Surface patch binding induced interaction of anisotropic nanoclays with globular plasma proteins

We report on the morphology dependent interaction of model anisotropic nanoparticles (LAPONITE (R), diameter = 30 nm and thickness = 1 nm, and montmorillonite MMT, diameter = 300 nm and thickness = 1 nm) with three globular plasma proteins, namely, bovine serum albumin (BSA), human serum albumin (HSA), and b-lactoglobulin (b-Lg). Acidic residues of these proteins were found to adsorb onto the platelet surfaces through electrostatic interaction which was evidenced from static fluorescence intensity and lifetime quenching data. The binding pattern followed the hierarchy HSA > b-Lg > BSA, indicating lower binding affinity for protein molecules with lower pI value. Larger platelet surface area offered preferential binding leading to substantial conformational changes in the protein secondary structure.