Three species of photosynthetic flagellates capable of phagotrophy (mixotrophic species) were tested for their abilities to use inorganic iron colloids for growth. Ochromonas sp., Chrysochromulina ericina (a coastal strain) and C. ericina (an oceanic strain) were grown in iron-free seawater supplemented with 1 muM goethite, hematite, magnetite/maghemite or ferrihydrite (90°) in the presence and absence of desferrioxamme B, an iron-binding siderophore. Both strains of Chrysochromulina grew at 35--70% of their maximum rates with goethite, hematite, and magnetite/maghemite, but were unable to use ferrihydrite. Ochromonas, however, grew well with ferrihydrite, but could not use any of the other forms. All the flagellates were able to acquire iron from ingested bacteria. Diatoms that were known only to take up dissolved forms of iron, Thalassiosira oceanica (clone 1003) and T. pseudonana (clone 3H), were unable to use any of the colloids tested. The mechanism of iron acquisition by the flagellates appeared to involve ingestion of the iron colloids as DFB had no effect on colloidal iron availability and bacteria resident in the cultures were unable to use the iron contained in the colloids. Variations in the size of the colloids were hypothesized to account for differences in their availability, independent of colloid chemical stability. The results provide the first strong evidence for direct utilization (i.e. without prior dissolution) of colloidal iron by mixotrophic phytoplankton and document a new pathway of iron acquisition that may be important for their survival in low-iron waters of the sea.

A very interesting class of nanoparticles extensively used for bio-applications is that of hydrogel particles, also called nanogels. There is an increasing interest in the design of hydrogel nanoparticles that have biofunctionality for applications in cell targeting, drug delivery, and biomedicine. The dissertation focuses on developing synthetic strategies for making diverse hydrogel nanoparticles customized to have desirable properties for various bio-applications. We have also investigated the potential of such nanoparticles as coatings for biomedical implants. Chapter 1 gives a brief introduction to hydrogel nanoparticles and the properties that make them attractive for various applications. The details of the syntheses of well defined, stable nanoparticles, commonly used in literature, are described in Chapter 2. Chapter 3 describes our synthesis of hollow sub-50 nm nanogels, which are otherwise difficult to synthesize based on the strategy discussed in Chapter 2. Chapter 4 also demonstrates how simple strategies borrowed from organic chemistry help in producing nanogels with multiple functionalities that are otherwise difficult to obtain, which also is an important advance over the synthetic methods discussed in Chapter 2. Chapter 5 describes how a general strategy based on photoaffinity labeling can yield materials with many applications ranging from optical materials, drug delivery, to biosensing. The latter part of the dissertation describes applications of various nanogels in biology especially as coatings that can control inflammation caused by biomaterials. Chapter 6 describes a method to functionalize flexible biomaterials with the nanogels, thus enabling in vivo investigations of the nanogels as potential coatings for controlling inflammation. Chapter 7 describes the biological studies performed (in collaboration with Garcia Group in the School of Mechanical Engineering at Georgia Tech) on various nanogels, aimed towards obtaining the most functional and efficient materials for implant applications. Chapter 8 describes application of hollow nanogels for covalently immobilizing biomolecules. This chapter also demonstrates how simple non-functional materials can be made unique and functional by means of traditional organic reactions. Finally, in order to broaden the applications of nanogel based materials.

Thesis (MAppSc)--University of South Australia, 2000.

The surface force apparatus (SFA) has been an important technique for making direct force measurements and has contributed enormously to our understanding of colloidal interactions. The conventional SFA has been limited to measuring forces between solid surfaces, until recently when a modified SFA was developed at the Ian Wark Research Institute [1]. A fluid drop (mercury) is introduced into the apparatus which allows a range of deformable surfaces to be studied in the SFA. This project is an extension of this technique. Interactions between a mica sheet and a mercury drop are studied, including the modification of mercury with self-assembled monolayers (SAMs) of thiol surfactants, and the drop deformation due to non-equilibrium adsorption effects and hydrodynamic forces.

Thesis (MAppSc)--University of South Australia, 2000.

Thesis (M.S.)--University of North Texas, Dec., 2007. / Title from title page display. Includes bibliographical references.

Thesis (M.Sc. (Tech.))--University of Waikato, 2006. / Title from PDF cover (viewed March 5, 2008). Includes bibliographical references (p. 107-110)

Thesis (Ph.D.) -- University of Western Sydney, 2004. / Title from disc. Includes bibliography.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2007. / Committee Chair: Prof. Charles L. Liotta; Committee Member: Prof. Arthur J. Ragauskas; Committee Member: Prof. Charles A. Eckert; Committee Member: Prof. John D. Muzzy; Committee Member: Prof. Rigiberto Hernandez.

Thesis (M.S.)--West Virginia University, 1998. / Title from document title page. "December 10, 1998." Document formatted into pages; contains viii, 64 p. Vita. Includes abstract. Includes bibliographical references (p. 60-62).