含纳米微粒的低温保护剂热物性的DSC研究

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摘要

玻璃化保存可以避免生物体在冻结和复温过程中的损伤，实现生物体长期

稳定保存，是目前最理想的低温保存方法之一。但由于受降温速率和低温保护剂

溶液浓度的限制，相对复杂和较大的组织和器官很难实现玻璃化保存。通过改变

物质外部的温度环境而提高降温速率的方法已经做了大量研究，并取得了显著成

果，而针对改变物质内部传热传质特性，以提高降温速率的方法研究还鲜见报

道。

常温下纳米微粒可以显著增强溶液的传热效果，将纳米微粒应用到低温保

存领域，分析纳米低温保护剂溶液在冻结过程中热物性参数的变化及纳米微粒对

玻璃化趋势影响的研究是非常必要的。本课题通过配制稳定的纳米悬浮液，利用

差示扫描量热仪（DSC）判定羟基磷灰石（HA）纳米微粒对低温保护剂丙三醇

溶液过冷度、水合性质、玻璃化性质及比热等物性影响规律，分析玻璃化过程中

纳米微粒对临界降温速率的影响。主要内容如下：

1.采用超声振荡方法制备不同粒径、不同浓度的纳米低温保护剂，应用沉降

观测法、Zeta 电位法及分光光度法检测悬浮液的均匀稳定性。实验结果表明，震

荡时间是影响悬浮液稳定性的主要因素。超声功率为 400W，震荡时间为 2h 可

获得均匀稳定的纳米悬浮液，配制的纳米低温保护剂在 48h 内不会发生明显的团

聚沉淀现象。震荡时间过长或过短都会降低纳米微粒在低温保护剂溶液中的分散

效果。

2.研究了纳米微粒对丙三醇低温保护剂成核温度、过冷度及水合性质的影

响。结果表明：加入纳米微粒后，丙三醇溶液的成核温度升高，过冷度减小，且

存在最佳浓度即当纳米微粒浓度为 0.3%时使得成核温度升高程度和过冷度减小

程度达到最大，皆可至 10℃左右。丙三醇溶液的过冷度随纳米微粒粒径增大而

减小越明显。纳米微粒能够促进丙三醇溶液的水合性质，当丙三醇溶液浓度较大

时，会表现出明显的规律性。丙三醇溶液的结晶焓随着所加入的纳米微粒粒径的

增大而明显降低。

3.纳米微粒能够降低玻璃化过程中丙三醇纳米低温保护剂溶液的比热。加入

纳米微粒的低温保护剂的比热值比未加入纳米微粒的低温保护剂的的比热值有明

显的下降；浓度为 50%的丙三醇低温保护剂的比热值随着 HA 纳米粒子质量分数

的增加和纳米微粒粒径（20nm~60nm）的减小而降低。

4.测量了不同浓度、不同粒径的纳米低温保护剂的玻璃化转变温度和反玻璃

化转变温度。结果表明：纳米颗粒可以明显提高低温保护剂溶液的反玻璃化温

度，当保护剂浓度大于 50%时，玻璃化温度也有所升高。加入纳米颗粒后 Tm-Tg

明显减小，这表明纳米颗粒可以提高玻璃化溶液在升温过程中的稳定性。纳米颗

粒降低了低温保护剂溶液在玻璃化过程中的结晶量，并可以推断纳米颗粒可以降

低低温保护剂溶液实现玻璃化所需的临界降温速率。

关键词：纳米微粒低温保护剂过冷度水合作用比热容玻璃化

反玻璃化临界降温速率 DSC

ABSTRACT

Vitrification is presently one of the best method for long-term preservation of

biomaterials as a series of injuries during freezing and warming are avoided. But it is a

challenge to preserve relatively large and complicate tissues and organs by vitrification,

as result of restriction of cooling rate and concentrations of cryoprotective agents

(CPAs). Although many studies have been done to improve cooling rate by changing

several thermal situation except the solution itself. There are few reports to study the

heat and mass transfer property of CPAs to enhance the vitrification capability.

Nanoparticles can improve the conductivity of fluid at room temperature. It is

essential to analyse the thermal physical properties of Nano-CPAs which is a new type

of heat transfer carriers by suspending nanoscaled metallicor nonmetallic particles in

base CPAs. In this paper different scanning calorimeter (DSC) is used to study the

supercooling, hydration, vitrification and specific heat of Nano-CPAs and analyse the

effect of nanoparticles on critical cooling rate, as follows:

1. Different sizes and concentrations of Nano-CPAs were prepared by using

ultrasonic oscillation method and the stability and uniformity of suspensions were

evaluated by using sedimentation observation, Zeta electric potential and

spectrophotometer. The results show that the oscillation time is the main factor to

influence stability of suspensions. When the power of ultrasound is 400W and the

oscillation time is 2 hours, the well-distributed and stable nano-fluid could be got to

ensure that the agglomeration and sedimentation would not happen in 48 hours.

2. The effects of nanoparticles on the nucleation temperatures, supercooling and

hydration of Nano-CPAs of different mass concentrations (30%,40%, 50%) with

different amount of HA(Hydroxyapatite) nanoparticles are measured respectively. The

results show that the nucleation temperature increased and the supercooling decreased.

When the concentration of HA nanoparticles is 0.3%, the increment of nucleation

temperatures and supercooling decrements reach maximum values(~10 ℃). The

supercoolings reduce with the increasing size of nanoparticles. The hydration could be

improved by addition of nanoparticles. The crystallization enthalpies will decline with

the increasing size of nanoparticles.

3. The specific heat values of glycerol solutions with nanopartices decreased

during glass transition process. For the 50% glycerol solution, the specific heat values

decreased with the increasing mass fractions and deceasing sizes (20nm~60nm) of HA

naoparticles.

