A Theoretical Investigation on Rectifying Performance of a Single Motor Molecular Device

We report ab initio calculations of the transport behavior of a phenyl substituted molecular motor. The calculated results show that the transport behavior of the device is sensitive to the rotation degree of the rotor part. When the rotor part is parallel with the stator part, a better rectifying performance can be found in the current-voltage curve. However, when the rotor part revolves to vertical with the stator part, the currents in the positive bias region decrease slightly. More importantly, the rectifying performance disappears. Thus this offers us a new method to modulate the rectifying behavior in molecular devices.

A non-Markov ratchet model of molecular motors：processive movement of single-headed kinesin KIF1A

A fluctuating ratchet model of non-Markov process is presented to describe the processive movement of molecular motors of single-headed kinesin KIF1A, where the fluctuation perturbation to the local potential is introduced and the detailed ATPase pathway of the motor is included. The theoretical results show good quantitative agreement with the previous experimental ones.

Drug Transport Microdevice Mimicking an Idealized Nanoscale Bio-molecular Motor

Molecular motors are nature＇s nano-devices and the essential agents of movement that are an integral part of many living organisms. The supramolecular motor, called Nuclear Pore Complex （NPC）, controls the transport of all cellular material be- tween the cytoplasm and the nucleus that occurs naturally in biological cells of many organisms. In order to understand the design characteristics of the NPC, we developed a microdevice for drug/fluidic transport mimicking the coarse-grained repre- sentation of the NPC geometry through computational fluid dynamic analysis and optimization. Specifically, the role of the central plug in active fluidic/particle transport and passive transport （without central plug） was investigated. Results of flow rate, pressure and velocity profiles obtained from the models indicate that the central plug plays a major role in transport through this biomolecular machine. The results ofthis investigation show that fluidic transport and flow passages are important factors in designing NPC based nano- and micro-devices for drug delivery.

Periodic thermodynamics of laser-driven molecular motor

Operation of a laser-driven nano-motor inevitably generates a non-trivial amount of heat, which can possibly lead to instability or even hinder the motor＇s continual running. This work quantitatively examines the overheating problem for a recently proposed laser-operated molecular locomotive. We present a single-molecule cooling theory, in which molecular details of the locomotive system are explicitly treated. This theory is able to quantitatively predict cooling efficiency for various candidates of molecular systems for the locomotive, and also suggests concrete strategies for improving the locomotive＇s cooling. It is found that water environment is able to cool the hot locomotive down to room temperature within 100 picoseconds after photon absorption. This cooling time is a few orders of magnitude shorter than the typical time for laser operation, effectively preventing any overheating for the nano-locomotive. However, when the cooling is less effective in non-aqueous environment, residual heat may build up. A continuous running of the motor will then lead to a periodic thermodynamics, which is a common character of many laser-operated nano-devices.

A simplified tether model for molecular motor transporting cargo

Molecular motors are proteins or protein complexes which function as transporting engines in biological cells. This paper models the tether between motor and its cargo as a symmetric linear potential. Different from Elston and Peskin＇s work for which performance of the system was discussed only in some limiting cases, this study produces analytic solutions of the problem for general cases by simplifying the transport system into two physical states, which makes it possible to discuss the dynamics of the motor--cargo system in detail. It turns out that the tether strength between motor and cargo should be greater than a threshold or the motor will fail to transport the cargo, which was not discussed by former researchers yet. Value of the threshold depends on the diffusion coefficients of cargo and motor and also on the strength of the Brownian ratchets dragging the system. The threshold approaches a finite constant when the strength of the ratchet tends to infinity.

Molecular Motors—Self-Organization of Cytoskeletal Network

Molecular motors play an important role in the organization of cytoskeletal filament networks. These nanometer-sized natural molecular machines opened up a new frontier of nano-technology. This article describes biomolecular nano-machines, their internal structures, and dynamical interactions between molecular motors and their molecular tracks which reorganize a network of long protein filaments, particularly during cell division to form cytoskeleton of daughter cells. Towards the end, the article also takes up some still-to-be resolved matters and prospects for future developments in this exciting multidisciplinary area of science.

分子motor定向输运的反常扩散机制

研究了分子motor在非对称闪烁周期势中的反常扩散引起的输运过程 .通过解析和数值方法求解广义Langevin方程 ,得到了粒子稳定定向流 ,研究了其随反常扩散指数δ和无势停留时间τoff的变化规律 .

