Functional plasma polymer films engineered at the nanoscale for biomaterial
applications
Krasimir Vasilev
Mawson Institute and School of Advanced Manufacturing, University of South Australia, Mawson
Lakes Campus, Mawson Lakes, SA 5099, Australia
Functional coatings presenting a variety of functional surface groups (e.g. amine, carboxyl, epoxy,
aldehyde, etc) can be readily prepared by plasma polymerisation in an easy one step process.
Applications of such films span over a range of fields from modification of biomaterials to protective
coatings.
In my talk I will present recent developments from our group on various biomaterial coatings prepared
by plasma polymerisation which include chemical and biomolecular gradients, antibacterial coatings
and drug release platforms.
Surface gradients are important tools for studying and guiding cellular responses such as migration,
adhesion, differentiation, etc. In our group we generate gradients of various surface chemistries via
plasma co-polymerisation over a moving mask. We used density gradients of chemical functional
groups to direct differentiation of kidney (KSC) and embryonic stem cells. We found that KSC express
proximal tubule markers at medium amine group surface concentration and adapt a podocyte-like
morphology at high.We also extended these surface chemical gradients to density gradients of surface
bound ligands, proteins or nanoparticles. We also developed gradients of two proteins since gradients
of single protein which have been employed in cell studies up to now are probably too simplistic to
mimic natural biological processes. We are particularly interested in density gradients of nanoparticles
which we aim to use as a tool to study how the magnitude and spacing of the nanoscale surface
features affect cell behaviour.
In the second part of my talk I will present our recent research on development of antibacterial
coatings. One approach is based on amine plasma polymer films loaded with silver nanoparticles. A
fast, simple and convenient procedure was developed to first load plasma polymer films with silver
ions and a subsequent reduction to silver nanoparticles. Varying parameters such as time of reduction,
time of silver loading and thickness of the plasma polymer film gave us a versatile tool for controlling
the amount of silver nanoparticles loaded in the films. Bacterial tests showed excellent antibacterial
properties against both gram positive and gram negative bacteria. We also demonstrated that we can
control the rate of release of silver atoms from the films which is very important when extended time
of action is required. Moreover we show that we can tune the release rate in a way to allow our
coatings to be tolerant to adhesion and spreading of mammalian cells while preserving their
antibacterial properties.
In the last part of my talk I will present methods for fabrication of drug delivery platforms for
controlled release. The drug is deposited on a surface via drop or spray casting. Control of the release
rate of the drug is exercised via a plasma polymer films which covers the drug particles, and the
thickness of the plasma polymer film determines the release kinetics. Another approach is based on
nanotube arrays filled with drugs or proteins. A plasma polymer deposited on the rims of the tubes
controls the release rate.
I will also touch on same of our studies aiming to gain fundamental understanding on how plasma
polymers grow from substrates of different materials.
References:
K. Vasilev, V. Sah, K. Anselme, C. Ndi, M. Mateescu, B. Dollmann, P. Martinek, H. Ys, L. Ploux
and H. J. Griesser “Tunable antibacterial coatings that support mammalian cell growth” Nano Letters
10 (1), 202–207 (2010)
K. Vasilev, A. Mierczynska, A. L. Hook , J. Chan, N. H. Voelcker and R. D. Short, “A PEG-density
gradient to control protein binding: creating gradients of two proteins”, Biomaterials 31, 392–397
(2010)
S. Simovic, D. Losic and K Vasilev*, “Controlled drug release from mesoporous materials by plasma
polymer deposition” Chemical communications 46, 1317 - 1319 (2010)
K. Vasilev, Z. Poh, K. Kant, J. Chan, A. Michelmore, D. Losic, “Tailoring the surface functionalities
of titania nanotube arrays”, Biomaterials 31, 532–540 (2010)
K. Vasilev, V. R. Sah, R. V. Goreham, C. Ndi, R. D. Short and H. J. Griesser, “Antibacterial surfaces
by adsorptive binding of polyvinyl sulphonate stabilized silver nanoparticles”, Nanotechnology 21
(21), 215102 (2010)
K. Vasilev, A. Michelmore, H. J. Griesser and R. D. Short, “Substrate Influence on the Initial Growth
Phase of Plasma-Deposited Polymer Films”, Chemical communications (24), 3600 - 3602 (2009)
K. Vasilev, L. Britcher, A. Casanal, and H. J. Griesser, “Solvent-Induced Porosity in Ultrathin Amine
Plasma Polymer Coatings”, J. Phys Chem B 112( 35), 10915-10921 (2008)
K. Vasilev, A. Casanal, H. Challougui and H. J. Griesser, “Template assisted generation of
nanocavities within plasma polymer films”, J. Phys Chem B 113(20), 7059-7063 (2009
P. Murray, K. Vasilev, C. F. Mora, E. Ranghini, H. Tensaout, A. Rak-Raszewska, B. Wilm, D.
Edgar, R. D. Short, S. E. Kenny, “The potential of small chemical functional groups for directing the
differentiation of kidney stem cells”, Biochemical Society Transactions (2010) – in press
K. Vasilev, J. Cook and H. J. Griesser, “Antibacterial surfaces for biomedical devices”, Expert
Reviews of Medical Devices, 6(5), Pages 553-567 (2009)