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Mechanism for Alternating Electric Fields Induced-Effects on Cytosolic Calcium

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Chinese physics Letters 2009年第1期26卷 245-248页

作者：罗明艳宋昆张旭李任植 Department of biophysics School of Physics and Key Laboratory of Bioactive Materials (Ministry of Education) Nankai University Tianjin 300071

In this work, from the point of calcium ions in the cytosol, we extend a Vm-[Ca^2＋]cyt model to explain the changes of action potential Vm of the plasma membrane and the calcium concentration in the cytosol [Ca^2＋]cyt under an alternating electric field in ceils. An alternating external electric field may exert an oscillating force to each of the free electrolytes, existing on both sides of the plasma membrane. The mechanism for the alternating electric field induced-effects on Vm and [Ca^2＋ ]cyt is elucidated. The simulation results show a correlation between the changes of [Ca2＋]cyt and the alternating electric field. When the numerical ratio between the intensity Eo（mV/m） and the frequency v （Hz） of the field was about 1-2, the [Ca^2＋]cyt signal is changed dramatically. The bioactive changes of [Ca^2＋ ]cyt appear at low frequency, in the range of 0-100 Hz.

关键词： ELECTRIC fields CYTOSOL CALCIUM ions CELL membranes CELLS -- Electric properties SIMULATION methods & models

A network of conformational transitions in an unfolding process of HP-35 revealed by high-temperature MD simulation and a Markov state model

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Chinese physics B 2018年第1期27卷 175-181页

作者：邵丹丹高恺夫 Institute of biophysics and Department of physics Central China Normal University

An understanding of protein folding/unfolding processes has important implications for all biological processes, in- eluding protein degradation, protein translocation, aging, and diseases. All-atom molecular dynamics （MD） simulations are uniquely suitable for it because of their atomic level resolution and accuracy. However, limited by computational ca- pabilities, nowadays even for small and fast-folding proteins, all-atom MD simulations of protein folding still presents a great challenge. An alternative way is to study unfolding process using MD simulations at high temperature. High temper- ature provides more energy to overcome energetic barriers to unfolding, and information obtained from studying unfolding can shed light on the mechanism of folding. In the present study, a 1000-ns MD simulation at high temperature （500 K） was performed to investigate the unfolding process of a small protein, chicken villin headpiece （HP-35）. To infer the folding mechanism, a Markov state model was also built from our simulation, which maps out six macrostates during the folding/unfolding process as well as critical transitions between them, revealing the folding mechanism unambiguously.

关键词： molecular dynamics simulation Markov state model folding/unfolding HP-35

Conjugated Polymers for Combatting Antimicrobial Resistance

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Chinese Journal of Chemistry 2022年第6期40卷 759-772页

作者： Zijuan Wang Hao Geng Chenyao Nie Chengfen Xing School of Materials Science and Engineering Hebei University of TechnologyTianjin 300130China Key laboratory of Biotechnology and pharmaceutical Engineering School of Pharmaceutical SciencesCixi Biomedical Research InstituteWenzhou Medical UniversityWenzhouZhejiang 325035China Key laboratory of Hebei Province for Molecular biophysics Institute of BiophysicsHebei University of TechnologyTianjin 300130China

Antimicrobial resistance(AMR)is one of the major challenges in pathogenic infections,which endangers human health and brings devastating public health ***,developing new materials to reduce the over-reliance on antibiotics or to replace antibiotics is in great need to solve this *** polymers(CPs)with excellent light-harvesting properties and good biocompatibility are ideal candidate materials for combat-ting AMR through photodynamic antimicrobial therapy(PACT)by sensitizing oxygen and photothermal therapy(PTT)by light to heat ***-nificant works of CPs-based antimicrobial approaches have been reported in recent ***,we summarize the types of CPs-based antimicrobial materials,illustrate their antimicrobial mechanisms,and discuss their applications in combating AMR mainly by PACT or antimicrobial *** addi-tion,we proposed some other antimicrobial treatment strategies based on CPs,hoping to provide inspiring insight for overcoming AMR.

