Development of Plasmonic Nanoplatforms for Diagnostics, Therapy, and Sensing

Recent advances in nanotechnology have led to the application of nanoparticles in a wide variety of fields. In the field of nanomedicine, there is great emphasis on combining diagnostic and therapeutic modalities into a single nanoparticle construct (theranostics). In particular, anisotropic nanoparticles have shown great potential for surface-enhanced Raman scattering (SERS) detection due to their unique optical properties. Gold nanostars are a type of anisotropic nanoparticle with one of the highest SERS enhancement factors in a non-aggregated state. By utilizing the distinct characteristics of gold nanostars, new plasmonic materials for diagnostics, therapy, and sensing can be synthesized. The work described herein is divided into two main themes. The first half presents a novel, theranostic nanoplatform that can be used for both SERS detection and photodynamic therapy (PDT). The second half involves the rational design of silver-coated gold nanostars for increasing SERS signal intensity and improving reproducibility and quantification in SERS measurements.

The theranostic nanoplatforms consist of Raman-labeled gold nanostars coated with a silica shell. Photosensitizer molecules for PDT can be loaded into the silica matrix, while retaining the SERS signal of the gold nanostar core. SERS detection and PDT are performed at different wavelengths, so there is no interference between the diagnostic and therapeutic modalities. Singlet oxygen generation (a measure of PDT effectiveness) was demonstrated from the drug-loaded nanocomposites. In vitro testing with breast cancer cells showed that the nanoplatform could be successfully used for PDT. When further conjugating the nanoplatform with a cell-penetrating peptide (CPP), efficacy of both SERS detection and PDT is enhanced.

The rational design of plasmonic nanoparticles for SERS sensing involved the synthesis of silver-coated gold nanostars. Investigation of the silver coating process revealed that preservation of the gold nanostar tips was necessary to achieve the increased SERS intensity. At the optimal amount of silver coating, the SERS intensity is increased by over an order of magnitude. It was determined that a majority of the increased SERS signal can be attributed to reducing the inner filter effect, as the silver coating process moves the extinction of the particles far away from the laser excitation line. To improve reproducibility and quantitative SERS detection, an internal standard was incorporated into the particles. By embedding a small-molecule dye between the gold and silver surfaces, SERS signal was obtained both from the internal dye and external analyte on the particle surface. By normalizing the external analyte signal to the internal reference signal, reproducibility and quantitative analysis are improved in a variety of experimental conditions.

Problèmes de routages dans les réseaux optiques

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Diagnostics robustes à des délais individuels en utilisant les estimateurs robustes RA-ARX

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Heart failure in sub-Saharan Africa: review of the aetiology of heart failure and the role of point-of-care biomarker diagnostics

Within Africa, the burden of heart failure is significant. This arises from the increase in cardiovascular disease and associated risk factors such as hypertension and diabetes, as well as causes of heart failure which are particular to sub-Saharan Africa, such as endomyocardial fibrosis. The lack of access to echocardiography and other imaging modalities, from a cost and technical perspective, combined with the predominantly rural nature of many countries with poor transport links, means that the vast majority of people never obtain an appropriate diagnosis. Similarly, research has been limited on the causes and treatment of heart failure in Africa and in particular endemic causes such as EMF and rheumatic heart disease. This review outlines the burden of heart failure in Africa and highlights the opportunity to expand diagnosis through the use of biomarkers, in particular natriuretic peptides. This builds on the success of point-of-care testing in human immunodeficiency virus and tuberculosis which have been extensively deployed in community settings in Africa.

Surface plasmon resonance biosensing: Approaches for screening and characterising antibodies for food diagnostics

