Experimental and Modeling of the Structural and Rheological Properties of Silica-Protein Systems Under pH Variations

Silica-protein conjugates exhibit unique physicochemical properties arising from their nanoscale dimensions, high surface area, and quantum confinement effects, making them

promising candidates for biosensing, drug delivery, imaging, and advanced materials design. Despite their growing importance, the relationship between microstructure and rheological

behavior in silica-protein systems, particularly those involving lysozyme and BSA (Bovine Serum Albumin), remains insufficiently understood. Here, we investigate a model system of silica-lysozyme and silica-BSA to elucidate how protein adsorption modulates colloidal interactions and flow properties in dense suspensions. Rheological experiments reveal pronounced non-Newtonian characteristics, including shear thinning and transient viscoelasticity, indicative of dynamic microstructural rearrangements driven by protein-mediated interactions and shear-induced alignment or clustering. To gain microscopic insight, we developed a Brownian Dynamics simulation incorporating shear flow and protein-modified interparticle potentials modeled via double- Yukawa interactions. Simulations capture anisotropic structural features and stress evolution consistent with experimental observations. Future Rheo-SANS measurements at neutron scattering facilities are planned to directly probe shear-induced nanoscale ordering, providing critical validation of the simulations and bridging nanoscale structure with macroscopic rheology. This integrated approach advances fundamental understanding of soft matter systems where biomolecular adsorption governs complex structural and flow behaviors.