We present an electrokinetically enhanced aptamer sensing platform on a disposable plastic chip for label-free detection of neuropeptide Y (NPY), which is a key neurological biomarker. The sensor consists of aptamer-functionalized graphene-gold nanocomposites (Gr-AuNs) patterned inside a nanoslit that is embossed on cyclic olefin copolymer via nanoimprint lithography. Analyte molecules are dielectrophoretically focused through the nanoslit onto aptamer-immobilized Gr-AuNs for rapid and selective electrochemical detection of NPY at picomolar levels.