Self-assembly of decylphosphonic acid (DPA) and octadecylphosphonic acid (ODPA) was studied on aluminum films using XPS, ToF-SIMS and surface wettability. Modified aluminum films were tested for passivation against silanization and subsequent oligonucleotide attachment. Passivation ratios of at least 450: 1 compared to unprotected aluminum were obtained, as quantified by attachment of radio-labeled oligos. (C) 2010 Elsevier B.V. All rights reserved.