关键词： Polymers Antimicrobial resistance Photochemistry Materials science Phototherapy

Trapping and Driving Individual Charged Micro-particles in Fluid with an Electrostatic Device

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Nano-Micro Letters 2016年第3期8卷 270-281页

作者： Jingjing Xu Zijing Lei Jingkun Guo Jie Huang Wei Wang Uta Reibetanz Shengyong Xu Key laboratory for the physics & Chemistry of Nanodevices and Department of Electronics Peking University Institute of Microelectronics Peking University Medical Faculty Institute for Medical Physics and Biophysics University of Leipzig

A variety of micro-tweezers techniques, such as optical tweezers, magnetic tweezers, and dielectrophoresis technique, have been applied intensively in precise characterization of micro/nanoparticles and bio-molecules. They have contributed remarkably in better understanding of working mechanisms of individual sub-cell organelles, proteins, and DNA. In this paper, we present a controllable electrostatic device embedded in a microchannel, which is capable of driving,trapping, and releasing charged micro-particles suspended in microfluid, demonstrating the basic concepts of electrostatic tweezers. Such a device is scalable to smaller size and offers an alternative to currently used micro-tweezers for application in sorting, selecting, manipulating, and analyzing individual micro/nanoparticles. Furthermore, the system offers the potential in being combined with dielectrophoresis and other techniques to create hybrid micro-manipulation systems.

关键词： Electrostatic tweezers Charged particles Coulomb potential well Manipulation Trap

A mathematical model of a P53 oscillation network triggered by DNA damage

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Chinese physics B 2010年第4期19卷 112-116页

作者：夏俊峰贾亚 Department of physics and Institute of biophysics Central China Normal University

Taking the interaction between a DNA damage repair module, an ATM module, and a P53--MDM2 oscillation module into account, this paper presents a mathematical model of a P53 oscillation network triggered by a DNA damage signal in individual cells. The effects of the DNA damage signal and the delay time of P53-induced MDM2 expression on the behaviours of the P53 oscillation network are studied. In the oscillatory state of the P53--MDM2 oscillator, it is found that the pulse number of P53--P oscillation increases with the increase of the initial DNA damage signal, whereas the amplitude and the period of P53--P oscillation are fixed for different initial DNA damage signals, and the period numbers of P53--P oscillations decrease with the increase of time delay of MDM2 expression induced by P53. These theoretical predictions are consistent with previous experimental results. The combined negative feedback of P53--MDM2 with the time delay of P53-induced MDM2 expression causes oscillation behaviour in the P53 network.

关键词： P53 oscillation network DNA damage signal time delay kinetic model

Life under tension: the relevance of force on biological polymers

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biophysics Reports 2024年第1期10卷 48-56页

作者： Matthew T.J.Halma Longfu Xu Department of physics and Astronomy and Laser Lab Vrije Universiteit Amsterdam LUMICKS B.V.

Optical tweezers have elucidated numerous biological processes, particularly by enabling the precise manipulation and measurement of tension. One question concerns the biological relevance of these experiments and the generalizability of these experiments to wider biological systems. Here, we categorize the applicability of the information garnered from optical tweezers in two distinct categories: the direct relevance of tension in biological systems, and what experiments under tension can tell us about biological systems, while these systems do not reach the same tension as the experiment, still, these artificial experimental systems reveal insights into the operations of biological machines and life processes.

关键词： Tension Optical tweezers Molecular force

The orientational preferences of backbones of proteins

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Chinese Science Bulletin 2006年第21期51卷 2559-2565页

作者： CHEN Ying WANG Jun XUE Bin WANG Wei National laboratory of Solid State Microstructure Department of Physics and Institute of Biophysics Nanjing University Nanjing 210093China

The orientation between the backbone residues of proteins is defined based on the local configurations and the corresponding preferences are analyzed by *** is found that all the residue pairs have some specific preferences of *** statistical analysis is mainly concen-trated in the orientational distributions for two kinds of groupings of residues based on the hydrophobicity and secondary structural *** statistics for such two types of groupings shows different orienta-tional *** is found that for the former grouping the orientational preference is rather weak, while for the later a kind of strong orientational *** suggests that the formation of local structures and of secondary structures are highly related to the orientational preferences.

