Baselt D R, Revel J P, Baldeschwieler J D
Noyes Laboratory of Chemical PHysics, California Institute of Technology 127-72, Pasadena 91125.
Biophys J. 1993 Dec;65(6):2644-55. doi: 10.1016/S0006-3495(93)81329-8.
We have imaged native rat tail and reconstituted bovine dermal type I collagen by atomic force microscopy, obtaining a level of detail comparable to that obtained on the same samples by transmission electron microscopy. The characteristic 60-70 nm D periodicity consists of ridges exhibiting high tip-sample adhesion alternating with 5-15-nm-deep grooves having low adhesion. We also observe an intraperiod or "minor" band consisting of 1-nm-deep grooves, and "microfibrils" arranged parallel to or inclined approximately 5 degrees to the fibril axis. In air collagen fibrils exhibit negligible compression under the forces exerted by the tip. When immersed in water the subfibrillar features disappear and the fibrils become softer, compressing by 5% of their height under an 11-nN force. Material on the surface of the sample sometimes accumulates on the atomic force microscope tip; contrary to expectation such tip contamination can improve as well as reduce resolution.
我们利用原子力显微镜对天然大鼠尾巴和重组牛真皮I型胶原蛋白进行了成像，获得的细节水平与通过透射电子显微镜对相同样本获得的相当。其特征性的60 - 70纳米的D周期由高尖端-样本粘附力的脊与5 - 15纳米深的低粘附力凹槽交替组成。我们还观察到由1纳米深的凹槽组成的周期内或“小”带，以及与纤维轴平行或倾斜约5度排列的“微原纤维”。在空气中，胶原纤维在尖端施加的力下表现出可忽略不计的压缩。当浸入水中时，亚纤维特征消失，纤维变得更软，在11纳牛顿的力下压缩其高度的5%。样本表面的物质有时会积聚在原子力显微镜的尖端；与预期相反，这种尖端污染既可以提高也可以降低分辨率。
