查找使用阿拉丁产品的科研文献

Modulating the electronic structure of PtFe alloys supported on carbon onions for enhancing pH-universal hydrogen evolution reaction

Tianyu Zhang,Xiaoli Yan,Guangda Zhou,Kui Wang,Jingtao Zhang,Hua Zhang,Junjie Guo

Optimizing platinum-based catalysts for hydrogen generation via water electrolysis in pH-universal electrolytes is significant, and modulating the electronic structure is a viable strategy. Herein, platinum-iron (Pt–Fe) alloys with varying composition supported on carbon onions (CNOs) were successfully synthesized: Pt x Fe y @CNOs (x, y = 0.6, 0.4; 0.5, 0.5; 0.4, 0.6). Beneficial from the precisely modulated crystal plane spacing and electronic structure by tuning the Pt/Fe composition, in general pH electrolytes, Pt x Fe y @CNOs display outstanding hydrogen evolution reaction (HER) activity. The as-prepared Pt 0.5 Fe 0.5 @CNOs shows low overpotentials (η 10 ) of 11, 30, and 19 mV at −10 mA cm −2 in 0.5 M H 2 SO 4 , 1.0 M phosphate-buffered saline (PBS), and 1.0 M KOH electrolyte, respectively. Compared to commercial Pt/C, it displays enduring stability up to 24 h. Density functional theory (DFT) calculations indicate that Pt 0.5 Fe 0.5 @CNOs displays the lowest H* Gibbs free energy (ΔG H* ) and water dissociation energy values, due to the suitable proton adsorption and H 2 O dissociation processes offered by its electronic structure. Moreover, it is proven that the support with better wettability has a positive effect on HER performance of the catalyst. The optimal electronic structure and improved wettability provide novel insight into developing a Pt-based HER pH-universal catalyst.

Adsorption of phosphate in water by La/Al bimetallic-organic frameworks-chitosan composite with wide adaptable pH range

Yi Liu,Dengjie Zhong,Yunlan Xu,Haixing Chang,Lin Dong,Zhuofan Han,Jun Li,Nianbing Zhong

The limited metal sites of monometallic MOFs and the high influence of pH limit their adsorption capacity. To solve these problems, La/Al bimetallic MOFs/chitosan composite was prepared by hydrothermal synthesis and impregnation methods and then characterized by XRD, FTIR, SEM, BET and XPS techniques. The doping of La has no obvious effect on the structure of Al-MOFs, but chitosan has greatly changed the structure of La/Al bimetallic MOFs. The phosphate adsorption of the composite was affected by La/Al molar ratio, chitosan/bimetallic MOFs mass ratio, temperature, phosphate initial concentration, adsorbent dosage, pH, and coexisting ions. The optimum molar ratio of La/Al and mass ratio of chitosan/bimetallic MOFs are 0.5:1 and 5.0%, respectively. The addition of La and chitosan can provide additional adsorption active sites, inhibit metal leaching, and enhance the phosphate adsorption performance, stability, and acid-alkali resistance of the composite. Its maximum adsorption capacity was 264.48 mg·g −1 . Its phosphate removal efficiency is above 90% at pH= 3.0–9.0. The actual phosphorus-containing wastewater with 7.064 mg·L −1 PO 4 3- and initial pH 7.4 can be treated to meet Chinese first-class effluent quality standard. La, Al, amino groups, and hydroxyl groups play an important role in the adsorption process of phosphate. When pH < pH pzc (4.99), phosphate is adsorbed by electrostatic gravitation between it and protonated positively charged amino and hydroxyl groups on La and Al, while when pH > pH pzc , phosphate is removed by ligand exchange between it and hydroxyl groups on La and Al. A stable, low-cost, and efficient bimetallic MOFs-based phosphate adsorbent was designed and prepared in this paper, and the results can provide reference for researchers in environmental chemical engineering .

