Biomineralisation arises due to a partnership between the biological and inorganic components of a living system. The final structure and form of the inorganic material is in some way controlled by the nature of the specific organic entities present. This manifests itself in the initiation of the growth, by providing the appropriate matrix in which the inorganic material forms and/or by providing a defect base such that the inorganic crystal packing may be appropriately perturbed. Working with proteins is not necessarily the best or easiest way to understand a physical process and over past years people have turned to simple organic molecules, surfactants, small biological moieties and organic substrates in order to determine, at least in part, the import of organic/inorganic interactions during the growth of the inorganic material. As one example of these additives, surfactants, which represent approximately 50% of the cell membrane, display a diverse and vast array of geometrical forms in aqueous solution, many of which bare striking resemblance to biominerals, albeit on considerably smaller length scales. They also have the ability to associate in solution with inorganic material precursors, such as calcium ions. Hence, while they may not be the main driving force in the formation of biominerals, they are certainly present during the process and may, when used as model systems, allow us some way into the world of nanomaterials. Surfactants, a series of simple alcohols and carboxylic acids, and proteins extracted from the spines of adult sea urchins, have been used by our group to study the formation of calcium carbonate based inorganic materials. The growth of the calcium carbonate is significantly affected by the inclusions, with deviations varying from simple stepped growth to the formation of curved surfaces.
Thin film form birefringence depends on the shape or bunching of nanostructural columns and on the difference in the refractive indices of the columns and the surrounding voids. When moisture from the atmosphere enters the nanostructure the linear form birefringence may decrease by a large amount, of the order of 50%. However, current data refers to tilted-columnar films. We report here on moisture penetration effects in films fabricated by serial bideposition and engineered for large linear form birefringence or large circular form birefringence. As well, we consider post-deposition processes that may retard the uptake of moisture.
Vacuum deposition results in oxygen deficient surfaces which rapidly absorb oxygen from the atmosphere either in the form of O2 or H2O. In order to retard water uptake this deficiency must be reduced, possibly by annealing samples in an oxygen rich atmosphere subsequent to deposition. Alternatively, surface oxide and hydroxyl groups can be rendered hydrophobic via reaction with silane derivatives. Both methods have been tested for their effectiveness in retarding water uptake.
Conference Committee Involvement (5)
Nanosensors and Microsensors for Bio-Systems
11 March 2008 | San Diego, California, United States
Nano-, Micro- and Bio-Sensors and Systems
21 March 2007 | San Diego, California, United States
Smart Electronics, MEMS, BioMEMS, and Nanotechnology
27 February 2006 | San Diego, California, United States
Smart Electronics, MEMS, BioMEMS, and Nanotechnology
7 March 2005 | San Diego, California, United States
Smart Electronics, MEMS, BioMEMS, and Nanotechnology
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.