As the developments in nanoscale fabrication and characterization technology, the investigation and applications of light in metal nanostructures have been becoming one of the most focused research areas. Metal materials allow to couple the incident light energy into electromagnetic waves propagating on the metal surface under certain configurations, which is called surface plasmon (SP). This feature tremendously expanded the application possibility of metals in optical regime, such as extraordinary transmission (EOT), near-field optics and surface enhanced spectroscopies. In this talk, various metal structures will be demonstrated which could control SP’s propagation, resonance andlocal field enhancement. A number of SP applications are benefited – the plasmonic bragg reflector (PBR), the frequency sensitive plasmonic microcavity, the subwavelength metallic taper, the long range surface plasmon (LRSP) waveguide and surface enhanced Raman spectroscopy (SERS). Especially for SERS, long-term effort was devoted into it to achieve the single molecule detection limit. / Graduate

Thesis (Ph. D.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains xvii, 169 p. : ill. Vita. Includes abstract. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains xi, 81 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

Thesis (M.Sc.Eng.) / Sepsis is a serious medical condition in which a person becomes infected with bacteria in his or her bloodstream. The symptoms of sepsis are a result of the immune system’s interaction with the infecting agent. Currently, to diagnose a patient with sepsis, a blood sample must be collected and cultured for 24-48 hours before the infection can be confirmed. In the meantime, a broad-scope antibiotic is administered which may or may not be effective in treating the patient. If the antibiotic is ineffective, a different antibiotic must be chosen. When the results of the blood culture are available, a narrow scope antibiotic, appropriate to treat the infection is administered. However, sepsis has a mortality rate of 18-30% depending on the infecting agent and the treatment is highly time sensitive. Within 24 hours, the syndrome may progress to septic shock and mortality rates reach 50%. Therefore, it is important to quickly and correctly identify the infecting agent and provide immediate targeted treatment. Surface Enhanced Raman Spectroscopy (SERS) can be used to quickly identify and distinguish between different bacterial strains; however it requires higher bacterial concentrations than are present in the blood during the early stages of sepsis. A microfluidic evaporator chip has been developed to concentrate bacteria samples from 4μl to 100nl; the chip has been evaluated for concentration efficiency on Escherichia coli and methicillin-sensitive Staphylococcus aureus. Various blocking methods using bovine serum albumin (BSA) have been tested to reduce bacterial adhesion to the chip and have improved bacterial recovery to around 70% for both strains tested. Ongoing tests are being performed to improve bacterial recovery and sample purity for identification. / 2031-01-01

The rational combination of dielectric and metallic nano particles brings novel optical properties to conventional subwavelength structures. This thesis introduces the optoplasmonic geometries demonstrating versatile ability in both far and near field modification within nano scale. Template-assisted self-assembly approaches are applied creating nano entities with titanium dioxide and gold nano spheres. A top-bottom mono hybrid unit and interdigitated array are developed. With the examination of the elastic and inelastic response of these hybrid materials, physical models are simulated to depict the scenario of varied geometry and combination of nano particles. In contrast to solely metal or dielectric particle arrays, this type of artificial material not only enhances the near electric field intensity within the metal nano cluster hot spots, but also expands the overall volume of enhanced electric field. Further study reveals that the additional enhancement and redistribution of near field are derived from the coupling between the nano gold cluster plasmon resonance and the in-plane diffractive mode of the dielectric array. The redirected emission profile of the fluorescent dyes within the hybrid array is explored.

