tailieunhanh - Innovations in Biotechnology Part 8

Tham khảo tài liệu 'innovations in biotechnology part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Controlling Cell Migration with Micropatterns 201 images through the interference of light reflected from glass-medium and medium-cell membrane interfaces. The thickness of the thin medium layer is evaluated using the reflective index of the medium cell membrane and glass and the wavenumber and angle of incident light Bereiter-Hahn et al. 1979 Simson et al. 1998 . Izzard and Lochner reported that the nearest distance between cell membranes and substrates is approximately 10 nm which is shown as dark areas in RICM images. These are focal adhesions or focal contacts Izzard and Lochner 1976 . Sackmann et al. and others significantly developed RICM using a model cell membrane that is composed of giant vesicles bearing membrane protein or that has been modified with polymers Bruinsma et al. 2000 Smith et al. 2008 Limozin and Sengupta 2009 Streicher et al. 2009 . RICM has drawn much attention as a non-probing microscopy for observing focal adhesions Yin et al. 2003 Sengupta et al. 2006 Théry et al. 2006 . Let us briefly summarize the principles of RICM Fig. 6a . The intensities of the incident light the light reflected from the interface of the medium and the surface of the glass substrate and the light reflected from the interface of the medium and the cell membrane are depicted by I0 I01 and I12 respectively. The intensity profile I x of the interference between I01 and I12 is obtained by I x I01 102 2 I0J02 1 2 2kh x cose 8 1 where k is the wavenumber of light the phase of which is shifted with 8 and h x is the distance of the cell membrane from the glass surface. Using the Fresnel equation with the reflection amplitude coefficients of each interface r01 r12 I01 and I12 are substituted as follows I01 r012 I0 and I12 1-r012 r122I0. Therefore the maximum Imax and minimum intensity Imin of the interference are obtained from Imax I01 I12 2 I01I12 1 2 and Imin I01 I12-2 I01I12 1 2 which allows the deduction of the following equation n refractive index h x J. 4nn arccos J .