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Efficient Production of Melanin by Aureobasidium Melanogenum Using a Simplified Medium and pH-Controlled Fermentation Strategy with the Cell Morphology Analysis

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APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY 2024年第2期196卷 1122-1141页

作者： Zhou, Ran Ma, Lan Qin, xuwen Zhu, Hui Chen, Guiguang Liang, Zhiqun zeng, Wei Guilin Med Univ Key Lab Biochem & Mol Biol Educ Dept Guangxi Zhuang Autonomous Reg 1 Zhiyuan Rd Guilin 541199 Guangxi Peoples R China Guilin Med Univ Sch Intelligent Med & Biotechnol 1 Zhiyuan Rd Guilin 541199 Guangxi Peoples R China Guangxi Univ Coll Life Sci & Technol Guangxi Microorganism & Enzyme Res Ctr Engn Techno State Key Lab Conservat & Utilizat Subtrop Agrobio 100 Daxue Rd Nanning 530004 Guangxi Peoples R China

Natural melanin is a biopolymer with wide application prospects in medicine, food, cosmetics, environmental protection, agriculture, and so on. Microbial fermentation is an important and effective way to produce melanin. In this study, Aureobasidium melanogenum, known as black yeast with cellular pleomorphism, was used for the production of melanin. Based on the characteristic of A. melanogenum secreting melanin under oligotrophic stress, a simple medium containing only glucose, MgSO4 center dot 7H(2)O, and KCl was constructed for the production of melanin. The melanin titer of 6.64 +/- 0.22 g/L was obtained after 20 days of fermentation without pH control. The cell morphological changes of A. melanogenum during the production of melanin were recorded, and the results showed that chlamydospore might be the most favorable cell morphology for melanin synthesis. Then, different fermentation strategies with cell morphology analysis were developed to further improve the production of melanin in a 5-L fermenter. Results showed that the maximum titer of melanin reached 18.50 g/L by using the fermentation strategy integrating pH control, ammonium salt addition, and H2O2 stimulation, which increased by 178.6% than that of the strategy without pH control. Furthermore, the melanin obtained from the fermentation broth was characterized as eumelanin containing an indole structure. This study provided a potentially feasible fermentation strategy for the industrial production of melanin.

关键词： Melanin Aureobasidium melanogenum Simplified medium pH-controlled strategy Cell morphology Characterization

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Mid-Miocene (17-11 Ma) fast exhumation in the upper Jinsha River and its implication for regional faulting in Southeast Tibet

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GEOMORPHOLOGY 2024年 466卷

作者： Shen, xuwen Jing, Liu-zeng Shen, Xiaoming zeng, Xianyang Wang, Zijun Xing, Yukun Wang, Heng Li, Mohan Tianjin Univ Sch Earth Syst Sci Tianjin 300072 Peoples R China Minist Emergency Management China Natl Inst Nat Hazards Beijing 100085 Peoples R China China Earthquake Adm Inst Geol State Key Lab Earthquake Dynam Beijing 100029 Peoples R China Univ Melbourne Sch Geog Earth & Atmospher Sci Parkville Vic 3010 Australia

The rugged southeast (SE) Tibet hosts a network of evolving faults, many of which are poorly understood due to a lack of sedimentary records and poor accessibility. The Jinsha River fault zone (JRFZ) is vaguely considered as a major fault bounding the Chuan-Dian Block in the northwest, yet little is known about its tectonic evolution history, which hinders our clear understanding of the tectonic deformation pattern, process and geomorphic response of SE Tibet. Here, we collected 10 samples from the hanging wall of the Xiongsong reverse fault, one strand of the JRFZ, near Markam area and on the trunk of the upper Jinsha River, to reveal its exhumation and kinematic history through low-temperature thermochronology. The ZHe ages (similar to 17-13 Ma) of the samples from the hanging wall are much younger than the published ones in the footwall, but the AFT (similar to 11-9 Ma) and AHe ages (similar to 14-6 Ma) are only slightly younger than those in the footwall. The QTQt and 3-D thermo-kinematic Pecube modeling suggest consistently that the Xiongsong fault experienced strong activity during the mid-Miocene (similar to 17-11 Ma) and then weakened. Post-11 Ma decreases in exhumation here on the trunk of the Jinsha river, if interpreted as river incision, is opposite to previously inferred river response to late Miocene surface uplift driven by the lower crust flow. Significant differences in thermochronological data and modeling results on both sides of the Jinsha River indicate the importance of local faulting in the development of large rivers. In addition, late Miocene fault activity shifts have also been observed on other major structures in SE Tibet, such as the left-lateral faulting of the Xianshuihe-Xiaojiang fault, the enhanced thrusting of the Longmen Shan-Yalong thrust belt and the kinematic reversal of the Ailao Shan-Red River shear zone. We infer that the near synchronized change in regional fault activity may be caused by the clockwise rotation of SE Tibet,

