Bioactivated and PEG-Protected Circa 2 nm Gold Nanoparticles for in Cell Labelling and Cryo-Electron Microscopy.
Fiche publication
Date publication
avril 2023
Journal
Small methods
Auteurs
Membres identifiés du Cancéropôle Est :
Dr CIANFERANI Sarah, Dr SCHULTZ Patrick, Dr ZUBER Guy, Dr DONZEAU Mariel
Tous les auteurs :
Groysbeck N, Hanss V, Donzeau M, Strub JM, Cianférani S, Spehner D, Bahri M, Ersen O, Eltsov M, Schultz P, Zuber G
Lien Pubmed
Résumé
Advances in cryo-electron microscopy (EM) enable imaging of protein assemblies within mammalian cells in a near native state when samples are preserved by cryogenic vitrification. To accompany this progress, specialized EM labelling protocols must be developed. Gold nanoparticles (AuNPs) of 2 nm are synthesized and functionalized to bind selected intracellular targets inside living human cells and to be detected in vitreous sections. As a proof of concept, thioaminobenzoate-, thionitrobenzoate-coordinated gold nanoparticles are functionalized on their surface with SV40 Nuclear Localization Signal (NLS)-containing peptides and 2 kDa polyethyleneglycols (PEG) by thiolate exchange to target the importin-mediated nuclear machinery and facilitate cytosolic diffusion by shielding the AuNP surface from non-specific binding to cell components, respectively. After delivery by electroporation into the cytoplasm of living human cells, the PEG-coated AuNPs diffuse freely in the cytoplasm but do not enter the nucleus. Incorporation of NLS within the PEG coverage promotes a quick nuclear import of the nanoparticles in relation to the density of NLS onto the AuNPs. Cryo-EM of vitreous cell sections demonstrate the presence of 2 nm AuNPs as single entities in the nucleus. Biofunctionalized AuNPs combined with live-cell electroporation procedures are thus potent labeling tools for the identification of macromolecules in cellular cryo-EM.
Mots clés
bioconjugation, electroporation, gold labeling, gold particles, nuclear import, transduction
Référence
Small Methods. 2023 04 10;:e2300098