pH responsive adhesion of phospholipid vesicle on poly(acrylic acid) cushion grafted to poly(ethylene terephthalate) surface.

Polymer-supported lipid bilayer is a key enabling technology for the design and fabrication of novel biomimetic devices. To date, the physical driving force underlying the formation of polymer-supported lipid bilayer remains to be determined. In this study, the interaction between dipalmitoylphosphocholine (DPPC) vesicle and poly(ethylene terephthalate) [PET] surface with or without grafted poly(acrylic acid) [PAA] layer is examined with several biophysical techniques. First, vesicle deformation analysis shows that the geometry of adherent vesicle on either plain PET or PAA-grafted PET surface is best described by a truncated sphere model. At neutral pH, the degree of deformation and adhesion energy are unaltered by the grafted polymerization of acrylic acid on PET surface. Interestingly, the average magnitude of adhesion energy is increased by 185% and -43% on PAA-grated PET and plain PET surface, respectively, towards an increase of pH at room temperature. Our results demonstrate the possibility of tuning the adhesive interaction between vesicle and polymer cushion through the control of polyelectrolyte ionization on the solid support.