Philosophiae Doctor - PhD / Organic noncyclic compounds were used in the development of immunosensor for rapid fish species detection. Flourene derivatives show unique chemical and physical properties because they contain a rigid planar biphenyl unit, and the facile substitution at C9 position of the flourene can improve the solubility and processability of materials containing flourene without significantly increasing of steric interactions in the compounds backbone. 9-(4- methoxyphenyl)-9H-xanthen-9-ol is bulky, rigid and has an hydroxyl moiety that may act as a hydrogen – bond donor, as well as a pyranyl oxygen which is a potential hydrogen –bond acceptor. We have successfully synthesised 9,9’-(ethyne1,2-diyl)bis(flouren-9-ol) by reflux method and 9-(4-methoxyphenyl)-9H-xanthen-9-ol through stirring at room temperature. The products were characterised using spectroscopic methods and were found to be both UV/Vis active (λmax = 400 nm flourene derivative and λmax = 337 nm xanthene derivative ) and fluorescent (440nm and 467nm flourene derivative and 344 and 380 xanthene derivative). These compounds were drop coated onto commercial glassy carbon electrode (GCE) to produce thin films. Scan rate dependent cyclic voltammetry (CV) confirmed the electrodynamics of the thin films to be consistent with monolayer diffusion (De = 1.37x10-21 cm2/s flourene derivative and De = 9.79x10-21 cm2/s xanthene derivative). Surface concentration was estimated to be 1.55x10-13 mol cm-2 flourene derivative and 2.00x10-13 mol cm-2. These compounds were used for the inclusion of parvalbumin antibodies immobilised onto clathrate platform by incubation and were evaluated as immunosensors for fish species identification. The antibody/antigen binding event was evaluated using UV/Vis spectroscopy, electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). The immunosensor response to parvalbumin in real samples of snoek (an indigenous fish species), tuna, fish paste, eyeshadow, lipstick, omega 3&6 and Scott's emulsion was evaluated. The sensitivity as calculated from EIS for each immunosensor was found to be 5.36x104 flourene derivative immunosensor and 4,11x104 xanthene derivative immunosensor and the detection limit of 1.50 pg/ml flourene derivative immunosensor and 2.42 pg/ml xanthene derivative immunosensor. The antibody/antigen binding was monitored as decrease in charge transfer resistance and increase in capacitance by EIS. The interfacial kinetics of the immunosensors were modelled as equivalent electrical circuit based on EIS data. The UV/Vis spectroscopy was used to confirm the binding of the antibody/antigen in solution by monitoring the intensity of the absorption peak.

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For centuries scientific ingenuity and innovation have been influenced by Mother Natures perfect design. One of her more elusive designs is that of the sensory olfactory system, an array of highly sensitive receptors responsible for chemical vapor recognition. In the animal kingdom this ability is magnified among canines where ppt (parts per trillion) sensitivity values have been reported. Today, detection dogs are considered an essential part of the US drug and explosives detection schemes. However, growing concerns about their susceptibility to extraneous odors have inspired the development of highly sensitive analytical detection tools or biosensors known as electronic noses. In general, biosensors are distinguished from chemical sensors in that they use an entity of biological origin (e.g. antibody, cell, enzyme) immobilized onto a surface as the chemically-sensitive film on the device. The colloquial view is that the term biosensors refers to devices which detect the presence of entities of biological origin, such as proteins or single-stranded DNA and that this detection must take place in a liquid. Our biosensor utilizes biomolecules, specifically IgG monoclonal antibodies, to achieve molecular recognition of relatively small molecules in the vapor phase.

