DPN writing on non-flat gold surfaces and detection by SERS

There is a need for fast, reliable and sensitive biosensor arrays. We have used nanostructured plasmonic gold surfaces for the detection of biological species by surface enhanced resonance Raman scattering (SERRS). Careful, directed placement by Dip-Pen Nanolithography (DPN) of the biological species or capture chemistry, within the array facilitates efficient read out via fast Raman line mapping. In addition, we can apply parallel deposition methods to enhance the throughput of these combined techniques. SERRS is an extremely sensitive spectroscopic technique that offers several advantages over conventional fluorescence detection. For example, the high sensitivity of the method allows detection of DNA capture from single plasmonic array "pixels" ∼1 μm² in area. Additionally, the information rich nature of the SERRS spectrum allows multiple levels of detection to be embedded into each pixel, further increasing the information depth of the array. By moving from micro-to nano-scale features, sensor chips can contain up to 105 times more information, dramatically increasing the capacity for disease screening.