关键词： Southeastern Tibet Chuan-Dian Block Jinsha River fault zone Low-temperature thermochronology Late Miocene

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Coreactant-free and Near-Infrared Electrochemiluminescence Immunoassay with n-Type Au Nanocrystals as Luminophores

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ANALYTICAL CHEMISTRY 2022年第34期94卷 11934-11939页

作者： Fu, Li Liu, Xiancheng zeng, Ying Zhang, Qingqing Zhang, Bin Gao, xuwen Zou, Guizheng Shandong Univ Sch Chem & Chem Engn Jinan 250100 Peoples R China Shenzhen Lifotron Technol Co Ltd Shenzhen 518055 Peoples R China

The electrochemiluminescence (ECL) bioassay is prominently carried out with the involvement of the coreactant. To remove the detrimental effects of the coreactant on the ECL of luminophores, herein, a promising ECL immunoassay strategy with biocompatible nanoparticles as the luminophore is proposed, which involves directly and electrochemically oxidizing the luminophore methionine-capped Au (Met@Au) nanocrystals (NCs) without the participation of any coreactant. Met@Au NCs are a kind of n-type nanoparticles, and they can be electrochemically injected with valence band (VB) holes around +0.80 and +1.10 V (vs Ag/AgCl). The electrochemically injected exogenous VB hole can recombine with the endogenous conduction band electron of Met@Au NCs and eventually bring out two coreactant-free and near-infrared ECL processes around 0.80 V (ECL-1) and 1.10 V (ECL-2). The intensity of coreactant-free ECL is primarily determined by the electrochemical oxidation-induced hole-injection process. ECL-2 is considerably stronger than ECL-1 and can be exploited for determining the carcinoembryonic antigen (CEA) in a sandwich immunoassay procedure with a linear range from 0.1 to 50 pg/mL as well as a limit of detection of 0.03 pg/mL (S/N = 3).

关键词： Immunoassay Electrochemiluminescence Infrared

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Recent Advances in Mechano-Responsive Hydrogels for Biomedical Applications

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ACS APPLIED POLYMER MATERIALS 2020年第3期2卷 1092-1107页

作者： Chen, Jingsi Peng, Qiongyao Peng, xuwen Han, Linbo Wang, Xiaogang Wang, Jianmei zeng, Hongbo Univ Alberta Dept Chem & Mat Engn Edmonton AB T6G 1H9 Canada Shenzhen Technol Univ Coll Hlth Sci & Environm Engn Shenzhen 518118 Peoples R China Taiyuan Univ Sci & Technol Heavy Machinery Engn Res Ctr Educ Minist Taiyuan 030024 Peoples R China

Mechanical responsiveness is prevalent in biological systems and plays an essential role in many biomechanical processes. The past two decades have witnessed enormous effort devoted to the development of biomimetic mechano-responsive hydrogels which are capable of adapting their physical and chemical properties to external mechanical stimuli. Due to the combination of tissue similarity and mechano-responsive properties, this type of hydrogel offers great advantages for diverse biomedical applications. Strain-stiffening and self-healing hydrogels duplicate the physiological properties of biological tissues, serving as promising candidates for artificial tissues, tissue scaffolds, and wound dressings. The shear-thinning property provides the hydrogels injectability, and the regional delivery contributes to minimally invasive treatment. Mechanochromic hydrogels allow the direct visualization of mechanical stress, holding great promise in biosensing and diagnosing. This review highlights the most recent developments in mechano-responsive hydrogels with various applications in the biomedical field. Different types of mechano-responsive hydrogels are introduced with focus on their responsive mechanisms, design strategies, and in vitro/in vivo performances, providing useful insights into the understanding and future research directions of mechano-responsive hydrogels with applications in biomedical engineering.

关键词： mechano-responsive hydrogel strain-stiffening self-healing shear-thinning mechanochromic

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DNA methyltransferases: emerging targets for the discovery of inhibitors as potent anticancer drugs

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DRUG DISCOVERY TODAY 2019年第12期24卷 2323-2331页

作者： Yu, Jie Xie, Tianli Wang, Zhe Wang, xuwen zeng, Su Kang, Yu Hou, Tingjun Zhejiang Univ Coll Pharmaceut Sci Hangzhou 310058 Zhejiang Peoples R China

DNA methyltransferases (DNMTs) are a conserved family of cytosine methylases with crucial roles in epigenetic regulation. They have been considered as promising therapeutic targets for the epigenetic treatment of cancer. Therefore, DNMT inhibitors (DNMTis) have attracted considerable interest in recent years for the modulation of the aberrant DNA methylation pattern in a reversible way. In this review, we provide a structure-based overview of the therapeutic importance of DNMTs against different cancer types, and then summarize recently investigated DNMTis as well as their inhibitory mechanisms, focusing on recent advances in the development of DNMTis with specificity and/or selectivity using computational approaches.

