A simple strategy of transgenic sequence-specific detection without a special amplification procedure was developed on the basis of aluminum(III)/poly(L-glutamic acid) (PLGA) film. An aluminum ion (Al(III)) thin film was assembled on the surface of PLGA via the electrostatic binding of Al(III) with carboxyl, namely Al(III)/PLGA. The immobilization of deoxyribonucleic acid (DNA) was carried out on this Al(III)/PLGA film by Al(III)-single strand DNA (ssDNA) interaction. Surface hybridization between the immobilized ssDNA and its complementary ssDNA was monitored by electrochemical impedance spectroscopy (EIS) using [Fe(CN)(6)](3-/4-) as a redox probe. Under the optimal conditions, this DNA electrochemical sensor was applied to determine the specific gene sequence related to phosphinothricin acetyltransferase transgene (PAT) in the transgenic plants by label-free EIS. (C) 2009 Elsevier B.V. All rights reserved.