二维界面上偶氮苯糖脂的光响应行为

Photo-Responsivity of Azobenzene-Containing Glycolipid within Liquid-Gas Interface

设计合成了含偶氮苯基团的糖脂Gal-azo-Cn,通过Langmuir Blodgett(LB)膜、原子力显微镜技术对该糖脂在气液界面上的光异构化行为进行研究。实验表明,气液界面上的纯偶氮苯糖脂及与磷脂混合形成单分子膜的偶氮苯糖脂均具有反-顺、顺-反异构化行为。紫外光引起的异构化过程导致表面压力上升,但是由于二维界面上膜压的存在对其反-顺异构化行为有抑制作用,膜压越大,压力上升越小,黑暗环境中顺-反异构化过程则越快。对比纯偶氮苯糖脂的界面异构化行为,混合体系中磷脂分子与偶氮苯糖脂分子间的相互作用,对二维界面上糖脂的反-顺异构化有促进作用,提高了偶氮苯糖脂的反-顺异构化程度。磷脂-糖脂混合体系中,混合组分中含不饱和碳链的磷脂含量越高,膜的流动性越强,稳定性越差,对偶氮苯糖脂异构化行为的促进作用越弱。

Azobenzene-containing glycolipid, Gal-azo-Cn, was synthesized and its photoisomerization behavior within the liquid-gas interfaces was investigated by Langmuir Blodgett （LB） film measurements and atomic force microscopy. The results showed that Gal-azo-Cn could undergo trans-cis and cis-trans isomerization in both pure glycolipid and phospholipid-mixed films. UV-light induced isomerization increased the surface pressure. However, the membrane pressure within the liquid-gas interface could hinder the trans-cis isomerization. The high membrane pressure prevented the increase of surface pressure, weakening the trans-cis isomerization. In contrast, the cis-trans isomerization sped up in the dark. Compared with the isomerization behavior of pure glycolipid, the interaction between phospholipid and glycolipid could promote the trans-cis isomerization within the liquid-gas interface. In the mixed system, the increase in phospholipid containing unsaturated carbon chains increased the fluidity of the membrane but decreased its stability, which weaken the promotion effect of isomerization.