Liquid Droplet Formation and Facile Cytosolic Translocation of IgG in the Presence of Attenuated Cationic Amphiphilic Lytic Peptides

Abstract Fc region binding peptide conjugated with attenuated cationic amphiphilic lytic peptide L17E trimer [FcB(L17E) 3 ] was designed for immunoglobulin G (IgG) delivery into cells. Particle‐like liquid droplets were generated by mixing Alexa Fluor 488 labeled IgG (Alexa488‐IgG) with FcB(L17E) 3 . Droplet contact with the cellular membrane led to spontaneous influx and distribution of Alexa488‐IgG throughout cells in serum containing medium. Involvement of cellular machinery accompanied by actin polymerization and membrane ruffling was suggested for the translocation. Alexa488‐IgG negative charges were crucial in liquid droplet formation with positively charged FcB(L17E) 3 . Binding of IgG to FcB(L17E) 3 may not be necessary. Successful intracellular delivery of Alexa Fluor 594‐labeled anti‐nuclear pore complex antibody and anti‐mCherry‐nanobody tagged with supernegatively charged green fluorescence protein allowed binding to cellular targets in the presence of FcB(L17E) 3 .