The complexity of biological soft matter at the sub-micrometer level is fundamentally correlated to the functionalities at the larger scale. Reflecting the level of heterogeneities in the properties of systems remains challenging when probing small scales, due to the mismatch between the area surveyed with the tools offering nanoscale resolution, such as atomic force microscopy (AFM), and the scale of natural variations inherent to biology. Hence, to understand the physiological and mechanical alterations that occur within a single cell relative to a cell population, a multiscale approach is necessary. In this work we show that it is possible to observe molecular, chemical and physical alterations in both plant and human cells with a multiscale approach. Biophysical and biochemical traits of cell populations are studied with Fourier Transform infrared spectroscopy (FTIR) and in turn, guide higher resolution discovery with Raman spectroscopy and nanoscale infrared spectroscopy using AFM (NanoIR) to access finer details. We illustrate this with three examples of biological soft matter systems: 1) a preliminary study of cellular interactions with naturally occurring vehicles applicable to human health, 2) a qualitative examination of antibiotics and new pesticide treatments in food crop systems, and 3) a fundamental investigation of the deconstruction mechanisms of plant cells during pre-treatments in preparation for biofuel production.

Development and application of engineered nanomaterials to a variety of industrial and medical fields have progressed rapidly. Metal nanoparticles are predominantly desirable for their enhanced catalytic properties due to their high surface area-to-volume ratio as a result of their size reduction. Incorporating metal nanoparticles into another nanomaterial creates a nanocomposite that exhibits novel and better properties. There is a search for a stable flexible substrate that can contain the aqueous reaction of metal reduction for nanoparticle formation. In this study, we developed nanocomposite mats that are comprised of hydrogel nanofibers of polyelectrolytes poly(acrylic acid) and poly(allylamine hydrochloride) and loaded metal nanoparticles. The nanofibers are fabricated by the electrospinning technique, and subsequently immersed into a metal salt solution to absorb the metal ions. The metal ions within the fibers are then chemically reduced to form metal nanoparticles inside and on the surface of the nanofibers. Redox studies on various organic compounds were conducted to observe the catalytic reduction by the nanocomposites. The proposed fabrication process is advantageous in terms of simplicity, controllability and versatility.

In this thesis, we present an efficacious way of tracking nanoparticle movement in plant tissue through the use of fluorescence lifetime imaging (FLIM) and spectroscopy as well as a review of nanoparticle uptake in plants and the proposed mechanisms governing them. Given the increasing number of nanomaterials in agriculture and society as a whole, proper imaging tools and proactive measures must be taken to track nanoparticle movement in plant tissues and create infrastructure and products to keep things sustainable and safe. Herein we report a ZnO comparable nanoparticle— a CdS:Mn/ZnS/ N-acetyl cysteine (NAC) quantum dot— which boasts longer lifetimes and suitable fluorescent properties above ZnO to properly delineate from plant tissue fluorescence of chlorophyll and cinnamic acids. In addition to FLIM mapping, quantum dot localization in plant vascular tissue was clearly seen and confirmed via characteristic emission spectra and time correlated single photon counting decay curves (TCSPC). Most quantum dots were seen to reside in the xylem. Plant age and structure was seen to affect uptake. QD size likely restricted extensive translocation. Inhibitive effects of QDs were likely water and mechanical stress. We surmise that travel of the cadmium quantum dots up the leaf and branch plant tissues is likely most governed by diffusion as the quantum dots bound to the cell structures create a diffusion gradient which aids travel up the leaf.