Artificial molecular machines:Design and observation

Natural molecular machines have inspired the development of artificial molecular machines,which have the potential to revolutionize several areas of technology.Artificial molecular machines commonly employ molecular switches,molecular motors,and molecular shuttles as fundamental building blocks.The observation of artificial molecular machines constructed by these building blocks can be highly challenging due to their small sizes and intricate behaviors.The use of modern instrumentation and advanced observational techniques plays a crucial role in the observation and characterization of molecular machines.Furthermore,a well-designed molecular structure is also a critical factor in making molecular ma-chines more observable.This review summarizes the common methods from diverse perspectives used to observe molecular machines and emphasizes the significance of comprehending their behaviors in the design of superior artificial molecular machines.

Modelling of a DNA packaging motor

During the assembly of many viruses, a powerful molecular motor packages the genome into a preassembled capsid. The Bacillus subtilis phage φ29 is an excellent model system to investigate the DNA packaging mechanism because of its highly efficient in vitro DNA packaging activity and the development of a single-molecule packaging assay. Here we make use of structural and biochemical experimental data to build a physical model of DNA packaging by the φ29 DNA packaging motor. Based on the model, various dynamic behaviours such as the packaging rate, pause frequency and slip frequency under different ATP concentrations, ADP concentrations, external loads as well as capsid fillings are studied by using Monte Carlo simulation. Good agreement is obtained between the simulated and available experimental results. Moreover, we make testable predictions that should guide future experiments related to motor function.

Hydrodynamic Interactions Introduce Differences in the Behaviour of a Ratchet Dimer Brownian Motor

We use the Brownian dynamics with hydrodynamic interactions simulation in order to describe the movement of an elastically coupled dimer Brownian motor in a ratchet potential. The only external forces considered in our system were the load, the random thermal noise and an unbiased thermal fluctuation. We observe differences in the dynamic behaviour if hydrodynamic interactions are considered as compared with the case without them. In conclusion, hydrodynamic interactions influence substantially the dynamics of a ratchet dimer Brownian motor;consequently they have to be considered in any theory where the molecular motors are in a liquid medium.

纳米材料中的界面现象

在课程教学中融入科学前沿实例不仅可以阐明所学基本原理的实际意义,还可以为基本原理的灵活应用提供范例,启发学生独立思考能力。界面化学是物理化学课程中的重要学习内容,但由于在常规尺度的多相体系中界面现象并不显著,学生对该部分知识常有忽视。近年来纳米材料已成为国内外研究的热点。纳米材料由于其高界面分子比例而表现出更为显著的界面现象。将界面化学的基本原理应用于纳米材料的研究中,已取得了一系列令人瞩目的成果。本文首先对附加压力、接触角等相关界面现象的基本原理进行梳理,然后分别介绍根据这些基本原理所发展出的分子马达、光控微流控器件、液体门控技术以及超疏水表面四项科技突破。

分子泵用无位置传感器无刷直流电机控制器设计

首先介绍了无刷直流电机的基本模型和特性,对无位置传感器控制方式的基本原理进行研究。随后据此设计了一种分子泵用无位置传感器无刷直流电机控制系统,该系统采用反电势过零点检测方法获取转子位置信息,以进行换相逻辑控制,改进了电机的预定位及启动方式,降低了分子泵电机结构设计的复杂度,提高了分子泵的可靠性。接着从硬件设计和软件控制策略部分详细介绍了该控制系统。最后在实验平台上进行验证。使用所设计的控制器对分子泵进行驱动实验,结果表明,分子泵能够稳定启动并进入额定工作状态,分子泵额定转速可达90 000 r/min,且转速波动可稳定在±60 r/min内。

Engineering The Neck Hinge Reshapes The Processive Movement of Kinesin-3

Objective In kinesin-3,the neck coil correlates with the following segments to form an extended neck that contains a characteristic hinge diverse from a proline in KIF13B to a long flexible linker in KIF1A.The function of this neck hinge for controlling processive movement,however,remains unclear.Methods We made a series of modifications to the neck hinges of KIF13B and KIF1A and tested their movement using a single-molecule motility assay.Results In KIF13B,the insertion of flexible residues before or after the proline differentially impacts the processivity or velocity,while the removal of this proline increases the both.In KIF1A,the deletion of entire flexible neck hinge merely enhances the processivity.The engineering of these hinge-truncated necks of kinesin-3 into kinesin-1 similarly boosts the processive movement of kinesin-1.Conclusion The neck hinge in kinesin-3 controls its processive movement and proper modifications tune the motor motility,which provides a novel strategy to reshape the processive movement of kinesin motors.

Multi-state photoluminescent properties of an overcrowded alkene-based molecular motor in aggregates

Photoisomerization and photoluminescence are two distinct energy dissipation path-ways in light-driven molecular motors.The photoisomerization properties of discrete molecular motors have been well established in solution,but their photoluminescent properties have been rarely reported-especially in aggregates.Here,it is shown that an overcrowded alkene-based molecular motor exhibits distinct dynamic prop-erties in solution and aggregate states,for example,gel and solid states.Despite the poor emissive properties of molecular motors in solution,a bright emission is observed in the aggregate states,including in gel and the crystalline solid.The emis-sion wavelength is highly dependent on the nature of the supramolecular packing and order in the aggregates.As a result,the fluorescent color can be readily tuned reversibly via mechanical grinding and vapor fuming,which provides a new platform for developing multi-stimuli functional materials.

