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Download fileFluorescence-Detected Mid-Infrared Photothermal Microscopy
journal contribution
posted on 2021-07-16, 19:11 authored by Minghe Li, Aleksandr Razumtcev, Ruochen Yang, Youlin Liu, Jiayue Rong, Andreas C. Geiger, Romain Blanchard, Christian Pfluegl, Lynne S. Taylor, Garth J. SimpsonWe demonstrate instrumentation and
methods to enable fluorescence-detected
photothermal infrared (F-PTIR) microscopy and then demonstrate the
utility of F-PTIR to characterize the composition within phase-separated
domains of model amorphous solid dispersions (ASDs) induced by water
sorption. In F-PTIR, temperature-dependent changes in fluorescence
quantum efficiency are shown to sensitively report on highly localized
absorption of mid-infrared radiation. The spatial resolution with
which infrared spectroscopy can be performed is dictated by fluorescence
microscopy, rather than the infrared wavelength. Intrinsic ultraviolet
autofluorescence of tryptophan and protein microparticles enabled
label-free F-PTIR microscopy. Following proof of concept F-PTIR demonstration
on model systems of polyethylene glycol (PEG) and silica gel, F-PTIR
enabled the characterization of chemical composition within inhomogeneous
ritonavir/polyvinylpyrrolidone-vinyl acetate (PVPVA) amorphous dispersions.
Phase separation is implicated in the observation of critical behaviors
in ASD dissolution kinetics, with the results of F-PTIR supporting
the formation of phase-separated drug-rich domains upon water sorption
in spin-cast films.