Programming the detection limits of biosensors through controlled nanostructuring

Advances in materials chemistry offer a range of nanostructured shapes and textures for building new biosensors(1-10). Previous reports have implied that controlling the properties of sensor substrates can improve detection sensitivities, but the evidence remains indirect(11-13). Here we show that by nanostructuring the sensing electrodes, it is possible to create nucleic acid sensors that have a broad range of sensitivities and that are capable of rapid analysis. Only highly branched electrodes with fine structuring attained attomolar sensitivity. Nucleic acid probes immobilized on finely nanostructured electrodes appear more accessible and therefore complex more rapidly with target molecules in solution. By forming arrays of microelectrodes with different degrees of nanostructuring, we expanded the dynamic range of a sensor system from two to six orders of magnitude. The demonstration of an intimate link between nanoscale sensor structure and biodetection sensitivity will aid the development of high performance diagnostic tools for biology and medicine.