Fresh foods, including meats and produce are the fastest growing market in the supermarket and the class of foods most likely to cause a bacterial foodborne illness. As the rate of consumption of perishable products increases, rapid detection of pathogens within the food supply becomes a critical issue. Current methods used for the detection of bacteria that cause food-borne illnesses are time consuming, expensive and often require selective enrichment. In this study we adapted a separation technique originally developed for PCR to extract bacteria from ground beef using β-cyclodextrin (β-CD) and milk protein coated activated carbon (MP-CAC) as filtration agents. The recovered bacteria were bound to a gold slide via a 3-mercaptophenylboronic acid (3-MPBA) sandwich assay and detected with Surface Enhanced Raman Spectroscopy (SERS). The 3-MPBA sandwich assay used with the separation technique allowed detection of Salmonella enterica Enteritidis (BAA-1045), separated from a ground beef matrix, as low as 1x102 CFU/g. Detection at this level was accomplished in less than 8 hours, significantly faster than plate count or enrichment methods that require multiple days. Previously, SERS has been used to detect bacteria within simple matrices; this is the first study to have utilized SERS bacterial detection in a ground beef.

Raman spectroscopy is an extremely versatile technique with molecular sensitivity and fingerprint specificity. However, the translation of this tool into a deployable technology has been stymied by irreproducibility in sample preparation and the lack of complex data analysis tools. In this dissertation, a droplet microfluidic platform was prototyped to address both sample-to-sample variation and to introduce a level of quantitation to surface enhanced Raman spectroscopy (SERS). Shifting the SERS workflow from a cell-to-cell mapping routine to the mapping of tens to hundreds of cells demanded the development of an automated processing tool to perform basic SERS analyses such as baseline correction, peak feature selection, and SERS map generation. The analysis tool was subsequently expanded for use with a multitude of diverse SERS applications. Specifically, a two-dimensional SERS assay for the detection of sialic acid residues on the cell membrane was translated into a live cell assay by utilizing a droplet microfluidic device. Combining single-cell encapsulation with a chamber array to hold and immobilize droplets allowed for the interrogation of hundreds of droplets. Our novel application of computer vision algorithms to SERS maps revealed that sialic sugars on cancer cell membranes are found in small clusters, or islands, and that these islands typically occupy less than 30% of the cell surface area. Employing an opportunistic mindset for the application of the data processing platform, a number of smaller projects were pursued. Biodegradable aliphatic-aromatic copolyesters with varying aromatic content were characterized using Raman spectroscopy and principal component analysis (PCA). The six different samples could successfully be distinguished from one another and the tool was able to identify spectral feature changes resulting from an increasing number of aryl esters. Uniquely, PCA was performed on the 3,125 spectra collected from each sample to investigate point-to-point heterogeneities. A third set of projects evaluated the ability of the data processing tool to calculate spectral ratios in an automated fashion and were exploited for use with nano-pH probes and Rayleigh hot-spot normalization. / Ph. D. / How can we understand the dynamic behavior of the cell membrane? Do certain polymeric structures in biodegradable plastic favor bacterial growth and subsequent degradation? To answer these and other intriguing scientific questions, techniques and technologies must be borrowed from a diverse array of fields and combined with fundamental understanding to create innovative solutions. In this dissertation, a two-dimensional surface enhanced Raman spectroscopy (SERS) assay was translated into a live cell assay by utilizing a droplet microfluidic device. Combining single-cell encapsulation with a chamber array to hold and immobilize droplets allowed for the interrogation of hundreds of droplets. Shifting the SERS workflow from a manual cell-to-cell mapping routine to the mapping of tens to hundreds of cells demanded the development of an automated processing tool to perform basic SERS analyses such as baseline correction, peak feature selection, and SERS map generation. Our novel application of computer vision algorithms to SERS maps was able to reveal that sialic sugars on cancer cell membranes are found in small clusters, or islands, and that these islands typically occupy less than 30% of the cell surface area. With an opportunistic mindset, several smaller projects that combine Raman and SERS with