Rhodamine-based caged dye for aqueous MTV with green lasers

Implantable photonic neural probes with 3D-printed microfluidics and applications to uncaging

“…The luminescence of a photoactivatable fluorophore is prevented by cage groups, which can be removed from the fluorophore molecule by photocleavage of the chemical bonds. The peak absorption wavelength of cage groups is typically UV or near-UV (Fort and Bardet, 2021 ). Here, we focus on CMNB-caged fluorescein, which has two CMNB cage groups bonded to the fluorescein molecule, and photocleavage of the cages at 405 nm allows fluorescence emission upon excitation with blue light (Chan et al, 2016 ).…”

“…In addition, a 473-nm emission wavelength overlaps the excitation spectrum of fluorescein, enabling simple beam profile measurements in fluorescein solutions. Probe 2 ( Figure 2F ) had a higher optical transmission at a 405-nm wavelength, a widely used uncaging wavelength (Fort and Bardet, 2021 ), and was used for the uncaging experiments (Sections 5, 7). Additional differences between Probes 1 and 2 include ( Supplementary Figure 1 ): (1) fabrication on different wafers, (2) Probes 1 and 2 had nominal SiN thicknesses of 200 and 150 nm, respectively, (3) Probe 2 had an extra SiN waveguide layer for defining bi-layer edge couplers, as in Lin et al ( 2021 ) and Sacher et al ( 2023 ), and (4) Probe 1 had a single column of four grating emitters (170 μm pitch) and Probe 2 had 2 columns of grating emitters (16 emitters in total, 85 μm and 110 μm lateral and longitudinal inter-grating pitches, respectively).…”

“…Photoactivatable caged fluorophores or bioactive agents are initially non-fluorescent or inert due to the cage compound, and photolysis by UV or near-UV irradiation cleaves the chemical bond between the cage group and the caged compound, releasing the fluorophores or bioactive agents to become fluorescent or active again. Photoactivatable fluorophores have been widely used in high-resolution photoactivated localization microscopy (Hess et al, 2009 ; Hauke et al, 2017 ), fluid dynamics studies (Fort and Bardet, 2021 ), and molecular transport tracing in biological tissues (Martens et al, 2004 ; Schuster et al, 2017 ). Photoactivatable neurotransmitters (e.g., caged glutamate) are also widely used to mimic the temporal and spatial properties of physiological responses of neural circuits (Trigo et al, 2009 ).…”