等温微量热法在生命科学研究中的应用

简要介绍了等温微量热法的原理、典型的仪器及其在生命科学研究中应用所具有的特点。通过它可获得完整的细胞代谢过程产热曲线及其热动力学方程；可以研究细胞器的代谢规律；可以获取生物大分子与小分子相互作用的热动力学特征。     

细胞不同代谢类型的热化学研究Ⅰ.生长、非生长及内源代谢水平的量热测定

细胞是生命的基本单位．对其代谢过程能量输出水平的直接测定，对细胞生理学来说是重要的实验基础数据，对于生物生理和研究能量代谢方面也有一定的理论意义．当然细胞的多样性及其代谢过程的复杂性使这一研究工作相当困难·作为开展研究的第一步我们选择便于培养处理的单细胞生物大肠杆菌作为研究对象，并对其所进行时三种基本代谢类型29Llxi：L谢；非生长依队和内派代谢分别进行研究，本文分别测定了＊烟三种不同类型代谢的热功率输出水平，得到了单个细胞在上述代谢过程热功率输出的定量数据．实验结果表明，不同类型代谢的能量输出水平…     

基于微流控热泳的生物传感技术※

复杂生命体系中关键分子及微纳生物粒子的高灵敏、高特异检测, 对理解多层次多尺度生物学过程、阐明疾病发生发展机制和探索新型生物标志物等具有重要意义. 微流控生物传感器整合了微流控技术和生物传感技术的诸多优势, 在微量生物样本精准测量方面取得了显著进展. 近年来, 微流控热泳生物传感技术(Thermomicrofluidic biosensing)利用物质在局域温度梯度场中的热泳定向迁移现象, 并结合均相生物传感及信号放大新策略, 实现了复杂样本中生物分子及微纳生物粒子的快速、高灵敏、原位检测. 重点阐述了以热泳为核心的微流控传感技术, 包括微量热泳、热泳-对流耦合、热泳-扩散泳耦合以及热泳-电泳耦合等方法, 总结了不同传感方法的原理、特点及其在生物分子(蛋白、核酸等)与微纳生物粒子(细胞外囊泡、病毒、细胞等)检测中的应用, 并探讨了微流控热泳技术在生物医学检测领域中面临的挑战与未来发展方向.     

硝酸镧引起Escherichia coli B代谢过程热爆发及其机理研究

采用微量热法研究了硝酸镧对Escherichia coli B生长代谢过程的影响, 发现高浓度硝酸镧引起E. coli B热谱图出现异常变化: 生长速率常数k值增大、产热峰显著升高和总发热量异常增加. 当硝酸镧浓度为300和500 mg/L时, 培养物在培养过程的总发热量分别是正常条件下的3.89和2.54倍. 用生物学方法对细胞存活率和生物量进行测定结果表明, 细胞在高浓度硝酸镧条件下增殖受到抑制、细胞生物量减少. 表明高浓度的硝酸镧存在时, E. coli B细胞生长受到抑制反而释放出比正常生长细胞多得多的热量, 将抑制状态细胞释放大量热量的现象称为热爆发. 分析热爆发的原因, 认为是La^3＋离子破坏细胞壁外膜而增加其透性, 导致细胞膜与外膜间的质子电化学势因质子外泄而降低或者不能形成, 氧化磷酸化过程中的能量不能有效地转化为ATP, 而以热能的方式释放出来. 细胞由于缺乏生物通用能量ATP, 因而其生长受到抑制.     

种子萌发生长的微量热及非平衡热力学研究

生命系统中发生的许多过程都有放热和吸热现象.人们对于生命过程的热现象进行了很多研究.对于植物生长的能量效应研究也做了一些工作[1—4].种子萌发生长的热释出是植物产热的一个很好例子,在种子萌发生长过程中伴随着物质和能量的转化,用微量热法测定种子萌发生长热谱并解析这些热谱,将有助于我们认识种子萌发生长机理及其影响因素.Ｐｒａｔ等人曾对小麦、玉米及一些蔬菜种子的萌发生长进行过较为系统的研究[1,2].他们的工作为用量热法研究植物产热开辟了道路.但由于当时测量技术与仪器设计的限制,其研究结果是粗糙的,且与种子萌发的实际情…     

生物电化学仪器的发展现状与展望

电荷传递是生命运动的基本过程之一,电化学方法在生命科学中的应用为相关生命现象的研究提供了一个有效而独特的物理化学视角,并带来超出常规生物学检测的丰富信息.随着生物电化学研究的不断扩展和深化,已从早期的生物分子电化学研究深入向活体、活细胞、单活细胞水平甚至活细胞中单分子水平发展.研究者对仪器设备性能如灵敏度、分辨率(时间分辨、空间分辨和能量分辨)和操作性等提出了越来越高的要求.本文综述了生物电化学仪器在应用领域和研究领域的现状,重点介绍单细胞电化学检测系统的构建,并初步探讨国内生物电化学研究仪器的发展趋势.     

