太赫兹技术在生物医学中的应用

在人类可持续发展的道路上,生物医学研究始终处于核心地位。太赫兹(THz)技术依靠其自身的优势,在生物医学领域得到了广泛的应用。本文着重介绍了太赫兹表征技术以及太赫兹生物效应在生物医学方面的应用。太赫兹表征技术应用领域的介绍主要分为5个部分:氨基酸和多肽、DNA、蛋白质、癌症的检测和龋齿诊断等其他领域的应用。太赫兹生物效应的研究则集中于THz对机体组织和细胞的作用上。此外,本文简单介绍了化学计量学方法以及其与THz技术结合在生物医学方面的应用。最后总结了THz技术在生物医学领域的不足,并对进一步研究的方向进行了讨论。本文主要对太赫兹技术在生物医学方面的应用进行综述,为相关研究奠定了基础。     

太赫兹辐射及其生物效应研究进展

随着太赫兹源和探测技术的不断进步,太赫兹技术迅速发展并在众多领域有着广泛的应用前景.特别是在生物医学领域,太赫兹技术有望成为一种新型治疗手段.本文首先介绍了太赫兹的电磁波特点及3种太赫兹波产生方式.其次介绍了太赫兹辐射在生物上的两大效应:热效应和非热效应.最后从细胞和生物体两大层面上,详细介绍了太赫兹辐射对不同细胞的生...     

褪黑素的太赫兹时域光谱

太赫兹时域光谱技术是一种新兴的无损探测技术。利用太赫兹波的低能性以及大部分生物分子的振动跃迁和旋转在该频段表现出的强色散和吸收作用等特点,可以对生物分子及生命体的活动进行无损探测和研究。本文分别采用透射式和反射式太赫兹时域光谱系统,对不同质量比的褪黑素压片进行测试,分析它在太赫兹波段的光学性质,发现它在0.29、0.50、0.70、0.91、1.20、2.17和2.55 THz处存在特征吸收峰;频域谱的强度随样品浓度的变化呈线性关系。利用Gaussian 09及Gaussian VIEW软件进行模拟分析,得到褪黑素在0.46、0.91、1.15、2.01、2.23和2.61 THz处存在特征吸收峰,为实验结果提供了有力地支持。这些工作为褪黑素等生化样品的检测和鉴定提供了依据和参考。     

太赫兹刺激听神经的测试平台搭建

目的 近年来，用于脑功能调控的神经调控技术蓬勃发展，很多方法已在临床上被推广应用，主要包括电极深部脑刺激、经颅磁刺激、光遗传技术、超声深脑刺激等。但是这些调控技术存在刺激靶点改变灵活性差、空间分辨率不足、需要注射病毒转染等问题。与这些技术相比，太赫兹波调控则能以较高的时空分辨率、无需引入外源基因的方式对神经活动进行干预。激光神经刺激是一种具有较明确靶向性的刺激方法，可以通过调整不同激光参数（激光波长、脉冲能量等）控制引起神经兴奋或者抑制。但是由于该研究方向的实验手段和实验平台的缺乏，相关研究开展较少。方法 针对这个问题，从听觉神经入手，在分子、细胞和在体不同层面为相关领域的研究搭建了不同的测试平台。结果 实验结果表明，这些系统在时间和空间上具有良好的耦合性和靶向性，测得的信号受噪音干扰小。结论 这些系统可以有效测试神经系统对太赫兹刺激的响应并精确控制刺激时间和位置。     

稀土荧光探针在生物大分子研究中的应用

钙(Ⅱ)、镁(Ⅱ)离子是生物体内最重要的闭壳层无机阳离子。引入具有适当光性质的、与钙(Ⅱ)等离子成键性质相近的铽(Ⅲ)或铕(Ⅲ),利用荧光光谱技术,是研究一些与钙(Ⅱ)有关的生物大分子在水溶液中构象的一条有效途径。本文综述了稀土荧光探针技术的研究进展。     

