posted on 2024-02-12, 13:04authored byChen Ma, Jennifer Maria Mohr, German Lauer, Justus Tom Metternich, Krisztian Neutsch, Tim Ziebarth, Andreas Reiner, Sebastian Kruss
Neurotransmitters
are important signaling molecules in the brain
and are relevant in many diseases. Measuring them with high spatial
and temporal resolutions in biological systems is challenging. Here,
we develop a ratiometric fluorescent sensor/probe for catecholamine
neurotransmitters on the basis of near-infrared (NIR) semiconducting
single wall carbon nanotubes (SWCNTs). Phenylboronic acid (PBA)-based
quantum defects are incorporated into them to interact selectively
with catechol moieties. These PBA-SWCNTs are further modified with
poly(ethylene glycol) phospholipids (PEG-PL) for biocompatibility.
Catecholamines, including dopamine, do not affect the intrinsic E11 fluorescence (990 nm) of these (PEG-PL-PBA-SWCNT) sensors.
In contrast, the defect-related E11* emission (1130 nm)
decreases by up to 35%. Furthermore, this dual functionalization allows
tuning selectivity by changing the charge of the PEG polymer. These
sensors are not taken up by cells, which is beneficial for extracellular
imaging, and they are functional in brain slices. In summary, we use
dual functionalization of SWCNTs to create a ratiometric biosensor
for dopamine.