Work

Minimally Invasive Infrared Imaging of Caenorhabditis elegans Enabled by Reversible Chemical Immobilization and Second-Derivative Spectral Mapping

Year: 2026

Type: article

Abstract: The nematode Caenorhabditis elegans is a widely used model organism, yet its infrared (IR) spectroscopic characterization has been limited by motion and strong water absorption in the mid-infrared region. Here, we establish a minimally invasive mid-infrared imaging method for C. elegans by combining reversible immobilization with sodium azide (NaN3) and measurements in deuterium oxide (D2O). NaN3 effectively suppressed locomotion without inducing irreversible physiological damage, enabling high-quality acquisition of IR images. Mid-IR hyperspectral data were analyzed to extract lipid- and protein-specific bands for each pixel, followed by second-derivative analysis of the Amide I band to resolve protein secondary-structure components. This allowed decomposition of α-helical (1658 cm–1) and β-sheet (1628 cm–1) components and visualization of their spatial distributions in vivo. Notably, the 1628 cm–1/1658 + 1628 cm–1 ratio was significantly lower in the anterior region of the head, indicating region-specific differences in protein composition. Following imaging, worms recovered normal locomotion and retained reproductive capability, demonstrating that the method is minimally invasive and reversible. Overall, this work establishes a quantitative IR imaging framework for analyzing protein structure in living organisms at the micrometer scale. The combination of reversible immobilization and second-derivative spectral narrowing provides a powerful approach for investigating spatial variations in biomolecular structure in vivo.

Source: ACS Omega

DOI: 10.1021/acsomega.6c03485