Definition of a near real time microbiological monitor for space vehicles

Efforts to identify the ideal candidate to serve as the biological monitor on the space station Freedom are discussed. The literature review, the evaluation scheme, descriptions of candidate monitors, experimental studies, test beds, and culture techniques are discussed. Particular attention is given to descriptions of five candidate monitors or monitoring techniques: laser light scattering, primary fluorescence, secondary fluorescence, the volatile product detector, and the surface acoustic wave detector

Molecular Contrast Optical Coherence Tomography: A Review

This article reviews the current state of research on the use of molecular contrast agents in optical coherence tomography (OCT) imaging techniques. After a brief discussion of the basic principle of OCT and the importance of incorporating molecular contrast agent usage into this imaging modality, we shall present an overview of the different molecular contrast OCT (MCOCT) methods that have been developed thus far. We will then discuss several important practical issues that define the possible range of contrast agent choice, the design criteria for engineered molecular contrast agent and the implementability of a given MCOCT method for clinical or biological applications. We will conclude by outlining a few areas of pursuit that deserve a greater degree of research and development

Optical Drug Monitoring: Photoacoustic Imaging of Nanosensors to Monitor Therapeutic Lithium in Vivo

Personalized medicine could revolutionize how primary care physicians treat chronic disease and how researchers study fundamental biological questions. To realize this goal, we need to develop more robust, modular tools and imaging approaches for in vivo monitoring of analytes. In this report, we demonstrate that synthetic nanosensors can measure physiologic parameters with photoacoustic contrast, and we apply that platform to continuously track lithium levels in vivo. Photoacoustic imaging achieves imaging depths that are unattainable with fluorescence or multiphoton microscopy. We validated the photoacoustic results that illustrate the superior imaging depth and quality of photoacoustic imaging with optical measurements. This powerful combination of techniques will unlock the ability to measure analyte changes in deep tissue and will open up photoacoustic imaging as a diagnostic tool for continuous physiological tracking of a wide range of analytes

Light-Matter Interactions of Metal-Semiconductor Nanostructures

The field of plasmonics has been shown to possess a versatile property of localized field enhancement around noble metal nano-systems that has been researched extensively in the context of sensing, communication, and microscopy, among others. Additionally, semiconducting nanotechnologies has seen great advances in recent history owing to their attractive optical properties that has landed them in the cutting edge of research with applications into display technologies, microscopy, and sensing. Therefore, it seems natural to see the two fields joined resulting in exciting research outputs that continue to shape the way nanotechnology is studied. To this end, this thesis focuses on the combined optical behaviour of plasmonic and semiconducting nanoparticles to help advance this progressive field. Here, Quantum Dots (QDs) were used as the semiconducting nanoparticles of choice. To do so, different methods of fabrication were explored that utilises both gold nanostructures and QDs, and their optical behaviours were investigated in terms of their energy coupling and transfer.Firstly, a relatively sophisticated lithographic method will be introduced, allowing for fine control of nanoparticle and nanostructure positioning. The viability of such a technique shall be discussed for certain industrial purposes and how recent developments may be used to overcome certain shortcomings including throughput and resolution limits related to electron scattering. Secondly, the fluorescence lifetime of an alternative gold-QD layered structure and a colloidally shelled gold-QD hybrid construction are investigated as a potential platform for light harvesting applications. For both, a pulsed laser source is used to excite the samples and the excitation behaviour over each pulse cycle is studied. It was demonstrated that the structures fabricated possess excellent optical energy transfer characteristics that may make them suitable for energy harvesting platforms

Lithographic patterning of polymeric media for biotechnology applications

Lithographic patterning has heavily utilized in the semiconductor industry for its ability to pattern vast numbers of complex shapes down to the nanometer scale. However, only recently has this technology been employed in the biotechnology field despite the fact that most of that the most important biological components such as cells, antibodies, DNA and proteins operate at this level. This work is an exploration of the use of lithographic printing methods in two areas deeply-entrenched in biotechnology: self assembly and microarray-based manipulation of biological media. It was inspired by the natural self assembly which occurs in nature and in our bodies at all scales. The majority of this work dealt with the patterning of bioreactive copolymers into different three-dimensional microshapes which could be functionalized with single strands of DNA for subsequent sequence-specific particle assembly. This type of technology, where very small-scale matter can be directed to self assembly into programmed macrostructures in a highly-specific manner has the capability to be adapted for many next-generation applications in drug delivery, nanofabrication, biosensing, and microelectronics. A secondary technology was explored in this work involving the paired sequencing of antibody gene sequences with the aid of lithographically-patterned microarrays. This methodology represents a bridging of bottom-up fabrication methods of DNA and proteins with top-down optical fabrication techniques which is already finding increasing utility in applications such as vaccine discovery, diagnostics, and autoimmune research. Because of the versatile nature of the components of this research, it is the hope of the author that the techniques discovered and explored here provide support and inspiration for future research in the biotechnology field as well as in other fields which may benefit as well.Chemical Engineerin

