This thesis is concerned with the fabrication methodology of polymeric photonic crystals operating in the visible to near infrared regions and the correlation between the chemical deposition morphologies and the resultant photonic stopband enhancements of photonic crystals. Multiphoton lithography (MPL) is a powerful approach to the fabrication of polymeric 3D micro- and nano-structures with a typical minimum feature size ~ 200 nm. The completely free-form 3D fabrication capability of MPL is very well suited to the formation of tailored photonic crystals (PCs), including structures containing well defined defects. Such structures are of considerable current interest as micro-optical devices for their filtering, stop-band, dispersion, resonator, or waveguiding properties. More specifically, the stop-band characteristics of polymer PCs can be finely controlled via nanoscale changes in rod spacings and the chemical functionalities at the polymer surface can be readily utilized to impart new optical properties. Nanoscale features as small as 65 ± 5 nm have been formed reproducibly by using 520 nm femtosecond pulsed excitation of a 4,4'-bis(di-n-butylamino)biphenyl chromophore to initiate crosslinking in a triacrylate blend. Dosimetry studies of the photoinduced polymerization were performed on chromophores with sizable two-photon absorption cross-sections at 520 and 730 nm. These studies show that sub-diffraction limited line widths are obtained in both cases with the lines written at 520 nm being smaller. Three-dimensional multiphoton lithography at 520 nm has been used to fabricate polymeric woodpile photonic crystal structures that show stop bands in the visible to near-infrared spectral region. 85 ± 4 nm features were formed using swollen gel photoresist by 730 nm excitation MPL. An index matching oil was used to induce chemical swelling of gel resists prior to MPL fabrication. When swollen matrices were subjected to multiphoton excitation, a similar excitation volume is achieved as in normal unswollen resins. However, upon deswelling of the photoresist following development a substantial reduction in feature size was obtained. PCs with high structural fidelity across 100 µm × 100 µm × 32 layers exhibited strong reflectivity (>60% compared to a gold mirror) in the near infrared region. The positions of the stop-bands were tuned by varying the swelling time, the exposure power (which modifies the feature sizes), and the layer spacing between rods. Silver coatings have been applied to PCs with a range of coverage densities and thicknesses using electroless deposition. Sparse coatings resulted in enhanced reflectivity for the stop band located at ~5 µm, suggesting improved interface reflectivity inside the photonic crystal due to the Ag coating. Thick coatings resulted in plasmonic bandgap behavior with broadband reflectivity enhancement and PC lattice related bandedge at 1.75 µm. Conformal titania coatings were grown onto the PCs via a surface sol-gel method. Uniform and smooth titania coatings were achieved, resulting in systematically red-shifted stopbands from their initial positions with increasing thicknesses, corresponding to the increased effective refractive index of the PC. High quality titania shell structures with modest stopbands were obtained after polymer removal. Gold replica structures were obtained by electroless deposition on the silica cell walls of naturally occurring diatoms and the subsequent silica removal. The micron-scaled periodic hole lattice originated from the diatom resulted in surface plasmon interferences when excited by infrared frequencies. The hole patterns were characterized and compared with hexagonal hole arrays fabricated by focused ion beam etching of similarly gold plated substrate. Modeling of the hole arrays concluded that while diatom replicas lack long-ranged periodicity, the local hole to hole spacings were sufficient to generate enhanced transmission of 13% at 4.2 µm. The work presented herein is a step towards the development of PCs with new optical and chemical functionalities. The ability to rapidly prototype polymeric PCs of various lattice parameters using MPL combined with facile coating chemistries to create structures with the desired optical properties offers a powerful means to produce tailored high performance photonic crystal devices.

