Grafting of Functional Monomers on Biomaterials - Biointerfaces: Where Material Meets Biology - page 334

distribution of the graft co-polymer. 9,88,107 An illustration of the principle of
m-ATR-FTIR mapping is shown in Figure 11.1. The m-ATR objective makes
contact with the sample and records a spectrum (Figure 11.1C). Each spec-
trum is then analysed (e.g., area ratios of specific bands calculated) and each
of these obtained values are then displayed as an area of the map which is
produced (Figure 11.1D). The resolution of m-ATR-FTIR mapping is con-
trolled by the aperture size and typically results in 30 30 mm being analysed
at each position. 9 Furthermore, mapping of functional groups across a
surface can be acheived using XPS and ToF-SIMS which provide high reso-
lution images of the spatial distribution of elements or fragments. 9,99 An
example of ToF-SIMS images (analysing a total area of 200 200 mm) of the
CF 1 ion from the surface of an ePTFE membrane before and after grafting is
displayed in Figure 11.2. It can be seen that while the lateral distribution of
the CF 1 ion on the untreated membrane is homogeneous, the grafted
membrane displays a patchy distribution. It should be noted that the tech-
niques described here have different penetration depths into the grafted

d n 3 r 4 n g | 2

.

Figure 11.1 (A) FTIR spectra of PLGA film (bottom) and AA grafted PLGA film

(top) in the 4000-2000 cm 1 region; (B) FTIR spectra of the same
samples in the 2000 to 600 cm 1 region; (C) schematic illustration of
the m-ATR objective making contact with a sample; (D) each spectrum
recorded by m-ATR is analysed to obtain a parameter (area or intensity
ratio) and each of these obtained values are displayed as an area in the
map where the relative colour intensity indicates the magnitude of the
value.