ed throughout the coating and not just on the surface.
The same enzyme, when incorporated into an emulsion-based paint, was shown to catalyze ester hydrolysis. 14 In
this case though, the reaction took place on the surface
only. These results confirm that by understanding how
polymer matrices impact and drive enzyme reactivity, it
is possible to design highly functional and even multi-functional coatings.
The Reactive Surfaces product DeGreez contains lipases
as the active biocomponent. Coatings containing DeGreez
are capable of catalyzing the breakdown of natural greases, fats and oils, known as triacylglycerols, via ester
hydrolysis (see Figure 2). This class of enzymes has been
used for many years in the food, detergent and pharmaceutical industries, and the biotechnology to produce them
is readily available.
Paints and coatings containing hydrolytic enzymes
have many potential applications. In addition to those
described above (decontamination, self-healing, chemical
catalysis, marine anti-foulants), there is at least one
example of a bioactive coating patented for in use in a
medical device. 15 Such bioengineered coatings have also
been investigated for food packaging applications. 16
Oxidases, particularly glucose oxidase, have also been
investigated as antimicrobial agents16, 17 and oxygen scavengers18 for food preservation.
PEPTIDES AND PROTEINS
Like enzymes, peptides—and larger, non-catalytic proteins—are comprised of a specific sequence of amino acids,
but are much shorter in length. These smaller biomolecules
have unique structures and play important roles in many
different biological mechanisms. As with the enzymes, they
too have significant potential as bioengineered additives in
paints and coatings. Two companies—Marical and Reactive
Surfaces—have been successful in identifying promising
candidates in this category.
Marical has incorporated modulators of Calcium
Sensing Receptor (CaSR) proteins into paint formulations
that are linked to the settling behavior of various invertebrate marine organisms. 19 When these modulators bind to
the CaSR, different activities such as selection of a settlement site, attachment to a site, and even metamorphosis
and growth are altered by changing the expression, sensitivity, activity, signaling and/or physiological function of
the receptor.
Reactive Surfaces has bioengineered antimicrobial peptides for incorporation into paint formulations and offers
them through its ProteCoat product line. These antimicrobial peptides (AMPs) are designed to selectively target the
cell membranes of microorganisms as opposed to cell membranes of plants and animals. 20 Microbial cell membranes
contain negatively charged lipids generally lacking in the
outer membranes of plants and animals. AMPs interact
with the negatively charged lipids, disrupting the cell
membrane and ultimately killing the microorganism. With
this mode of action, AMPs target characteristics common to
microorganisms and thus offer true broad spectrum activi-
Figure 2
Lipolytic coatings created by blending DeGreez additive
with Glidden Vinyl latex (1424). The time course of
reactivity flows from the top to bottom with the control
panel on the left and the reactive panel on the right.
The decrease in surface fouling oil is obvious over
time, and is quantitated by surface albedo in the bar
graph following the last digital image.