extensive data analysis were also pursued. Biodegradable plastics of varying content were studied with Raman spectroscopy. The aliphatic and aromatic polymeric units within these plastics both contain esters, but it is hypothesized that enzymatic hydrolysis occurs at the units asymmetrically. For each of six different samples, five maps were collected, processed using the analysis tool, and then analyzed using a multivariate analysis toolbox. Principal component analysis (PCA) was used to distinguish the polymers and to identify spectral feature changes resulting from an increasing v number of aryl esters. Uniquely, PCA was performed on the 3,125 spectra collected from each sample to investigate point-to-point heterogeneities. A third set of projects evaluated the ability of the data processing tool to calculate spectral ratios in an automated fashion and it was exploited for use with nano-pH probes and Rayleigh hot-spot normalization

The objectives of the work presented were to 1) fabricate reproducible nanorod array SERS substrates, 2) detection of bacteria using nanorod substrates, 3) detection of DNA hybridization using nanorod substrates and 4) critically evaluate the sensing method. Important findings from this work are as follows. A novel method for batch fabrication of substrates for surface enhanced Raman scattering (SERS) has been developed using a modified platen machined to fit in a commercial electron beam evaporator. The use of this holder enables simultaneous deposition of silver nanorod (AgNR) arrays onto six microscope slide substrates utilizing glancing angle deposition. In addition to multiple substrate fabrication, patterning of the AgNR substrates with 36 wells allows for physical isolation of low volume samples. The well-to-well, slide-to-slide, and batch-to-batch variability in both physical characteristics and SERS response of substrates prepared via this method was nominal. A critical issue in the continued development of AgNR substrates is their stability over time, and the potential impact on the SERS response. The thermal stability of the arrays was investigated and changes in surface morphology were evaluated using scanning electron microscopy and x-ray diffraction and correlated with changes in SERS enhancement. The findings suggest that the shelf-life of AgNR arrays is limited by migration of silver on the surface. Continued characterization of the AgNR arrays was carried out using fluorescent polystyrene microspheres of two different sizes. Theory suggests that enhancement between nanorods would be significantly greater than at the tops due to contributing electromagnetic fields from each nanostructure. In contrast to the theory, SERS response of microspheres confined to the tops of the AgNR array was significantly greater than that for beads located within the array. The location of the microspheres was established using optical fluorescence and scanning electron microscopy. The application of SERS to characterizing pathogens such as bacteria and viruses is an active area of investigation. AgNR array-based SERS substrates have enabled detection of pathogens present in biofluids. Specifically, several publications have focused on determining the spectral bands characteristic of bacteria from different species and cell lines. Studies were carried out on three strains of bacteria as well as the medium in which the bacteria were grown. The spectra of the bacteria and medium were surprisingly similar, so additional spectra were acquired for commonly used bacterial growth media. In many instances, these spectra were similar to published spectra purportedly characteristic of specific bacterial species. In addition to bacterial samples, nucleic acid hybridization assays were investigated. Oligonucleotide pairs specifically designed to detect respiratory syncytial virus (RSV) in nasal fluids were prepared and evaluated. SERS spectra acquired on oligos, alone or in combination, contain the known spectral signatures of the nucleosides that comprise the oligo. However, spectra acquired on an oligo with a 5'- or 3' thiol were distinctly different from that acquired on the identical oligo without a thiol pendant group suggesting some control over the orientation of the oligo on the nanorod surface. The signal enhancement in SERS depends markedly upon the location of the probe relative to the substrate surface. By systematic placement of nucleotide markers along the oligo chain, the point at which the nucleotide disappears from the spectrum was identified. The overall findings for AgNR SERS substrates suggest that the applicability of SERS for detecting nucleic acid hybridization is limited. The strong distance dependence coupled with the lack of substrate stability at temperatures required for annealing oligos during hybridization suggest that AgNRs are not the platform to use for hybridization assays.

