SCIENCE OF THE TOTAL ENVIRONMENT
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2020
·
IF 6.551
Cong Pan,Libin Fu,Yaobin Ding,Xueqin Peng,Qihang Mao
The application of MoS 2 to enhance Co(II)/peroxymonosulfate (Co(II)/PMS) system for organic pollutants degradation was developed, and the mechanism for pH dependent catalytic activity in the MoS 2 co-catalyzed Co(II)/PMS processes was systematically investigated. It was found that MoS 2 presented enhancement effect for Co(II)/PMS system in the tested pH range from 4.0 to 7.0, especially at pH 5.5 and 6.0. The pseudo first order reaction rates for Rhodamine B (RhB) degradation in MoS 2 -Co 2+ /PMS system at pH 5.5 and 6.0 were 3.2 and 1.8 times that in Co 2+ /PMS system (Co 2+ 2 μmol L −1 , PMS 0.2 mmol L −1 , MoS 2 0.5 g L −1 ). The redox recycle of Co 3+ /Co 2+ was promoted by Mo(IV) and S(-II) on MoS 2 surface and regenerated Co 2+ induced homogeneous activation of PMS for the robust production of free radical with the major of hydroxyl radicals . Increasing MoS 2 dosage, Co 2+ and PMS concentration can linearly raise RhB degradation rate in MoS 2 -Co(II)/PMS system. Moreover, MoS 2 exhibited excellent catalytic and chemical stability in recyclability and reuse for catalytic decontamination in MoS 2 -Co(II)/PMS system. This work gains new insight into the enhancement effect of MoS 2 in the meal ions/PMS system, and provides a high performance wastewater treatment process of Co(II)/PMS at low concentrated Co 2+ .
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RSC Advances
·
2019
·Vol. 9
·期 68
·40131-40145
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IF 3.049
Jizheng Song,Yuling Liu,Longfei Lin,Ye Zhao,Xiuqing Wang,Ming Zhong,Tanggui Xie,Yuting Luo,Shaojing Li,Ruocong Yang,Hui Li
Curcumin (CUR), a natural polyphenolic compound existing in plants, exhibits anticancer potential in inhibiting the growth of various types of human cancer. However, the poor aqueous solubility and low bioavailability limit its clinical applications. pH-sensitive macromolecule F68-acetal-PCL (FAP) and active targeting macromolecule F68-glycyrrhetinic acid (FGA) were designed to fabricate mixed micelles for efficient delivery of CUR. The thin film hydration method was used to prepare CUR loaded mixed (MIX/CUR) micelles. The drug loading rate (DL) of MIX/CUR micelles was 6.31 ± 0.92%, which remained stable for 15 days at 4 °C. The particle size and zeta potential of the MIX/CUR micelles were 91.06 ± 1.37 nm and −9.79 ± 0.47 mV, respectively. The MIX/CUR micelles exhibited pH sensitivity in a weak acid environment, and showed rapid particle size variation and drug release. In addition, in vitro tests demonstrated that MIX/CUR micelles induced higher cytotoxicity and apoptosis than free CUR, non-pH-sensitive F68-PCL (FBP)/CUR micelles and pH-sensitive FAP/CUR micelles in SMMC7721 and Hepa1-6 cells. Besides, mixed micelles were more effective than FBP and FAP micelles in a cell uptake experiment, which was medicated by a GA receptor. All in all, these results indicated that MIX/CUR micelles could be regarded as an ideal drug administration strategy against hepatoma carcinoma cells.
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Nano Energy
·
2019
·
IF 15.548
Mingli Zhang,Changhyeok Choi,Rupeng Huo,Geun Ho Gu,Song Hong,Chao Yan,Suying Xu,Alex W. Robertson,Jieshan Qiu,Yousung Jung,Zhenyu Sun
Electrochemical nitrogen fixation under mild conditions is highly demanded yet remains a grand challenge. Herein we report metal-free electrocatalysis of aqueous N 2 reduction to produce NH 3 over reduced graphene oxide (DrGO) with tuned defects. The defect sites in DrGO, consisting of unsaturated carbon [single vacancy (SV), double vacancy (DV), and –COOH], were examined, and showed an improved NH 3 selectivity due to the strong binding of N 2 instead of H. In addition to improved selectivity, the calculated free energies for N 2 reduction reaction at DrGO-COOH and DrGO-DV sites suggest that the thermodynamic overpotentials of these metal-free catalysts are comparable to the most efficient transition metal-based catalysts reported thus far. Our nonmetallic and dopant-free catalysts can convert N 2 to NH 3 at a faradaic efficiency of up to 22.0% at −0.116 V (versus the reversible hydrogen electrode vs . RHE) in 0.1 M HCl and 10.8% at −0.166 V ( vs . RHE) in 0.1 M KOH, surpassing most earlier reported catalysts. An NH 3 formation rate exceeding 7.3 μg h −1 mg −1 was achieved at low overpotentials in both acidic and alkaline environments , comparable to the values shown by metal electrocatalysts under similar conditions.
