Protein-containing conditioning film

Films or membranes of silkworm silk have been produced by air-drying aqueous solutions prepared from the concentrated salts, followed by dialysis (11,28). The films, which are water soluble, generally contain silk in the silk I conformation with a significant content of random coil. Many different treatments have been used to modify these films to decrease their water solubiUty by converting silk I to silk II in a process found usehil for enzyme entrapment (28). Silk membranes have also been cast from fibroin solutions and characterized for permeation properties. Oxygen and water vapor transmission rates were dependent on the exposure conditions to methanol to faciUtate the conversion to silk II (29). Thin monolayer films have been formed from solubilized silkworm silk using Langmuir techniques to faciUtate stmctural characterization of the protein (30). ResolubiLized silkworm cocoon silk has been spun into fibers (31), as have recombinant silkworm silks (32). 

Under such conditions, the recording ellipsometer shows adsorption rates out of bulk solutions onto hydrophobic substrates that are not unlike those on hydrophilic ones (2). Where the hydrophobic solid slide is then dipped deeper into the container of protein, data and recordings show that the slide has gained thickness instantaneously and must therefore have dragged a surface film down into the light-path. This film may appear not much thinner than the one that had been more slowly adsorbed out of the bulk solution (2). 

Some more complex reactions were also shown to be applicable to the monolayer assemblies. Peptide synthesis protocols are frequently used to attach biomolecules to the surface of the monolayer. However, such reactions are sometimes poorly characterized. N-Hydroxysuccinimide esters containing a mercapto group form well-behaved monolayers which are stable at neutral conditions and do not hydrolyse easily. They react smoothly with amines in solution, giving rise to the appropriate amides. This reaction can also be used to attach proteins to the surface of monolayers. iV-Hydroxysulphosuccinimide ester can be generated in the monolayer in situ, by treating the film of cu-mercaptoalkanoic... 

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