Bright fluorophores in the near-infrared and shortwave infrared (SWIR) regions of the electromagnetic spectrum are essential for optical imaging in vivo. In this work, we utilized a 7-dimethylamino flavylium heterocycle to construct a panel of novel red-shifted polymethine dyes, with emission wavelengths from 680 to 1045 nm. Photophysical characterization revealed that the 1- and 3-methine dyes display enhanced photostability and the 5- and 7-methine dyes exhibit exceptional brightness for their respective spectral regions. A micelle formulation of the 7-methine facilitated SWIR imaging in mice. This report presents the first polymethine dye designed and synthesized for SWIR in vivo imaging.
Photodynamic therapy (PDT) requires a photosensitizer, light, and oxygen to induce cell death. The majority of efforts to advance PDT focus only on the first two components. Here, we employ perfluorocarbon nanoemulsions to simultaneously deliver oxygen and a photosensitizer. We find that the implementation of fluorous soluble photosensitizers enhances the efficacy of PDT.
The bioorthogonal nature of perfluorocarbons provides a unique platform for introducing dynamic nano-and microdroplets into cells and organisms. To monitor the localization and deformation of the droplets, fluorous soluble fluorophores that are compatible with standard fluorescent protein markers and applicable to cells, tissues, and small organisms are necessary. Here, we introduce fluorous cyanine dyes that represent the most red-shifted fluorous soluble fluorophores to date. We study the effect of covalently appended fluorous tags on the cyanine scaffold and evaluate the changes in photophysical properties imparted by the fluorous phase. Ultimately, we showcase the utility of the fluorous soluble pentamethine cyanine dye for tracking the localization of perfluorocarbon nanoemulsions in macrophage cells and for measurements of mechanical forces in multicellular spheroids and zebrafish embryonic tissues. These studies demonstrate that the red shifted cyanine dyes offer spectral flexibility in multiplexed imaging experiments and enhanced precision in force measurements.
Bright fluorophores in the near‐infrared and shortwave infrared (SWIR) regions of the electromagnetic spectrum are essential for optical imaging in vivo. In this work, we utilized a 7‐dimethylamino flavylium heterocycle to construct a panel of novel red‐shifted polymethine dyes, with emission wavelengths from 680 to 1045 nm. Photophysical characterization revealed that the 1‐ and 3‐methine dyes display enhanced photostability and the 5‐ and 7‐methine dyes exhibit exceptional brightness for their respective spectral regions. A micelle formulation of the 7‐methine facilitated SWIR imaging in mice. This report presents the first polymethine dye designed and synthesized for SWIR in vivo imaging.
Perfluorocarbon (PFC)
nanoemulsions, droplets of fluorous solvent stabilized by surfactants
dispersed in water, are simple yet versatile nanomaterials. The orthogonal
nature of the fluorous phase promotes the formation of nanoemulsions
through a simple, self-assembly process while simultaneously encapsulating
fluorous-tagged payloads for various applications. The size, stability,
and surface chemistry of PFC nanoemulsions are controlled by the surfactant.
Here, we systematically study the effect of the hydrophilic portion
of polymer surfactants on PFC nanoemulsions. We find that the hydrophilic
block length and identity, the overall polymer hydrophilic/lipophilic
balance, and the polymer architecture are all important factors. The
ability to modulate these parameters enables control over initial
size, stability, payload retention, cellular internalization, and
protein adsorption of PFC nanoemulsions. With the insight obtained
from this systematic study of polymer amphiphiles stabilizing PFC
nanoemulsions, design features required for the optimal material are
obtained.
The clinical utility of emulsions as delivery vehicles is hindered by a dependence on passive release. Stimuliresponsive emulsions overcome this limitation but rely on external triggers or are composed of nanoparticle-stabilized droplets that preclude sizes necessary for biomedical applications. Here, we employ cleavable poly(2-oxazoline) diblock copolymer surfactants to form perfluorocarbon (PFC) nanoemulsions that release cargo upon exposure to glutathione. These surfactants allow for the first example of redoxresponsive nanoemulsions in cellulo. A noncovalent fluorous tagging strategy is leveraged to solubilize a GFP plasmid inside the PFC nanoemulsions, whereupon protein expression is achieved selectively when employing a stimuli-responsive surfactant. This work contributes a methodology for nonviral gene delivery and represents a general approach to nanoemulsions that respond to endogenous stimuli.
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