CRISPR-Cas9 is considered a revolutionary gene editing tool, but its applications are limited by a lack of methods by which it can be safely and efficiently delivered into cells. Recently, a research team has constructed a highly flexible CRISPR-Cas9 carrier using aminated polyrotaxane (PRX) that can not only bind with the unusual structure of Cas9 and carry it into cells, but can also protect it from intracellular degradation by endosomes.