热动力学研究的新进展

根据变化过程的放（吸）热速率研究过程动力学规律并融热化学与化学动力学于一体的分支学科称为热动力学。本文回顾了国内外学者在各种量热体系中研究热动力学的进展情况，着重介绍了最近五年中热动力学在化学反应、酶促反应和生物代谢过程研究中的应用，并预测了热动力学在未来十年中的发展趋势。     

热谱重建法及其在热动力学研究中的应用

在热动力学研究中,大多数实验是在热导式热量计中进行的。由于量热系统的热惯性,记录得到的热谱会出现“失真”,为了正确方便地分析被研究过程的动力学性质,必须对所得热谱进行改造或重建。本文系统地提出了一种新的重建法,即热谱重建法。实验结果表明,该法可广泛应用于热动力学研究。     

中国化学会第四届全国热分析动力学与热动力学学术会议(第一轮通知)

受中国化学会委托,由中国化学会化学热力学和热分析专业委员会主办,河北师范大学承办的第四届全国热分析动力学与热动力学学术会议将于2013年5月17-19日在石家庄召开。本次会议将就近年来热分析动力学和热动力学以及热分析与量热在理论研究、新仪器设计与分析技术方面的进展以及在无机、有机、高分子、新材料、生物医药等各个领域中的应用进行学术研讨和交流。会议将邀请国内从事热分析动力学和热动力学及热化学领域的著名专家、中青年学者和仪器生产厂商参加学术交流和技术探讨。会议期间还将展示一批国内外最新热分析仪器及相关产品,提供大量的最新技术、最新测试方法等资料。欢迎广大科技工作者踊跃投稿,积极参加。欢迎相关企业     

重金属生物吸附的研究进展

本文综述了重金属生物吸附的机理、影响生物吸附的物理化学因素和生理条件、生物吸附动力学、生物吸附过程的数学模型化、生物细胞的固定化和从生物量上回收被吸附的重金属等方面的研究进展。     

超快扫描量热技术表征高分子结晶动力学

高分子结晶行为是高分子材料加工过程研究的热点,因为高分子组分和加工工艺控制着高分子结晶及其产物性能。差示扫描量热仪(DSC)是研究高分子结晶动力学常规手段。但是,普通DSC所能达到的最快降温速率一般无法抑制较快的样品结晶,结晶行为将在等温结晶动力学测试之前发生,因此可进行等温结晶的研究温度范围局限于较低结晶过冷度的高温区域。近年来,具有超快速升降温扫描速率和精准控温的快速扫描芯片量热仪(FSC,其商业化版本Flash DSC 1)得到了广泛应用。FSC可以抑制高分子样品在升降温过程中的结晶成核,避免对之后的结晶动力学测试产生影响。因此FSC技术将高分子结晶动力学的研究温度区间延伸至具有较大过冷度的低温区,加深了我们对高分子结晶成核机理以及高分子工业加工过程的理解。本文首先介绍了由初级成核方程描述的高分子结晶动力学原理,初级成核自由能位垒(?G~*)和扩散活化能位垒(?U)分别控制了高低温区的结晶动力学。我们还总结了FSC技术的发展,包括氮化硅薄膜芯片技术、快速扫描量热仪、商业化Flash DSC 1在不同高分子结晶熔融行为研究中的应用。然后介绍表征高分子等温结晶动力学的方法,其中包括样品制备、质量估算、消除热历史、临界扫描速率的确定等,并举例介绍FSC在高分子结晶动力学研究中的应用,涵盖高分子总结晶动力学、结晶成核动力学、高分子焓松弛对结晶成核的影响、FSC联用技术等方面。应用举例中对应形貌和结晶信息,分析了通过FSC测试得到的结晶成核动力学特点。另外通过比较不同结构特点的高分子,总结了我们对结晶动力学行为的基本理解。总之,FSC技术是一种能够提供相转变动力学和热力学信息的高效工具,特别是应用于分析只能在快速扫描中得到的样品结构变化信息。同时我们希望本文能够帮助读者考虑超快扫描量热技术在其他材料研究上的应用,包括合金、药物、生物大分子等。     