4. The glass transition temperature and the devitrification temperature of different

nano-CPAs were measured. The results show that the devitrification temperatures of

CPAs could be increased significantly by nanoparticles. When the concentration of

solutions is larger than 50%, the glass transition temperatures increase slowly. The

values of Tm-Tgreduce after adding nanoparticles, which shows that the stability of

glass solutions during heating process is improved by nanoparticles. Based on the

above results, the conclusion can be drawn that the critical cooling rate can be reduced

by suspending nanoparticles into the CPAs.

Key words: Nanoparticles, Cryoprotectant, Supercooling,

Hydration, Specific heat, Glass transiton, Devirification, Critical

cooling rate, DSC

摘要

ABSTRACT

第一章绪论.....................................................................................................................1

§1.1 低温保存的原理 ...............................................................................................1

§1.2 玻璃化保存 ........................................................................................................2

§1.2.1 玻璃化保存理论基础 .....................................................................................3

§1.2.2 玻璃化保存的影响因素 .......................................................................... 5

§1.3 纳米流体 ............................................................................................................6

§1.3.1 纳米材料 .................................................................................................. 6

§1.3.2 纳米流体的发展 ...................................................................................... 7

§1.4 纳米微粒在低温生物中应用的国内外研究进展 ...........................................8

§1.4.1 国内研究现状 .......................................................................................... 9

§1.4.2 国外研究现状 .......................................................................................... 9

§1.5 立题的背景和意义 ..........................................................................................10

§1.6 本课题的目的及主要研究内容 ...................................................................... 10

第二章纳米低温保护剂的制备及稳定性表征...........................................................12

§2.1 引言 ...............................................................................................................12

§2.2 实验仪器及试剂 ...........................................................................................12

§2.2.1 实验仪器 .............................................................................................. 12

§2.2.2 实验材料与试剂 .................................................................................... 13

§2.3 制备流程及稳定性表征 ...............................................................................13

§2.3.1 制备流程 .............................................................................................. 13

§2.3.2 稳定性表征方法 .................................................................................... 14

§2.4 实验结果与分析 ...........................................................................................16

§2.4.1 超声功率及震荡时间的影响 .............................................................. 16

§2.4.2 超声震荡时间对悬浮液 zeta 电位、吸光度及粒径的影响 .............. 18

§2.5 本章小结 .......................................................................................................19

第三章纳米低温保护剂的冻结特性...........................................................................20

§3.1 引言 ..................................................................................................................20

§3.2 实验材料与方法 .............................................................................................. 20

§3.2.1 实验材料与仪器 .................................................................................... 20

§3.2.2 实验方法与步骤 .................................................................................... 21

§3.2.3 实验数据处理 ........................................................................................ 21

§3.3 结果分析与讨论 .............................................................................................. 22

§3.3.1 降温和复温过程观察 ............................................................................ 22

§3.3.2 纳米悬浮液成核温度的变化 ................................................................ 23

§3.3.3 纳米悬浮液过冷度比较 ........................................................................ 25

§3.3.4 不同质量分数的纳米悬浮液过冷度比较 ............................................ 25

§3.3.5 纳米低温保护剂溶液水合性质分析 .................................................... 26

§3.4 本章小结 .........................................................................................................28

第四章纳米低温保护剂比热的测定...........................................................................29

§4.1 引言 .................................................................................................................. 29

§4.2 实验设备、材料与方法 ..................................................................................29

§4.2.1 材料与试剂 ............................................................................................ 29

§4.2.2 实验方法 ................................................................................................ 29

§4.2.3 数据处理 ................................................................................................ 30

§4.3 结果分析与讨论 .............................................................................................31

§4.3.1 不同温度下纳米微粒对溶液比热的影响 ........................................... 31

§4.3.2 纳米微粒粒径的影响 ......................................................................... 32

§4.3.3 纳米微粒质量浓度的影响 ................................................................. 33

§4.4 本章小结 ..........................................................................................................36

第五章纳米低温保护剂玻璃化性质研究...................................................................37

§5.1 序言 .................................................................................................................. 37

§5.2 纳米悬浮液玻璃化性质试验设定 .................................................................. 37

§5.2.1 实验材料与设备 .................................................................................... 37

§5.2.2 实验方法与步骤 .................................................................................... 37

§5.2.3 DSC 测量悬浮液玻璃化转变温度方法 ...............................................38

§5.2.4 实验数据处理 ........................................................................................ 38

§5.3 实验结果分析与讨论 .....................................................................................39

§5.3.1 玻璃化转变温度的影响 ....................................................................... 40

§5.3.2 反玻璃化温度的影响 ........................................................................... 41

§5.3.3 玻璃化过程中结晶量的影响 ............................................................... 43

§5.4 本章小结 ..........................................................................................................44

第六章结论与展望.......................................................................................................45

§6.1 主要结论 ..........................................................................................................45

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摘要：

摘要玻璃化保存可以避免生物体在冻结和复温过程中的损伤，实现生物体长期稳定保存，是目前最理想的低温保存方法之一。但由于受降温速率和低温保护剂溶液浓度的限制，相对复杂和较大的组织和器官很难实现玻璃化保存。通过改变物质外部的温度环境而提高降温速率的方法已经做了大量研究，并取得了显著成果，而针对改变物质内部传热传质特性，以提高降温速率的方法研究还鲜见报道。常温下纳米微粒可以显著增强溶液的传热效果，将纳米微粒应用到低温保存领域，分析纳米低温保护剂溶液在冻结过程中热物性参数的变化及纳米微粒对玻璃化趋势影响的研究是非常必要的。本课题通过配制稳定的纳米悬浮液，利用差示扫描量热仪（DSC）判定羟基磷灰石（HA）...

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