Multiplexed charge-selective surface enhanced Raman scattering based on plasmonic calligraphy

Multiplexed surface enhanced Raman scattering (SERS) substrates, which enable chemically selective detection of two or more target analytes from a complex chemical mixture, are highly attractive for chemical detection in real-world settings. We introduce a new approach called plasmonic calligraphy that involves the formation of chemically selective test domains on paper substrates using functionalized plasmonic nanostructures as ink in a regular ballpoint pen. We demonstrate selective detection of positively and negatively charged analytes (rhodamine 6G and methyl orange) from complex chemical mixtures using polyelectrolyte-coated gold nanorods as SERS medium. The approach demonstrated here obviates the need for complex patterning techniques such as photolithography to create isolated test domains on paper substrates for multiplexed chemical detection. Plasmonic calligraphy can be easily extended to other shape-controlled nanostructures with different surface functionalities and potentially automated by implementation with a robotic arm. This journal is