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    Realization and Characterization of Porous Gold for Increased Protein Coverage on Acoustic Sensors

    Year: 2004

    Journal: Anal. Chem. 2004, 76, 4299-4306, 20100827

    Authors: Bonroy K., Friedt J-M., Frederix F., Laureyn W., Langerock S., Campitelli A., Sára M., Borghs G., Goddeeris B., Declerck P.

    Last authors: Paul Declerck

    Organizations: IMEC, MCP-BIO, Kapeldreef 75, B-3001 Leuven, Belgium, Coördination Chemistry, KULeuven, Celestijnenlaan 200G, B-3001 Leuven, Belgium, Center for Ultrastructure Research and Ludwig Boltzmann-Institute for Molecular Nanotechnology, A-1180 Vienna, Austria, Laboratory for Physiology and Immunology of Domestic Animals, KULeuven, Kasteelpark Arenberg 30, B-3001 Leuven, Belgium, and Laboratory for Pharmaceutical Biology and Phytopharmacology, KULeuven, Van Evenstraat 4, B-3000 Leuven, Belgium

    Country: Belgium

    Immunosensors show great potential for the direct detection of biological molecules. The sensitivity of theseaffinity-based biosensors is dictated by the amount of receptor molecules immobilized on the sensor surface. An enlargement of the sensor area would allow for an increase of the binding capacity, hence a larger amount of immobilized receptor molecules. To this end, we use electrochemically deposited "gold black" as a porous sensor surface for the immobilization of proteins. In this paper, we have analyzed the different parameters that define the electrochemical growth of porous gold, starting from flat gold surfaces, using different characterization techniques. Applied potentials of -0.5 V versus a reference electrode were found to constitute the most adequate conditions to grow porous gold surfaces. Using cyclic voltammetry, a 16 times increase of the surface area was observed under these electrochemical deposition conditions. In addition, we have assessed the immobilization degree of alkanethiols and of proteins on these different porous surfaces. The optimized deposition conditions for realizing porous gold substrates lead to a 11.4-fold increase of thiol adsorption and a 3.3-fold increase of protein adsorption, using the quartz crystal microbalance (QCM-D) as a biological transducer system. Hence, it follows that the high specific area of the porous gold can amplify the final sensitivity of the original flat surface device.