Abstract
Generally, the high diversity of protein properties necessitates the development of unique nanoparticle bio-conjugation methods, optimized for each different protein. Here we describe a universal bio-conjugation approach which makes use of a new recombinant fusion protein combining two distinct domains. The N-terminal part is Glutathione S-Transferase (GST) from Schistosoma japonicum, for which we identify and characterize the remarkable ability to bind gold nanoparticles (GNPs) by forming gold–sulfur bonds (Au–S). The C-terminal part of this multi-domain construct is the SpyCatcher from Streptococcus pyogenes, which provides the ability to capture recombinant proteins encoding a SpyTag. Here we show that SpyCatcher can be immobilized covalently on GNPs through GST without the loss of its full functionality. We then show that GST-SpyCatcher activated particles are able to covalently bind a SpyTag modified protein by simple mixing, through the spontaneous formation of an unusual isopeptide bond.
Highlights
The high diversity of protein properties necessitates the development of unique nanoparticle bio-conjugation methods, optimized for each different protein
We extensively characterized the interaction and adsorption of Glutathione S-Transferase (GST) onto the surface of gold nanoparticles (GNPs), as in our design this constitutes the primary interface between gold and subsequently attached proteins
GST binding was initially characterized by time-resolved dynamic light scattering (DLS), under the assumption that the increase of average particle diameter (Δd) was proportional to the amount of protein that binds to the particles[28]
Summary
The high diversity of protein properties necessitates the development of unique nanoparticle bio-conjugation methods, optimized for each different protein. There exist a plethora of methods suitable for studying proteinnanoparticle interactions[19,20,21,22] Expanding this knowledge could lead to the synthesis of designer recombinant proteins to facilitate the production of functionalized nanoparticles by forming a stable, artificial corona that modulates nanoparticle properties. This could be used to replace existing methods, for example based on pegylation, streptavidin-biotin interaction or tailored surface chemistry[23,24], which require the chemical modification of either the protein, the particle or both. The ΔdMAX estimates ( listed in the table inset) are significantly different, as indicated by the dashed horizontal line a9 b
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