What is the difference between CRISPR and ZFNs (zinc finger nucleases)?
In contrast to CRISPR, the process of transfecting and selecting cells can be quite arduous and laborious. Also, the cost of multiple protein-DNA complex formation and recognition can be quite expensive when compared to merely injecting RNA targeted to the RISC.
Reference:
1. J. Doudna and E.J. Sontheimer. “The Use of CRISPR/Cas9, ZFNs, and TALENs in Generating Site-Specific Genome Alterations,” Methods in Enzymology 2014.