Grafting of Functional Monomers on Biomaterials - Biointerfaces: Where Material Meets Biology - page 337

A range of techniques which do not require destructive sample prepar-
ation have been employed to determine the depth of penetration of grafted
chains including dye assays, 11 angle-dependent XPS 9,99 and MRI. 9 In angle-
dependent XPS the stage position is altered allowing a more shallow depth of
the sample to be analysed. While, in general, angle dependent XPS can be
used to investigate the outermost sample surfaces, dye assays and MRI are
very useful for examining the position of the grafted chains for the entire
depth of the substrate up to hundreds of microns in thickness, albeit at a
lower resolution. Both techniques require that the dye solution or water will
be able to penetrate into areas where the graft co-polymer is present. MRI
relies on the polymer substrate being hydrophobic, thus water will only
penetrate the substrate when interacting with the hydrophillic graft co-
polymer. This has been shown to provide a useful method of visualising the
graft co-polymer distribution within a porous membrane. 9

d n 3 r 4 n g | 2

11.4 Concluding Remarks
Grafting of functional monomers on biomaterials offers a wealth of oppor-
tunities for tailoring the surface properties for specific medical applications.
As illustrated in this chapter it is important to carefully select an appropriate
grafting method and grafting conditions based on the polymer substrate and
the required position of the grafted chains. It is equally important to thor-
oughly characterise the modified material if a sound analysis of a resultant
biological response is to be made. It was noted in this chapter that for
grafting in 3D scaffolds the methods that dominated were plasma poly-
merisation and simultaneous grafting. It is envisaged that the future will see
CRP methods being used in this regard. Finally, it is hoped that through
careful selection of grafting methods coupled with thorough analysis of
grafted substrates that more optimised materials will make their way to the
medical implant market.

.

Acknowledgements
Professor Sebastien Perrier (The University of Warwick, UK) and Doctor
Adrienne Chandler-Temple are thanked for helpful suggestions. Doctor
Imelda Keen (The University of Queensland, Australia) is acknowledged for
providing the spectra for the FTIR figure and Doctors Adrienne Chandler-
Temple and Marek Jasieniak for obtaining the ToF-SIMS images.

References
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Polym., 2006, 3, 392.
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Biomacromolecules, 2009, 10, 2351.
3. E. A. Dubiel, Y. Martin and P. Vermette, Chem. Rev., 2011, 111, 2900.