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Materials Science & Engineering C-Materials for Biological Applications
·
2019
·
IF 4.959
Wei Long,Hui Ouyang,Weimin Wan,Wenfeng Yan,Chaoqun Zhou,Hongye Huang,Meiying Liu,Xiaoyong Zhang,Yulin Feng,Yen Wei
Nanodiamond (ND) has been widely studied as a new type of carbon nanomaterials that is expected to be used as a promising candidate in various fields especially in the field of biomedicine. However, its poor water dispersibility and insufficient controlled release limit its practical applications. In this paper, ND-based composites with pH-responsive hydrazone bonds were successfully prepared by a simple chemical reaction between ester groups and hydrazine hydrate, in which ester groups were conjugated on the surface of ND via thiol-ene click reaction. On the other hand, CHO-PEG and doxorubicin hydrochloride (DOX) were linked on the carriers through formation of hydrazone bonds, resulting in improving water dispersibility and high drug loading capacity. The structure, thermal stability, surface morphology and particle size of ND carriers were characterized by different equipment. Results demonstrated that we have successfully prepared these functionalized ND. The release rate of DOX in acidic environment was significantly greater than that in normal physiological environment. More importantly, cell viability and optical imaging results showed that ND-based composites possess good biocompatibility, therapeutic effect, and could successfully transport DOX to HepG2 cells. Considering the above results, we believe that our new ND carriers will become promising candidates for intracellular controlled drug delivery and cancer treatment.
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BIOMACROMOLECULES
·
2019
·
IF 5.667
Yanqian Wu,Yi Xiao,Yushu Huang,Yanyun Xu,Donglei You,Wei Lu,Jiahui Yu
A biodegradable brush-type copolymer PHF-g-(PCL-PEG) based on a cleavable polyacetal backbone and biodegradable side chain modified with polyethylene glycol (PEG) was synthesized in this paper. This particular structure was directional to facilitate the formation of spherical or rod-shaped micelles. Flow cytometry showed that rod-shaped micelles displayed enhanced cellular uptake compared to spherical micelles. Rod-shaped micelles were selected to investigate their drug delivery abilities in detail. In vitro experiments verified the pH-triggered drug release of DOX-loaded micelles, and the release rate of doxorubicin (DOX) was 77% at pH 5.0 and 26% at pH 7.4. In drug-release kinetic analysis, a double-exponential model achieved the best fit. The copolymer appeared to be almost nontoxic, while the DOX-loaded micelles showed equivalent cytotoxicity compared to DOX at high concentration. The endocytosis of DOX-loaded micelles was two times that of DOX. Our findings suggest that the pH-sensitive brush type copolymer could be a possible carrier in drug delivery.
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ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2019
·
IF 7.149
Xiao-Cheng Liu,Wen-Qiang Li,Yi-Ran Wang,Guan-Nan Zhou,Yi-Xuan Wang,Chuan-Shu He,Gong-Ming Wang,Yang Mu
Promotion of iron solubility using ligands is the preliminary step in the homogeneous electro-Fenton (EF) process at a mild pH, but the chelate efficiencies of most organic ligands are unsatisfactory, resulting in insufficient Fe(II) availability. In this study, atomic H* was, for the first time, introduced to the EF process to accelerate the regeneration of the Fe(II)-complex at a mild pH using a Ni-deposited carbon felt (Ni-CF) cathode. The introduction of atomic H* significantly elevated total organic carbon (TOC) abatement of ciprofloxacin (CIP) from 42% (CF) to 81% (Ni-CF) at a natural pH. In the presence of humic acids (HAs), atomic H* introduced via Ni-CF enhanced the CIP degradation rate to 10 times that of the CF at a mild pH. The electron spin resonance (ESR), density functional theory (DFT) calculations, electrochemical characterization, and in situ electrochemical Raman study clearly demonstrated that the atomic H* generated from the Ni-CF cathode was highly efficient at reducing Fe(III)-complexes at a natural pH. Additionally, the Ni-CF could generate atomic H* without significant nickel leaching. Thus, the atomic H* could continuously facilitate iron cycling and, consequently, enhance pollutant mineralization via the homogeneous EF process at a mild pH in an environmentally friendly manner.
