title: Complement activation and cell uptake responses toward polymer-functionalized protein nanocapsules.
abstract: Self-assembling protein nanocapsules can be engineered for various bionanotechnology applications. Using the dodecahedral scaffold of the E2 subunit from pyruvate dehydrogenase, we introduced non-native surface cysteines for site-directed functionalization. The modified nanoparticle's structural, assembly, and thermostability properties were comparable to the wild-type scaffold (E2-WT), and after conjugation of poly(ethylene glycol) (PEG) to these cysteines, the nanoparticle remained intact and stable up to 79.7 ± 1.8 °C. PEGylation of particles reduced uptake by human monocyte-derived macrophages and MDA-MB-231 breast cancer cells, with decreased uptake as PEG chain length is increased. In vitro C4-depletion and C5a-production assays yielded 97.6 ± 10.8% serum C4 remaining and 40.1 ± 6.0 ng/mL C5a for E2-WT, demonstrating that complement activation is weak for non-PEGylated E2 nanoparticles. Conjugation of PEG to these particles moderately increased complement response to give 79.7 ± 6.0% C4 remaining and 87.6 ± 10.1 ng/mL C5a. Our results demonstrate that PEGylation of the E2 protein nanocapsules can modulate cellular uptake and induce low levels of complement activation, likely via the classical/lectin pathways.
authors.affiliation: Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697-2575, United States.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Molino
authors.forename: Kateryna
authors.initials: K
authors.lastname: Bilotkach
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Fraser
authors.forename: Dongmei
authors.initials: D
authors.lastname: Ren
authors.forename: Szu-Wen
authors.initials: SW
authors.lastname: Wang
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D003167:Complement Activation; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D051047:Dihydrolipoyllysine-Residue Acetyltransferase / Q000737:chemistry / Q000378:metabolism; D005260:Female; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D053769:Nanocapsules / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry / Q000378:metabolism; D021381:Protein Transport; D013499:Surface Properties
chemical_list: D053769:Nanocapsules; D011092:Polyethylene Glycols; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; D003545:Cysteine