Well-Defined Shell-Sheddable Core-Crosslinked Micelles with pH and Oxidation Dual-Response for On-Demand Drug Delivery

Xinfeng Cheng,Qiyang Li,Xiaomeng Sun,Yuxin Ma,Huanping Xie,Weiguang Kong,Xianchao Du,Zhenghui Zhang,Dongfang Qiu,Yong Jin

Micellar-nanocarrier-based drug delivery systems possessing characteristics such as an excellent circulation stability, inhibited premature release and on-demand site-specific release are urgently needed for enhanced therapeutic efficacy. Therefore, a novel kind of shell-sheddable core-crosslinked polymeric micelles with pH and oxidation dual-triggered on-demand drug release behavior was facilely constructed. The multifunctional micelles were self-assembled from a carefully designed amphiphilic triblock PEGylated polyurethane (PEG-acetal-PUBr-acetal-PEG) employing an acid-labile acetal linker at the hydrophilic–hydrophobic interface and pendant reactive bromo-containing polyurethane (PU) as the hydrophobic block, followed by a post-crosslinking via oxidation-cleavable diselenide linkages. These well-defined micelles exhibited an enhanced structural stability against dilution, achieved through the incorporation of diselenide crosslinkers. As expected, they were found to possess dual pH- and oxidation-responsive dissociation behaviors when exposure to acid pH (~5.0) and 50 mM H2O2conditions, as evidenced using dynamic light-scattering (DLS) and atomic force microscopy (AFM) analyses. An in vitro drug release investigation showed that the drug indomethacin (IND) could be efficiently encapsulated in the micelles, which demonstrated an inhibited premature release compared to the non-crosslinked ones. It is noteworthy that the resulting micelles could efficiently release entrapped drugs at a fast rate in response to either pH or oxidation stimuli. Moreover, the release could be significantly accelerated in the presence of both acid pH and oxidation conditions, relative to a single stimulus, owing to the synergetic degradation of micelles through pH-induced dePEGylation and oxidation-triggered decrosslinking processes. The proposed shell-sheddable core-crosslinked micelles with a pH and oxidation dual-response could be potential candidates as drug carriers for on-demand drug delivery.Keywords:shell-sheddable;core-crosslinking;pH-responsive;oxidation-responsive;drug delivery

Fluorescent filter paper with pH-responsive carbon dots for the on-site detection of biogenic amines in food

Jianfeng Yan,Quanbin Fu,Shikai Zhang,Xianbao Shi,Yuanhong Zhang,Juying Hou,Junling Duan,Shiyun Ai

As a kind of organic basic compound containing nitrogen, biogenic amine is released from food spoilage and considered as an indicator for monitoring food freshness. Herein, an excellent dual-emission ratiometric fluorescent sensor for eight kinds of biogenic amines was established via the facile mixing of pH-responsive carbon dots and Rhodamine B. The developed sensor shows a rapid response (10 s), low limit of detection (0.733–3.943 μM) and a wide linear range (0–150 μM). More importantly, a portable fluorescent filter paper was prepared by simple dispersing the filter paper in a solution mixture of carbon dots and Rhodamine B. The obtained fluorescent filter paper based sensor showed an obvious color change in the presence of biogenic amine vapor derived from shrimp and mushroom. The results revealed that this sensor could realize the on-site and visual detection of biogenic amines in real food samples, making it suitable for potential application in food safety monitoring.

Controllable cross-linking of VA-co-VAm/PAN composite membranes for efficient pervaporation desalination under extreme pH conditions

Jiawen Fu,Haowei Pan,Mingzhe An,Zihao Li,Hong Wang,Xinping He,Chunhai Yi

Polyvinyl alcohol (PVA) is a promising membrane material for pervaporation (PV) desalination. However, the adjustment and control of the cross-linking structure is still a challenge for PVA membrane. In this study, a novel pH-resistant PVA-based composite membrane for efficient pervaporation desalination was developed by precisely adjusting the cross-linking behavior. Vinyl alcohol-vinylamine copolymer (VA-co-VAm) containing both hydroxyl and amino groups was synthesized. Cross-linking reaction was carried out based on the Schiff base reaction between amino groups (in VAm moiety) and glutaraldehyde (GA) under alkaline conditions. Cross-linking degree of PVA selective layer was carefully controlled by adjusting the amino group content in copolymer. Results showed that membrane prepared with VA-co-VAm that containing 5 wt% N-vinylformamide (NVF) displayed superior hydrophilicity and the largest free volume fraction. Pervaporation test indicated that the modified cross-linking membrane showed good stability under extreme pH conditions. Specifically, under strong acid conditions (pH ~ 1) and alkaline conditions (pH ~ 14), the membrane showed excellent desalination performance with water flux over 12 kg/(m 2 h), and the salt rejection higher than 99.95%. Based on the above results, the prepared membrane offers a promising platform for desalination under extreme pH conditions, which shows great potential in industrial wastewater treatment.