The object of this thesis research is to facilitate the appraisal and analysis of the signatures of the modern acoustic wave biosensors, as well as to improve the experimental methodology to enhance sensor performance. For this purpose, both theoretical characterization of acoustic wave sensor signatures and experimental studies for the most frequently used acoustic wave biosensors, the liquid phase QCM (quartz crystal microbalance) and the vapor phase SAW (surface acoustic wave) sensors, are presented. For the study of SAW vapor phase detection, the author fabricated different types of two-port SAW resonator sensors on quartz substrates and designed and performed a significant number of detection experiments. These were conducted both with calibrated or known target samples under laboratory conditions at Georgia Tech Hunt Lab and with samples of unknown concentrations such as seized crack cocaine (courtesy of Georgia Bureau of Investigation, GBI) to see the sensors capability to work in the field conditions. In addition, the dependence of the SAW sensor signatures on specific locations of the surface perturbation was investigated to account for some observed abnormal responses. Finally, a novel approach to classify and visualize chemically analogous substances is introduced. The author expects that the thesis work herein may contribute to the study of the modern acoustic wave biosensors which includes but is not limited to: the establishment of underpinning theory that will aid in the evaluation of the signatures; the practical aspects of design and fabrication of SAW devices specific to the vapor phase immunoassay; the development of efficient experimental methodologies; the strategic immobilization of a biolayer on SAW resonator based biosensors; and, the acquisition of reference data for the development of commercial acoustic wave sensors.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2015. / Immunosensors are analytical devices comprising antibody (Ab) molecules intimately integrated with electronic physicochemical transducers. Abs are responsible for specific recognition of an analyte so called antigen (Ag) while transducers are responsible for the conversion of chemical changes brought about by Ab-Ag interactions into measurable and processable signal. Amongst the many analytical tools, immunosensors have shown outstanding performance in applications in fields such as clinical diagnostics, agricultural purposes and environmental monitoring. They have come in place of the many conventional analytical methods which showed a number of disadvantages; high cost and longer time of operation, and requirement of highly knowledgeable personnel. On the other hand, immunosensors have shown potential to overcome these constraints. Their advantages include possibilities of portability, miniaturization, and simplified procedures. Of the possible fields of immunosensor applications, this study focussed on the environmental aspect. The safety of the environment is good for the well-being even though there are still some environmental threats that exist. Polychlorinated biphenyls (PCBs) have reportedly been found to be some of the potential substances to pose such threats due to their toxic and persistent behaviour. In this study, we have developed an electrochemical immunosensor as an analytical tool for the analysis and monitoring of PCBs. The development was based on the use of silver nanoparticles-doped polyaniline (PANI/Ag NPs) for modification of an electrode as a process for fabrication of the transducer. The PANI/Ag NPs composite was deposited on the glassy carbon (GC) and platinum (Pt) electrodes by oxidative electropolymerization of aniline in the presence of Ag NPs in 1 M HCl using cyclic voltammetry (CV) by ramping the potential from -0.1 to 1.4 V at 50 mV/s. The composite was then characterized and evaluated as a potential material for electrochemical transduction. Evaluation was on electroactivity, which is the main property of interest for materials used in the fabrication of electrochemical devices. The PANI composites were characterized using spectroscopic (FTIR), microscopic (TEM) and electrochemical CV techniques. Results confirmed the formation of PANI in its emeraldine form and the presence of Ag NPs. Characteristic functional groups and peaks of PANI were observed in FTIR and CV respectively. TEM micrograms showed one dimensional nanofibric tubes and crystalline-like structure of the composite. The incorporation of Ag NPs was indicated by the transition from the amorphous (PANI) to crystalline (PANI/Ag NPs) structure accompanied by increase in size as well as smoothness of the tubes. EDS-TEM counts increase of the chlorine (Cl) peaks is due to the closeness of these peaks to those of Ag, thus confirming incorporation of Ag NPs.

Ce travail s’est focalisé sur l’apport des nanoparticules d’or (GNPs) dans la construction d’immunocapteurs piézoélectriques et plasmoniques. Deux stratégies ont été mises en œuvre, mettant à profit les propriétés physico-chimiques uniques des GNPs La première approche a consisté à nanostructurer la surface de capteurs piézoélectriques par des GNPs en exploitant leur haut rapport volume / surface. La deuxième stratégie a consisté à employer les GNPs comme transducteur de biocapteurs colorimétriques en exploitant leurs propriétés optiques. Dans une première partie, la nanostructuration de matériaux plans recouverts d'or ou de silicium par des GNPs (14 nm) a été réalisée. Chaque étape d'élaboration des films fins de nanoparticules a été vérifiée par différentes techniques de caractérisation de surface comme la mesure d’angle de contact, la spectroscopie IR, XPS et MEB. Ces surfaces ont