A ToF-SIMS imaging technique has been used to obtain dye label-free chemical images of gradient polyethylene (PE) and its amine-functionalized surfaces. The gradient PE surface was prepared by a corona treatment with a power increase along the PE length and confirmed by ToF-SIMS. Amine reagents with varying molecular weights (MW 158,600,1200, 10,000 and 60,000) were successively reacted with a gradient PE surface and examined using ToF-SIMS. Our work found that the lower the molecular weight of amine reagent, the more gradient surface of amine surface density was generated. The amine-functionalized gradient surface can be used as a template surface for evaluating bioactive molecules on the gradient surface in just one experiment. (c) 2006 Elsevier B.V. All rights reserved.