Biomedical Engineering Reference
In-Depth Information
Fig. 7.23. Examples of proteins and protein oligomers inserted in lipid membranes. Left: low-
resolution imaging of single outer membrane proteins (OmpF) inserted into DMPC supported lipid
bilayer 308 . The inset histogram shows two peaks in the histogram of protein heights suggesting two
insertion mechanisms. Right: high-resolution images of light-harvesting complex incorporated into a
DOPC/DPPC SLB. The inset shows an averaged image of the complexes, showing the discrimin-
ation of the 16 sub-units. Reproduced with permission from [662] (right).
crystallized complexes, which are presumably closer to the native structures. AFM is the
only technique to allow high-resolution imaging of protein complexes in near-native
conditions [662]. An example showing high-resolution imaging of protein complexes
inserted into an SLB is given in Figure 7.24.
7.3.4 Mammalian cell imaging
Due to their importance in biological and particularly biomedical sciences, animal cells
have been widely studied by AFM. As a high-resolution microscopy technique able to
image samples under physiological conditions (in buffer or growth medium, at controlled
temperature, with controlled ionic strength), AFM has some unique advantages for cell
biology. In addition, the ability to make mechanical/chemical measurements using the
AFM probe enables further possibilities. AFM is also particularly easy to combine with
Fig. 7.24. Examples of AFM imaging of live animal cells. Left: contact-mode images; height and
deflection images of osteoblast cells on a polystyrene culture dish (height image z -scale: 3.9 m).
Right: IC-AFM image (amplitude image) living fibroblast cell layer on PLL-coated glass slide. With
cells, error signal images such as the deflection and amplitude images shown here are usually
presented as they show more details. Reproduced with permission from [678] and [103].
 
 
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