Η χρήση των πολυμερών στον τομέα της ιατρικής βιομηχανίας κερδίζει ολοένα και μεγαλύτερο έδαφος τα τελευταία χρόνια έχοντας ήδη κάνει ισχυρή την παρουσία τους σε ένα ευρύ πεδίο κλάδων της βιοϊατρικής όπως στη μηχανική ιστών, στην εμφύτευση ιατρικών συσκευών και τεχνητών οργάνων, στην προσθετική και την οφθαλμολογία, στην οδοντιατρική και την αποκατάσταση οστών, στη χημειοθεραπεία και σε ποικιλία άλλων ιατρικών εφαρμογών. Με τη χρήση πολυμερικών συστημάτων μεταφοράς δραστικών ουσιών καθίσταται ικανή η ελεγχόμενη αργή αποδέσμευση φαρμάκων στο σώμα καθώς και η στοχευμένη απελευθέρωσή τους σε σημεία όπου υπάρχουν φλεγμονές ή όγκοι. Τοιουτοτρόπως, χημειοθεραπείες με χρήση βιοπολυμερών ως διαμεσολαβητές, προβάλλουν ως δυνητικές υποψήφιοι στην αντιμετώπιση του καρκίνου του εγκεφάλου με ενθαρρυντικά αποτελέσματα. Συγκρινόμενη με την τυπική συστημική χημειοθεραπεία, η ενδοογκική απελευθέρωση φαρμάκου με τη χρήση βιοπολυμερών θεωρητικώς παρουσιάζει αρκετά πλεονεκτήματα: τα βιοπολυμερή μπορούν να μεταφέρουν το φάρμακο απευθείας στον όγκο-στόχο αυξάνοντας τη συγκέντρωση τοπικά και παράλληλα μειώνοντας τη συστημική τοξικότητα· μπορούν έτσι να χρησιμοποιούνται στη θεραπεία ανοσοκατασταλμένων ασθενών που δεν μπορούν να υποβληθούν σε συστημική χημειοθεραπεία. Από τη στιγμή που είναι απαραίτητη η ποσοτικοποίηση των φαρμάκων για τον χαρακτηρισμό των συστημάτων αποδέσμευσης και για μελέτες φαρμακοκινητικής, θα πρέπει να επιλέγεται η καταλληλότερη μέθοδος ποσοτικοποίησης παρέχοντας υψηλή ευαισθησία και ακρίβεια, εξασφαλίζοντας μεγάλη ανιχνευτική ικανότητα ακόμη και για πολύ χαμηλές συγκεντρώσεις. Στην παρούσα εργασία δύο αναλυτικές τεχνικές, η απορρόφηση υπεριώδους-ορατού και η επιφανειακή ενίσχυση της σκέδασης Raman (Surface Enhanced Raman Scattering, SERS), χρησιμοποιήθηκαν για την ποσοτική εκτίμηση του αντινεοπλασματικού φαρμάκου Mitoxantrone και του αντιμυκητιακού παράγοντα Ambisome (Αμφοτερισίνη Β) που αποδεσμεύτηκαν από βιοσυμβατές πολυμερικές μήτρες συμπολυμερούς αιθυλενίου-οξικού βινυλεστέρα, συμπολυμερούς γλυκολικού-γαλακτικού οξέος και πολυπροπυλενίου. Το SERS είναι ένα νέο, εναλλακτικό, ταχύ και μη καταστροφικό εργαλείο που μπορεί να βρεί εφαρμογή και στην ποσοτική εκτίμηση ουσιών πάρα πολύ χαμηλών συγκεντρώσεων. Χάρις στην ενίσχυση που παρέχεται στο σήμα Raman από τα νανο-εκτραχυμένα υποστρώματα ευγενών μετάλλων ή τα νανο-συσσωματώματα κολλοειδών διαλυμάτων ευγενών μετάλλων, έχει αναφερθεί ακόμη και συλλογή φάσματος SERS από ένα μόνο μόριο. Συνεπώς, η εφαρμογή του SERS σε μελέτες ουσιών εξαιρετικά χαμηλών συγκεντρώσεων φαίνεται να είναι πολύ ενδιαφέρουσα. Κατασκευάστηκαν πολυμερικά υμένια με εγκλωβισμένες τις δραστικές ουσίες και η μελέτη αποδέσμευσης πραγματοποιήθηκε σε νερό. Ποσοτικές μετρήσεις με τη χρήση του SERS σε πολύ μικρές συγκεντρώσεις έδειξαν μεγαλύτερη ανιχνευτική ευαισθησία σε σχέση με αυτές που πραγματοποιήθηκαν με την απορρόφηση UV-Vis. Συμπερασματικά, το SERS δείχνει ικανό στον ποσοτικό προσδιορισμό ενεργών ουσιών που αποδεσμεύονται από βιοσυμβατά πολυμερικά συστήματα μεταφοράς δραστικών ουσιών σε πολύ μικρές συγκεντρώσεις. / The application of polymeric materials for medical purposes is growing very fast. Polymers have found applications in such diverse biomedical fields as tissue engineering, implantation of medical devices and artificial organs, prosthesis, ophthalmology, dentistry, bone repair, chemotherapy and many other medical fields. Polymer-based delivery systems enable controlled slow release of drugs into the body and also they make possible targeting of drugs into sites of inflammation or tumors. Thus, biopolymer-mediated chemotherapy has shown promising results in the treatment of brain tumors. When compared to conventional systemic chemotherapy, intratumoral