IMMUNOGLOBULIN IMMOBILIZATION BY THE LANGMUIR-BLODGETT METHOD

A systematic study of immunoglobulin G (IgG) immobilization on Langmui r-Blodgett films has been carried out with the aim of characterizing t he immobilization efficiency and the protein activity. A quantitative evaluation of the amount of immobilized protein has been carried out b y IR spectroscopy. Maximum IgG immobilization (400-900 ng cm-2) has be en obtained with buffers of low ionic strength (0.005 M) and pH near b ut below the isoelectric point of the protein. No desorption has been observed in pure water, but in buffers desorption increases with the i onic strength of the buffer. The probable mechanism of desorption is a screening of the charges responsible for protein attachment, by small ions from the buffer. As expected, this desorption leads to high non- specific binding (75% in 0.1 M buffer) by dynamic protein exchange.