微梁传感研究PNIPAM分子链热致折叠构象转变  

A Study on Conformation transition of Thermally Sensitive Poly(N-isopropylacrylamide) Chains by Micro-cantilever Sensing

作　　者：李凯[1] 张青川[1] 刘红[2] 伍小平[1] 张广照[2] 

机构地区：[1]中国科学技术大学中科院材料力学行为和设计重点实验室,合肥230027 [2]中国科学技术大学化学物理系,合肥230026

出　　处：《实验力学》2006年第3期259-264,共6页Journal of Experimental Mechanics

基　　金：国家重点基础研究发展计划(973计划;2006CB300404);国家自然科学重点基金(10232030);面上基金(10472112)资助项目

摘　　要：大分子的构象转变问题，作为人类认识生命现象的基础，是当前生命科学研究的热点问题之一。本文运用光杠杆放大原理，通过检测单侧表面上修饰有聚N-异丙基丙烯酰胺（PNIPAM）分子的微悬臂梁在水溶液中随温度变化时发生的变形，获得了修饰于微梁表面的PNIPAM分子链在溶液温度变化时，由于亲／疏水性改变所导致的分子构象转变信息。实验结果显示，PNIPAM分子链的这种构象转变在20℃-40℃之间连续进行，整个过程具有迟滞性。另一方面，微梁表面应力的变化，反映的是分子构象转变过程中PNIPAM分子链之间的相互作用的信息，这对我们深入认识构象转变过程中微观机制是很有帮助的。本文提出的方法，是基于大分子构象转变过程中分子之间相互作用，反映的是过程中的力学信号，具有较高的灵敏度和较广的应用范围。The conformation transition of macromolecules is a very important problem, because it is the groundwork of understanding life phenomena at all levels. It is also a fundamental problem in life sciences. In this study, thermally sensitive poly（N-isopropylacrylamide） （PNIPAM） brushes were grafted on top surface of a micro-cantilever. Using the optical lever amplification technique to monitor the bending of the micro-cantilever, we investigated the thermally induced conformation transition of PNIPAM chains. The results indicate that the conformation transition occurs over a broad range of temperatures （20℃-40℃） and the collapse-swelling process has a clearly hysteresis effect. On the other hand, the surface stress changes at the grafted surface of the micro-cantilever reflect the micromechanism in the conformation transition process. It should be noted that the present method is based on measuring the mechanical signal during the conformation transition process. It has a higher sensitivity and wider application fields.

关 键 词：微悬臂梁 PNIPAM分子链 构象转变 表面应力 

分 类 号：O63[理学—高分子化学] O34[理学—化学]