Effect of the Emulsion Solvent Evaporation Technique Cosolvent Choice on the Loading Efficiency and Release Profile of Anti-CD47 from PLGA Nanospheres

Side effects associated with using antibodies as therapeutics can limit systemic administration at the high concentrations often needed for therapeutic impact. Thus, therapeutic antibodies are usually considered for targeted delivery. Antibody encapsulation in polymeric nanoparticles via the emulsion-based nanofabrication methods typically yields low loading efficiencies. Therefore, the fabrication techniques need to be modified to maximize the loading efficiency of antibodies. In this work, we utilized various cosolvents with the emulsion solvent evaporation technique to improve the loading efficiency of anti-CD47, a therapeutic antibody used to block CD47 activity in atherosclerotic plaques and cancer lesions.

The double emulsion solvent evaporation technique was used to fabricate anti-CD47-loaded polymeric nanoparticles. The primary oil phase solvent, chloroform, was doped with different cosolvents, including ethyl acetate, acetonitrile, ethanol, and methanol, to investigate the impact of cosolvents on the loading efficiency of anti-CD47. The release profile and loading efficiency were quantified by measuring the fluorescence signal of the released antibody. The activity of the antibody released from particles fabricated in the presence of the cosolvent was confirmed by quantifying its adherence to red blood cells. Ethyl acetate was the optimum cosolvent, improving the loading efficiency of anti-CD47 in poly(lactic-co-glycolic acid), PLGA, nanoparticles to 90% or higher, and the antibody was found to retain its activity after being released from nanoparticles.

Our results demonstrate that a minimum amount of a cosolvent with minimal hydrophilicity can stabilize the antibody in the oil phase; thus, improving the antibody's loading efficiency significantly.