Controlled covalent surface immobilisation of proteins and peptides using plasma methods Bryan R. Coad, Marek Jasieniak, Stefani S. Griesser, Hans J. Griesser ⁎ Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia abstract article info Available online 22 May 2013 Keywords: Bio-interfaces Plasma polymerisation Coating Aldehyde Epoxide Antibacterial coating Coated layers of biologically active molecules on synthetic biomaterials and biomedical devices can promote a variety of desirable biological reactions by the host body or the biological medium, such as cell and tissue attachment or deterring bacterial biofilm formation. Such coated layers should be immobilised covalently in order to avoid competitive displacement phenomena, and the use of surface-activating plasmas or plasma polymer interlayers with suitable chemical surface groups has proved to be very convenient means of grafting bioactive molecules onto solid materials surfaces. We review selected work on the covalent immobilisation of proteins and peptides onto solid biomaterial surfaces and describe efforts towards plasma methods that allow biomolecules to be covalently captured in a single step. After reviewing a number of approaches, we discuss in more detail the use of plasma polymer interlayers that possess aldehyde or epoxide surface groups; these groups react readily with amine groups on proteins and peptides without undesirable side reactions, and avoid other issues such as crosslinking. We also emphasise the importance of detailed surface analysis to verify that covalent grafting has indeed taken place, and to assess the surface density of grafted molecules. With suitably chosen peptides or proteins, such covalently grafted layers can support the surface attachment of delicate cells, or combat bacterial biofilm formation. © 2013 Elsevier B.V. All rights reserved. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 2. General considerations for the covalent grafting of proteins and peptides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 3. Multi-step conjugation methods involving plasma oxidation of surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 4. Multi-step conjugation methods through plasma polymer interlayers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 5. One-step immobilisation methods based on ion implantation methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 6. One-step immobilisation methods based on plasma polymer interlayers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 7. Immobilisation onto aldehyde plasma polymer interlayer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 8. Epoxide pp interlayers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 9. Antibacterial coatings via plasma polymerisation and peptide immobilisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 10. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176 1. Introduction It has become clear in biomaterials research that synthetic polymers elicit nonspecific responses by the host body; at best a biomedical device is tolerated without becoming integrated into natural tissues, but often there is an immune response, thrombosis, and other adverse events [1]. Consequently, much research has focussed on coating biomedical device surfaces with molecules that can elicit a desirable biological response, such as the attachment and spreading of human cells and tissue [e.g.,2]. Much research has also focussed on producing surfaces that do not activate blood clotting or complement activation [e.g., 3]. Immobilised proteins, particularly antibodies, have also been of great interest for the development of biosensors and other bio-diagnostic devices. Moreover, more recently the problem of bacterial infections on biomedical devices Surface & Coatings Technology 233 (2013) 169–177 ⁎ Corresponding author. Tel.: +61 8 8302 3703. E-mail address: hans.griesser@unisa.edu.au (H.J. Griesser). 0257-8972/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.surfcoat.2013.05.019 Contents lists available at ScienceDirect Surface & Coatings Technology journal homepage: www.elsevier.com/locate/surfcoat