Fluorescence-Detected Mid-Infrared Photothermal Microscopy

Minghe Li; Aleksandr Razumtcev; Ruochen Yang; Youlin Liu; Jiayue Rong; Andreas C. Geiger; Romain Blanchard; Cristian Pfluegl; Lynne S. Taylor; Garth J. Simpson

arXiv · 2104.02900

Fluorescence-Detected Mid-Infrared Photothermal Microscopy

Minghe Li·Aleksandr Razumtcev·Ruochen Yang·Youlin Liu·Jiayue Rong·Andreas C. Geiger·Romain Blanchard·Cristian Pfluegl·Lynne S. Taylor·Garth J. Simpson

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Abstract

We demonstrate instrumentation and methods to enable fluorescence-detected photothermal infrared (F-PTIR) microscopy, 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. 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 absorption in spin-cast films.

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Minghe Li, Aleksandr Razumtcev, Ruochen Yang, Youlin Liu, Jiayue Rong, Andreas C. Geiger, Romain Blanchard, Cristian Pfluegl, Lynne S. Taylor, Garth J. Simpson. 2021-04-07. Fluorescence-Detected Mid-Infrared Photothermal Microscopy. https://arxiv.org/abs/2104.02900

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