biopolymer-mediated drug delivery has several theoretical advantages: Biopolymers can deliver drugs into the tumor bed, thus maximizing local concentration while minimizing systemic toxicity. They may therefore be employed in the treatment of immunodepressed patients etc. Since drugs need to be quantified for drug delivery system characterization, intracellular distribution studies, free or vehicular, and for pharmacokinetic assays, the most suitable quantification method must be chosen. It should have a high sensitivity, specificity and reproducibility and should be capable of measuring at very low concentration range, as well. In the present study, two analytical techniques are utilized to quantitatively evaluate the antineoplastic drug Mitoxantrone and the antifungal agent Ambisome (Amphotericin b) released from active agents-loaded biocompatible polymer matrices poly(propylene), poly(ethylene-co-vinyl acetate), poly(lactic-co-glycolic acid); the UV-Vis absorption and the Surface Enhance Raman Scattering (SERS). SERS is a new, versatile, fast and non destructive tool for the estimation of extremely small amounts of substances. Due to the enhancement provided to the Raman signal by the nano-rough noble-metal substrates or the nano-structured colloidal clusters of noble metals, even single molecule detection has been reported. Therefore, applying SERS to extremely low concentration measurements proves to be challenging. Drug loaded polymer specimens were prepared and the in vitro drug release was determined in water. Fast SERS quantitative measurements showed enhanced sensitivity compared to the UV-Vis absorption; SERS may enable low concentration quantitative assessment of controlled release of drugs from biopolymer-based delivery systems.

Plasmonic nanoparticles, specifically gold and silver nanoparticles, exhibit unique optical, physical, and chemical properties that are exploited in many biomedical applications. Due to their nanometer size, facile surface functionalization and enhanced optical performance, gold and silver nanoparticles can be used to investigate cellular biology. The work herein highlights a new methodology that has exploited these remarkable properties in order to probe various aspect of cancer cell biology, such as cell cycle progression, drug delivery, and cell death. Cell death mechanisms due to localized gold and silver nanoparticle exposure were also elucidated in this work. Chapter 1 introduces the reader to the synthesis and functionalization of gold and silver nanoparticles as well as reviews their implementation in biodiagnostic and therapeutic applications to provide a foundation for Chapters 3 and 4, where their use in spectroscopic and cytotoxic studies are presented. Chapter 2 provides the reader with detailed explanations of experimental protocols for nanoparticle synthesis and functionalization, in vitro cellular biology experiments, and live-cell Raman spectroscopy experiments that were utilized throughout Chapters 3 and 4. Chapter 3 presents the use of nuclear-targeted gold nanoparticles in conjunction with a Raman microscope modified to contain a live-cell imaging chamber to probe cancer cell cycle progression (Chapter 3.1), examine drug efficacy (Chapter 3.2), monitor drug delivery (Chapter 3.3), and detect apoptotic molecular events in real-time (Chapter 3.4). In Chapter 4, the intracellular effects of gold and silver nanoparticles are explored through live-cell Rayleigh imaging, cell cycle analysis and DNA damage (Chapter 4.1), as well as through the elucidation of cytotoxic cell death mechanisms after nanoparticle exposure (Chapter 4.2) and live cell imaging of silver nanoparticle treated cancer cell communities (Chapter 4.3).