Sodium Alginate/carboxymethyl chitosan-CuO hydrogel beads as a pH-sensitive carrier for the controlled release of curcumin

Lu Wang,Xin Gang,Yu Xiao,Yi Ren,Jianhong Wang,Baolong Niu,Wenfeng Li

In this study, CMCS-CuO nanoparticles were added to the SA matrix by blending method to prepare SA/CMCS-CuO composite microspheres. The chemical structure and morphology of the composite beads were characterized. The results showed that there was a certain molecular interaction between CMCS-CuO NPs and SA matrix. The swelling experiment showed that with the increase of the mass of CMCS-CuO NPs, the maximum swelling ratio of gel microspheres decreased from 49.83% to 38.2%, and the time to reach the maximum swelling ratio also increased from 8 h to 11 h. Cytotoxicity test, hemolysis test, and cell migration test showed that the composite microspheres had good biocompatibility. Curcumin was added to the composite bead matrix by the blending method, and curcumin-loaded SA/CMCS-CuO composite beads were prepared by the crosslinking method. In vitro release experiments showed that SA/CMCS-CuO composite microspheres had good pH sensitivity, and the addition of CMCS-CuO NPs prolonged the in vitro release time of cur. It has certain application potential in the field of drug release.

Simultaneous Detection of Temperature, Strain, Refractive Index, and pH Based on a Phase-Shifted Long-Period Fiber Grating

Ting Liu,Yaowei Li,Xinyi Dai,Wenbo Gan,Xunsi Wang,Shixun Dai,Baoan Song,Tiefeng Xu,Peiqing Zhang

Design of pH-sensitive methotrexate prodrug-targeted curcumin nanoparticles for efficient dual-drug delivery and combination cancer therapy

Jiajiang Xie,Zhongxiong Fan,Yang Li,Yinying Zhang,Fei Yu,Guanghao Su,Liya Xie,Zhenqing Hou

Preparation and characterization of pH and thermally responsive perfluoropolyether acrylate copolymer micelles and investigation its drug-loading properties

Dezhong Xu,Ao Li,Weijie Lin,Qiuxia Zou,Shuai Wu,Ajoy Kanti Mondal,Wangchuan Xiao,Fang Huang

In this study, pH and thermally responsive P(PFPHM 9 - b -DMAEMA- b -PEGMEA 480 ) was prepared by atom transfer radical polymerization (ATRP) using perfluoropolyether hydroxyethyl methacrylate (PFPHM) as hydrophobic core, 2-(Dimethylamino) ethyl methacrylate as pH and thermal response function segment, and poly (ethylene glycol) methyl ether acrylate 480 as hydrophilic shell, respectively. The chemical structure, critical micelle concentration (CMC), lower critical solution temperature (LCST), biological toxicity, stability of micelles, drug-loading performance and cumulative drug release rate of prepared P(PFPHM 9 - b -DMAEMA- b -PEGMEA 480 ) were analyzed by 19 F NMR, 1 H NMR, FTIR, DLS, UV–Vis, laser confocal microscopy and fluorescence spectrophotometer. The results show that P(PFPHM 9 - b -DMAEMA- b -PEGMEA 480 ) exhibites a CMC of 7.5 g/L, LCST of 37.6°C and excellent micelle stability. Moreover, the analysis of drug-loading indicates that the polymer displayed drug loading efficiency (DL) is 21.3% and the encapsulation efficiency (EE) is 90.0%. Its cumulative drug release rates at pH = 6.5 (42°C) is almost double of those at pH = 7.4 (42°C), pH = 6.5 (37°C) and pH = 7.4 (37°C). These results suggeste that the P(PFPHM 9 - b -DMAEMA- b -PEGMEA 480 ) at pH ranging from 6.5 to 7.4 and temperature ranging from 37 to 42°C are pH and temperature sensitive. It has great potential application as a drug loading for DOX.

