Fig. 3.

CRISPR/Cas9 delivery system being plasmid protein, mRNA or DNA. The elements of this delivery system (being protein, mRNA or DNA) are delivered into cells to win a determined gene-editing performance. During delivery mediated by non-viral nano-particle, the encapsulation occurs for each element in nano-carriers to intracellularly uptake. Following the endocytosis, the nanoparticles inside the cell must move away from the endosome/ lysosome. To deliver the plasmid DNA, the DNA must be transported to the nucleus, and the pathway of native transcription of target cells needs be used for gene transcription to the mRNA, the mRNA transportation to the cytoplasm and then translation to the protein. The protein returns to the nucleus in which the CRISPR pathway influence the genomic DNA of the cell. To deliver the mRNA, it must be liberated in the cytosol to be translated to protein. Transient and instantaneous delivery of the protein results in the fastest initiation of gene editing, thus preventing the permanent integration of CRISPR genes into the host genome.