Table 1.

Different strategies for CRISPR/Cas9 delivery are shown below, with each strategy having its own advantages and limitation

Delivery Strategy		Definition and/or Use	Source of Cas9 Protein	Application	Limitations	Text References
Physical Methods	Microinjection	Use of a glass micropipette to inject a liquid substance at a microscopic	DNA plasmid; mRNA (Cas9 + sgRNA); protein (RNP)	in vitro, ex vivo	Not possible on in vivo experiment	46–47
	Electroporation	Use of electrical pulse to create temporary pores in cell membranes through which substances can pass into cells	DNA plasmid; mRNA (Cas9 + sgRNA); protein (RNP)	in vitro, ex vivo	Difficult to perform in in vivo experiment	46–47
Viral Vectors	Adeno-associated viruses [AAVs]	Vectors for genetic information; has a high gene editing capacity	DNA plasmid	in vivo	Cloning capacity is limited	46–47, 65
	Adenoviruses [AVs]	Vectors for genetic information; has a high gene editing capacity	DNA plasmid	in vitro, ex vivo	May cause off-target effects	46–47
	Lentiviruses [LVs]	Vectors for genetic information; has a high gene editing capacity	DNA plasmid	in vitro, ex vivo	May cause off-target effects	46–47
Non-viral Vectors	Lipid-based Nanoparticles	Composed of lipids; size is of spherical form and size ranges from 10 to 1000 nm	DNA plasmid; mRNA (Cas9 + sgRNA)	in vitro, in vivo	Efficiency depends on cell types	73, 76
	Gold Nanoparticles [AuNPs]	Composed of the element gold; size ranges from 1 to 100 nm	Protein (RNP)	in vitro, in vivo	Efficiency depends on cell types	98, 99
	Iron Oxide Nanoparticles [IONPs]	Composed of magnetic compounds (magnetite/maghemite); size ranges from 1 to 100 nm	DNA plasmid	in vitro, in vivo	Efficiency depends on cell types	103
	Mesoporous Silica Nanoparticles [MSNs]	Comprised of silicon oxide (SiO2); pore diameter ranges from 2 to 50 nm	DNA plasmid	in vitro, in vivo	Efficiency depends on cell types	105, 106