Self-assembling peptides have emerged as new nanobiomaterials and received considerable attention in the areas of nanoscience and biomedical engineering. In this category are ionic-complementary peptides, which contain a repeating charge distribution and alternating hydrophobic and hydrophilic residues in the amino acid sequence, leading to the unusual combination of amphiphilicity and ionic complementarity. Although their self-assembled nanostructures have been successfully applied as scaffoldings for tissue engineering, novel materials for regenerative medicine and nanocarriers for drug and gene/siRNA delivery, aspects of the assembly process remain unclear. Since many of these applications involve peptide-modified interfaces and surfaces, a better understanding and control of the peptide assembly on a surface are very crucial for future development of peptide-based applications in nano-biotechnology. This thesis contains two major parts: (i) fundamental study of the assembly of a model ionic-complementary peptide EAK16-II on surfaces and (ii) potential applications of such a peptide in surface modification and nanofabrication. In the fundamental study, EAK16-II assembly on negatively charged mica was first investigated via in-situ Atomic Force Microscopy (AFM). It was found that EAK16-II nanofiber growth on mica is surface-assisted and follows a nucleation and growth mechanism involving two steps: (i) adsorption of nanofibers and fiber clusters (from the bulk solution) on the surface to serve as the seeds and (ii) fiber elongation from the active ends of the seeds. Such a process can be controlled by adjusting the solution pH since it modulates the adsorption of the seeds and the growth rates. Unlike what is observed on mica, EAK16-II formed well-ordered nanofiber patterns with preferential orientations at angles of 60° or 120° to each other on hydrophobic highly ordered pyrolytic graphite (HOPG) surfaces, resembling the crystallographic structure of the graphite. Nanofiber formation on HOPG is also surface-assisted and adopts a nucleation and growth mechanism that can be affected by solution pH. The pH-dependent adsorption of peptides to HOPG is attributed to the resulting changes in peptide hydrophobicity. It was also found that EAK16-II assembly can be induced by the mechanical force of a tapping AFM tip. It occurs when the tip cuts the adsorbed EAK16-II nanofibers into segments that then serve as seeds for new nanofiber growth. This finding allows one to locally grow nanofibers at specific regions of the surface. The tip cutting has been combined with the effect that solution pH has on peptide assembly to develop a new AFM lithography method to fabricate local patterned peptide nanostructures on HOPG. To study the use of EAK16-II for surface modification applications, the wettability and stability of the peptide-modified surfaces were characterized. EAK16-II-modified mica becomes slightly hydrophobic as the water contact angle increases from <10° to 20.3 ± 2.9°. However, the hydrophobicity of the HOPG surface is significantly reduced, as reflected in a contact angle change from 71.2 ± 11.1° to 39.4 ± 4.3°. The EAK16-II-modified mica surface is stable in acidic solution, while the modified HOPG surface is stable in both acidic and alkaline solutions. The peptide-modified HOPG shows potential as a biocompatible electrode for (bio)molecular sensing. The ability of EAK16-II to form nanofibers on surfaces has also promoted research on peptide-based metallic nanowire fabrication. Our approach is to provide EAK16-II with metal ion binding ability by adding a GGH motif to the C-terminus. This new peptide EAK16(II)GGH has been found to form one-dimensional nanofibers while binding to Cu2+ ions. The dimensions of the nanofibers were significantly affected by the nature of the anions (SO42-, Cl- and NO3-) in the copper salt solution. This work demonstrates the potential usage of EAK16-II for nanowire fabrication.

Self-assembling peptides have emerged as new nanobiomaterials and received considerable attention in the areas of nanoscience and biomedical engineering. In this category are ionic-complementary peptides, which contain a repeating charge distribution and alternating hydrophobic and hydrophilic residues in the amino acid sequence, leading to the unusual combination of amphiphilicity and ionic complementarity. Although their self-assembled nanostructures have been successfully applied as scaffoldings for tissue engineering, novel materials for regenerative medicine and nanocarriers for drug and gene/siRNA delivery, aspects of the assembly process remain unclear. Since many of these applications involve peptide-modified interfaces and surfaces, a better understanding and control of the peptide assembly on a surface are very crucial for future development of peptide-based applications in nano-biotechnology. This thesis contains two major parts: (i) fundamental study of the assembly of a model ionic-complementary peptide EAK16-II on surfaces and (ii) potential applications of such a peptide in surface modification and nanofabrication. In the fundamental study, EAK16-II assembly on negatively charged mica was first investigated via in-situ Atomic Force Microscopy (AFM). It was found that EAK16-II nanofiber growth on mica is surface-assisted and follows a nucleation and growth mechanism involving two steps: (i) adsorption of nanofibers and fiber clusters (from the bulk solution) on the surface to serve as the seeds and (ii) fiber elongation from the active ends of the seeds. Such a process can be controlled by adjusting the solution pH since it modulates the adsorption of the seeds and the growth rates. Unlike what is observed on mica, EAK16-II formed well-ordered nanofiber patterns with preferential orientations at angles of 60° or 120° to each other on hydrophobic highly ordered pyrolytic graphite (HOPG) surfaces, resembling the crystallographic structure of the graphite. Nanofiber formation on HOPG is also surface-assisted and adopts a nucleation and growth mechanism that can be affected by solution pH. The pH-dependent adsorption of peptides to HOPG is attributed to the resulting changes in peptide hydrophobicity. It was also found that EAK16-II assembly can be induced by the mechanical force of a tapping AFM tip. It occurs when the tip cuts the adsorbed EAK16-II nanofibers into segments that then serve as seeds for new nanofiber growth. This finding allows one to locally grow nanofibers at specific regions of the surface. The tip cutting has been combined with the effect that solution pH has on peptide assembly to develop a new AFM lithography method to fabricate local patterned peptide nanostructures on HOPG. To study the use of EAK16-II for surface modification applications, the wettability and stability of the peptide-modified surfaces were characterized. EAK16-II-modified mica becomes slightly hydrophobic as the water contact angle increases from <10° to 20.3 ± 2.9°. However, the hydrophobicity of the HOPG surface is significantly reduced, as reflected in a contact angle change from 71.2 ± 11.1° to 39.4 ± 4.3°. The EAK16-II-modified mica surface is stable in acidic solution, while the modified HOPG surface is stable in both acidic and alkaline solutions. The peptide-modified HOPG shows potential as a biocompatible electrode for (bio)molecular sensing. The ability of EAK16-II to form nanofibers on surfaces has also promoted research on peptide-based metallic nanowire fabrication. Our approach is to provide EAK16-II with metal ion binding ability by adding a GGH motif to the C-terminus. This new peptide EAK16(II)GGH has been found to form one-dimensional nanofibers while binding to Cu2+ ions. The dimensions of the nanofibers were significantly affected by the nature of the anions (SO42-, Cl- and NO3-) in the copper salt solution. This work demonstrates the potential usage of EAK16-II for nanowire fabrication.

