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Human serum transferrin (Tf) is a bilobal glycoprotein responsible for the transport and metabolism of two ferric ions. However, at only 30% saturation in human serum, reports have found that Tf can bind a variety of other metals. Titanium, as it is similar ionic size and Lewis acidity to Fe, unsurprisingly is one of these metals that can coordinate to Tf. The hydrolysis prone nature of Ti allows us to visualize features of its binding that have otherwise been unseen in previously utilized spectroscopic methods used to detail the Ti-Tf interaction. This thesis explores the binding motifs of both titanocene dichloride and titanium oxide and reveals interesting binding profiles outside of the traditional binding lobes of Tf. Titanocene dichloride (TDC) is a hydrolysis prone anticancer agent that has been shown to cause a ligand to metal charge transfer as it binds into the lobes of Tf. While UV/Vis proved the characteristic 2:1 metal to protein binding, ICP-OES detected spectroscopically mute interactions revealing higher binding equivalents were still prevalent in solution, up to approximately 50 equivalents of TDC to Tf, far past that seen in controls due to hydrolysis. Further studies showed an inability of TDC to cause a typical lobe closure of Tf as would have been seen with Fe. Lobe closure of Tf in the presence of TDC directly analyzed through protein volume SAXS measurements and denaturing urea-PAGE gels. Additionally, studies with Fe2Tf, or Fe(III) bound Tf, still showed solubilized TDC, which speaks further on the surface binding properties of Tf and possible new pathways of Ti cellular introduction. In addition to being used as drug agents, titanium has many commercial applications in cosmetics, sunscreens, and medical devices such as implants. The introduction of TiO2 into human serum and complexation with Tf is highly probable and a previously untapped area. Exploring this interaction showed not only the dissolution of Ti seen spectroscopically in the binding pocket and a higher concentration of Ti found through ICP-OES, but interesting results through transmission electron microscopy (TEM) that show the changing morphology of the TiO2 particle as it reacts with Tf over time. TEM images showed the particle sizing degrading to smaller particles over the course of 168 h. TEM was also able to detect selective uptake of nanoparticles by Tf. An equilibrium of Ti-Tf uptake was found in ICP-OES and UV/Vis results, yet the ability of Tf to change the features of TiO2 particle’s size could not have been understood fully without TEM. The formation of smaller particles and their introduction into human serum or transport with Tf could be the means of cellular accumulation of metal particles. Finally, to analyze possible surface interactions on Tf, deglycosylation techniques were implemented. Tf has two glycan chains residing on the C-terminal lobe that can be cleaved off with an enzyme PNGase F. Preliminary experiments had varied results among the binding capabilities deglycosylated Tf has with TiO2 and TDC. The differences among these two could help reveal further information about the binding lobe capacity or the site directed binding on the surface of the protein in coordination complexes versus oxides. The superstoichiometric interaction of TDC with Tf was uninterrupted by deglycosylation of Tf. However, uptake of TiO2 by Tf was affected by the removal of the glycan chains on the surface of the protein. Experiments with Fe2Tf could help decipher exact coordination and complete the telling of this story of superstoichiometric Ti binding. In our results, deglycosylated Fe2Tf did not prevent TDC interacting with the protein surface, but ICP-OES results showed far less solubilized Ti from TiO2. / Chemistry

Doctor of Philosophy / Department of Chemistry / Takashi Ito / This research was focused on understanding how external stimuli affect the permeability of the chemically modified electrodes, and how the materials used in modifying the working electrodes respond to the changes in the surface charge. We adopted a voltammetric type electrochemical sensor to investigate the permeability effects induced by pH and organic solvents. The working electrodes used in this research were chemically modified with thioctic acid self assembled monolayer (TA SAM), track etched polycarbonate membranes (TEPCM) and PS-b-PMMA nanoporous films (polystyrene-block-polymethylmethacrylate). We studied the permeability behavior of each of the material upon application of external stimuli. In chapter 3, the permeability changes induced by change in surface charge of thioctic acid SAM was investigated. The surface charge of the monolayer was tuned by changing pH of the medium, which resulted in decrease of redox current of a negatively charged marker due to deprotonation of the surface –COOH groups of TA SAM. Decrease in redox current reflected a decrease in the reaction rate, and by using closed form equations the effective rate constants at several pKa values were extracted. In chapter 4, permeability changes induced by pH in TEPCM were investigated. We assessed the surface charge of these membranes via cyclic voltammetry generated for neutral and charged redox molecules. Limiting current of charged markers were affected by the surface charge induced by pH, where as the redox current for the neutral marker was not affected. Experimental redox currents were larger than the theoretical current, indicating that redox molecules preferentially distributed in a surface layer on the nanopore. Organic solvent induced permeability changes of PS-b-PMMA nanoporous films were investigated via electrochemical impedance spectroscopy and AFM. Higher response of pore resistance in the presence of organic solvents indicated either swelling of the nanoporous film or partitioning of organic solvents in the pores. However AFM data revealed that the permeability changes are due to partitioning of the solvents rather than swelling of the porous film, since there was no appreciable change if the pore diameter in the presence of solvents.