Interfacial interactions play a major role in a wide range of applications from our everyday life to high-tech industrial applications. These interactions act between almost all the surfaces around us. In this work, we particularly study interfacial interactions in solid/water/liquid and solid/air/solid systems. In the first system, we mainly explored hydrophobic interactions that can take place only in a liquid medium. Long-range hydrophobic attractions between mesoscopic surfaces in water play an important role in many colloid and interface phenomena. Despite having been studied in different ways, the origin of these forces has yet to be explained. While previous research has focused on solid/water/solid and solid/water/air scenarios, we investigated a solid/water/liquid situation to gain additional insight. Here we directly measure long-range interactions between a solid and a hydrophobic liquid separated by water using force spectroscopy, where colloidal probes were functionalized with graphene oxide (GO) to interact with immobilized heptane droplets in water. We detected attractions with a range of ≈0.5 µm that cannot be explained by standard Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. When the GO was increasingly reduced to rGO to become more hydrophobic, these forces increased in strength and ranged up to 1.2 μm. This suggests that the observed attractions are indeed a result of long-range hydrophobic forces. Based on our results, we propose nanoscale air bubbles attached to the colloidal probe and molecular rearrangement at the water/oil interface as possible origins of the observed interactions. This knowledge will be useful to understand and motivate the formation of Pickering emulsions using 2D materials and other amphiphilic/hydrophobic particles. We studied interfacial interactions in solid/air/solid systems to understand attraction and adhesion between 2D materials (graphene and hexagonal boron nitride) and polymers. These 2D materials and their derivatives are widely used in nanocomposites due to outstanding mechanical, thermal, and electric properties. The interfacial bonds in the nanocomposite should be strong to transfer these properties of the nanomaterials to the polymer. In this study, we present a simple method to directly measure the interactions between different types of polymers and graphene versus hBN using force spectroscopy technique. We use polymer colloidal probes which were fabricated in the lab to carry out force spectroscopy measurements on graphene and hBN. We have studied some of the widely used polymers for nanocomposites such as polystyrene, PMMA, and epoxy. The attraction and adhesion between polymers and 2D materials were quantitatively studied. The results suggest that we cannot predict adhesive forces based on known van der Waals forces and the direct measurement of adhesive forces is required. With these two studies carried out in liquid and air media, we have uncovered interfacial phenomena that can be used in many applications such as mass production of nanomaterials, Pickering emulsions, oil/water separation, and nanocomposites.

The aim of the study described herein is to quantify the in-vitro kinetics of internalization of polystyrene nanoparticles (PS NPs) by cells. We used different charges, sizes and doses of fluorescently labelled PS NPs. Nanoparticles were characterized with UV-Vis, Fluorescence emission Dynamic Light Scattering (DLS) and Zeta potential for knowing their absorption, fluorescence spectra, size, charge, respectively. Additionally, cell viability was tested to know the toxicity of PS NPs. The quantitative uptake, the kinetics profile and rate of uptake were studied by using a new in-vitro fluorescence assay. This was achieved quantitatively and qualitatively by fluorescent plate reader and confocal imaging, respectively. It was found that the amine PS NPs are higher in cytotoxicity than the carboxy PS NPs due to the proton sponge phenomenon. It was observed that the fraction uptake of PS NPs changes by changing the physiochemical properties as charge, size & dose. The fraction uptake of neutral and amine PS NPs was higher than that of carboxy PS NPs. For the neutral PS NPs, the uptake depends on the macropinocytosis. For the amine PS NPs, the uptake depends on the electrostatic interaction and the rapid regeneration of new binding sites. Regarding the dose of PS NPs, for the amine PS NPs, it was found that the concentrations lower and higher than 5nM had lower fraction uptake, because the 5nM achieved the balance between the available number of binding sites and the rapid regeneration of new binding sites. For the kinetics profile of the amine and carboxy PS NPs, by comparing both of them, it was observed that the rate of uptake of applied doses lower than 5nM was different, but higher than 5nM was similar. However, for the neutral Ps NPs, they exhibit a steady state of rate of uptake in between the amine and carboxy PS NPs. Also, it was confirmed by the confocal images that as the concentration of amine PS NPs increase, the stress on the cells increase, leading to the cell death. These results were aligned with the results obtained from the cytotoxicity test.

<p>The phenomenon of radiation pressure has fascinated scientists since it was first proposed by Maxwell in the late 19th century. Numerous experiments involving optical forces have been carried out, however the optical force acting on a curved waveguide does not appear to have been previously investigated. An experiment to measure the force acting on a waveguide due to the optical power it contains is proposed here. This experiment takes advantage of the sensitivity of MicroElectroMechanical Systems (MEMS) and the performance of silicon integrated optics in a single hybrid device.</p> <p>Devices are fabricated from silicon-on-insulator (SOI) wafers using conventional micromachining techniques. Anisotropic alkali etches are used to produce smooth vertical side-walls for a mechanical structure and a rib waveguide. An analysis of the electrical systems and measurement techniques is provided. Using these techniques, the resonant operation of the devices is demonstrated by means of capacitive actuation and sensing. The application of this system to the measurement of radiation pressure is discussed.</p> / Master of Applied Science (MASc)