Research in biosensing approaches as alternative techniques for food diagnostics for the detection of chemical contaminants and foodborne pathogens has increased over the last twenty years. The key component of such tests is the biorecognition element whereby polyclonal or monoclonal antibodies still dominate the market. Traditionally the screening of sera or cell culture media for the selection of polyclonal or monoclonal candidate antibodies respectively has been performed by enzyme immunoassays. For niche toxin compounds, enzyme immunoassays can be expensive and/or prohibitive methodologies for antibody production due to limitations in toxin supply for conjugate production. Automated, self-regenerating, chip-based biosensors proven in food diagnostics may be utilised as rapid screening tools for antibody candidate selection. This work describes the use of both single channel and multi-channel surface plasmon resonance (SPR) biosensors for the selection and characterisation of antibodies, and their evaluation in shellfish tissue as standard techniques for the detection of domoic acid, as a model toxin compound. The key advantages in the use of these biosensor techniques for screening hybridomas in monoclonal antibody production were the real time observation of molecular interaction and rapid turnaround time in analysis compared to enzyme immunoassays. The multichannel prototype instrument was superior with 96 analyses completed in 2h compared to 12h for the single channel and over 24h for the ELISA immunoassay. Antibodies of high sensitivity, IC50's ranging from 4.8 to 6.9ng/mL for monoclonal and 2.3-6.0ng/mL for polyclonal, for the detection of domoic acid in a 1min analysis time were selected. Although there is a progression for biosensor technology towards low cost, multiplexed portable diagnostics for the food industry, there remains a place for laboratory-based SPR instrumentation for antibody development for food diagnostics as shown herein.

A new generation of companion diagnostics: cobas BRAF, KRAS and EGFR mutation detection tests

The cobas® (Roche) portfolio of companion diagnostics in oncology currently has three assays CE-marked for in vitro diagnostics. Two of these (EGFR and BRAF) are also US FDA-approved. These assays detect clinically relevant mutations that are correlated with response (BRAF, EGFR) or lack of response (KRAS) to targeted therapies such as selective mutant BRAF inhibitors in malignant melanoma, tyrosine kinases inhibitor in non-small cell lung cancer and anti-EGFR monoclonal antibodies in colorectal cancer, respectively. All these assays are run on a single platform using DNA extracted from a single 5 µm section of a formalin-fixed paraffin-embedded tissue block. The assays provide an ‘end-to-end’ solution from extraction of DNA to automated analysis and report on the cobas z 480. The cobas tests have shown robust and reproducible performance, with high sensitivity and specificity and low limit of detection, making them suitable as companion diagnostics for clinical use.

Personalized cancer medicine: molecular diagnostics, predictive biomarkers, and drug resistance.

The progressive elucidation of the molecular pathogenesis of cancer has fueled the rational development of targeted drugs for patient populations stratified by genetic characteristics. Here we discuss general challenges relating to molecular diagnostics and describe predictive biomarkers for personalized cancer medicine. We also highlight resistance mechanisms for epidermal growth factor receptor (EGFR) kinase inhibitors in lung cancer. We envisage a future requiring the use of longitudinal genome sequencing and other omics technologies alongside combinatorial treatment to overcome cellular and molecular heterogeneity and prevent resistance caused by clonal evolution.

“Digital Diagnostics and Communication (DDC) system” Redesigning the Emergency Ambulance

During the development of a new treatment space for the UK emergency ambulance participatory observations with front-line clinicians revealed the need for an integrated patient monitoring, communication and navigation system. The research identified the different information touch-points and requirements through modes of use analysis, day-in-the-life study and simulation workshops with clinicians. Emergency scenario and role-play with paramedics identified 5 distinct ambulance modes of use. Information flow diagrams were created and checked by paramedics and digital User Interface (UI) wireframes were developed and evaluated by clinicians during clinical evaluations. Feedback from clinicians defined UI design specification further leading to a final design proposal. This research was a further development from the 2007 EPSRC funded “Smart Pods” project. The resulting interactive prototype was co-designed in collaboration with ambulance crews and provides a vision of what could be achieved by integrating well-proven IT technologies and protocols into a package relevant in the emergency medicine field. The system has been reviewed by over 40 ambulance crews and is part of a newly co-designed ambulance treatment space.