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JOURNAL OF MEMBRANE SCIENCE
·
2019
·
IF 7.015
Huawen Liu,Shanshan Yang,Yuanwei Liu,Mengjie Miao,Yan Zhao,Arcadio Sotto,Congjie Gao,Jiangnan Shen
Environmental stimuli-responsive membranes have many latent applications in numerous fields, for example, chemical/biological separations, water treatment, drug delivery, self-cleaning material and chemical sensor. In this study, a pH-responsive membrane with in-situ assembled stimuli-responsive microgels on membrane surface and internal channels wall was fabricated by the coagulation step of the phase-inversion process. Interestingly, it was found that poly(4-vinyl pyridine) (P4VP) microgel can be mobilized onto the membrane surface by using an acidic coagulation bath. Meanwhile, the membrane-based materials with different hydrophobic properties showed a great effect on the migration of microgel onto the channel surface. The inner pores of these responsive membranes can self-adjust its size with the changes of outside pH stimulus. Moreover, the gate-controlled water permeability of pH-responsive membranes was explored at the pH interval from pH 2 to pH 6. Investigations revealed that the P4VP microgel-assembled membrane had excellent pH-responsive performance. In addition, these pH-responsive membranes with embedded microgels on surface and inner pores wall also exhibited excellent reversible behaviors and self-cleaning properties.
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MICROCHIMICA ACTA
·
2019
·Vol. 186
·期 7
·1-9
·
IF 5.479
Wang Qin,Yang Haitao,Zhang Qiang,Ge Hongguang,Zhang Shengrui,Wang Zhiyin,Ji Xiaohui
New green-emissive carbon dots (G-CDs) are described here and shown to be viable fluorescent nanoprobes for the detection of changes in cellular pH values. By using m -phenylenediamine as the carbon source, G-CDs with an absolute quantum yield of 36% were solvothermally synthesized in the presence of strong H 2 SO 4 . The G-CDs have an average size of 2.3 nm and display strong fluorescence with excitation/emission peaks at 450/510 nm. The fluorescence intensity depends on the pH value in the range from 6.0 to 10.0, affording the capability for sensitive detection of intracellular pH variation. The nanosensor with excellent photostability exhibited good fluorescence reversibility in different pH solutions, and showed excellent stability against the influence of other biological species. The nanoprobe was successfully used in confocal fluorescence microscopy to determine pH values in SMMC-7721 cells.
Schematic presentation of green-emissive carbon dots (G-CDs) synthesized using m -phenylenediamine and sufuric acid through a solvothermal method for real-time fluorometric monitoring of intracellular pH values. Mechanism can be ascribed to PET process from the electron lone pair in amino group to the CDs.
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ACS Sustainable Chemistry & Engineering
·
2019
·
IF 6.97
Mancong Li,Yongteng Qian,Jimin Du,Haoran Wu,Linyu Zhang,Gang Li,Kaidi Li,Weimin Wang,Dae Joon Kang
The design and fabrication of eco-friendly, highly efficient, and non-noble-metal-based catalysts are demanding challenges in energy-conversion technologies. Herein, we successfully synthesized CuS nanosheets decorated with CoS2 nanoparticles through a facile route. The optimized 3% CoS2-7% CuS catalysts exhibited remarkable electrocatalytic performance, with excellent cyclic stability at all pH values for the hydrogen evolution reaction (HER). They exhibited lower Tafel slopes (46, 52, and 59 mV dec–1) and smaller overpotentials (62, 85, and 106 mV) at 10 mA cm–2 in 0.5 M H2SO4, 1 M KOH, and 0.5 phosphate buffer aqueous solutions, respectively, than other CoS2/CuS, pure CoS2, and pure CuS catalysts. We attribute their high electrocatalytic performance to their unique heterostructure and the synergistic effects between the constituent metal sulfides that provides a large interfacial contact area, numerous charge-transfer pathways, as well as abundant surface reaction active sites, enhancing the charge-carrier transfer during the HER activity.