The effect of solid-liquid effluents from anaerobic digesters on soilmicrobial activity

A calorimetric procedure is developed to study the effect on the soil of the effluents resulting for the anaerobic digestion of slaughtering houses residues. DSC was used to study the pyrolysis properties of the effluent and the soil while isothermal calorimetry is applied to study the microbial activity in the effluent and to assess on its effect on the microbial activity of the soil where the industrial digester will be situated. The calorimetric data were studied together with the chemical and biological properties of that residue. Results showed that effluent is constituted by low levels of carbon and high levels of nitrogen. The power-time curves of the effluent have the typical shape of microbial growth yielding microbial growth rate constants between 0.37 and 0.53 h⁻¹ for about 4 and 11 h. The addition of the effluent to the soil decreases the heat of pyrolysis with time and stimulates the heat flow rate of the microbial metabolism.     

Calorimetric studies of solid wastes,sewage sludge,wastewaters and their effects on soil biodegradation processes

Calorimetric studies of solid wastes, sewage sludge, wastewaters and their environmental effects focus on three main research areas. The first research area involves determination of selected thermal and physical parameters characterizing the above substances, such as specific heat, thermal conductivity and others. The second area covers processes of total or gradual destruction of the examined substances at a fixed composition of the gaseous phase. The methods applied in this case enable to determine the heat of combustion or the calorific value of the analyzed material, as well as changes in the rate of heat production, measured by differential scanning calorimetry (DSC). The third area of calorimetric studies covers microbial calorimetry as a method for non-destructive monitoring of organic matter biodegradation in order to measure the kinetic and thermodynamic parameters of the investigated processes, i.e., wastewater treatment, composting and decomposition of organic soil matter, as well as to determine the stability of wastes. This paper describes, based on available literature data, the major directions of investigations, using different calorimetric methods, of solid wastes, sewage sludge and wastewaters and additionally their effects on soil microbial processes. The paper also presents the selected calorimetric studies and analyses the biodegradation kinetics of organic wastewaters and glucose decomposition in the presence of phosphogypsum in different soils.     

Three important calorimetric applications of a classic thermodynamic equation

The thermodynamic background to three calorimetric techniques is discussed; (i) titration microcalorimetry, (ii) adiabatic calorimetry, and (iii) heat conduction calorimetry. Relevant equations for each technique are derived from a common equation for the enthalpy H of a closed system. General patterns which emerge in the measured parameters are presented for adiabatic and heat conduction calorimeters linked to applications of these techniques.     

Calorimetry and thermodynamic aspects of heterotrophic,mixotrophic, and phototrophic growth

A simple stoichiometric model is proposed linking the biomass yield to the enthalpy and Gibbs energy changes in chemo-heterotrophic, mixotrophic, and photo-autotrophic microbial growth. A comparison with calorimetric experiments on the algae Chlorella vulgaris and Chlorella sorokiniana confirmed the trends but revealed large calorimetric measurement inaccuracies. The calorimetric data on purely photo-autotrophic growth was, however, in fair agreement with calculations. The thermodynamic characteristics of photosynthetic growth, including an estimation of the Gibbs energy dissipation, are compared with similar data for chemotrophic microbes.     

An enthalpy balance approach to the study of metabolic activity in mammalian cells

After a formal explanation of Mayer's enthalpy balance method as applied to biological reaction rates, the history of its application is traced from Rubner's dog to accounting for the energy of muscle contraction. The introduction of microcalorimetry allowed the method generally to be used for cells in vitro and now particular emphasis can be paid to the growth of cells for the production of therapeutically-important heterologous proteins. In these systems, enthalpy balance studies contribute to defining catabolic processes, designing media, understanding the mechanisms of growth and controlling cultures using heat flux as an on-line sensor of metabolic activity.Plenary LectureThe authors are grateful to the BBSRC (UK) for a research grant, 2/3680.     

