Biofunctional multilayer film on silicon surface-tethered poly(acrylic acid) brushes

Layer-by-layer assembly of oppositely charged polyelectrolytes has been recognized as a powerful, yet simple strategy to engineer surfaces with specific properties. in this contribution, poly (acrylic acid) (paa) brushes covalently tethered to the silicon surface was used as a substrate for layer-by-layer assembly of selected polyelectrolytes. chitosan, poly (acrylic acid) and poly (10, 12-pentacosadiynoic acid) vesicles to generate multilayer films. generated by surface-initiated atom transfer radical polymerization of teri-butyl acrylate followed by acid hydrolysis. the graft density of the paa brushes was high enough to induce chain stretching allowing a thicker individual adsorbed layer to be formed. it was demonstrated that the thickness of each individual layer and multilayer varied in proportion to the thickness of the paa brushes. an increment of up to 10 nm in thickness of the individual layer can be achieved under an appropriate adsorption condition. the contact angle and afm data suggested that the assembled multilayer film was stratified. according to protein adsorption studies, the bioactivity of the multilayer film can be tailored by changing the last polyelectrolyte deposited. this approach offers a great benefit for applications which require fabrication of stable nanometer-thick film without having to use many cycles of deposition.