Carboxymethyl Dextran Coated Iron Oxide Magnetic Nanoparticles as Vehicles for CRISPR Ribonucleoproteins

The efficient and safe intracellular delivery of CRISPR ribonucleoproteins (RNPs) remains a major challenge for the development of genome editing strategies. Magnetic iron oxide nanoparticles (MNPs) offer an attractive and biocompatible delivery platform. However, their use for the delivery of functional CRISPR RNPs remains comparatively underexplored. Here, we developed carboxymethyl dextran (CMD)-coated MNPs as non-viral carriers for Cas9 and Cas12a RNPs. Nanocomplexes were formed through electrostatic interactions, without the need for chemical coupling reagents or additional surface functionalization. Both RNPs efficiently associated with MNPs, and the resulting nanocomplexes exhibited stable physicochemical properties and retained their cargo in serum-supplemented culture medium for up to 24 hours. Cellular uptake was confirmed by microscopy, while biocompatibility assays revealed no overt cytotoxicity. Functional genome editing was demonstrated at reporter and endogenous gene loci in HEK-293T cells, as well as in primary human dermal fibroblasts. Finally, we explored the therapeutic potential of this platform for recessive dystrophic epidermolysis bullosa (RDEB) by targeting COL7A1 exon 80, with the aim of removing the prevalent c.6527insC mutation while preserving the reading frame. Cas9 RNP nanocomplexes enabled exon 80 deletion. These findings establish CMD-coated MNPs as a versatile platform for the delivery of Cas9 and Cas12a RNPs and support further investigation of magnetic nanoparticle-mediated genome editing for inherited skin disorders.