Macdonald, Peter M.

Research

We are interested in understanding how polymers interact with self-assembled amphiphilic systems, particularly lipid bilayer membranes, and how these interactions influence the properties of both partners. Such questions are important from a fundamental scientific perspective, since many of the functions performed by biological membranes are carried out by biomacromolecules. But they are also relevant from an applied science viewpoint, because polymer-lipid bilayer combinations are widely used in, for example, novel biotechnological devices.

Our principle tool for such studies is nuclear magnetic resonances (NMR) spectroscopy. One of our favorite experiments is pulsed field gradient (PFG) NMR which permits one to measure molecular diffusion. For example, we have used PFG NMR to follow diffusion of polymers hydrophobically bound to lipid bilayers, or confined within the aqueous slit-channels formed by two neighbouring lipid bilayers. An entirely different class of NMR experiment uses 2H NMR to examine the consequences of strong electrostatics interactions between charged polymers and lipid bilayer surfaces. We are also developing new polymer hydrogel-supported lipid bilayer systems designed to exhibit improved stabilities, to better mimic real biological membranes, and, potentially, to yield enhanced drug delivery vehicles. In addressing such challenges we bring to bear the entire battery of liquid-state and solid-state NMR techniques. We have full access to 300 MHz and 500 MHz solid state NMR spectrometers, as well as to 400 MHz and 600 MHz liquid-state NMR spectrometers.