Dynamic Control of Multiple Optical Patterns of Cholesteric Liquid Crystal Microdroplets by Light-Driven Molecular Motors

The key to high-level encryption and anti-counterfeiting techniques is the storage of multiple levels of distinct information that can be individually and precisely addressed by certain stimuli.This continues to be a formidable challenge as the concealed images or codes must be read with fast response and high resolution without cross-talk to the first layer of information.Here,we report a non-fluorescencebased strategy to establish responsive encryption labels taking advantage of solely tuning multiple optical patterns of cholesteric liquid crystal(CLC)microdroplets doped with light-driven molecular motors.The photo-triggered unidirectional rotation of the motor induced not only changes in the helical twist power value but the opposite helical orientation of the superstructure in CLCs as well,resulting in changes in both the structural color and the selective reflection of circularly polar light.The designed labels,which featured highly selective addressability of dual-level distinct information,good reversibility,and viewing angle-independence,were applied to build devices for daily practical use,demonstrating great potential in anti-counterfeiting technology and provide a versatile platform for enhanced data protection and encryption of authentic information.

驱动蛋白的研究进展

驱动蛋白是一类典型的分子马达蛋白,它在胞内运输、有丝分裂、细胞形成、细胞功能等方面起着至关重要的作用.驱动蛋白不仅负责运输各种膜细胞器、蛋白复合体、mRNA等以保证细胞的基本活性,还在大脑的发育、记忆功能以及神经元的活性等方面扮演着极其重要的角色,可以说驱动蛋白是生命体系赖以生存的基础之一.

分子马达不等间距四态跃迁模型

用主方程方法研究分子马达一维周期性四态不等间距随机跃迁模型 ,得出稳态情况下分子马达的漂移速度V、扩散系数D及随机参数r,将三者随ATP的浓度 [ATP]及外力F的变化进行了曲线拟合 ,并同大量实验结果进行了比较 。

细菌鞭毛马达——一种卓越的分子机器

鞭毛马达 (flagellarmotor)是一种分子旋转马达 ,它在细菌鞭毛的结构与功能中起着中心作用 .鞭毛马达的结构已基本清楚 ,主要由MotA、MotB、FliG、FliM和FliN 5种蛋白组成定子 (stator)和转子 (rotor) ,其驱动力来自于跨膜的H+或Na+流 .目前对鞭毛马达的旋转动力学及旋转力矩产生机制已有初步的了解 .鞭毛马达可作为研究分子旋转马达的理想模型 。

利用分子马达技术检测霍乱弧菌

利用载色体chromatophore上的F0F1-ATPase分子马达生物传感器,建立了应用在食品检测中的快速检测方法。首先在ATP合酶的ε亚基上连接ε亚基抗体-生物素-链霉亲和素-生物素-ompW探针,将待测霍乱弧菌和阴性对照分别与此生物传感器结合,比较其催化ATP合成30 min后的ATP产生量,进而对霍乱弧菌的DNA进行检测。ATP合成的量可以通过环境H+的量进行测定,H+的量通过F-DHPE所体现的荧光强度大小标定。结果表明,Chro ompW的浓度在0.078 mg/mL,单核增生李斯特菌DNA浓度在40 ng/mL为最适检测条件。通过与实际检测样品的传统检测方法及PCR检测方法对照,具有良好的检测符合性。

F_0F_1-ATPase生物传感器检测食品中食源性诺如病毒

应用分子马达生物传感技术,建立食品中诺如病毒特异性快速检测方法。以嗜热菌中提取的载色体(chromatophore)为材料,根据诺如病毒ORF1和ORF2连接处的高度保守区设计探针,利用生物素-亲和素系统将诺如病毒探针连接在F0F1-ATPase的ε亚基上构建生物传感器。提取病毒RNA并将其与生物传感器结合的同时启动ATP合成,比较其荧光强度的差别,对样品中的RNA进行检测。建立并优化了F0F1-ATPase生物传感技术检测食源性诺如病毒的方法。所建立的方法具有良好的特异性,12个含诺如病毒样品均能检出,3个不含诺如病毒样品均未检出,无假阴性或假阳性情况出现。该方法可在1 h内完成检测,检测灵敏度在RNA水平上达到0.005 ng/m L。所建立的分子马达生物传感技术可以较好的检测食品中的诺如病毒,并为其他病毒的检测提供参考。