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“O-PTIR measurements of biological samples under aqueous conditions are possible in principle and may help in studying the metabolism of cells better than using dry cells. Live and fixed cells can be effectively measured in water, as demonstrated here.”
Reporting in Elsevier, Sensors and Actuators: B Chemical, researchers at Jagiellonian University demonstrate the superior capabilities of optical-photothermal infrared (O-PTIR) and Raman spectroscopy for comprehensive single-cell metabolic analysis. Korona et al. address critical limitations in current metabolic imaging approaches, where traditional techniques suffer from poor spatial resolution, sample preparation requirements, and inability to perform measurements in aqueous environments essential for live cell studies. The research team needed to develop a robust platform capable of tracking multiple metabolic pathways simultaneously while maintaining subcellular resolution in physiologically relevant conditions.
The authors report that O-PTIR spectroscopy successfully achieved submicron spatial resolution imaging of lipid metabolism in both hydrated and dried endothelial cells using deuterated and azido-tagged palmitic acid probes. They demonstrate that O-PTIR measurements of biological samples under aqueous conditions revealed distinct spectral differences within cellular compartments, with strong signals detected from deuterated fatty acids at 2200 and 2100 cm⁻¹, and triacylglycerols at 1750 cm⁻¹.
The researchers report that aqueous environments preserved subcellular structures and chemical composition, providing reliable biomolecular information about cellular metabolic states.
The authors further demonstrate O-PTIR’s effectiveness through ratiometric imaging approaches, where calculation of 1750/1555 cm⁻¹ and 1735/1655 cm⁻¹ ratios successfully highlighted lipid-rich areas within the cytoplasm. They report that single-band imaging at specific wavenumbers corresponding to lipid esters and newly synthesized lipids provided clear visualization of metabolic processes, with excellent agreement between spectral data and imaging results confirming the accumulation of labeled fatty acids in lipid droplets.
The authors conclude that O-PTIR spectroscopy represents a transformative analytical platform for metabolic research, offering unique advantages over conventional techniques through its ability to perform high-resolution measurements in aqueous conditions without sample preparation requirements. They emphasize that this non-destructive approach enables comprehensive metabolomics studies that would be impossible with traditional methods, establishing O-PTIR as an essential tool for advancing single-cell metabolic characterization and future medical applications.
Wiktoria Korona et al,
Jagiellonian University, Krakow, Poland