Doctor of Philosophy / Department of Chemistry / Daniel A. Higgins / In this dissertation, state-of-the-art fluorescence microscopy techniques are employed to probe unique nanoscale phenomena in poly(dimethylsiloxane) (PDMS) films and on single carbon nanofibers. In one study, the mobility and physical entrapment of single dye molecules in dry and solvent-loaded PDMS films is explored. Experiments are performed under dry nitrogen and at various levels of isopropyl alcohol (IPA) loading from the vapor phase, as monitored by a PDMS-coated quartz-crystal microbalance. Single molecules are shown to be predominantly immobile under dry conditions and mostly mobile under IPA-saturated conditions. FCS is used to measure the apparent diffusion coefficient, yielding a mean that is virtually independent of IPA loading and sample class. An increase in the population of mobile molecules under high IPA conditions is attributed to the filling of film micropores with solvent, rather than by incorporation of molecularly dispersed solvent into the PDMS. In a second study, the molecular mobility of both neutral and cationic molecules in cured PDMS films is studied as a function of oligomer extraction. Cross correlation and Bayesian burst analysis methods were used to quantify the populations of fixed and total molecules, respectively. The results show that the total concentration of dye increases with increased oligomer extraction, while the relative populations of fixed and mobile molecules decrease and increase, respectively. These results are relevant to the use of PDMS in microfluidics, nanofiltration and pervaporation membranes and solid phase microextraction fibers. In a final study, molecular beacons (MBs) were immobilized onto the ends of single, sol-gel encapsulated vertically-alligned carbon nanofibers (VACNFs) attached to a silicon electrode. MB fluorescence was monitored as a function of the potential applied to the VACNF in a three-electrode electrochemical cell. Application of positive potentials attracts the negatively charged backbone of the MB, causing hybridization of the stem and a reduction in beacon fluorescence. Negative potentials cause dehybridization of the stem, and an increase in MB fluorescence. This study presents the first measurement of potential-dependent dehybridization/rehybridization of MBs attached directly to the end of a single VACNF. These studies will help to characterize the mechanism by which future lab-on-a-chip devices will detect harmful bio-organisms.

The dissociative chemisorption of oxygen and water on Fe, Ti, and adlayers of each metal on the other have been explored via surface electron spectroscopies. Auger Electron Spectroscopy (AES) and X-ray Photoelectron Spectroscopy (XPS) have been used to monitor the reactions of titanium and iron with low exposures (from one to several hundred langmuirs) of oxygen and/or water vapor. Comparisons and contrasts are drawn between bulk metals and adlayer alloys--alloys formed by vapor depositing a few angstroms of one metal on top of a relatively thick film of the other metal. Most notable is the ability of a very thin layer of titanium to lessen the reactivity of a thick iron film toward oxygen.

