Polymer collapse due to pH or electric potential change monitored with MP-SPR
Conductive polymers (CP) are utilized in drug delivery systems, microelectronics, photonics and also for material in biomedical engineering. CP polymer poly (3,4-ethylenedioxythiophene) (PEDOT) was deposited on a sensor slide and above that Poly (acrylic acid) (PAA) brush which is a promising biointerface material.
Multi-Parametric Surface Plasmon resonance (MP-SPR) was utilized to follow PAA polymer brushes swelling and collapse caused by pH or electric potential change. MP-SPR with electrochemical cell was utilized to form potential change to the conductive sensor surface. Multi wavelength MP-SPR measures whole SPR curve with two different wavelength and this can be utilized to calculate deposited layer thickness (more detailed see AN#128).
On a sensor slide had 18 nm thick PBrEDOT layer and 15 nm thick PAA layer on top of that. BrEDOT-g-PAA revealed to be pH sensitive as expected. In acidic environment (pH4) PAA polymer brushes collapsed resulting a decrease in thickness of the layer and an increase in refractive index of brushes. Electric potential change seemed to cause PAA brushes conformational collapse also in basic environment due to conductive polymer oxidation.
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