Protein Nanoparticle Fabrication for Optimized Reticuloendothelial System Evasion and Tumor Accumulation

Nanoparticles (NPs) of protein-based materials have become one of the most promising candidates for drug carriers in drug-delivery systems because of their in vivo nontoxicity, biodegradability, compatibility with hydrophilic drugs, and adaptability to the human body. Many studies have investigated the fabrication of protein NPs from human serum albumin (HSA) as a new drug carrier. It is important for these NPs to remain in the blood until they reach their therapeutic target to achieve the desired effect; the quicker the clearance of drugs from the body, the shorter is the residence time of drugs in the body, which eventually reduces drug efficacy. Macrophage uptake is a major mechanism for clearance of NPs from the body, so, reducing the degree of macrophage uptake is a major challenge in drug-delivery systems. Original studies of HSA NP uptake by macrophages showed that denatured HSA and HSA NPs synthesized with 80% (v/v) ethanol showed a high degree of macrophage uptake. We found that HSA NPs synthesized with lower ethanol content at pH 7 showed lower macrophage uptake in in vitro macrophage cellular uptake experiments. The effects of the preparation parameters of ethanol concentration, pH, and glutaraldehyde on the macrophage uptake of NPs were thoroughly studied. This newly developed protein NP with lower macrophage uptake has potential application as a drug carrier for many delivery systems.