AVS 53rd International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI-WeA

Paper BI-WeA4
Immobilisation Strategies for Grafted Dendron Surfaces

Wednesday, November 15, 2006, 3:00 pm, Room 2014

Session: Bio-Interfacial Modification and Bio-Immobilization II (Honoring Marcus Textor, ETH-Zürich for Substantial Contributions to the Field)
Presenter: N.D. Pollock, University of Sheffield, UK
Authors: N.D. Pollock, University of Sheffield, UK
L.J. Twyman, University of Sheffield, UK
S.L. McArthur, University of Sheffield, UK
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Surface immobilisation of dendrimers presents an exciting opportunity for creating a wide variety of functionalised polymeric architectures suitable for the immobilisation and delivery of biomolecules. In solution, these perfectly branched monodisperse, globular macromolecules have been utilised in gene transfection, drug delivery and catalysis. In this study we investigate a range of graft-to and graft-from approaches for immobilising dendrimers for biotechnology applications. The immobilisation strategies all start with plasma polymerised acrylic acid thin films enabling the polymers to be grafted to a wide variety of substrates. The tethering of polyamidoamine (PAMAM) dendritic macromolecules to the plasma polymers was achieved via 2 routes. In the graft-to regime, water soluble carbodiimide chemistry has been used to covalently immobilise a range of PAMAM dendrons (G1-G6) possessing aniline focal points. The affect of solution pH and ionic strength on the structure of the resultant grafted layer were also investigated. In the graft-from regime plasma polymerised acrylic acid provided a platform for the physisorption of polycationic polyethyleneimine (PEI) to the surface. Michael addition was then utilised to immobilise methyl acrylate to the amine terminated surface, yielding an ester terminated surface (G0.5). Subsequent amidation with ethylenediamine generated a dendritic molecule furnished with amine groups (G1) and the process repeated to produce higher generation dendrons. Characterisation of each stage in the grafting process via XPS, ToF-SIMS and AFM illustrated the complex interactions that occur when immobilising polymers at interfaces. Successful step by step growth of immobilised dendrons with enhanced control was achieved using the graft-from regime. The results showed that the graft-to strategy gave a simple one step process for immobilisation of different generation dendrons at the interface.