Biomedical Engineering Reference
In-Depth Information
on mica by the solution droplet evaporation technique resulted in patterned surfaces
formed by a single layer of protein [
150
] and that AFGP aggregates prior to
deposition. Raman spectroscopy has also been used to monitor the interaction of
AFGP8 on HOPG and Ag-coated glass-ceramic surfaces [
151
,
152
].
A novel attempt to mimic the active domain of AFGPs in a simple monolayer
is achieved by Hederos et al. A disaccharide-functionalized alkyl thiol chain
was co-adsorbed with C2H5OC2H4NHCOC15H30SH to form statistically mixing
self-assembled monolayers on gold [
153
]. Ice crystallization was examined by
optical microscopy as the surface was cooled under an atmosphere of constant
relative humidity. Water molecules appeared to organize and nucleate onto the self-
assembled monolayer surface with high disaccharide content (>30%, i.e., the same
ratio as AFGP) with behavior consistent with the absorption-inhibition model of
AFGPs. Nonetheless, any direct comparison between the results with this system
and native AFGPs is not yet possible as noted by the authors.
2.5.2
Protein-Based Anti-Ice Coating
The described features of AFPs are very interesting for nano(bio)technological
applications, and the feasibility of both anti-ice and ice nucleation coatings has been
demonstrated in proof-of-concept studies [
154
]. Wierzbicki et al. [
155
] described
the structure-function relationship of a de novo synthesized 43-residue alanine-
lysine-rich antifreeze polypeptide that is able to bind to designated ice planes along
a specific direction [
155
]. A new protein-based ice-nucleating coating containing
locally isolated nucleation points in a low surface energy matrix was synthesized
by Zwieg et al. [
156
] using a sol-gel method. In addition to ice nucleation, this
coating also displayed improved ice-repellent properties compared with commercial
coatings. In addition, inspired by the sacred lotus leaf, anti-icing of surfaces has been
performed with superhydrophobic coatings [
157
].
A feasibility study to modify lacquer surfaces with AFPs was conducted at the
Fraunhofer IFAM, Germany [
158
]. Winter flounder and the European fir budworm
were chosen as suitable AFP model organisms. Defined peptide sequences were
produced by solid-phase peptide synthesis on a laboratory scale. Three different
strategies were used to achieve the bonding of the artificial AFP residues to commer-
cially available lacquer systems. The first approach consists of spraying an aqueous
protein solution onto the lacquer by means of an ultrasound nebulizer. The coating
system contained epoxy resin and a polyamine hardener. The epoxide groups on
the lacquer surface reacted with the amino groups of the proteins and the protein
became incorporated into the polymer. The second approach involves integrating
photochemically active molecule into the lacquer system and AFPs were attached
by photochemical means. The third approach consists of attaching the peptides to
the lacquer via linker molecules, thus displaying the AFP residues on the surface.
Among the three approaches, the third approach proved to be very promising.
Control tests were carried out with various coating setups in a frosting chamber
