Ultralarge Modulation of Single Wall Carbon Nanotube Fluorescence Mediated by Neuromodulators Adsorbed on Arrays of Oligonucleotide Rings

Abstract

Non-covalent interactions between single-stranded DNA (ssDNA) oligonucleotides and single wall carbon nanotubes (SWNTs) have provided a unique class of tunable chemistries for a variety of applications. However, mechanistic insight into both the photophysical and intermolecular phenomena underlying their utility is lacking, resulting in obligate heuristic approaches for producing ssDNA-SWNT based technologies. In this work, we present an ultrasensitive "turn-on" nanosensor for neuromodulators dopamine and norepinephrine with strong ΔF/F0 of up to 3500%, a signal appropriate for in vivo imaging, and uncover the photophysical principles and intermolecular interactions that govern the molecular recognition and fluorescence modulation of this nanosensor synthesized from the non-covalent conjugation of (GT)6 ssDNA strands on SWNTs. The fluorescence modulation of the ssDNA-SWNT conjugate is shown to exhibit remarkable sensitivity to the ssDNA sequence chemistry, length, and surface density, providing a wealth of parameters with which to tune nanosensor dynamic range and strength of fluorescence turn-on. We employ classical and quantum mechanical molecular dynamics simulations to rationalize our experimental findings.Calculations show that (GT)6 ssDNA form ordered loops around SWNT, inducing periodic surface potentials that modulate exciton recombination lifetimes. Further evidence is presented to elucidate how analyte binding modulates SWNT fluorescence. We discuss the implications of our findings for SWNT-based molecular sensing applications. MainSingle wall carbon nanotubes exhibit advantageous electronic and photophysical properties that make them attractive for a diverse field of applications in electronics 1-5 , sensing 6-9 , imaging [10][11][12]13 ,and molecular transport [14][15][16] . SWNT fluorescence originates from radiative

Chemometric Approaches for Developing Infrared Nanosensors To Image Anthracyclines

“…We therefore propose an alternative mechanism, whereby DOX modulates nucleobase stacking on the nanotube surface, inducing a conformational change in the DNA. The increased accessibility of solvent to the SWNT surface induces a red-shift in fluorescence emission, , while changes to the periodic surface potential on the nanotube surface modulate exciton lifetimes, which results in an increase in fluorescence emission . This increase in fluorescence is likely dependent on the formation of a highly ordered arrangement of the polymer on the SWNT surface, corroborated by the dependence on DNA surface coverage density we observe.…”

Electrostatic Assemblies of Single-Walled Carbon Nanotubes and Sequence-Tunable Peptoid Polymers Detect a Lectin Protein and Its Target Sugars

“…Prior work has confirmed that this stabilization effect represents a strong and selective binding interaction between the molecular analyte and the polymer-SWNT assembly. 38 To confirm we may attribute the additional stability provided to ProLoop-SWNT assemblies by selective binding of WGA, we showed that WGA by itself does not associate strongly to SWNT, and showed that attempted assembly of WGA with SWNT produced a highly unstable complex (SI. 15).…”

Imaging striatal dopamine release using a nongenetically encoded near infrared fluorescent catecholamine nanosensor

“…This technology makes use of an SWNT noncovalently functionalized with single-strand (GT) 6 oligonucleotides to form the nIR catecholamine nanosensor (nIRCat). nIRCats respond to DA with Δ F / F of up to 24-fold in the fluorescence emission window of 1000 to 1300 nm ( 24 ), a wavelength range that has shown utility for noninvasive through-skull imaging in mice ( 25 ).…”