Optical Sensors using Biological Photonic Crystals

This dissertation focuses on the application of diatom frustules, the biosilica shell of an algae possessing physical and photonic properties capable of enhancing optical signals, for the enhancement of optical sensing. In this work, we incorporate diatom frustules into biosensors for signal enhancement and improved target molecule detection. The potential for immunoassay improvement from frustules is first demonstrated using standard sandwich immunoassay fluorescence detection and various analytical methods are explored to analyze the signal. The diatom-based sandwich fluorescence immunoassay is then employed to the detection of the clinically important biomarker, N-terminal pro-B-type natriuretic peptide (NT-proBNP), for the screening of heart failure. Machine learning analyses are employed to further improve the results and enable efficient screening in human plasma. Lastly, the versatility of the frustules is demonstrated by utilizing the frustule, paired with a core-shell nanoparticle, to perform surface-enhanced Raman spectroscopy detection of vapors from explosives. This work validates the utilization of diatom frustules as a means of enhancing optical signals and highlights their unique capabilities to enable superior analyte detection

ACS Nano

Personalized medicine could revolutionize how primary care physicians treat chronic disease and how researchers study fundamental biological questions. To realize this goal, we need to develop more robust, modular tools and imaging approaches for in vivo monitoring of analytes. In this report, we demonstrate that synthetic nanosensors can measure physiologic parameters with photoacoustic contrast, and we apply that platform to continuously track lithium levels in vivo. Photoacoustic imaging achieves imaging depths that are unattainable with fluorescence or multiphoton microscopy. We validated the photoacoustic results that illustrate the superior imaging depth and quality of photoacoustic imaging with optical measurements. This powerful combination of techniques will unlock the ability to measure analyte changes in deep tissue and will open up photoacoustic imaging as a diagnostic tool for continuous physiological tracking of a wide range of analytes.DP1 EB016986/DP/NCCDPHP CDC HHS/United StatesDP1 EB016986/EB/NIBIB NIH HHS/United StatesF32 EB015270/EB/NIBIB NIH HHS/United StatesF32EB015270/EB/NIBIB NIH HHS/United StatesR01 CA157277/CA/NCI NIH HHS/United StatesR01 CA157277/CA/NCI NIH HHS/United StatesR01 CA186567/CA/NCI NIH HHS/United StatesR01 CA186567/CA/NCI NIH HHS/United StatesR01 GM084366/GM/NIGMS NIH HHS/United StatesR01 GM084366/GM/NIGMS NIH HHS/United StatesR01 NS081641/NS/NINDS NIH HHS/United StatesR01 NS081641/NS/NINDS NIH HHS/United States2016-02-24T00:00:00Z25588028PMC436441

Next Generation Optical Analysis for Agrochemical Research & Development

The world’s population is increasing rapidly and higher calorific diets are becoming more common; as a consequence the demand for grain is predicted to increase by more than 50% by 2050 without a significant increase in the available agricultural land. Maximising the productivity of the existing agricultural land is key to maintaining food security and agrochemicals continue to be a key enabler for the efficiency gains required. However, agrochemicals can be susceptible to significant losses and thus often require further chemical to be applied to compensate. Sources of such losses include spray drift, poor spray retention/capture by the target and poor penetration through the plant cuticle. The effectiveness of a crop protection agent depends not only on the intrinsic activity of the active ingredient (AI) but also on the physicochemical properties of the formulation. These properties can be modified by using formulation components, known as adjuvants, which can be used to help mitigate such losses. Adjuvants exert their effects by, for example, controlling droplet size and distribution through their effect on surface tension which can also improve penetration into leaves through the cuticle wax which coats the epidermis of leaves and acts as a protective barrier. However, characterising how they alter the movement of the AIs can be challenging. Optical techniques have shown promise in a multitude of scientifically related areas, such as in vivo tissue imaging, but none have yet been applied to aiding the agrochemical industry. By probing the interactions between leaf surface and agrochemical agent, with light, one is able to obtain a large amount of diagnostic information, non-invasively. Whereas techniques like Raman 3 spectroscopy are limited by long acquisition times, coherent Raman techniques such as coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) are coherently driven and provide an enhanced signal, and also allow for video-rate imaging. In this thesis, I have applied this cutting-edge laser imaging technique as a novel analytical technique that allows the in situ analysis of agrochemicals in living plant tissues at a cellular level. In Chapters 4 through 7, multiple factors essential for a functional and efficient agrochemical were considered and experimented. In Chapter 4, a typical industry study highlights the need for innovative and rapid technologies in the agrochemical industry. The resulting chapters (5, 6, and 7) outline several ways in which Coherent Raman Scattering (CRS) techniques can improve the current capabilities of agrochemical testing. By utilising a model system, paraffin wax, a cheap and rapid protocol can provide accurate diffusion information and repeatable results. Chapters 6 and 7 use both this protocol to gain comparative data on several adjuvants and active ingredients in paraffin wax and in vivo, in a variety of plants. The ability to visualise agrochemical products on a leaf surface to reveal interactions between the materials of the product and with the leaf surface will enable a step change in the agrochemical design process, through determination of the spatial distribution of the materials and their roles within the applied products. It is hoped that the technology developed in this thesis could play a big role in the development of future agrochemical products that are tailored to maximise efficacy and minimise environmental impact