盐酸胍诱导CP43和CP47变性的太赫兹时域光谱技术研究

太赫兹时域光谱技术(THz-TDS)是近年来新兴的一种研究分子构型状态的技术. 把这项技术运用到两种光合膜蛋白CP43和CP47的研究上, 研究结果表明, 运用太赫兹时域光谱技术能有效地把具有相似结构的蛋白质区分开来, 这项技术也是监测蛋白质变性的一种有力工具. 在盐酸胍(GuHCl)作用下, CP47和游离叶绿素a(Chl a)的太赫兹(THz)振幅谱中都出现一个明显的位于1.8 THz处的峰. 我们认为这个峰来自于叶绿素a和盐酸胍的相互作用. 和CP43相比, CP47中的叶绿素a更易于和盐酸胍发生作用.     

生物质谱技术在蛋白质组学研究中的应用

随着技术的进步,蛋白质组学的研究重心由最初旨在鉴定细胞或组织内基因组所表达的全部蛋白质转移到从整个蛋白质组水平上阐述包括蛋白翻译后修饰、生物大分子相互作用等反映蛋白质功能的层次。多种质谱离子化技术的突破使质谱技术成为蛋白质组学研究必不可少的手段。质谱技术联合蛋白质组学多角度、深层次探索生命系统分子本质成为现阶段生命科学研究领域的主旋律之一。本文简要综述了肽和蛋白质等生物大分子质谱分析的原理、方式和应用,并对其发展前景做出展望。     

生物质谱及其在蛋白质组学研究中的应用

生物质谱是蛋白质组学研究必不可少的关键技术。近年来,生物质谱在鉴定通量、分辨率和灵敏度等方面均有质的飞跃,从而促进了蛋白质组研究各个领域的飞速发展。本文就生物质谱技术的原理、技术和仪器发展现状,及其在蛋白质组学研究中的应用进展作一简要的综述。     

分子拥挤条件下生物大分子性质研究

细胞中成千上万种生物分子以不同的浓度发挥着各自的生理作用,但是体外研究中常常忽略细胞内的拥挤环境,随着分子拥挤理论的提出,体外添加大分子拥挤试剂被越来越多的生物学家和化学家所重视,众多的研究结果显示分子拥挤试剂的加入对细胞内的生物大分子的性质造成了一定的影响。从分子拥挤试剂对蛋白质折叠与聚集以及核酸分子结构与性质的影响等方面探讨了拥挤环境下生物大分子的性质和功能,为以后大分子拥挤条件下生物分子的研究提供一定的参考依据。     

生物质谱在细胞信号转导研究中的应用

近几年快速发展起来的生物质谱技术 ,依靠 (酶解后肽段 )精确质量数测定和随机肽序列标签分析 ,实现了对蛋白质高通量的鉴定 ,并被成功地用于蛋白质相互作用和蛋白质磷酸化等翻译后修饰研究。与传统的研究手段相比 ,上述技术能够在一次实验中对多信号通路中所有磷酸化的蛋白质分子及其磷酸化位点进行鉴定 ,已成为蛋白质组学最新发展中令人关注的一个热点。简要综述质谱技术应用于上述工作中的 3种策略     

Light-induced Difference Terahertz Spectroscopy

Visible/near-infraredlaser-induced difference spectroscopy basedon a time-domain terahertz system has beendeveloped, and used to study copperpathancyonine. We find that the absorptionpeak of this molecule at 1.08 THz changessignificantly under 790 nm laserexcitation, suggesting that we haveobserved the first evidence of vibrationalmode changes in the THz range induced byvisible/near-infrared light.     

Investigations on Graphene-Based Ultra-Wideband (UWB) Microstrip Patch Antennas for Terahertz (THz) Applications

Plasmonics - An investigation on graphene-based hexagonal microstrip patch antenna has been carried out in this article. The hexagonal-shaped radiators have been designed and modified by...     