关键词：蛋白质主链定向参数选择残渣天然结构

In vivo real-time monitoring delayed administration of M2 macrophages to enhance healing of tendon by NIR-II fluorescence imaging

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Nano Research 2024年第5期17卷 4379-4390页

作者： Yuzhou Chen Mo Chen Chengxuan Yu Huizhu Li Liman Sai Nguyen T.K.Thanh Yueming Wang Yan Wo Jian Zhang Xing Yang Evgenii L.Guryev Andrei V.Zvyagin Hao De Min Tang Shiyi Chen Yunxia Li Yuefeng Hao Sijia Feng Jun Chen Sports Medicine Institute of Fudan University Department of Sports MedicineHuashan HospitalFudan UniversityShanghai 200040China Department of Orthopedic Surgery Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of MedicineShanghai 200092China Department of Bone and Joint Surgery Department of OrthopedicsRenji HospitalSchool of MedicineShanghai Jiao Tong UniversityShanghai 200001China Department of physics Shanghai Normal UniversityShanghai 200234China biophysics Group Department of Physics and AstronomyUniversity College LondonLondon WC1E 6BTUK UCL Healthcare Biomagnetic and Nanomaterials Laboratories London W1S 4BSUK Department of Anatomy and Physiology School of MedicineShanghai Jiao Tong UniversityShanghai 200025China Department of Orthopedics Affiliated Suzhou Hospital of Nanjing Medical UniversitySuzhou 215500China Institute of Biology and Biomedicine Lobachevsky State University of Nizhny NovgorodNizhny Novgorod 603950Russia Mathematical Institute University of OxfordOxford OX26GGUK Institute of Natural Sciences School of MathematicsShanghai Jiao Tong UniversityShanghai 200240China

The administration time is a critical but long-neglected point in cell therapy based on macrophages because the incorrect time of macrophage administration could result in diverse outcomes regarding the same macrophage *** this work,the second near-infrared(NIR-II)fluorescence imaging in vivo tracking of M2 macrophages during a pro-healing therapy in the mice model of rotator cuff injury revealed that the behavior of administrated macrophages was influenced by the timing of their *** delayed cell therapy(DCT)group had a longer retention time of injected M2 macrophages in the repairing tissue than that in the immediate cell therapy(ICT)*** Keller-Segel model and histological analysis further demonstrated that DCT altered the chemotaxis of M2 macrophages and improved the healing outcome of the repaired structure in comparison with *** results offer a possible explanation of previous conflicting results on reparative cell therapy and provoke reconsideration of the timing of these therapies.

关键词： macrophage cell therapy NIR-II in vivo imaging delayed therapy tendon healing

Effects of time delays in a mathematical bone model

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Chinese physics B 2017年第3期26卷 251-257页

作者：王莉芳仇康贾亚 Institute of biophysics and Department of physics Central China Normal University Department of Mathematics and physics Xuzhou Medical University

In this paper we propose a mathematical model of bone remodeling with time delays of both osteoclast-derived paracrine signaling of tumor and tumor-derived paracrine signaling of osteoclast. The effects of time delays on the growth of tumor cells and bone system are studied in multiple myeloma-induced bone disease. In the case of small osteoclast-derived paracrine signaling, it is found that the growth of tumor cells slows down, the oscillation period of the ratio of osteoclasts to osteoblasts is extended with increasing time delay, and there is a competition between the delay and osteoclast-derived paracrine signaling. In the ease of large tumor-derived paraerine signaling, the tumor-derived paracrine signaling can induce a more significant decline in tumor growth for long time delay, and thus slowing down the progression of bone disease. There is an optimal coupling between the tumor-derived paracrine signaling of osteoclasts and time delay during the progressions of bone diseases, which suppresses the tumor growth and the regression of bone disease.

关键词： time delays oscillation model of bone remodeling