été ensuite employées au développement d’immunocapteurs piézoélectriques pour la détection de diclofénac, un polluant pharmaceutique et d’entérotoxine A (SEA), une toxine bactérienne produite par la bactérie S. aureus.L’apport des GNPs a été mis en évidence par comparaison des performances des immunocapteurs plans et nanostructurés. Dans une deuxième partie, la construction d’un immunocapteur colorimétrique opérant en phase homogène a été réalisée en mettant à profit le changement de la position de la bande de résonance localisée de plasmon de surface (LSPR) résultant du changement d'indice de réfraction local induit par la réaction immunologique entre la SEA et un bioconjugué GNP-anti-SEA. Ces études constituent une alternative séduisante pour la détection rapide dans la gamme du ng/mL. / This project focussed on the asset of gold nanoparticles (GNPs) in the build up of piezoelectric and plasmonic immunosensors. Two strategies were implemented, taking advantage of the unique physico-chemical features of GNPs. The first approach consisted in nanostructuring the surface of piezoelectric sensors by GNPs, to exploit their high surface / volume ratio. The second approach consisted in employing the GNPs as transducer in colorimetric biosensors, by making use of their optical properties. In a first part, nanostructuration of planar materials covered with gold or silicon by GNPs (14 nm) was achieved. Each step of the construction of thin films of GNPs was checked by various surface characterization techniques, including contact angle measurements, IR spectroscopy, XPS and SEM. These surfaces were then employed in the development of piezoelectric immunosensors for the detection of the pharmaceutical pollutant diclofenac and staphylococcal enterotoxin A (SEA), a bacterial toxin produced by S. aureus. The input of GNPs was evidenced by comparison with the performances of planar immunosensors. In a second part, the build up of a colorimetric immunosensor operating in the homogeneous phase was achieved by making use of the shift of the localized surface plasmon resonance (LSPR) band resulting from the change of local refraction index induced by the immunological reaction between SEA and GNP-anti-SEA bioconjugate. These studies establish a model for the development of immunosensor for a rapid detection in the ng/mL range.

Magister Scientiae - MSc (Chemistry) / Pulmonary Tuberculosis (TB) a disease second to HIV/AIDS is a global health problem that arises in two states; as an active state and as a latent state. Diagnosis of active TB is tedious and requires expensive procedures since there is no recognizable method for the sole detection of active TB. The current diagnosis consists of chest X-rays and multiple sputum cultures used for acid-fast bacilli detection. The TB diagnosis of children is particularly difficult which further complicates the diagnosis. Thus, rapid identification of this pathogen is important for the treatment and control of this infection to allow effective and timely therapy. In an effort to solve this issue, this study reports the development of immunosensors constructed with electroactive layers of amino groups functionalized graphene oxide (GO) doped respectively with green synthesized zinc oxide (ZnO NPs) nanoparticles and silver (Ag NPs) nanoparticles on glassy carbon electrodes. The surface morphology of GO, ZnO NPs, Ag NPs and their composites was revealed by employing High-Resolution Transmission Electron Microscopy (HR-TEM) and High-Resolution Scanning Electron Microscopy (HR-SEM) while the composition and structure of these materials were studied using Fourier Transform Infra-Red Spectroscopy (FTIR). The resultant graphene oxide-metallic composites were covalently attached with CFP-10 and/or ESAT-6 antibodies to achieve the electrochemical detection. The immunosensor was then used for the impedimetric and amperometric detection of anti-CFP-10 and/or anti-ESAT-6 antigens in standard solutions.

Ces dernières années, différents épisodes d’intoxication ont touché les coquillages sur le littoral français et tout particulièrement les huîtres dans le Bassin d’Arcachon. Afin de venir en aide à la profession ostréicole, le Conseil Régional d’Aquitaine a mis en place un vaste projet de recherche. Au sein de ce programme, nous avons proposé d’étudier la faisabilité d’un immunocapteur, basé sur la reconnaissance anticorps/antigène, capable de détecter la présence de phycotoxines dans l’eau de mer. Les synthèses de molécules (haptènes), présentant une analogie structurale avec la partie commune des phycotoxines de la famille des ASP ont été réalisées à l'ISM. Après couplage de ces molécules à une protéine, des anticorps montrant une bonne reconnaissance des ASP ont été obtenus. La mise au point de l'immunocapteur a été effectuée en collaboration avec deux autres Unités de Recherche : le LIP (Univ. Bx II) pour l'immunologie et l'IMS (Univ. Bx I) pour la lecture et la transcription du signal sur le capteur. / In the last few years, oysters from the Arcachon Bay have been touched by several toxic episodes. To help oyster industry, an important research program was funded by the Conseil Régional d’Aquitaine. In this project, we proposed to study the feasibility of an immunosensor, based onantibody/antigen reaction, able to detect phycotoxins in seawater. Haptens showing astructural analogy with the common part of ASP toxins were synthesized at ISM. Aftercoupling of haptens with a protein carrier (BSA), antibodies showing a good ASP recognition were obtained. The transducer, a Love wave acoustic device, was developed by IMS (Univ.Bx I) and the antibodies used for specific biorecognition were characterized by LIP (Univ. BxII).

