| AVS 57th International Symposium & Exhibition | |
| Biomaterial Interfaces | Thursday Sessions |
| Session BI-ThP |
| Session: | Biomaterial Interfaces Poster Session |
| Presenter: | R.A. Rincón, University of New Mexico |
| Authors: | R.A. Rincón, University of New Mexico K. Artyushkova, University of New Mexico D. Ivnitski, University of New Mexico M. Eby, Universal Technology Corporation H.R. Luckarift, Air Force Research Laboratory G.R. Johnson, Air Force Research Laboratory P. Atanassov, University of New Mexico |
| Correspondent: | Click to Email |
Our recent work has made extensive use of X-ray photoelectron spectroscopy (XPS) in order to identify molecular interactions at a series of bio-inorganic and bio-organic interfaces.
In the first project, biologically-synthesized silica-enzyme and silica-peptide nanocomposite materials were analyzed by means of high resolution XPS. Biosilicification, i.e., rapid precipitation of silica mediated by a biological catalyst at ambient conditions, provides an efficient method for controlled synthesis of complex nanoscale structures. The process mimics reactions that organisms use to form rigid structures such as diatom exoskeletons and sponge spicules. The molecular interactions that allow these peptides to induce silica mineralization have not been elucidated. The focus of our study used the antimicrobial decapeptide KSL (KKVVFKVKFK), which induces rapid biosilica formation from pre-hydrolyzed tetramethyl orthosilicate in phosphate buffer. XPS was used to probe elemental composition and coordination chemistry of hybrid peptide-silica nanoparticle surfaces and ultimately identify the molecular interactions at the bio-inorganic interface.
In separate work, XPS was used to define interactions between biomolecules and various materials molecules used for bioelectrochemical architectures. One complex used the in vitro biosilicification process to help associate glucose oxidase (GOx) and carbon nanotubes (CNT) to yield a conductive composite matrix. Silica encapsulation of GOx provided an immobilization efficiency of ~25% in the presence of CNT. XPS analysis confirmed that the formation of a heterogeneous silica matrix had incorporated lysozyme, GOx and CNT. Another materials approach used layer-by layer assembly (LbL) to immobilize a redox enzyme. The LbL approach fixed bilirubin oxidase (BOD) on an electrode surface by using a glutaraldehyde as a “cross-linker” in combination with electrostatic interactions between the negatively charged enzyme and the positively charged polymer. The composite matrix was characterized using angle resolved XPS and multivariate analysis. The methods defined: the physical architecture of BOD layers immobilized on the electrode, the relative thickness of each assembled layer, along with their elemental and chemical composition.
In the third project we have studied poly-azines, which have been popular electrocatalysts of choice for NADH oxidation for sensors and biofuel cell applications using NAD-dependent enzymes. Little is known about their structure and mechanism of polymerization. Through detailed XPS analysis of monomers and polymers we were able to propose mechanism of electropolymerization and elucidate polyazine structure.