Adsorption kinetics of tannic acid onto an albumin-terminated multilayer thin films

The protein-polyphenol multilayer film is a promising material for protection functional food ingredients from gastric digestion and their targeted delivery to small intestine. Here, we study the process of layer-by-layer assembly of bovine serum albumin—tannic acid (BSA-TA) multilayer films by precision ellipsometry. We demonstrate that TA adsorption has both irreversible and reversible components which contribute to 43% and 57% of bound TA molecules, respectively. The kinetic of TA adsorption/desorption process is analyzed using a phenomenological function approach. The rate-limiting stage of the process is the kinetics of molecules adsorption (desorption) to (from) a planar surface and not diffusion of TA molecules from (to) a solution bulk. For irreversible adsorption, the rate constant is 3.9 × 10  M  s . For the reversible process, the adsorption rate constant, K is 5.14 × 10  M  s ; desorption rate constant, K is 79.4 s ; and equilibrium constant, K is 64.7 M . [Figure not available: see fulltext.].