Locally Excited State–Charge Transfer State Coupled Dyes as Optically Responsive Neuron Firing Probes

Abstract

A selection of NIR-optically responsive neuron probes was produced comprising of a donor julolidyl group connected to a BODIPY core and several different styryl and vinylpyridinyl derived acceptor moieties. The strength of the donor-acceptor interaction was systematically modulated by altering the electron withdrawing nature of the aryl unit. The fluorescence quantum yield was observed to decrease as the electron withdrawing effect of the aryl subunit increased in line with changes of the Hammett parameter. The effectiveness of these fluorophores as optically responsive dyes for neuronal imaging was assessed by measuring the toxicity and signal-to-noise ratio (SNR) of each dye. A great improvement of SNR was obtained when compared to the first-generation BODIPY-based voltage sensitive dyes with concomitant toxicity decrease. The mechanism for the optical response is disparate from conventional cyanine-based dyes, opening up a new way to produce effective voltage sensitive dyes that respond well into the NIR region.

Devising Efficient Red‐Shifting Strategies for Bioimaging: A Generalizable Donor‐Acceptor Fluorophore Prototype

“…This might be detrimental to brightness (see below). For example, many red and NIR dyes have been built on the well‐known fluorophore scaffolds (GFP, rhodamine, cyanine, coumarin, BODIPY featured in Figure b) to take advantage of their appealing properties such as high FQY. The push‐pull structure is usually established by incorporating the electron‐donating groups (EDGs) and electron‐withdrawing groups (EWGs) on the opposite ends of the parent backbone.…”

Voltage-induced fluorescence lifetime imaging of a BODIPY derivative in giant unilamellar vesicles as potential neuron membrane mimics

“…The main electronic transition is significantly broadened and shifted to 648 nm. Unlike similar julolidine BODIPY compounds, where the two units are connected at the meso-BODIPY position and display an additional broad charge transfer CT band in the red/near-IR region, 14 no obvious CT band is observed for aJBD in DMF. The intense fluorescence observed in the very low polarity solvent hexane is almost extinguished in DMF, supporting that an efficient quenching process is introduced.…”

Enhanced in vivo Optical Imaging of the Inflammatory Response to Acute Liver Injury in C57BL/6 Mice Using a Highly Bright Near‐Infrared BODIPY Dye

“…Solvents for spectroscopic investigations were of the highest purity available. The title compound BD was available from previous studies [17] and purified by column chromatography before use and its purity checked by NMR spectroscopy.Q uantum yields of fluorescence were measured by the comparison method using AzaBODIPY (5,5-difluoro-3,7bis(4-methoxyphenyl)-1,9-5H-4l4,5l4-dipyrrolo[1,2-c:2',1f[1,3,5,2]triazaborinine). [24] Selected data are shown in Table S1.…”

“…In our line of research into producing optically responsiven euron firing probest he neutralB ODIPY derivative BD (Figure 1) was developed. [17] As part of these studies it was noted that BD localiseds trongly in membranes with intense fluorescencei nt he near-infrared region. [18] Perceiving the potential for BD to track inflammatorycells using an IVIS to monitor acute liver damage, the dye was directly compared with CD under identical conditions; BD outperforms CD in brightness and importantly,d oes not causec ell apoptosis.…”