Stimuli-responsive assembly of nanoparticles with solid binding proteins

Abstract

Solid binding peptides (SBPs) are short sequences of amino acids selected by combinatorial techniques for their high affinity for inorganic surfaces. When genetically encoded within proteins, SBPs can function as linkers to create hybrid materials comprising inorganic components and the proteins to which they are fused. In this project, we explored how such solid binding proteins may be employed to achieve dynamic control over the assembly and disassembly of silica nanoparticles and how the process is influenced by SBP sequence, insertion point, and solution conditions. Using fluorescent-resonant energy transfer (FRET), dynamic light scattering (DLS) and scanning electron microscopy (SEM), we show that bifunctional derivatives of super-folder green fluorescent protein (sfGFP) engineered with two strong, or with a strong and a weak silica-binding peptides support the pH-dependent aggregation and disaggregation of rhodamine-containing silica nanoparticle (RhSiNP). We further demonstrate that pH shifts can be used to cycle nanoparticle between assembled and dispersed states and that aggregate size can be tuned with different SBPs and salt concentrations. This new paradigm for the synthesis of dynamic nanoparticle systems should find applications in biosensing, diagnostics and advanced materials.