生物谷综合：日本科学家最新研究发现，通过观察被陷入碳纳米管中的单个分子的运动，就可以直接观察到视觉形成的过程，此研究结果发表在7月出版的《自然—纳米技术》（Nature Nanotechnology）期刊上。
眼睛中视网膜分子形状的变化会刺激负责视觉的生物化学通道，从而导致视觉的形成。通过将单个视网膜分子锚定在足球状的C60富勒烯分子中，Kazu Suenaga和同事就能够将它们捕获在单壁的碳纳米管中，并用高分辨率的透射电子显微镜为其成像。用碳纳米管做样品支架可以确保单个分子之间有很好的隔离，并能保护它们在观察时免遭电子束的损伤。
连续的透射电子显微镜图像展现了视网膜分子在碳纳米管中的移动和形状改变过程。尽管这种图像展现的是视网膜分子在人工环境中的运动，与正常的生物学环境有差异，但眼睛在观察外界时会发生非常类似的过程，从而揭示出当我们看见某种东西时，眼睛内部究竟发生了什么事。
本期的一篇新闻评述文章写道：“这项工作首次观察到了共轭碳链的动力学行为，提供了一种在原子水平清晰度下研究视紫质中视网膜分子作用的可能性。”
原始出处:
Nature Nanotechnology 2, 422 - 425 (2007)
Published online: 1 July 2007 | doi:10.1038/nnano.2007.187
Subject Categories: Carbon nanotubes and fullerenes | Surface patterning and imaging
Imaging the dynamic behaviour of individual retinal chromophores confined inside carbon nanotubes
Zheng Liu1, Kazuhiro Yanagi2, Kazu Suenaga1, Hiromichi Kataura2 & Sumio Iijima1
Abstract
Retinal is the molecule found in photoreceptor cells that undergoes a change in shape when it absorbs light. Specifically, the cis/trans isomerization of a carbon–carbon double bond in this chromophore sets in motion the chain of biochemical processes responsible for vision1, 2, 3. Here, we obtain atomically resolved images of individual structural isomers of the retinal chromophore attached to C60 molecules and study their dynamic behaviour inside a confined space—that is, inside single-walled carbon nanotubes—using high-resolution transmission electron microscopy (HR-TEM). Sequential HR-TEM images with sub-second time resolution directly reveal the isomerization between the cis and all-trans forms of retinal, as well as conformational changes and volume-conserving effects. This work opens up the possibility of investigating in vitro the biological activities of these photoresponsive molecules on an individual basis, and the molecular imaging technique described here is a general one that can be applied to a wide range of systems.
Research Center for Advanced Carbon Materials, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
Nanotechnology Research Institute (NRI), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8562, Japan
Correspondence to: Kazu Suenaga1 e-mail: suenaga-kazu@aist.go.jp
