Plasma Polymer and PEG-Based Coatings for DNA, Protein and Cell Microarrays

DNA, protein and cell microarrays are increasingly used in a multitude of bioassays. All of these arrays require substrates that are suitable for the immobilisation and display of arrayed probe molecules whilst at the same time resisting non-specific interactions of biomolecules with the substrate in areas between printed spots. To meet these conflicting requirements, three different approaches have been developed, all of which were based on low-fouling, high-density poly(ethylene glycol) (PEG) background coatings. In the first approach, the coating was based on allylamine plasma polymerisation (ALAPP) and the subsequent high-density grafting of PEG, followed by the generation of a surface chemical pattern using laser ablation. In the second approach, a photoreactive polymer was printed on the same ALAPP–PEG background. The third approach was based on ALAPP deposition followed by the formation of a multifunctional layer by spin coating a PEG-based polymer that also displayed epoxy groups. The successful demonstration of DNA, protein and cell microarrays has been achieved on each of these coatings.