The invention relates to a Cas-based, preferably Cas9-based nuclease complex, wherein the guide RNA sequence is irreversibly crosslinked to the Cas9 protein. The cross-link may be a covalent binding or a non-covalent binding. Such a complex may be used in delivering constructs to a cell that are capable of gene-editing. Use of this cross-linked complex will result in less off-targeting.
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