Polycationic polymers necessarily contain counterions to maintain the overall charged balance. Upon treatment of polypyrrole (PPy) films with thiol-terminated poly(ethylene glycol) (PEG), the films undergo efficient surface derivatization that reduces a portion of the film, freeing up some of the "dopant" counterions, while forming a brush-like layer. Quartz crystal microbalance (QCM) measurements show that the PEG brushes resist the adhesion of protein (fetal bovine serum (FBS)) as compared to unmodified PPy. When the dopant is polymeric dextran sulfonate, no change in the QCM resonance frequency is observed. However, when the dopant is dodecylbenzene sulfonic acid (DBSA), exposure of the film to protein causes an increase in the resonance frequency, indicating a loss of mass. X-ray photoelectron spectroscopy (XPS) and liquid chromatography−mass spectroscopy (LCMS) measurements demonstrate that the protein triggers the release of the dopant from the composite. Treatment of DBSA-doped PPy with alginate and PEG did not result in dopant release, but poly(ethyleneimine) proved to be an even more efficient trigger than FBS, revealing that an electrostatic-based mechanism is likely a primary driver for the measured DBSA release.