Surface grafting and modification of poly(acrylic acid) (PAA) were performed on nylon 6,6 carpet fibers to achieve permanent stain and soil resistance. PAA was grafted to nylon and modified with 1H, 1H-pentadecafluorooctyl amine (PDFOA) using an amidation agent, 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM). The first goal was to optimize acrylamide modification of PAA in solution. Aqueous reactions with taurine, hydroxyethyl amine, and butyl amine progressed ~100%, while PDFOA reactions in MeOH progressed ~80%. Reaction products precipitated at 77% butyl or 52% PDFOA acrylamide contents. The second goal was to optimize the PAA grafting process. First, PAA was adsorbed onto nylon 6,6 films. Next, DMTMM initiated grafting of adsorbed PAA. PAA surface coverage was ~78%, determined by contact angle analysis of the top 0.1-1 nm and x-ray photoelectron spectroscopy (XPS) analysis of the top 3-10 nm. The third goal was to modify PAA grafted nylon films with butyl amine and PDFOA. Randomly methylated beta-cyclodextrin (RAMEB) solubilized PDFOA in water. Contact angle detected ~ 100% surface reaction for each amine, while XPS detected ~77% butyl amine (H2O) and ~50% for PDFOA (MeOH or H2O pH=7) reactions. In H2O pH=12, the PDFOA reaction progressed ~89%, perhaps due to greater efficiency, access and solubility. The fourth goal was to perform surface depth profiling via angle-resolved XPS analysis (ARXPS). The PAA surface coverage from contact angle and XPS was confirmed. Further, adsorbed PAA was thicker than grafted PAA, supporting the theory that PAA adsorption occurs in thick layers onto nylon followed by DMTMM-activated spreading and grafting of thinner PAA layers across the surface. The PDFOA reaction in MeOH produced a highly fluorinated but thin exterior and an unreacted PAA interior. The PDFOA reaction in H2O pH=12 produced a completely fluorinated exterior and highly fluorinated interior. Thus surface modification levels from contact angle and XPS were confirmed. The final goal was to PAA-graft and PDFOA-modify nylon 6,6 fabrics and carpets. PDFOA modification achieved significant water and oil repellency. Stainblocking was slightly improved for ionized PAA-g-nylon and greatly improved for PDFOA-modified PAA-g-nylon. However, traditional stainblockers may be necessary to completely prevent dye penetration into carpet tufts.