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OPTICS EXPRESS
·
2019
·Vol. 27
·期 17
·23981-23995
·
IF 3.561
Anxin Jiao,Hua Zhang,Linlin Xu,Yue Tian,Xiangdong Liu,Ming Chen,Feng Chen
The blue laser beam-excited surface-enhanced Raman scattering (SERS)-based pH sensing holds great promise for avoiding undesired thermal heating effect on some special temperature-vulnerable molecules, as compared to the vast majority studies by exciting in the red or near-infrared (NIR). Herein, we report an ingenious approach to support core-shell Au@Ag nanodendrites (NDs) on TiO2 nanowires, which can possess enhanced SERS activity under 473 nm laser excitation, owing to the improved charge-transfer effect on modified TiO2 support by inserting plasmonic Au@Ag. By using pH-indicating 4-mercaptobenzoic acid (4-MBA), the obtained TiO2/Au@Ag NDs can not only exhibit high sensitive linear-responses of pH changes ranging from pH 4.0 to 9.0 in different solutions (deionized water, NaCl, CaCl2, and MgCl2) but also provide excellent temperature stability under 4°C, 25°C and 37°C temperatures as well as good time stability after storage for 10 days. The established SERS-pH sensing by using shorter wavelength laser excitation is highly desirable for understanding physiological process in temperature-vulnerable microenvironment.
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Frontiers in Chemistry
·
2019
·
IF 3.782
Hu Xiaohong,Gao Ziyu,Tan Huaping,Wang Huiming,Mao Xincheng,Pang Juan
Hydrogels with multifunctional properties attracted intensively attention in the field of tissue engineering because of their excellent performance. Also, object-oriented design had been supposed to an effective and efficient method for material design as cell scaffold in the field of tissue engineering. Therefore, a scaffold-oriented injectable composite hydrogel was constructed by two components. One was pH-sensitive bifunctional nanoparticles for growth factor delivery to improve biofunctionability of hydrogel scaffold. The other was Diels-alder click crosslinked hyaluronic acid hydrogel as matrix. pH dependent release behavior of nanoparticle component was confirmed by results. And, its bioactivity was verified by in vitro cell culture evaluation. In consideration of high-efficiency and effectiveness, low toxicity, controllability and reversibility, dynamic covalent and reversible Diels-alder click chemistry was used to design a HA hydrogel with two kinds of crosslinking points. The properties of hydrogel like gelation time and swelling ratio were influenced by pH value and polymer concentration. Composite hydrogel was formed by in situ polymerization, which exhibited acceptable mechanical property as a scaffold for biomedical field. Lastly, in vitro evaluation from results of viability, DNA content and cell morphology confirmed that hydrogels could maintain cell activity and support cell growth. Compared with pure hydrogel, composite hydrogel possessed better properties.
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JOURNAL OF MEMBRANE SCIENCE
·
2019
·
IF 7.015
Huawen Liu,Jiajie Zhu,Liang Hao,Yuliang Jiang,Bart van der Bruggen,Arcadio Sotto,Congjie Gao,Jiangnan Shen
Smart gating membranes with self-regulating nanopores/nanochannels are highly desirable for water gating and separation of small molecules. Based on the nanochannels in the graphene oxide (GO) membrane, we designed positive thermo- and negative pH-responsive GO/hydrogel composite membranes (GOGMs) through a simple filtration-accumulation of GO sheets and hydrogels. The shape-flabby hydrogels can be perfectly inlaid between two GO sheets by changing their shape, and also act as a bond between GO and substrates. Thermo- and pH-responsive hydrogels embedded between the GO sheets impart adjustable water channels to the GO membrane. The channel tunability of hydrogel-studded GO membrane derives from the size conversion of hydrogel and the constant layer spacing of GO sheets. The hydraulic permeability of GOGMs was explored within the wide pH range of 2–6 and the temperature interval of 20–44 °C. The results revealed that the hydraulic permeability of the GOGMs can be reversibly adjusted with a high thermo- and pH-responsive gating coefficients. The GOGMs with self-regulated channels have various permeability properties for small molecules under different conditions. Moreover, the membrane thickness and the ratio of microgel to GO both have an effect on the water permeation and response performance of the GOGMs. These environmental stimuli-responsive membranes with thermo- and pH-responsive channels has numerous potential for applications in smart gating systems, liquid-based controlled release systems and smart separation systems.
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