Nucleic Acid Diagnostics using Isotachophoresis and Isothermal Amplification

Thesis (Ph.D.)--University of Washington, 2016-08

Développement de fibres optiques composites pour la génération du supercontinuum dans l’infrarouge

Les sources laser à large bande possédant les caractéristiques requises pour émettre sur la plage spectrale correspondant à la seconde fenêtre de transmission atmosphérique (3 à 5 μm) exercent un attrait considérable pour divers domaines tels que la télédétection de polluants atmosphériques et les contremesures infrarouges. Les supercontinua générés à l’intérieur de fibres optiques représentent une option intéressante pour réaliser ce type de sources laser. En effet, ils possèdent une intensité élevée, un large contenu spectral, une excellente directionnalité de faisceau, ainsi qu’un bon potentiel pour constituer des sources lumineuses compactes et robustes. Toutefois, la génération d’un tel supercontinuum implique certains défis à relever sur le plan de la conception des fibres optiques employées. En fait, ces fibres optiques doivent présenter de faibles pertes de propagation sur la plage spectrale de 3 à 5 μm, posséder un paramètre de non-linéarité élevé et permettre le pompage en régime anomal de dispersion à des longueurs d’onde pour lesquelles des sources laser compactes sont offertes commercialement. En matière de robustesse, ces fibres doivent également démontrer de bonnes propriétés mécaniques ainsi qu’une stabilité chimique appropriée vis-à-vis de la corrosion causée par l’humidité. Dans le cadre de cette thèse, un nouveau type de fibres composites à saut d’indice fortement contrasté a été développé pour atteindre ces objectifs de génération de supercontinuum. Ce type de fibres combine respectivement un verre de tellurite et un verre de germanate pour son coeur et sa gaine permettant ainsi d’atteindre une différence d’indice de réfraction d’environ 0.3 entre ces deux dernières structures. Grâce à cet important saut d’indice, ces fibres peuvent fortement confiner les modes optiques à l’intérieur de leur coeur, ce qui leur donne la possibilité d’atteindre un niveau élevé de non-linéarité et d’optimiser leurs caractéristiques de dispersion chromatique pour la génération du supercontinuum. D’autre part, leur section transversale toute solide leur confère aussi une meilleure stabilité environnementale comparativement à celle démontrée par les fibres optiques microstructurées à base de verres d’oxydes de métaux lourds, de verres de chalcogénure et de verres fluorés. Toutefois, leur fabrication nécessite l’appariement de verres dont les propriétés thermomécaniques concordent suffisamment ensemble pour permettre leur fibrage. Les travaux effectués ici démontrent la production de fibres optiques composites et leur potentiel pour la génération du supercontinuum dans l’infrarouge moyen.

Techniques en appui des formats de modulation avancés pour les futurs réseaux optiques

Les systèmes de communication optique avec des formats de modulation avancés sont actuellement l’un des sujets de recherche les plus importants dans le domaine de communication optique. Cette recherche est stimulée par les exigences pour des débits de transmission de donnée plus élevés. Dans cette thèse, on examinera les techniques efficaces pour la modulation avancée avec une détection cohérente, et multiplexage par répartition en fréquence orthogonale (OFDM) et multiples tonalités discrètes (DMT) pour la détection directe et la détection cohérente afin d’améliorer la performance de réseaux optiques. Dans la première partie, nous examinons la rétropropagation avec filtre numérique (DFBP) comme une simple technique d’atténuation de nonlinéarité d’amplificateur optique semiconducteur (SOA) dans le système de détection cohérente. Pour la première fois, nous démontrons expérimentalement l’efficacité de DFBP pour compenser les nonlinéarités générées par SOA dans un système de détection cohérente porteur unique 16-QAM. Nous comparons la performance de DFBP avec la méthode de Runge-Kutta quatrième ordre. Nous examinons la sensibilité de performance de DFBP par rapport à ses paramètres. Par la suite, nous proposons une nouvelle méthode d’estimation de paramètre pour DFBP. Finalement, nous démontrons la transmission de signaux de 16-QAM aux taux de 22 Gbaud sur 80km de fibre optique avec la technique d’estimation de paramètre proposée pour DFBP. Dans la deuxième partie, nous nous concentrons sur les techniques afin d’améliorer la performance des systèmes OFDM optiques en examinent OFDM optiques cohérente (CO-OFDM) ainsi que OFDM optiques détection directe (DDO-OFDM). Premièrement, nous proposons une combinaison de coupure et prédistorsion pour compenser les distorsions nonlinéaires d’émetteur de CO-OFDM. Nous utilisons une interpolation linéaire par morceaux (PLI) pour charactériser la nonlinéarité d’émetteur. Dans l’émetteur nous utilisons l’inverse de l’estimation de PLI pour compenser les nonlinéarités induites à l’émetteur de CO-OFDM. Deuxièmement, nous concevons des constellations irrégulières optimisées pour les systèmes DDO-OFDM courte distance en considérant deux modèles de bruit de canal. Nous démontrons expérimentalement 100Gb/s+ OFDM/DMT avec la détection directe en utilisant les constellations QAM optimisées. Dans la troisième partie, nous proposons une architecture réseaux optiques passifs (PON) avec DDO-OFDM pour la liaison descendante et CO-OFDM pour la liaison montante. Nous examinons deux scénarios pour l’allocations de fréquence et le format de modulation des signaux. Nous identifions la détérioration limitante principale du PON bidirectionnelle et offrons des solutions pour minimiser ses effets.

