title: Hydrothermally shrunk alumina nanopores and their application to DNA sensing.
abstract: Hydrothermal treatment of anodized alumina membranes has been known for years and is believed to seal the pores by transforming aluminium oxide into lower density hydroxides. We demonstrate that, at least for 60 nm diameter pores grown from anodization in oxalic acid at 40 V, the hydrothermal treatment significantly shrinks but does not fully seal the nanopores. The pores shrink to a neck of less than 10 nm in diameter and 2-4 microm in length, in which the diffusion coefficient of ions is five orders of magnitude smaller than in the bulk. Because of a high electrolyte resistance through hydrothermally treated shrunken nanopores, they can be used for electrical sensing applications, as demonstrated using the example of DNA sensing. Hybridization of target DNA with a complementary ssDNA covalently immobilized inside the nanopores causes an increase in impedance by more than 50% while a noncomplementary ssDNA has no measurable effect.
authors.affiliation: Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003, USA.
authors.forename: Pavel
authors.initials: P
authors.lastname: Takmakov
authors.forename: Ivan
authors.initials: I
authors.lastname: Vlassiouk
authors.forename: Sergei
authors.initials: S
authors.lastname: Smirnov
mesh_terms: D000537:Aluminum Oxide; D004247:DNA / Q000032:analysis*; D017097:Electric Impedance; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004573:Electrolytes; D004867:Equipment Design; D006358:Hot Temperature; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures; D013499:Surface Properties
chemical_list: D004573:Electrolytes; D004247:DNA; D000537:Aluminum Oxide