To create reactive or functional coatings, polymer,
enzymes and reactants are blended to form a single macroscopic phase. Therefore, the next step in developing a functional coating is to prepare various formulations with different polymeric binders in order to determine the overall
performance of the system. Three main methods have been
reported for incorporating enzymes, peptides and other
active bioadditives into a paint or coating:
• mixing into a final coating formulation;
• chemical or physical binding to the resin and then formulation of the coating; and
• chemical or physical binding to the surface of the film
after the coating has been applied.
The simplest process involves blending the additive—
usually in powder form—into a prepared coating. This
method results in the additive being present throughout
the thickness of the applied film. In general, waterborne
coatings are preferred for this method because an aqueous
medium is the natural environment for biomolecules. It is
possible, however, to prepare enzymes and peptides that
can be solubilized in organic media and still possess high
reactivity. 6 As a result, these additives can be incorporated
into solvent-based coatings as well.
Chemical modification involves directly binding the additive to the resin that serves as a binder for the coating.
Since most of the bioengineered additives of interest are
comprised of amino acids, it is possible to react the amine
and carboxylic acid functionalities present in the biocompound backbone of the biomolecule with appropriate active
sites on the resin. In this way, the enzyme, peptide or other
bioadditive is tethered to the resin and enables the additive
to be present throughout the entire film.
Similar chemistry can be accomplished after the paint
or coating has been applied to the surface. This approach
is the least attractive because it requires the applicator to
carry out an additional step involving chemical reactants
and presents practical complications. On the other hand,
a smaller quantity of additive is required with this
method as the bioactive compound is bound only to the
coating surface.
Figure 7a & 7b
(a) Activity of the embedded OPDtox additive challenged against neat paraoxon monitored at 405 nm;
(b) Activity of the embedded OPDtox additive challenged against neat demeton-S monitored at 405 nm.
