet oxygen-triggered Ce6 release was demonstrated both in aqueous buffer and in Lewis lung carcinoma (LLC) cells. The cellular uptake study demonstrated that the dually responsive micelles could deliver significantly more Ce6 to the cells, which resulted in a substantially improved cytotoxicity. This concurred well with the superior in vivo antitumor ability of micelles in a LLC tumor-bearing mouse model. This study presented an intriguing nanoplatform to realize interactively triggered photosensitizer delivery and improved antitumor PDT efficacy