Enhanced electrochemical performance of ammonium vanadate (NH4V4O10) cathode for rechargeable aqueous zinc-ion batteries by altering pH regulators

Chao Lu,Zhi Yang,Yi Ding,Yujie Wang,Xiaolian Wang,Tao Li,Qiuyang Tan

Ammonium vanadate (NH 4 V 4 O 10 : NVO) as cathode for rechargeable aqueous zinc-ion batteries (AZIBs) have drawn extensive concern due to its high specific capacity and long cycle life. The controllable synthesis of high-performance NH 4 V 4 O 10 is greatly desirable for the development of AZIBs but still remains a significant challenge. In this work, sulfuric acid, hydrochloric acid, and nitric acid were used as pH regulators to prepare NVO via a simple one-step hydrothermal route. The resulting NVO product (NVO-1) based on sulfuric acid pH regulator has the optimal overall performance for its favorable structure stability originated from the high crystallinity and wonderful 3D cross-linked nanowire morphology, contributing to fast electron transfer in the (de)intercalation process of Zn 2+ . Consequently, NVO-1 electrode exhibits excellent rate capability and cyclic stability, delivering high reversible capacities of 418.9 and 257.1 mAh g −1 at current densities of 0.1 and 2 A g −1 , respectively, and demonstrating a discharge capacity of 105.7 mAh g −1 as well as superior long-term durability with an ultra-high capacity retention of 119.7 % at a large current density of 5 A g −1 after 2000 cycles. Investigation on the electrochemical kinetics reveals that surface capacitive behavior plays a significant role in the highly reversible Zn 2+ storage in NVO electrode.

Metal-organic framework decorated with glycyrrhetinic acid conjugated chitosan as a pH-responsive nanocarrier for targeted drug delivery

Liu Cui,Xi Wang,Zhaoyun Liu,Ziqi Li,Ziwei Bai,Kui Lin,Jian Yang,Yuanlu Cui,Fei Tian

Stimulus-responsive nanomaterials have become a hot spot in controllable drug delivery systems researches owing to their spatiotemporal controllable properties based on the differences between tumor microenvironment and normal tissue. Herein, iron (III) carboxylate metal-organic framework nanoparticles coated with glycyrrhetinic acid-chitosan conjugate (MIL-101/GA-CS) were successfully fabricated and acted as the pH-responsive and target-selective system to deliver doxorubicin (DOX) for hepatocellular carcinoma (HCC) therapy. The prepared nanocarrier possess the advantages of uniform size, comparable drug loading efficiency (28.89%), and superior pH-dependent controlled drug release (DOX release of 2.74% and 89.18% within 72 h at pH 7.4 and 5.5, respectively). In vitro cytotoxicity assays showed that the drug-loaded nanocarriers exhibited excellent inhibitory effects on HepG2 cells due to the sustained release of DOX, while the nanocarriers showed no significant toxicity. Furthermore, cell uptake experiments demonstrated that MIL-101-DOX/GA-CS could target HepG2 cells based on receptor-dependent internalization of glycyrrhetinic acid receptors mediated. In vitro 3D hepatoma cell microspheres experiments showed that MIL-101-DOX/GA-CS had excellent penetration and tumor killing ability. Therefore, MIL-101-DOX/GA-CS nanoparticles have a prospective application in cancer therapy as a pH-responsive controlled drug delivery system.

Redox and pH dual sensitive carboxymethyl chitosan functionalized polydopamine nanoparticles loaded with doxorubicin for tumor chemo-photothermal therapy

Yanfei Zhu,Junhong Ling,Xinyi Xu,Xiao-kun Ouyang,Nan Wang

The high expression of reduced glutathione (GSH) and low pH in tumor sites have encouraged new ideas for targeted drug release. The tumor microenvironment is a crucial target for studying the anti-tumor efficiency of photothermal therapy because the microenvironment plays a key role in cancer progression, local resistance, immune escaping, and metastasis. Herein, active mesoporous polydopamine nanoparticles loaded with doxorubicin and functionalized with N,N′ -bis(acryloyl)cystamine (BAC) and cross-linked carboxymethyl chitosan (CMC) were used to induce simultaneous redox- and pH-sensitive activity to achieve photothermal enhanced synergistic chemotherapy. The inherent disulfide bonds of BAC were able to deplete glutathione, thus increasing the oxidative stress in tumor cells and enhancing the release of doxorubicin. Additionally, the imine bonds between CMC and BAC were stimulated and decomposed in the acidic tumor microenvironment, improving the efficiency of light conversion through exposure to polydopamine. Moreover, in vitro and in vivo investigations demonstrated that this nanocomposite exhibited improved selective doxorubicin release in conditions mimicking the tumor microenvironment and low toxicity towards non-cancerous tissues, suggesting there is high potential for the clinical translation of this synergistic chemo-photothermal therapeutic agent.