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. The fluorescence intensity of SWCNTs changes in response to an analyte and this interaction can be chemical tailored by the surface chemistry. However, optical signals based on intensity 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 calibration-free method. For this purpose, we tailored a confocal laser scanning microscope (CLSM) for NIR signals (>800 nm) and employed time correlated single photon counting (TCSPC). (GT)10-DNA functionalized SWCNTs are then used as sensors because they increase their fluorescence (995 nm) in response to the important neurotransmitter dopamine. Their fluorescence lifetime (> 900 nm) follows a biexponential decay and the longer lifetime component (370 ps) changes with dopamine concentration. It increases by up to 25 % with detection limits in the nM range. These sensors serve as paint to cover cells and report extracellular dopamine in 3D via FLIM. We therefore show the potential of using fluorescence lifetime in combination with confocal microscopy as readout for SWCNT-based sensors.

Wide-field fluorescence lifetime imaging of neuron spiking and subthreshold activity in vivo

“…In voltage imaging, lifetime will enable improved measurement of FRET-opsin ( 3 , 7 ), hybrid FRET ( 6 ), and dye indicators ( 8 ). We also anticipate application to imaging calcium ( 27 ), neurotransmitters ( 28 , 29 ), and cyclic adenosine monophosphate ( 30 ).…”