Arsenic and perchlorate are two types of emerging contaminants commonly found in various water bodies worldwide. Therefore, the development of effective removal technologies has become an important issue today. To this end, the following research studies were conducted. First, trimethylchlorosilane (TMCS) was used for the surface modification of a laboratory-prepared outside-in tubular TiO2/Al2O3 composite membrane aiming at enhancing the filtration performance of the said membrane layer. Second, the TMCS-modified tubular ceramic membrane coupled with the simultaneous electrocoagulation/ electrofiltration (EC/EF) process was tested and evaluated their combined performance in the remediation of arsenic- and perchlorate-spiked waters and one actual As-contaminated groundwater. In this research, the results of a preliminary electrocoagulation study have indicated that aluminum outperformed iron as the anode material. Thus, aluminum was selected as the sacrificial anode for the EC/EF tests throughout this work. In the course of various EC/EF testing, the removal efficiencies of the target contaminant in the test water specimens were compared for the tubular TiO2/Al2O3 composite membranes with and without surface modification. Also evaluated included the permeate flux, unit mass of target contaminant removed, and relevant power consumption. Though surface modification might not yield a better removal efficiency of the concerned contaminant, it gave rise to a greater permeate flux resulting in a greater removed mass of the contaminant for each of the synthetic wastewaters. Meanwhile, lower power consumption was found as compared with the case of no surface modification. As for the actual As-contaminated groundwater, the optimal EC/EF conditions for the tubular composite membrane without surface modification could low the As concentration to meet the local irrigation water quality criteria.

Microfluidics emerged during the early 1990s with channel networks in silicon or glass. Microprocessing of these materials is labor-intensive and time-consuming, it requires sophisticated equipment in a clean room, and often involves hazardous chemicals. The subsequent use of polymer greatly simplified the fabrication of microchips and led to the rapid development of the field. Polymer such as poly(dimethylsiloxane) (PDMS), has other attractive properties, such as being elastic (easy to make efficient microvalves), permeable to gases, and compatible with culturing biological cells. Despite these advantages, applications of PDMS chips are severely limited by a few drawbacks that are inherent to this material: (i) strong adsorption of molecules, particularly large biomolecules, onto its surface; (ii) absorption of nonpolar and weakly polar molecules into PDMS bulk; (iii) leaching of small molecules from PDMS bulk into solutions; and (iv) incompatibility with organic solvents. To overcome all these problems, Teflon plastics seem to be the perfect solution. They are well-known for their superior inertness to almost all chemicals and all solvents; they also show excellent resistance to molecular adsorption and molecule leaching from the polymer bulk to solutions. However, Teflon has a high chemical inertness of the surface, which is restricted the bonding temperature (>260¢XC).It is not conducive to the low-temperature packaging process. This study presents a simple and rapid process for sealing Teflon-based microfluidic chip at a temperature of 140oC which is lower than typical bonding temperature of 260oC. A simple ammonium plasma treatment is used to enhance the surface energy of Teflon substrates such that the bonding temperature can be greatly reduced. Results indicate that the ammonium plasma treated Teflon substrates can be sealed using hot press bonding at a temperature of 140oC for 20 min. The measured iv bonding strength for the Teflon-based microfluidic devices is higher than those bonded at a reported temperature of 260oC for 60 min. It shows the measured contact angle for the Teflon substrates treated with different plasmas. Results indicated that the ammonium hydroxide plasma exhibited the best wettability property and the contact angle reached the minimum value of 45o after 5 min of treatment. The ESCA analysis showed the best Defluorination by ammonium plasma. The fluorine/carbon atomic ratio degraded from 1.96 to 1.10 by 5 minutes. The measured bonding strength for the Teflon substrates bonded with different surface activation protocols. Results showed that the bonding strength was enhanced upto 93% after the plasma treatment. The plasma treatment not only enhanced the bonding strength but also reduced the bonding temperature and time. The measured surface roughness only increased 15¡Ó5 nm (Ra) after the plasma treatment, which is acceptable for most applications in microfluidic systems. Finally, the fluorescence optical architecture and cross-chip successfully detected and isolated £XX-174 fragment of DNA samples confirmed the Teflon substrate for the emerging microfluidic plastic chip. The developed method provides a simple and rapid way to fabricate Teflon-based microfluidic devices.

In this study, pH-sensitive poly(acrylamide-co-acrylic acid) hydrogels were synthesized as controlled release systems in the presence of N,N-methylene bisacrylamide as crosslinker and ammonium persulfate as initiator. A set of hydrogels were used in the form they were prepared. One set of hydrogels were prepared as porous networks by incorporating sodium chloride into the reaction medium and then leaching of it after the completion of polymerization reaction. Two sets of hydrogels were modified by argon-plasma at different discharge powers. Hydrogels were characterized by 13C-NMR, XPS, SEM, ATR-FTIR, ESR as well as equilibrium degree of swelling (EDS) and contact angle measurements. Prepared hydrogels were loaded with a model antibiotic, ciprofloxacin-HCl (CPFX), and in-vitro release of CPFX from hydrogel matrices were examined in buffer solutions of varying pH values. There are two factors determining the release rates of CPFX / one is the pH-dependent solubility of CPFX and the other is EDS of the hydrogel samples. For porous samples drug loading and release rates were higher when compared to the control samples and CPFX solubility dominated over release kinetics. Plasma treatment resulted in prolonged release rates in acidic medium.

