Fabrication of layer-by-layer assembled bio-architecture on gold nanorods

We have successfully fabricated a layer-by-layer (LBL)-assembled functional bio-architecture on gold nanorod substrates with an increased number of immobilized biomolecules. The vertical array of gold nanorods was fabricated through an electrochemical process, using porous aluminum oxide as a template and the dispersed film of gold nanorods was prepared by using the Langmuir-Blodgett technique. Horse radish peroxidase was immobilized on the vertical array and on the dispersed film of gold nanorods through LBL assembly by using the specific interaction between avidin-biotin molecules. The levels of catalytic activity of the LBL-assembled bio-architectures fabricated on both the vertical array and the dispersed film of gold nanorods were, respectively, ∼2.8 and ∼1.5 times better than that of the fiat gold surface due to an increase in surface area and ease of substrate accessibility. Scanning electron microscopy (SEM) and fluorescence images clearly show a regular, successively well-controlled LBL-assembled bio-architecture with a bilayer structure of proteins on gold nanorods. This controlled fabrication of biologically active enzymes on gold nanorod structures via LBL assembly demonstrates a technique for the development of bio-functional molecular devices with enhanced sensitivities and fast response time.