Biomedical Engineering Reference
In-Depth Information
affects protein solubility and conformational stability. Although a variety of
detergents and lipids as surfactants have been used to solubilize, stabilize
and crystallize membrane proteins for several decades, these surfactants are
still unable to significantly maintain structural stability of membrane pro-
teins during experimental handling. In the other words, there is no “magic
material” surfactant working on membrane proteins and there is an urgent
need to develop new types of surfactants. We have used A6K (AAAAAAK)
and V6D (VVVVVVD) to stabilize the photosynthetic protein-molecular
complexes in solid-state devices and we showed that this new type of pep-
tide detergents was very effective in stabilizing membrane protein functions,
providing a powerful tool for membrane proteins research and application
(Fig. 3) [10, 52-54].
2.6
Other Systems
Molecular self-assembly systems using nucleic acids on a chip have been de-
veloped. This new technology is based entirely on the principles of nucleic
acid molecular self-assembly. Numerous new devices and technologies have
been advanced. The most well-known example is the biochip technology “Lab
on a Chip”, “GeneChip”, or “Microarray Technology” [55]. This microarray
system is widely used in gene expression analysis, the human genome project,
diagnostics, discovery of new functions of genes, and high-throughput drug
discovery and screenings. In addition, people are now beginning to turn to
testing the ability of peptide-based biomaterials to respond to external cues;
this responsiveness has been collectively referred to as “smart behavior”. Re-
sponsiveness can be defined at either the structural level or the functional
level [56].
3
Fabrication of Nanomaterials Through Self-Assembling Systems
3.1
Nanofibers
The peptide Lego molecules can undergo self-assembly in aqueous solutions
to form well-ordered nanofibers that further associate to form nanofiber scaf-
folds [15, 16, 57]. One of them, RADA16-I [58], is called PuraMatrix, because
of its purity as a designed biological scaffold in contrast to other biolog-
ically derived scaffolds from animal collagen and Matrigel. Because these
nanofiber scaffolds have 5-200 nm pores and have very high water content
(99.5%or5 mg
ml) (Fig. 4), they are useful in the preparation of 3D cell-
culture media. The scaffolds closely mimic the porosity and gross structure
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