Mid-infrared metabolic imaging with vibrational probes

Abstract

Understanding metabolism is indispensable to unraveling the mechanistic basis of many physiological and pathological processes. However, in situ metabolic imaging tools are still lacking. Herein we introduce a framework for mid-infrared (MIR) metabolic imaging by coupling the emerging high-information-throughput MIR microscopy with specifically designed IR-active vibrational probes. Three categories of small vibrational tags including azide bond, 13 C-edited carbonyl bond and deuterium-labeled probes are presented to interrogate various metabolic activities in cells, small organisms and mice. Two MIR imaging platforms are implemented including broadband Fourier transform infrared (FTIR) microscopy and discrete frequency infrared (DFIR) microscopy with a newly incorporated spectral region (2000–2300 cm −1 ). Our technique is uniquely suited for metabolic imaging with high-information-throughput. In particular, we performed single-cell metabolic profiling including heterogeneity characterization, and large-area metabolic imaging at tissue/organ level with rich spectral information.

Switchable stimulated Raman scattering microscopy with photochromic vibrational probes

“…Second, a series of switchable SRS probes with resolvable Raman peaks need to be achieved to enable super-multiplexing, and ideally super-resolution SRS with the principle of RESOLFT microscopy. Furthermore, with our design principle, other types of photochromic molecules and local chemical bonds may also be found for vibrational switching, which not only apply to Raman based microscopy modalities, but are also expected to benefit IR based imaging techniques 44 , 45 .…”

Monitoring the effects of chemical stimuli on live cells with metasurface-enhanced infrared reflection spectroscopy

“…IR spectro-chemical imaging of live cells is a powerful tool for analyzing biological samples such as tissue biopsies and fixed/live cells ( 31, 32, 58 ). For example, small quantities of highly heterogeneous cancer cells collected using minimally invasive biopsies benefit from imaging with cell-level imaging because drug-resistant minority of cells can be detected in a mixed population ( 70 – 72 ). Here, we demonstrate the suitability of MEIRS to spectroscopic imaging of sparsely seeded live A431 cells cultured on a metasurface.…”

Bond-selective imaging by optically sensing the mid-infrared photothermal effect

“…The Raman probes such as alkyne have been extensively explored and have shown applications in the study of metabolic activities in cells and tissue ( 103 ). The incorporation of IR probes in various sample has also been reported with IR spatial resolution ( 104 ). Therefore, coupling the IR probes into the MIP system would enable functional studies of small molecules at high resolution.…”