Deposition of pectin/poly-L-lysine multilayers with pectins of varying degrees of esterification

The effect of pectin esterification on the assembly of multilayers consisting of poly-L-lysine (PLL) and pectin was studied using surface plasmon resonance (SPR), Fourier transform infrared-attenuated total reflection spectroscopy (FTIR-ATR), and a quartz crystal microbalance with dissipation monitoring (QCMD). With each layer deposited, there was a progressive increase in mass. The net charge of the multilayers was positive and increased with increasing degree of esterification of the pectin. Multilayer fabrication involved a limited fractionation of the pectin preparations, with the more highly esterified pectins having a weaker affinity for PLL. The multilayers were relatively hydrated structures with estimates of solids content in the range 10-32% w/w. The more highly esterified pectins had a tendency to form more hydrated structures, which showed a strong deswelling when PLL was added to a freshly deposited pectin layer.