Metal-Free Raman Sensing Platforms of Organic Nanowire Arrays Produced by High Energy Charged Particles

An organic nanowire fabrication technique, i.e., single-particle-triggered linear polymerization, which yields nanowires consisting of a wide range of organic molecules with perfectly controlled sizes, is developed via chemical reactions induced by a high-energy charged particle. A freestanding purely organic nanowire array (ONA) structure is fabricated to maximize the surface area with the designed surface affinity for analyte molecules. The ONA is demonstrated as an effective sensing platform for Raman spectroscopy with a high enough sensitivity against a series of analytes including rhodamine, crystal violet, methylene blue, neutral red, methyl orange, as well as oligopeptides. The designed electron transfer reactions between the analytes and nanowires provide Raman signal enhancement factors of up to 10⁸ with the detection limit of the analytes as 10⁻⁹ M for the rhodamine, indicating the viability of these ONAs as a novel class of metal-free Raman sensing probes.