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Recent advances in designing conductive hydrogels for flexible electronics

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InfoMat 2020年第5期2卷 843-865页

作者： Qiongyao Peng Jingsi Chen Tao Wang xuwen Peng Jifang Liu Xiaogang Wang Jianmei Wang Hongbo zeng Department of Chemical and Materials Engineering University of AlbertaEdmontonAlbertaCanada The Fifth Affiliated Hospital Guangzhou Medical UniversityGuangzhouGuangdongChina Heavy Machinery Engineering Research Center of Education Ministry Taiyuan University of Science and TechnologyTaiyuanChina

Flexible electronics have emerged as an exciting research area in recent years,serving as ideal interfaces bridging biological systems and conventional electronic *** electronics can not only collect physiological signals for human health monitoring but also enrich our daily life with multifunctional smart materials and *** hydrogels(CHs)have become promising candidates for the fabrication of flexible electronics owing to their biocompatibility,adjustable mechanical flexibility,good conductivity,and multiple stimuli-responsive *** achieve on-demand mechanical properties such as stretchability,compressibility,and elasticity,the rational design of polymer networks via modulating chemical and physical intermolecular interactions is ***,the type of conductive components(eg,electron-conductive materials,ions)and the incorporation method also play an important role in the conductivity of ***-CHs usually possess excellent conductivity,while ion-CHs are generally transparent and can generate ion gradients within the hydrogel *** mini review focuses on the recent advances in the design of CHs,introducing various design strategies for electron-CHs and ion-CHs employed in flexible electronics and highlighting their versatile applications such as biosensors,batteries,supercapacitors,nanogenerators,actuators,touch panels,and displays.

关键词： biosensor composite hydrogel conductive hydrogel flexible electronics supercapacitor

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Thermally-activated upconversion based on triplet fusion for deep red photoactivation of Ru(ii) complexes

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NEW JOURNAL OF CHEMISTRY 2024年第15期48卷 6886-6892页

作者： Niu, Pengfei Da, xuwen Hu, Rui Yu, Tianjun Chen, Jinping Zhou, Qianxiong Luo, Guiwen zeng, Yi Li, Yi Tech Inst Phys & Chem Chinese Acad Sci Key Lab Photochem Convers & Optoelect Mat Beijing 100190 Peoples R China Inst Chem Chinese Acad Sci Key Lab Photochem Beijing 100190 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China

Expanding the anti-Stokes shift in triplet-triplet annihilation upconversion (TTA-UC) systems and harvesting light within the biological transparency window (700-900 nm) are of great importance for their biomedical applications. In this study, we have developed a TTA-UC system that converts deep red-light into blue photons using a highly endothermic sensitization pair, wherein the triplet energy level of the sensitizer is 0.19 eV below that of the acceptor. The thermally activated triplet energy transfer compensates the energy loss during intersystem crossing (ISC) of the sensitizer, achieving a 0.82 eV anti-Stokes shift upconversion with over 6% quantum yield. This TTA-UC system activates a Ru(ii)-based photoactivated chemotherapeutic agent, causing DNA to bleach under 700 nm LED irradiation. These results demonstrate a feasible way to develop upconversion systems that operate within the biological transparency window, with potential applications in biological phototherapy.

关键词： Transparency

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Probing the Interfacial Forces and Surface Interaction Mechanisms in Petroleum Production Processes

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Engineering 2022年第11期18卷 49-61页

作者： Diling Yang xuwen Peng Qiongyao Peng Tao Wang Chenyu Qiao Ziqian Zhao Lu Gong Yueliang Liu Hao Zhang Hongbo zeng Department of Chemical and Materials Engineering University of AlbertaEdmontonAB T6G 1H9Canada College of Petroleum Engineering China University of PetroleumBeijing 102249China

Despite the advances that have been made in renewable energy over the past decade,crude oil or petroleum remains one of the most important energy resources to the *** production presents many challenging issues,such as the destabilization of complex oil-water emulsions,fouling phenomena on pipelines and other facilities,and water *** problems are influenced by the molecular forces at the oil/water/solid/gas interfaces involved in relevant ***,we present an overview of recent advances on probing the interfacial forces in several petroleum production processes(e.g.,bitumen extraction,emulsion stabilization and destabilization,fouling and antifouling phenomena,and water treatment)by applying nanomechanical measurement technologies such as a surface forces apparatus(SFA)and an atomic force microscope(AFM).The interaction forces between bitumen and mineral solids or air bubbles in the surrounding fluid media determine the bitumen liberation and flotation efficiency in oil sands *** stability of complex oil/water emulsions is governed by the forces between emulsion drops and particularly between interface-active species(e.g.,asphaltenes).Various oil components(e.g.,asphaltenes)and emulsion drops interact with different substrate surfaces(e.g.,pipelines or membranes),influencing fouling phenomena,oil-water separation,and wastewater *** these intermolecular and interfacial forces has advanced the mechanistic understanding of these interfacial interactions,facilitating the development of advanced materials and technologies to solve relevant challenging issues and improve petroleum production *** challenges and suggestions on future research directions in the field are also presented.

