Formation and Properties of Protamine/Pectin LbL-Coatings☆

Abstract The adsorption regularities of protamine sulfate and pectin on the surfaces from solution with different ionic strength were investigated in situ using quartz substrate via the quartz crystal microbalance technique. Both polymers were observed to absorb according to Langmuir's adsorption isotherm. The value of Langmuir adsorption constant (k) is equal to 74,48 and 1,12 sm 3 /μg for pectin and protamine respectively. Maximum amount of biopolymer (A ∞ ) adsorbed on resonator is 0,87 μg/sm 2 for Pect and 0,57 μg/sm 2 for PtS. Ultrathin ( 8 LbL films were formed and adsorption kinetics of both polyions were studied. The rate constant of protamine and pectin adsorption are (3,9 ± 0,9)·10 -2 s -1 and (3,4 ± 0,3)·10 -2 s -1 respectively. It was shown, that film thickness increases by 2.5 times with polymers concentration in solution increasing from 0.1 to 3.0 mg/ml.