Peptide Secondary Structure Modulates Single-Walled Carbon Nanotube Fluorescence in Response to Nitroaromatics

This work introduces the concept of a chaperone sensor, where an analyte is detected indirectly via the optical transduction of the secondary structure changes to a polypeptide in solution. A class of amphipathic peptides, not previously known for nitroaromatic recognition, undergoes a unique conformational change upon binding, resulting in a specific analyte response involving wavelength shifting of the SWNT emission. The induced wavelength shift permits both the fingerprinting of the analyte via analysis of the response of different SWNT species, as well as the first demonstrated imaging of the solvatochromic shifting of single molecules. The binding was observed using a novel split-channel microscope to image quantized solvatochromic shifts by turning a shifting event into an anti-correlated intensity fluctuation which can be monitored spatially and in real-time.