(Invited) Near Infrared Fluorescence Lifetime Imaging of Biomolecules with Carbon Nanotubes

Abstract

Single wall carbon nanotubes (SWCNTs) are versatile building blocks for biosensors. Their near infrared (NIR) fluorescence enables detection of biomolecules in the optical tissue transparency window. Their surface chemistry can be tailored to selectively interact with analytes, which typically changes the fluorescence intensity. However, such signals are affected by external factors such as sample movement or fluctuations in excitation light. Here, we demonstrate fluorescence lifetime imaging microscopy (FLIM) of SWCNT-based sensors in the NIR as absolute and calibration-free method.For this purpose, we use a tailored laser scanning confocal microscope (LSCM) optimized for NIR signals (>800 nm) and time correlated single photon counting (TCSPC). (GT)10-DNA modified SWCNTs serve as sensor of the important neurotransmitter dopamine. The detected fluorescence signal > 900 nm increases in lifetime up to 25 %. These lifetime sensors are used as paint to cover cells and report extracellular dopamine in 3D. We therefore show the potential of using fluorescence lifetime in combination with confocal microscopy as readout for SWCNT-based sensors.