RETRACTED: Fabrication of stratified nanoporous gold for enhanced biosensing (Retracted Article)

By a dealloying/annealing/redealloying strategy, nanoporous gold (NPG) with hierarchical microstructure is fabricated for electrochemical biosensing application. The first dealloying and annealing would produce NPG/AuAg alloy composite with a large-pore NPG layer and the second dealloying would further etch the AuAg alloy part in the composite, generating a small-pore NPG layer. By using the large-pore (similar to 100 nm) layer as the glucose oxidase (GOx) container, and the small-pore (similar to 12 nm) layer as a signal producer, this novel hierarchical NPG is demonstrated to be a good support for enzyme immobilization and fabricating enzyme-based biosensors. The immobilized GOx retains similar to 92% of the initial activity after 7 repeated use. The GOx-loaded stratified NPG biosensor can detect glucose more sensitively with a wider linear range (up to 22 mM) than normal NPG with a uniform pore size of 30-40 nm (linear range: up to 17 mM). (C) 2012 Elsevier B.V. All rights reserved.