化学
结合
生物结合
胶体金
吸附
表面改性
表面电荷
蛋白质吸附
组合化学
纳米颗粒
Zeta电位
生物物理学
有机化学
纳米技术
数学分析
材料科学
数学
物理化学
生物
作者
Samuel Okyem,Olatunde Awotunde,Tosin Ogunlusi,McKenzie B. Riley,Jeremy D. Driskell
标识
DOI:10.1021/acs.bioconjchem.1c00261
摘要
Many emerging nanobiotechnologies rely on the proper function of proteins immobilized on gold nanoparticles. Often, the surface chemistry of the AuNP is engineered to control the orientation, surface coverage, and structure of the adsorbed protein to maximize conjugate function. Here, we chemically modified antibody to investigate the effect of protein surface chemistries on adsorption to AuNPs. A monoclonal anti-horseradish peroxidase IgG antibody (anti-HRP) was reacted with N-succinimidyl acrylate (NSA) or reduced dithiobissuccinimidyl propionate (DSP) to modify lysine residues. Zeta potential measurements confirmed that both chemical modifications reduced the localized regions of positive charge on the protein surface, while the DSP modification incorporated additional free thiols. Dynamic light scattering confirmed that native and chemically modified antibodies adsorbed onto AuNPs to form bioconjugates; however, adsorption kinetics revealed that the NSA-modified antibody required significantly more time to allow for the formation of a hard corona. Moreover, conjugates formed with the NSA-modified antibody lost antigen-binding function, whereas unmodified and DSP-modified antibodies adsorbed onto AuNPs to form functional conjugates. These results indicate that high-affinity functional groups are required to prevent protein unfolding and loss of function when adsorbed on the AuNP surface. The reduced protein charge and high-affinity thiol groups on the DSP-modified antibody enabled pH-dependent control of protein orientation and the formation of highly active conjugates at solution pHs (<7.5) that are inaccessible with unmodified antibody due to conjugate aggregation. This study establishes parameters for protein modification to facilitate the formation of highly functional and stable protein–AuNP conjugates.
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