Environmental Engineering Reference
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O
O
CH 3
O
CH 2
CH 2
O
CH 2
XH 2
C
NH
CH
C
OH
113
3
CH 2
OH
OH
Figure 2.21 mPEG-tri-DOPA peptide for reducing marine biofouling
Amphiphilic surfaces with chemical or textural complexity can effectively prevent
settlement of organisms. They are effective against a wide range of biomolecules,
cells, and organisms. Krishnan and co-workers [49] designed an amphiphilic block
polymer by grafting a side chain with a luroalkyl as the hydrophobic moiety and
PEG as the hydrophilic moiety to a block copolymer precursor ( Figure 2.22 ).
This block polymer, when it was immersed in water underwent a molecular
reconstruction and also exhibited bioadhesion properties. The PEGylated part of the
block migrated to the water-polymer interface and made the surface more hydrophilic.
The algal species, Navicula , which generally adheres strongly to hydrophobic surfaces,
and Ulva which generally adheres strongly to hydrophilic surfaces, both showed
weak adhesion to the amphiphilic surfaces. The attachment strength of the diatoms
was the lowest on the amphiphilic surface (81% ± 5% removal of diatom). Whereas
for glass and PDMS surfaces, the percentage removal of diatoms was 69 ± 3 and
11 ± 4, respectively. The settlement density of Ulva zoospores was roughly the same
on both the amphiphilic surfaces and on the PDMS coatings. The possible reason
given by the authors for the anti-fouling nature of the amphiphilic surface was its
ability to undergo an environment dependent transformation when they came in to
contact with the extracellular polymeric substances. Weinman and co-workers [85]
studied the protein adsorption characteristics of these surfaces using luorescence
microscopy and AFM with bovine serum albumin (BSA) as the test protein.
These surfaces were found to be extremely resistant to protein adsorption when
compared to PS- block -poly(ethylene- co -butylene)- block -PS tri-block thermoplastic
elastomer and glass. The AFM experiments demonstrated a very weak force of
adhesion between the BSA molecules and the amphiphilic block copolymer surfaces.
 
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