Biofouling-Resilient Nanoporous Gold Electrodes for DNA Sensing

Abstract

Electrochemical nucleic acid sensors are promising tools for point-of-care diagnostic platforms with their facile integration with electronics and scalability. However, nucleic acid detection in complex biological fluids is challenging as biomolecules nonspecifically adsorb on the electrode surface and adversely affect the sensor performance by obscuring the transport of analytes and redox species to the electrode. We report that nanoporous gold (np-Au) electrodes, prepared by a microfabrication-compatible self-assembly process and functionalized with DNA probes, enabled detection of target DNA molecules (10–200 nM) in physiologically relevant complex media (bovine serum albumin and fetal bovine serum). In contrast, the sensor performance was compromised for planar gold electrodes in the same conditions. Hybridization efficiency decreased by 10% for np-Au with coarser pores revealing a pore-size dependence of sensor performance in biofouling conditions. This nanostructure-dependent functionality in complex media suggests that the pores with the optimal size and geometry act as sieves for blocking the biomolecules from inhibiting the surfaces within the porous volume while allowing the transport of nucleic acid analytes and redox molecules.

An overview of dealloyed nanoporous gold in bioelectrochemistry

“…NPG has been the subject of much attention for a range of applications including catalysis [4][5][6], optical sensing [7,8] and analysis [9]. NPG electrodes have been used in the development of immunosensors [10][11][12], DNA sensors [13,14], enzymatic biosensors [15,16] and as enzyme-free sensors [17][18][19]. 35 In this mini-review, we describe the use of dealloyed NPG for bioelectrochemical applications in biosensors and enzymatic biofuel cells.…”

Ordering and defects in self-assembled monolayers on nanoporous gold

“…[1] The resulting mesoporous material is attractive for applications including energy conversion, [2] catalysis, [3,4] and sensing [5][6][7] because the nanoporous gold surface is chemically inert and conductive with tuneable pore size and surface area. [8] Self-assembled monolayers (SAMs) are critical in developing nanostructured gold for applications because they represent a potential link between a variety of molecular groups, including organic and biological species, and the gold surface.…”

Mechanisms of Reduced Astrocyte Surface Coverage in Cortical Neuron-Glia Co-cultures on Nanoporous Gold Surfaces

“…15, 20, 27, 33 For example, the large effective surface area of nanostructured sensor coatings reduces impedance of neural interfaces for higher fidelity electrophysiological recordings, 28 nanotubular structures allow for higher loading capacity and sustained delivery of pharmaceuticals, 16, 21 and nanopores act as size-selective sieves to enhance the performance of electrochemical DNA sensors in the presence of globular biofouling proteins. 7, 25 In addition to these attributes, micro- and nano-topographical cues from nanostructured materials have been shown to guide cell growth, phenotype, and differentiation across many cell types, which are important factors for interfaces where specific cell coupling is beneficial. 3, 4, 8, 13, 14 One emerging material that has shown promise in promoting specific cell coupling is nanoporous gold (np-Au).…”