关键词： Intermolecular and surface forces Interface Emulsion Colloids Fouling and antifouling Water treatment

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Stretchable, compressible, and conductive hydrogel for sensitive wearable soft sensors

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JOURNAL OF COLLOID AND INTERFACE SCIENCE 2022年 618卷 111-120页

作者： Peng, xuwen Wang, Wenda Yang, Wenshuai Chen, Jingsi Peng, Qiongyao Wang, Tao Yang, Diling Wang, Jianmei Zhang, Hao zeng, Hongbo Univ Alberta Dept Chem & Mat Engn Edmonton AB T6G 1H9 Canada Taiyuan Univ Sci & Technol Heavy Machinery Engn Res Ctr Educ Minist Taiyuan 030024 Peoples R China

Conductive hydrogels hold great promises in wearable soft electronics. However, the weak mechanical properties, low sensitivity and the absence of multifunctionalities (e.g., self-healing, self-adhesive, etc.) of the conventional conductive hydrogels limit their applications. Thus, developing multifunctional hydrogels may address some of these technical issues. In this work, a multifunctional conductive hydro gel strain sensor is fabricated by incorporating a conductive polymer Poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOT: PSS) into a mechanically robust poly (vinyl alcohol) (PVA)/ poly (acrylic acid) (PAA) double network (DN) hydrogel. The as-prepared hydrogel sensor could span a wide spectrum of mechanical properties by simply tuning the polymer composition and the number of freezing-thawing cycles. In addition, the dynamic hydrogen bonding interactions endow the hydrogel sensor with self healing property and reversible adhesiveness on diverse substrates. Moreover, the hydrogel sensor shows high sensitivity (Gauge Factor from 2.21 to 3.82) and can precisely detect some subtle human motions (e.g., pulse and vocal cord vibration). This work provides useful insights into the development of conductive hydrogel-based wearable soft electronics.(c) 2022 Elsevier Inc. All rights reserved.

关键词： Conductive hydrogel Interfacial interaction Self-healing Soft hydrogel sensors

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Probing Hydrophobic Interactions between Polymer Surfaces and Air Bubbles or Oil Droplets: Effects of Molecular Weight and Surfactants

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LANGMUIR 2022年第17期38卷 5257-5268页

作者： Yang, Diling Xie, Lei Mao, Xiaohui Gong, Lu Peng, xuwen Peng, Qiongyao Wang, Tao Liu, Qi zeng, Hongbo Zhang, Hao Univ Alberta Dept Chem & Mat Engn Edmonton AB T6G 1H9 Canada

Hydrophobic interaction plays an important role innumerous interfacial phenomena and biophysical and industrial processes. In this work, polystyrene (PS) was used as a modelhydrophobic polymer for investigating its hydrophobic interactionwith highly deformable objects (i.e., air bubbles and oil droplets) inaqueous solutions. The effects of polymer molecular weight,solvent (i.e., addition of ethanol to water), the presence of surface-active species, and hydrodynamic conditions were investigated, viadirect surface force measurements using the bubble/drop probeatomic force microscopy (AFM) technique and theoreticalcalculations based on the Reynolds lubrication theory andaugmented Young-Laplace equation by including the effect ofdisjoining pressure. It was found that the PS of low molecularweight (i.e., PS590 and PS810) showed slightly weaker hydrophobic interactions with air bubbles or oil droplets, as compared toglassy PS of higher molecular weight (i.e., PS1110, PS2330, PS46300, and PS1M). The hydrophobic interaction between PS and airbubbles in a 1 M NaCl aqueous solution with 10 vol % ethanol was weaker than that in the bare aqueous solution. Such effects onthe hydrophobic interactions are possibly achieved by influencing the structuring/ordering of water molecules close to thehydrophobic polymer surfaces by tuning the surface chain mobility and surface roughness of polymers. It was found that the additionof three surface-active species, i.e., cetyltrimethylammonium chloride (CTAC), Pluronic F-127, and sodium dodecyl sulfate (SDS),to the aqueous media could suppress the attachment of the hydrophobic polymer and air bubbles or oil droplets, most likely causedby the additional steric repulsion due to the adsorbed surface-active species at the bubble/polymer/oil interfaces. Our results haveimproved the fundamental understanding of the interaction mechanisms between hydrophobic polymers and gas bubbles or oildroplets, with useful implications on developing effective me

关键词： Atmospheric chemistry Bubbles Liquids Molecular mechanics Solution chemistry

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