Nanoparticle-mediated interactions governing thermal gelation of protein dispersions with tunable properties

Nanoparticle-protein dispersions constitute complex soft materials in which competing attractive and repulsive interactions can strongly influence their phase behavior, including gelation. In this work, we demonstrate a strategy to utilize interaction between anionic silica nanoparticles and anionic protein bovine serum albumin to achieve heat-induced gels with tunable physical properties. Upon heating, the protein molecules in solution undergo unfolding followed by hydrophobic aggregation, leading to the formation of a three-dimensional gel network. The introduction of negatively charged nanoparticles generates additional electrostatic repulsion that competes with the attractive hydrophobic interactions between partially unfolded proteins. This competition modifies both the structure and mechanical properties of the resulting gels. In particular, nanoparticle-protein gels exhibit markedly enhanced optical transparency (∼90%) compared with gels formed from pure protein solutions (