125j Effect of Polymer Grafting on the Bilayer Gel to Liquid Crystalline Transition

K. G. Ayappa, Department of Chemical Engineering, Indian Institute of Science, Bangalore, India and Foram Thakkar, Chemical Engineering, Indian Institute of Science, Bangalore, India.

Liposomes prepared from phospholipids along with grafted polymers

on the surface are used for potential applications in targeted drug delivery.

In this study we investigate the

effects of polymer grafting on the phase behaviour of

bilayers using dissipative particle dynamics.

The bilayer is made up of a single chain containing one head bead and

nine tail beads. The polymer is made up of 20 hydrophilic beads

and the bilayer is maintained in a tensionless state using a barostat.

The bilayer shows a sharp gel to liquid crystal

transition in the absence of the grafted polymer.

At a grafting density of 0.25, two additional phases are observed in

the gel to liquid crystalline transition. At low temperatures

the phase is transformed to the tilted phase and

upon further increase in temperature the interdigitated

phase is observed. The occurrence of the

tilted phase is accompanied by an increase in the area

per head group of the lipid and grafting was found to broaden

the temperature range for the gel to liquid crystalline transition.

Our study shows that the grafting density can be used to control the

temperature range and occurrence of a given bilayer phase.