This dissertation summarizes the investigation of interfacial phenomena using novel in situ techniques. The Quartz Crystal Microbalance (QCM) was employed to monitor polymer adsorption from solution onto gold surfaces. Kinetics, isotherms, and competition in polymer adsorption were studied. Adsorption kinetics for polymers of narrow or wide molecular weight distribution were observed. Adsorption of copolymers with thiol functional groups onto gold surfaces was monitored. Adsorption models were constructed assuming the formation of a uniform single-polymer chain layer on the gold surface. / Surface-enhanced Raman scattering (SERS) was measured for strongly chemisorbed compounds and water soluble polymers on colloidal gold in the mixed solvents using an 826 nm diode laser or on silver hydrosol with a 514.5 nm argon ion laser. The colloidal solution of gold was more stable in the mixed solvents of water and ethanol than in aqueous solvent alone. Strong SERS was generated with near-IR excitation on gold colloids for mercaptopyridine and thiophenol. The estimated enhancement is on the order of 10$\sp5.$ The enhancement kinetics and concentration correlation for mercaptopyridine on gold colloids were studied in order to obtain quantitative analysis. New adsorbates, such as 2-mercaptoethanesulfonate and ethanesulfonate sodium for SERS were examined with an argon ion laser on silver hydrosol. The effect of chemisorption and physisorption was compared. Strong SERS of poly(vinyl benzyl trimethylammonium chloride), and its monomer were measured on silver hydrosol. It was demonstrated that strong colloidal aggregation is not essential for generating SERS in a colloidal system. Transmission electron microscopy (TEM) was used to monitor the colloidal particle morphology changes during aggregation. / Modifications of conducting polymers were performed by extended oxidation on electrodes. The electrochemical behavior of conducting polymers was studied systematically by cyclic voltammetry. Well-defined, stable redox behavior was obtained. Temperature is found to play an important role in the overoxidation of conducting polymers. Water and oxygen also have significant effects on these processes. The conductance and destruction of polypyrrole film were examined at various applied potentials and temperatures. Compositional changes of polypyrrole during extended oxidation were detected by FTIR. / Source: Dissertation Abstracts International, Volume: 55-04, Section: B, page: 1412. / Major Professor: Joseph B. Schlenoff. / Thesis (Ph.D.)--The Florida State University, 1994.

The redox chemistry of UCl$\sb4$ was investigated in the solvent AlCl$\sb3$-1-ethyl-3-methylimidazolium chloride (AlCl$\sb3$-EMIC), a room temperature ionic liquid. In basic solutions ( / Source: Dissertation Abstracts International, Volume: 51-12, Section: B, page: 5857. / Major Professor: Gregory Robert Choppin. / Thesis (Ph.D.)--The Florida State University, 1990.

Rate constants for $\sp1$t* $\to$ $\sp1$p* twisting in the S$\sb1$ state of trans-stilbene in n-alkane series are treated by the medium enhanced barrier model, $\Delta H\sb{obsd}$ = $\Delta H\sb{t}$ + $aE\sb\eta$, where $\Delta H\sb{t}$ is the intrinsic barrier. Solvent independent values of $\Delta H\sb{t}$ = 2.85 $\pm$ 0.04 kcal/mol and a = 0.38 $\pm$ 0.02 are obtained in n-alkanes. By introducing a parameter $X\sb{H}$ to account for the diminishing polarity effect with increasing n-alcohol chain length, the model is modified, $\Delta H\sb{obsd}$ = $\Delta H\sb{t}(1 - bX\sb{H})$ + $aE\sb\eta$, to treat $k\sb{obsd}$'s of trans-stilbene in n-alcohols. $X\sb{H}$ is defined as the ratio between the enthalpies of vaporization of the backbone n-alkyl chain and the whole n-alcohol molecule. The $k\sb{obsd}$'s of trans-stilbene in n-alkanes are also successfully treated by the Kramers equation using microviscosity, defined by use of translational diffusion coefficients. / Principal component - self modeling (PC-SM) is applied; to resolve spectral mixtures of conformers which are present in thermodynamic equilibrium. The Lawton-Sylvestre SM method is extended to three-component systems. Fluorescence spectra of trans-1,2-di(2-naphthyl)ethenes are successfully resolved into the pure component spectra of individual conformers. The fluorescence excitation spectra of trans-1,2-di(2-naphthyl)ethene are obtained from a fluorescence-excitation two-dimensional matrix. A modified two-component SM method which employs the linearity of the van't Hoff plot as a constraint is used in the resolution of absorption spectrothermal matrices of 1,3-butadiene vapor and trans,trans-2,4-hexadiene vapor. Structured s-cis spectra are obtained, corresponding to $\Delta H$ = 2.95 $\pm$ 0.15 kcal/mol. / Dual fluorescence due to the equilibrium $\sp1$Ag* $\sbsp{\gets}{\to}$ $\sp1$Bu* in diphenylhexatriene is resolved into two pure component spectra using PC-SM. Values of the energy gap between the two excited states as functions of solvent and temperature are calculated. For the mechanism of fluorescence and radiationless decay, the relaxed two-state equilibrium model which assumes that the radiationless decay process leading to photoisomerization occurs primarily as a prompt event in the initially formed $\sp1$Bu* state in competition with rapid relaxation to a geometry more favorable to mixing of the two excited states is evaluated for two extreme cases, $\phi\sb{r}$ = $\phi\sb{f,obsd}$ and $\phi\sb{r}$ = 1. It is concluded that the coupling between the two excited states was overestimated in the literature and that the radiationless decay rate constants for the equilibrated $\sp1$Bu* state, if not zero, are only weakly temperature dependent. / Source: Dissertation Abstracts International, Volume: 51-01, Section: B, page: 0232. / Major Professor: Jack Saltiel. / Thesis (Ph.D.)--The Florida State University, 1989.

