Patterned and switchable surfaces for biomaterial applications

CHAPTER 6.OVERALL CONCLUSIONS6.6An increased understanding of the behaviour of biomolecules at surfaces coupledwith the continued development of tools for the advanced surface manipulation ofbiomolecules is imperative for studying complex biological systems or developingadvanced biomedical devices. One particularly useful approach to achievingadvanced biomolecular surface manipulation is the production of patterned orswitchable surfaces, which has been the focus of this thesis. A number of techniqueshave been developed to achieve these abilities, however, the most interesting anduseful systems are those that combine patterns on the micro- or even nanoscale withswitchable architectures to achieve both temporal and spatial control overbiomolecule surface interactions concurrently.Two examples of patterned and switchable systems have been described in thisthesis. The first system, described in CHAPTER 2, included the formation ofpatterned surface chemistries, which were able to spatially organise the adsorption ofDNA and cells for the formation of microarrays (section 2.3.2 and 2.3.4), combinedwith a switchable electrical bias generated on the application of a positive or negativevoltage to the substrate surface. A negative electrical bias stimulated DNAdesorption and enhanced solid phase transfection efficiency (section 2.3.2 and 2.3.3).The second patterned and switchable system reported in this thesis was theformation of a PNIPAAm microarray (section 5.4.1). Here, surface patterning wasachieved by robotic contact printing of PNIPAAm spots onto a low fouling coating.Switching was achieved by a temperature change exploiting the thermoreversibleproperties of PNIPAAm, which is adherent for biomolecules above its LCST andnon-adherent below the LCST. Although not explored in great depth in this thesis,6-208