Engineered polymer nanoparticles incorporating L-amino acid groups as affinity reagents for fibrinogen

Abstract Synthetic polymer hydrogel nanoparticles (NPs) were developed to function as abiotic affinity reagents for fibrinogen. These NPs were made using both temperature-sensitive N-isopropyl acrylamide (NIPAm) and L-amino acid monomers. Five kinds of L-amino acids were acryloylated to obtain functional monomers: L-phenylalanine (Phe) and L-leucine (Leu) with hydrophobic side chains, L-glutamic acid (Glu) with a negative charge, and L-lysine (Lys) and L-arginine (Arg) with positive charges. After incubating the NPs with fibrinogen, γ-globulin, and human serum albumin (HSA) respectively, the NPs that incorporated AArg monomers (AArg@NPs) showed the strongest and most specific binding affinity to fibrinogen, when compared with γ-globulin and HSA. Additionally, the fibrinogen-AArg binding model had the best docking scores, and this may have been due to the interaction of positively charged AArg@NPs to the negatively charged fibrinogen D domain. The specific adsorption of AArg@NPs to fibrinogen was also confirmed by the immunoprecipitation assay, as the AArg@NPs selectively trapped the fibrinogen from a human plasma protein mixture. AArg@NPs had a strong selectivity for, and specificity to, fibrinogen and may be developed as a potential human fibrinogen-specific affinity reagent.