Submitted by Airton Juliano Damaceno null (airtonjuliano@gmail.com) on 2016-06-30T13:04:07Z No. of bitstreams: 1 Dissertação_PGQ_Airton Juliano Damaceno.pdf: 4444619 bytes, checksum: 5d7d757e1406c83cd5cafcbf20263a65 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-07-04T13:54:47Z (GMT) No. of bitstreams: 1 damaceno_aj_me_sjrp.pdf: 4444619 bytes, checksum: 5d7d757e1406c83cd5cafcbf20263a65 (MD5) / Made available in DSpace on 2016-07-04T13:54:47Z (GMT). No. of bitstreams: 1 damaceno_aj_me_sjrp.pdf: 4444619 bytes, checksum: 5d7d757e1406c83cd5cafcbf20263a65 (MD5) Previous issue date: 2016-06-08 / O Brasil é líder na produção de cana-de-açúcar e a cada ano o setor vem crescendo e buscando novas formas para diversificar a planta de produção. Tal fato que o nome da indústria evoluiu de sucroalcooleira para sucroenergéticas devido à importância da co-geração de energia a partir da queima do bagaço nas caldeiras. A bioeletricidade de cana-de açúcar caminha a passos constantes e segue com vários projetos pelo país, devido as usinas estarem próximas dos centro e distribuição/consumo. Outra empresa que busca esta diversificação da sua planta são as indústrias de papel e celulose, principalmente dos seus rejeitos (lignina). Este trabalho tem como objetivo extrair lignina diferentes variedades de cana-de-açúcar para identificar a variedade que tem melhor rendimento na extração da lignina e rendimento energético, comparar com o bagaço misto (mistura de várias variedades) e por fim desenvolver imunossensores por meio da reação entre antígenos e anticorpos sobre superfícies condutoras de nanografite a partir da mistura de lignina de bagaço de cana e lignina Kraft. A grande questão é a aplicação eletroquímica com o desenvolvimento de imunossensores devido a alta sensibilidade e principalmente pelo baixo custo e utilização em área clínica. A partir do presente estudo pode-se inferir que a variedade SP83-2847 possui o maior rendimento na extração da lignina, já em relação a perda calorífica a variedade SP84-1431 obteve o maior valor e a RB86-7515 o menor. Após a extração da lignina o bagaço resultante contento celulose e hemicelulose apresentou ser mais estável termicamente. As Técnicas de Raios-x e infravermelho confirmaram a extração da liginina, além de demostrar que existe resquício da fração de celulose e hemicelulose na lignina extraída e que o mesmo ocorre quando extraímos a lignina, uma fração fica na celulose. O eletrodo construído a partir do compósito nonografite-lignina kraft modificado com cobre apresentou atividade eletroquímica, estabilidade mecânica e eletroquímica. / Brazil is a leader in sugarcane production, growing each year and looking for new ways to diversify the plant production. By the way, the industries names evolved from sugar and alcohol to sugar and energy due to its importance in energy cogeneration from bagasse burning in boilers. The cane bioeletricity walks in constant steps and continues with various projects around the country, because the plants are close downtown and distribution and consumption centers. Another company seeking this diversification of the plant are the industries of pulp and paper especially its residues (lignin). This project aims to extract lignin from different varieties of sugarcane to identify the the best performer in the extraction and energy efficiency compared with the mixed bagasse sample (mixture of several varieties) and finally develop immunosensors through the reaction between antigens and antibodies on conductive nanographite surfaces from Kraft lignin and bagasse’s lignin mixture. The great question is the development of immunosensors due to high sensitivity and especially the applicability in the clinical area. From this study it can infer that the SP83-2847 variety has the highest extraction yield of lignin, as compared to loss heat the variety SP84-1431 obtained the highest value and the lowest was the RB86-7515. After lignin extraction, the resulting residue containing cellulose and hemicellulose showed to be more thermally stable. XRD and FTIR results confirmed lignin extraction and demonstrated that there is remnant cellulose and hemicellulose fraction of extracted lignin and the same occurs when we extract lignin, a fraction remains in cellulose. The electrode constructed from the composite kraft lignin-nonographite modified with copper showed electrochemical activity, mechanical stability and electrochemistry. These were applied to investigate uric acid in simulated blood plasma samples. For sure lignin is a byproduct that in near future will be a very promising and profitable raw materials in different industries.