In this study calcium carbonate (CaCO3) particles are surface modified by using plasma polymerized natural gas and effects of surface modification of CaCO3 filler on mechanical properties of CaCO3-PP composites are investigated. Different combination of plasma factors / RF power, natural gas flow rate, and plasma discharge durations, are investigated. Mechanical properties such as tensile strength and Young&rsquo / s Modulus are measured by tensile testing machine. Storage modulus and loss modulus measurements are done by DMA. Some information about structures generated by natural gas plasma surface modification is obtained by FTIR tests. The tensile fracture surfaces of prepared composites are investigated by using SEM micrographs. It is concluded that, despite some enhancement obtained in the moduli / the technique of natural gas plasma surface modification of CaCO3 particles did not introduce significant improvement in mechanical properties of composite as expected. This result may partially be attributed to selected plasma parameters (i.e., flow rate, RF power, and discharge duration).

Thrombus formation and blood coagulation is a major problem associated with blood contacting products such as catheters, vascular grafts and artificial hearts. An intense research is being conducted towards the synthesis of new hemocompatible materials and mdifications of surfaces with biological molecules. In this study, polyurethane (PU) films were synthesized in medical purity from diisocyanate and polyol without using any other ingredients and the chemical, thermal and mechanical properties were characterized by solid state NMR, FTIR, GPC, mechanical tests, DMA and TGA. The surfaces of PU films were modified by covalent immobilization of different molecular weight heparins / low molecular weight heparin (LMWH) and unfractionated heparin (UFH) and these surfaces were examined by ESCA, ATR-FTIR, AFM and contact angle goniometer. Cell adhesion studies were conducted with whole human blood and examined by SEM. The effects of different types of heparins on blood protein adsorption and on platelet adhesion were analyzed by electrophresis and SEM, respectively. The surfaces of the UFH immobilized polyurethane films (PU-UFH) resulted in lesser red blood cell adhesion in comparison to LMWH immobilized polyurethane film surfaces (PU-LMWH). When the PU films were treated with blood plasma, the surfaces modified with two different heparin types showed a clearly different protein adsorption behavior especially in the early stage of blood plasma interaction. PU-LMWH samples showed about three times less protein adsorption compared to PU-UFH samples. The morphologies of platelets adhered on material surfaces demonstrated differences / such as PU-UFH had clusters with some pseudopodia extensions, while PU-LMWH had round shaped platelets with little clustering. PU surfaces modified by immobilization of LMWH and UFH, demonstrated promising results for the improvement of non-thrombogenic devices and surfaces.

Magnetic nanoparticles have been used in many areas owing to their variable characteristic behaviors. Among these iron oxide nanoparticles are one of the mostly preferred type of nanoparticles. In this study Fe3O4, namely magnetite, which is one type of magnetic iron oxide nanoparticles was used. Magnetite nanoparticles with a narrow size distribution were prepared in aqueous solution using the controlled coprecipitation method. They were characterized by electron microscopic methods (SEM and TEM), crystal structure analysis (XRD), particle size analyzer, vibrating sample magnetometer (VSM) and Raman spectrometry. The nanoparticles were coated with a thin (ca 20 nm) silica shell utilizing the hydrolysis and the polycondensation of tetraethoxysilane (TEOS) under alkaline conditions in ethanol. The presence of silica coating was investigated by energy dispersive X-ray spectrometer (EDX) measurement. After surface modification with an amino silane coupling agent, (3-Aminopropyl)triethoxysilane, histidine was covalently linked to the amine group using glutaraldehyde as cross-linker. Carbonyl complexes of rhenium [Re(CO)3(H2O)3]+ was prepared through reductive carboxylation utilyzing gaseous carbon monoxide as a source of carbonyl and amine borane (BH3NH3) as the reducing agent. The complex formation was followed by HPLC- ICP-MS system and 95% conversion of perrhanete into the complex was achieved. The magnetic nanoparticles were then labeled with the Re complex with a yield of 86.8% through the replacement of labile H2O groups with imidazolyl groups. Thus prepared particles were showed good stability in vitro. Herein rhenium was selected as a surrogate of radioactive 99mTc. However radioactive isotopes of rhenium (186-Re and 188 Re) is also used for radioactive therapy.