Raman spectroscopy performs direct analysis and therefore is non-destructive to paint and needs few sample pretreatments. In the first phase of the work, paint components, including polymeric binders, pigments and other additives, were characterized individually in order to give reference Raman spectra. This provided the basis for their identification when the dry paint films are measured. For chemical analysis of dry opaque paint films, Raman spectroscopy is breaking a new ground. Good Raman spectra were obtained from both solvent- and water-borne paints. / Based on the above successful measurements, the fiber-optic Raman spectroscopy was used for paint degradation studies. The corrosion of a two-part polyurethane paint caused by organic liquids was observed through the Raman spectra. The weathering effect on a water-borne vinyl acrylic latex paint was monitored quantitatively. Both chemical corrosion and weathering processes were measured in real time without disturbing the samples. / Raman spectroscopy has unique advantages in many aspects of paint analysis. It is a robust tool in monitoring the paint curing process and is helpful in new product development. / Source: Dissertation Abstracts International, Volume: 56-08, Section: B, page: 4289. / Major Professor: Chalres K. Mann. / Thesis (Ph.D.)--The Florida State University, 1995.

Novel porphyrin molecules having active peripheral groups, namely 5,10,15,20-tetrakis($\alpha$-bromo-p-tolyl)porphyrin (pTBTP), 5,10,15,20-tetrakis($\omega$-bromo-p-hexoxylphenyl)porphyrin (pTBHP), 5,10,15,20-tetrakis($\alpha$-mercapto-p-tolyl)porphyrin (pTMTP), 5,10,15,20-tetrakis($\omega$-mercapto-p-hexoxylphenyl)porphyrin (pTMHP) and 5,10,15,20-tetrakis($\alpha$-mercapto-m-tolyl)porphyrin (mTMTP), have been synthesized and characterized. Metallation of these porphyrins was also studied, only mTMTP among the three mercaptoporphyrins can be metallated (Cu(II) and Co(II)) directly. Chemisorption of the three mercaptoporphyrins and Co(II)mTMTP has been investigated. Porphyrin self-assembled monolayer(SAM)-modified gold electrodes were prepared and characterized with x-ray photoelectron spectroscopy, reflectance spectroscopy, surface enhanced resonance Raman spectroscopy and electrochemistry in nonaqueous media. Metallation of SAMs of the three mercaptoporphyrins was achieved in refluxing metal acetate solution, to different degrees. mTMTP monolayer was found to metallate easiest, which implies its molecular arrangement at the polycrystalline gold surface is different from the other two mercaptoporphyrins. The metallated porphyrin SAMs appeared to be capable of electrocatalysing oxygen reduction in acidic media. In the second part of this dissertation, free-standing ultrathin and thin films of the porphyrins linked by disulfides were reported for the first time. Obtaining free-standing organic thin fiims with such electronic and optical properties as possessed by porphyrins has been desirable but not successful before this research. Synthesis of porphyrin networks, such as disulfide-linked polymers, electropolymerized networks, and sized porphyrin networks was described. The free-standing ultrathin and thin disulfide-linked porphyrin films were formed by / oxidation of selected mercaptoporphyrins via interfacial polymerization using transition metal ions as the oxidant. Fabrication of these films was achieved by supercritical drying (also known as critical point drying). The two surfaces of the films appeared different. Spectroscopic, thermal and x-ray diffraction techniques were applied to characterize the free-standing porphyrin films. / Source: Dissertation Abstracts International, Volume: 56-08, Section: B, page: 4290. / Major Professor: Joseph B. Schlenoff. / Thesis (Ph.D.)--The Florida State University, 1995.