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arXiv · 2607.14780

Ultraviolet direct absorption microscopy for single particle protein/nucleic acid quantification

C. J. Richards·D. van de Lockand·D. Wolters·M. Liebel
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Abstract

Bio-nanoparticles are pivotal to next generation nanotherapeutics, but providing single-particle biomolecular characterization remains a crucial challenge. Herein we present ultra-violet direct absorption microscopy (UV-DAM) to tackle this challenge. UV-DAM is based on a tailored illumination scheme for absorption-only imaging, combined with a custom deep UV light source. Combined, they provide biomolecular specificity with single particle sensitivity. As such, UV-DAM provides rapid, label-free, high resolution, biochemical imaging. Enabled by these capabilities, we implement the classic nucleic acid:protein absorption assay at the single virus level where we demonstrate UV-DAM's ability to distinguish empty from DNA-loaded viral capsids based on bimolecularly specific absorption fingerprints. UV-DAM presents the translation from bulk UV-visible spectrometry to single-particle assessment, a crucial advancement for nanomedicine characterization where particle loading efficiencies are often heterogenous. Beyond this, UV-DAM is applicable to a wide range of nanomaterials or investigation of biological process with high spatio-temporal resolution and intrinsic molecular contrast.

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C. J. Richards, D. van de Lockand, D. Wolters, M. Liebel. 2026-07-16. Ultraviolet direct absorption microscopy for single particle protein/nucleic acid quantification. https://arxiv.org/abs/2607.14780

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