In a variety of biomedical applications (e.g., tissue engineering, drug delivery, etc.), the role of a bioactive material is to serve as a platform by which one can modulate the cellular response into a desired role. Of the methods by which one may achieve this control (e.g., shape, structure, binding, growth factor release), the control of the cellular redox state has been under evaluated. Ideally, the ability to tune the redox state of a cell provides an additional level of control over a variety of cellular responses including, cell differentiation, proliferation, and apoptosis. Yet, in order to achieve such control, it is important to know both the overall oxidative status of the cell and what molecular targets are being oxidized. In this work, poly (trolox ester) nanoparticles were evaluated for their ability to either inhibit or induce cellular oxidative stress in a dose-dependent fashion. This polymer delivery form possessed a unique ability to suppress protein oxidation, a feature not seen in the free drug form, emphasizing the advantage of the delivery/dosage formulation has upon regulating cellular response. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.