Facile synthesis of hierarchically aloe-like gold micro/nanostructures for ultrasensitive DNA recognition

Well-defined hierarchically aloe-like gold micro/nanostructures (HAG) are one-step electrochemically fabricated without introducing any template or surfactant. The formation kinetics of the HAG can be described as a nucleation and three-dimensional growth process controlled by the reactant diffusion from the solution side. As the applied electro-deposition potential moved in the negative direction, the gold crystal density increased, and the crystal shape changed from a quasi-spherical to dendritic fractal morphology. Under the optimal potential of -0.1. V and the time of 10. min, well-defined HAG possessing a hydrophilic surface with large effective area (ca. 8 times of its geometrical area) were obtained, which was used as the substrate for fabricating an ultrasensitive DNA biosensor. The DNA biosensor displayed a significantly enhanced detection limit of 12. aM, a wide linear response from 50. aM to 1. pM, as well as good selectivity, stability and reusability. This efficient DNA molecule immobilization platform may have implications in the preparation of many other gold micro/nanostructures (GMNs) with interesting properties and application potentials in many fields, such as biosensing, biocatalysis and biofuel cells.