Best Practice Guidelines on molecular diagnostics in Duchenne/Becker muscular dystrophies

Meeting participants: Rosário dos Santos, Porto, Portugal

Plasma diagnostics and ITO film deposition by RF-assisted closed-field dual magnetron system

Deposition of indium tin oxide (ITO) among various transparent conductive materials on flexible organic substrates has been intensively investigated among academics and industrials for a whole new array of imaginative optoelectronic products. One critical challenge coming with the organic materials is their poor thermal endurances, considering that the process currently used to produce industry-standard ITO usually involves relatively high substrate temperature in excess of 200°C and post-annealing. A lower processing temperature is thus demanded, among other desires of high deposition rate, large substrate area, good uniformity, and high quality of the deposited materials. For this purpose, we developed an RF-assisted closed-field dual magnetron sputtering system. The “prototype” system consists of a 3-inch unbalanced dual magnetron operated at a closed-field configuration. An RF coil was fabricated and placed between the two magnetron cathodes to initiate a secondary plasma. The concept is to increase the ionization faction with the RF enhancement and utilize the ion energy instead of thermal energy to facilitate the ITO film growth. The closed-field unbalanced magnetrons create a plasma in the intervening region rather than confine it near the target, thus achieving a large-area processing capability. An RF-compensated Langmuir probe was used to characterize and compare the plasmas in mirrored balanced and closed-field unbalanced magnetron configurations. The spatial distributions of the electron density ne and electron temperature Te were measured. The density profiles reflect the shapes of the plasma. Rather than intensively concentrated to the targets/cathodes in the balanced magnetrons, the plasma is more dispersive in the closed-field mode with a twice higher electron density in the substrate region. The RF assistance significantly enhances ne by one or two orders of magnitude higher. The effect of various other parameters, such as pressure, on the plasma was also studied. The ionization fractions of the sputtered atoms were measured using a gridded energy analyzer (GEA) combined with a quartz crystal microbalance (QCM). The presence of the RF plasma effectively increases the ITO ionization fraction to around 80% in both the balanced and closed-field unbalanced configurations. The ionization fraction also varies with pressure, maximizing at 5-10 mTorr. The study of the ionization not only facilitates understanding the plasma behaviors in the RF-assisted magnetron sputtering, but also provides a criterion for optimizing the film deposition process. ITO films were deposited on both glass and plastic (PET) substrates in the 3-inch RF-assisted closed-field magnetrons. The electrical resistivity and optical transmission transparency of the ITO films were measured. Appropriate RF assistance was shown to dramatically reduce the electrical resistivity. An ITO film with a resistivity of 1.2×10-3 Ω-cm and a visible light transmittance of 91% was obtained with a 225 W RF enhancement, while the substrate temperature was monitored as below 110°C. X-ray photoelectron spectroscopy (XPS) was employed to confirm the ITO film stoichiometry. The surface morphology of the ITO films and its effect on the film properties were studied using atomic force microscopy (AFM). The prototype of RF-assisted closed-field magnetron was further extended to a larger rectangular shaped dual magnetron in a flat panel display manufacturing system. Similar improvement of the ITO film conductivities by the auxiliary RF was observed on the large-area PET substrates. Meanwhile, significant deposition rates of 25-42 nm/min were achieved.