Session: Surface Chemistry:

Hierarchical nanoporous gold (hNPG) is of interest for biosensor applications due to its large surface area, high roughness factor, high loading capacity, rapid mass transport due to the presence of dual pore sizes, and deep channels making it a suitable candidate for applications such as electrochemical sensors, reactors, and catalysis. Biosensors have emerged to become the leading technologies for the detection of analytes of biological importance to meet needs to detect the presence of pathogens and also of biomarkers for early and rapid disease diagnosis. To develop the appropriate biosensor to meet this objective, we have chosen to take advantage of surface architectures of hNPG. There has recently been an increased emphasis on using nanotechnology to shrink the dimensions of electrochemical sensor elements to sizes which can increase the signal-to-noise ratio for processes designed to occur at the interface of the device. We present here our preparation of hNPG using a procedure involving alloy electrodeposition, controlled partial dealloying, annealing and final dealloying to yield a structure of larger pores of several hundred nanometers and smaller pores below 100 nm in size. We have used scanning electron microscopy (SEM), cyclic voltammetry (CV), and atomic force microscopy (AFM) to characterize the material. Results for protein loading into hNPG as determined using uv-vis spectroscopy are presented and compared with those from regular NPG. The electrochemical detection of the glycoproteins fetuin and asialofetuin has been carried out using electrochemical assays based on lectin binding interactions using lectins conjugated to alkaline phosphatase and detection of p-aminophenol produced by the action of the enzyme on its substrate p-aminophenylphosphate. hNPG is a material of great promise for biosensor development as it enhances the scaling relations between volume and accessible surface area.

Dharmendra Neupane

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