<p>Incorporating nanoparticles within a polymer to improve the mobility of the filmis one promising way of creating organic thin film transistors (OTFTs) with large mobilities that could be applicable in real world applications. Carbon nanotubes (CNTs)and graphene nanoplatelets (GNPs) are extensively studied for this application. In order to overcome their tendency to aggregate, a method for creating a stable dispersion within both the solution phase and the film is needed. Here an easy method is established for creating a stable dispersion of CNTs or GNPs within a polymer solution which results in excellent OTFT mobility.A non-percolating network of non-covalently functionalized single walled carbon nanotubes was embedded within poly[5,5’-bis(3-dodecyl-2-thienyl)-2,2’bithiophene](PQT-12) thin films for the purpose of enhancing field effect mobility in thin film transistors. The host polymer was used to stabilize the nanotubes in suspension by π orbital overlap caused by simple application of ultrasonication. The stable nanotube suspension was cast into two different device architectures both with excellent mobilities and on/off ratios. The effect of nanotube content on polymer interaction within suspension, film morphology and electrical properties are discussed. A CNT nanocomposite OTFT with enhanced mobility was also tested for applications in vapour sensing. A method is also presented for the creation of graphene nano-platelets (GNPs) for implementation in nano-composite films. Heat treatment of expandable graphite within a vacuum evaporation chamber yielded chemically pure GNPs of a few nanometer thickness. Exfoliating expandable graphite without heat treatment resulted in even higher concentrations but chemically impure GNPs. The material was non-covalently stabilizedwith PQT-12 in a similar method to CNTs and used to create OTFTs with enhanced mobility. The effect of heat treatment parameters and exfoliation conditions on GNP thickness, size and chemical purity are discussed, as well as effect of GNP content on mobility and on/off ratio.</p> / Master of Applied Science (MASc)

<p> At present modulators in communications industry utilize non-linear materials like indium tin oxide (ITO) and DLD-164 as a dielectric, which makes the fabrication process cumbersome and expensive. This thesis discusses the possibility of using only gold and air as conductor and dielectric to characterize a signal modulating device. Both electro-absorption modulation (EAM) and phase change driven modulation is possible with the design. For the change in phase a length of 2.992 &micro;<i>m</i> for the modulating arm of a Mach-Zehnder modulator (MZM) was achieved for operation at 525 <i>nm</i>. High absorptions of electromagnetic (EM) waves was seen at the 480 <i>nm</i> mark allowing a length of just 4.95 &micro;<i>m</i> for EAM. The results suggest that an all plasmonic noble metal modulator utilizing air as a dielectric is possible for operation in the visible 400 <i>nm</i> to 700 <i>nm</i> range. The concept is supported by proof-of-principle based simulations. </p><p> This thesis proposes a novel idea of an all plasmonic modulator driven by changes in free carrier concentration in gold and surface plasmon polariton (SPP) excitations under an applied potential. The prototype model is simulated using a commercial finite difference time domain solver. The simulation enviro<i> nm</i>ent allows Maxwell&rsquo;s equations to be solved in the time domain to investigate light propagation and absorption characteristics under an externally applied electric potential. The free carrier concentration dependent permittivity of gold is exploited to investigate possible applications in nano-photonics and optical communications.</p><p>

Emerging fields such as "Organs on a Chip", disease modeling in vitro, stem cell manufacturing and wearable bioelectronics are demanding rapid development of 3D Microelectrode Arrays (MEAs) for electrical interfacing with biological constructs. The work reported in this thesis focuses on two developmental tracks: "Dynamic 3D MEAs" and metal microfabrication for 3D MEAs. In the first part of the thesis, we explore the capabilities and limitations of 3D printed microserpentines (µserpentines) and utilize these structures to develop dynamic 3D microelectrodes. Analytical modeling of µserpentines flexibility followed by integration into a flexible Kapton® package and PDMS insulation are demonstrated. These 3D MEAs were further characterized in dynamic impedance measurement experiments and with an artificial skin model demonstrating their potential for wearable bioelectronics. In the second part of the thesis, microfabrication of the 3D metal MEAs for in vitro cell constructs is reported. These were fabricated using laser micromachining in 2D and transitioned out-of-plane to the final 3D conformation by a custom fabricated Hypodermic Needle Array (Hypo-Rig). The 3D metal MEAs were packaged on multiple substrates, and a 3D insulation layer was defined to fabricate microelectrodes that were subsequently characterized mechanically and electrically.

No description available.