Terahertz Time-Domain Spectroscopy of Four Hydroxycinnamic Acid Derivatives

The well-resolved absorption spectra of the hydroxycinnamic acid (HCA) derivatives, caffeic acid, ferulic acid, sinapic acid and chlorogenic acid, were measured over the frequency region from 0.3 to 2.0 THz at 294 K with terahertz time-domain spectroscopy (THz-TDS). Theoretical calculation was applied to assist the analysis and assignment of the individual THz absorption spectra of the HCA derivatives with density functional theory (DFT). The distinctive spectral features were originated from the collective motion of molecules held together by hydrogen bonds. The real and imaginary parts of dielectric function of the four HCA derivatives were also obtained.     

Terahertz Time-Domain Spectroscopy of Glucose and Uric Acid

We report the use ofterahertz time-domain spectroscopy for thestudy of two therapeutic bio-molecules:glucose and uric acid. Terahertztransmission spectra of crystalline samplesof both molecules were measured between 0.1–3.0 THz using an evacuated spectroscopysystem. We propose that the stereo-isomersof glucose show spectral featuresoriginating from intermolecular vibrationalmodes, as do uric acid and its derivativemolecule, allantoin. In addition, wepresent a full temperature dependence ofthe terahertz absorption of L-glucose.     

Terahertz Pulse Spectroscopy of Biological Materials: L-Glutamic Acid

We report the terahertzpulse spectra of L-glutamic acid. Thereare a number of well-resolved transitionsin the 1.75–2.5 THz (58–83 cm^-1)region. These are compared with publishedtheoretical data on intra andintermolecular transitions. We could notfind any correlation with the theoreticalvalues. However, it was noted that thetheoretical model did not include anycrystalline or hydrogen-bonding effects.     

Single Macromolecules: Hierarchic Thermodynamics, Irreversibility and Biological Function

Single homo-polymers show two different paths in the folding transition; a liquid-like spherical globule is generated for flexible polymers, whereas a rich variety of ordered structures are formed for semi-flexible polymers. This unique characteristic is discussed in relation to its biological significance.     

Terahertz vibrational signature of bacterial spores arising from nanostructure decorated endospore surface

This theoretical effort is the first to explore the possible hypothesis that terahertz optical activity of Bacillus spores arises from normal vibrational modes of spore coat subcomponents in the terahertz frequency range. Bacterial strains like Bacillus and Clostridium form spores with a hardened coating made of peptidoglycan to protect its genetic material in harsh conditions. In recent years, electron microscopy and atomic force microscopy has revealed that bacterial spore surfaces are decorated with nanocylinders and honeycomb nanostructures. In this article, a simple elastic continuum model is used to describe the vibration of these nanocylinders mainly in Bacillus subtilis, which also leads to the conclusion that the terahertz signature of these spores arises from the vibration of these nanostructures. Three vibrating modes: radial/longitudinal, torsional and flexural, have been identified and discussed for the nanocylinders. The effect of bound water, which shifts the vibration frequency, is also discussed. The peptidoglycan molecule consists of polar and charged amino acids; hence, the sporal surface local vibrations interact strongly with the terahertz radiation.      

Thermodynamic Characterization of Conformational States of Biological Macromolecules using Differential Scanning Calorimetry

Abstract

The Ras superfamily small G proteins are master regulators of a diverse range of cellular processes and act via downstream effector molecules. The first structure of a small G protein–effector complex, that of Rap1A with c-Raf1, was published 20 years ago. Since then, the structures of more than 60 small G proteins in complex with their effectors have been published. These effectors utilize a diverse array of structural motifs to interact with the G protein fold, which we have divided into four structural classes: intermolecular β-sheets, helical pairs, other interactions, and pleckstrin homology (PH) domains. These classes and their representative structures are discussed and a contact analysis of the interactions is presented, which highlights the common effector-binding regions between and within the small G protein families.