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bioRxiv · 10.1101/2025.06.01.657319

Self-Assembled siRNA-Gold Supraclusters Detected at the Single-Molecule Level in the NIR-II Window

Ayed, Z.·Martin Munoz, B.·Vandekerckhove, C. I.·Faure, V.·Ali, S. N. S.·Coll, J.-L.·Cognet, L.·Le Guevel, X.
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Abstract

Gold nanoclusters (AuNCs) possess unique photophysical properties that make them excellent candidates for advanced bioimaging and single-particle detection. In this work, we report the self-assembly of highly emissive, positively charged NIR-II AuNCs stabilized by cysteamine, directed by small interfering RNA (siRNA), which serves as both a structural and electrostatic modulator. The resulting supramolecular assemblies exhibit quasi-spherical morphologies around 100 nm in diameter, with outstanding colloidal stability, photostability, and enzymatic resistance. Their strong photoluminescence, extending up to 1400 nm, enables robust single- particle detection in solution. Spectroscopic and structural analyses--including fluorescence spectroscopy, small-angle X-ray scattering (SAXS), and single-particle tracking--highlight the pivotal role of siRNA in tuning the assembly process via charge balance and concentration- dependent interactions. Beyond providing insights into the structural and photophysical behavior of nucleic acid-guided AuNC assemblies, these results underscore their promise as multifunctional nanoplatforms for integrated imaging and gene-silencing therapies in biophotonic and theranostic applications.

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Ayed, Z., Martin Munoz, B., Vandekerckhove, C. I., Faure, V., Ali, S. N. S., Coll, J.-L., Cognet, L., Le Guevel, X.. 2025-06-03. Self-Assembled siRNA-Gold Supraclusters Detected at the Single-Molecule Level in the NIR-II Window. https://doi.org/10.1101/2025.06.01.657319

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