CRISPR/Cas technology has revolutionised the gene-editing field. This system comprises both DNA and RNA-targeting proteins. Cas9 and Cas12a are the most widely used DNA-targeting nucleases. They are both able to recognise complementary DNA sequences via their guide RNA and cleave them. DNA cleavage and the subsequent DNA repair can be exploited for knock-in and knock-out generation. However, the systemic delivery of CRISPR nucleases and their guides constitutes a major challenge limiting their therapeutic potential. So far, viral methods are the preferred approach for CRISPR delivery. However, they present important drawbacks such as low loading capacity and immunogenicity. Nanotechnology constitutes an interesting alternative to overcome these obstacles. This project is focused on the design of biocompatible nanostructures that allow for a safer and more efficient delivery of CRISPR ribonucleoproteins. In particular we have developed a strategy for the electrostatic and covalent conjugation of Cas9 and Cas12a nucleases to iron oxide magnetic nanoparticles (MNPs). MNP-Cas nanocomplexes are efficiently internalised by different cell lines and, once internalised, result in gene editing rates comparable to those obtained with commercially available delivery agents.