Application of bench-scale biocalorimetry to photoautotrophic cultures

Bench-scale biocalorimetry (≥1 L) allows for the determination of the metabolic heat flow during bioprocesses under complete control of all process conditions for extended periods of time. It can be combined with a number of on-line and off-line measurement techniques. This combination can significantly improve insight into the metabolism of microorganisms and the optimization of bioprocesses. In this study it is demonstrated that bench-scale biocalorimetry can also be applied to phototrophic microorganisms. The green microalga Chlorella vulgaris CCAP 211/11B was cultivated in a Mettler-Toledo RC1 calorimeter adapted for high-sensitivity biological calorimetry (BioRC1). Heat production was monitored in 1.5 L batch cultures. In the linear phase of growth, inhibitors of photosynthetic electron transport (DCMU, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, and DBMIB, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone), were used to stop photosynthesis and to monitor the resulting increase in the energy dissipating heat flux. This resulted in a calculated storage of light energy as chemical energy, i.e. biomass, of 141 ± 12.2 mW L⁻¹ (±S.D.). In addition, it was demonstrated that calorimetric determination of the total amount of light energy absorbed within the reactor was accurate by comparing two different calorimetric techniques. Using both the value of the total light input and the quantity stored as chemical energy, the photosynthetic efficiency could be calculated as 10.5% in this example.     

Calorimetric approach to metabolic carbon conversion efficiency in soils

Soil carbon is the largest reservoir of organic carbon on the planet and CO₂ production by soil thus has potentially large effects on atmospheric CO₂. Carbon sequestration in soil is determined by the metabolic efficiency (substrate carbon conversion efficiency) of soil micro-organisms. That could be measured by calorespirometric methodology (parallel measurement of metabolic heat rate and CO₂ production rate) and by theoretical thermodynamic models. Carbon conversion efficiency of the glucose degradation reaction in soil is calculated from both the calorespirometric ratio of heat rate to CO₂ rate and from energy and mass balance models combined with calorimetric heat rates. Results obtained, 0.77 and 0.75, are in good agreement.     

Plant calorimetry. Part 2. Modeling the differences between apples and oranges

In a previous review we discussed calorimetric methods for the study of plant metabolism. Since that review, a number of papers describing calorimetric measurements examining plant growth, stress responses and effects of temperature have appeared. This recent work is reviewed here.

In addition to the experimental work, a mechanistic model linking respiration rates to growth has been published. This model is derived from both mass and enthalpy balance equations. It describes specific growth rate and substrate carbon conversion efficiency as functions of the metabolic heat rate, the rate of CO₂ production, the mean oxidation state of the substrate carbon produced by photosynthesis, and enthalpy changes for conversion of photosynthate to biomass and CO₂. Application of this model to understanding the basis for variation in growth rates among individual genotypes in plants is reviewed.

The effects of environment on the plant respiration-growth relation has been an important focus for plant calorimetry studies. Climatic temperature is one of the most important variables determining growth. Extremes of temperature determine limits of growth, and diurnal variation and mean temperature have a major influence on growth rate. Calorimetric measurements of respiratory rates as a function of temperature can be used to relate the temperature influence on respiratory metabolism to the temperature influence on growth rate. These studies have also discovered the existence of an isokinetic point within the range of normal growth temperatures. Studies of temperature dependence are reviewed and the results analyzed in terms of the recently published mechanistic model.     

Detection of microorganisms in different growth states based on microcalorimetry

A challenging method for sterility test which was rapid and reliable had been established to assess the adaptability and robustness of the microbial under different conditions. There were material and energy metabolism or exchange with microbial on microcalorimetry, as a result this method can be served as one of the optimization of thermodynamics sterility test. Thermal power-time curves under various environmental conditions (including processing temperature, storage time, and drugs inhibition) were determined. Typical microbial growth thermal power-time curves were obtained. The curves were analyzed qualitatively and quantitatively by similarity values of bio-profiles and thermodynamics parameters, such as the exponential growth rate constant (k), detection time (T _d). The similarity showed that microbial growth curves of low processing temperature, short storage time (1?month), and Traditional Chinese Medicine injection (Shuanghuanglian, contained native compounds) inhibiting were match better with the normal than other circumstance. Thermodynamic parameters indicated that the microcalorimetric method could detect the positive bacteria within 18?h (less than 10?cfu), and more quickly identify the different states of the bacterium growth and metabolism than routine sterility. In conclusion, characterized by of the specific and strong two-dimensional information, microcalorimetry could supply thermograms as biological profiles to describe the microbial activity under different conditions, which were not only used as a rapid and reliable identification of microbial, but also as a method for sterility test of microcalorimetry optimization.