Biomedical Engineering Reference
In-Depth Information
process. Although the latter approach has become widely used and is rapidly
being perfected, fabrication of the finest feature using microcontact printing
is limited by the capabilities of lithography technologies currently used in the
semiconductor industry.
3.5
Other Nanomaterials
The most advanced top-down technology for fabricating complex optical
systems falls far short when compared with the accomplishments of liv-
ing organisms at ambient temperature and low pressure (and without clean
rooms) [93, 94]. Several groups have studied biomineralization in diverse ma-
rine organisms, notably the brittlestar Ophiocoma wendtii and the sponge
Euplectella. Some remarkable living optical systems have been uncovered,
such as the fiber-optical spicules from Euplectella that have the dimensions of
a single human hair and can act as multimode waveguides. These discoveries
have inspired Aizenberg et al. [95] to fabricate micropatterned single crys-
tals and photonics with potential applications in communication technology.
Christopher et al. report the synthesis and characterization of tethered PNA
molecules (bisPNAs) designed to assemble two individual DNA molecules
through Watson-Crick base pairing. The spacer regions linking the PNAs
were varied in length and contained amino acids with different electrostatic
properties [96, 97], their results indicate that the bisPNAs can be used for
nanotechnology applications and that their favorable characteristics may lead
to improved assemblies.
4
Application of Self-Assembling Systems
4.1
Simple Peptides Stabilize Mighty Membrane Proteins for Study
Cell membranes are largely made up of proteins, and membrane proteins ac-
count for about a third of all genes. Despite their importance, they are very
hard to isolate and stabilize, which therefore prevents further understand-
ing of membrane protein functions and related disease study. We have made
a new type of peptide detergent and successfully stabilized the dauntingly
large protein complex photosystem I (PS-I), an integral part of the photosyn-
thetic machinery.
Two key technologies were employed to preserve the functionality of
these photosynthetic complexes outside of their native environment. First,
we added two peptide surfactants, one cationic A6K (AAAAAAK), and the
other anionic V6D (VVVVVVD) into the photosynthetic complex fraction to
 
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