The unique properties of gold nanoparticles make them excellent candidates for applications in electronics, sensing, imaging, and photothermal therapy. Though abundant literature exists for isotropic gold nanoparticles, work on nanoparticles of different shapes has been gaining interest recently. Anisotropic gold nanoparticles, such as nanorods and nanoprisms, have tunable optical properties in the visible and near-infrared regions. Through synthesis and surface modification, the production of various shapes of these gold nanoparticles can be controlled to meet different applications. Two different types of gold nanorods were used in this thesis. The first type was stabilized with cetyltrimethylammonium bromide (CTAB) and had aspect ratios of 3-4 (defined as the nanorod length divided by the diameter). The second type was synthesized using CTAB and benzyldimethylhexadecylammonium chloride (BDAC) in a binary surfactant system which produced aspect ratios greater than 4. The nanorods were characterized with UV-Vis spectroscopy and transmission electron microscopy (TEM). Two types of bowl-shaped macrocyclic compounds called resorcinarenes were used to direct self-assembly of the nanorods. The first type of resorcinarene (R2S) consisted of thiol(SH)-terminated alkyl chains on both rims. The second type (R1S) contained thiol-terminated alkyl chains on only one rim. The monolayer formation of these resorcinarenes on planar gold surfaces was studied and characterized by FTIR spectroscopy. Resorcinarene-mediated assembly of gold nanorods was monitored with UV-Vis spectroscopy, dynamic light scattering (DLS), and TEM. In addition to gold nanorods, gold nanoprisms were synthesized through a kinetically-controlled reduction route in the presence of CTAB. The linking of nanoprisms using resorcinarenes was also explored.

<p>The fascinating optical properties of metallic nanostructures, dominated by collective oscillations of free electrons known as plasmons, open new opportunities for the development of devices fabrication based on noble metal nanoparticle composite materials. This thesis demonstrates a low-cost and versatile technique to produce stimuli-responsive ultrafast plasmonic nanostructures with reversible tunable optical properties. Albeit challenging, further control using thermal external stimuli to tune the local environment of gold nanoparticles embedded in VO2 host matrix would be ideal for the design of responsive functional nanocomposites. We prepared Au-VO2 nanocomposite thin films by the inverted cylindrical reactive magnetron sputtering (ICMS) known as hollow cathode magnetron sputtering for the first time and report the reversible tuning of surface plasmon resonance of Au nanoparticles by only adjusting the external temperature stimuli. The structural, morphological, interfacial analysis and optical properties of the optimized nanostructures have been studied. ICMS has been attracting much attention for its enclosed geometry and its ability to deposit on large area, uniform coating of smart nanocomposites at high deposition rate. Before achieving the aforementioned goals, a systematic study and optimization process of VO2 host matrix has been done by studying the influence of deposition parameters on the structural, morphological and optical switching properties of VO2 thin films. A reversible thermal tunability of the optical/dielectric constants of VO2 thin films by spectroscopic ellipsometry has been intensively also studied in order to bring more insights about the shift of the plasmon of gold nanoparticles imbedded in VO2 host matrix.</p>

On the verge of entering the post-antibiotic era, numerous efforts are in place to regain the waning charm of antibiotics which are proving ineffective against most “Superbugs”. Engineered nanomaterials, especially gold nanoparticles (GNPs) capped with antibacterial agents, are proving to be an effective and novel strategy against multidrug resistant (MDR) bacteria. In this study, we report a one-step synthesis of antibioticcapped GNPs (25 ± 5 nm) utilizing the combined reducing and capping ability of a cephalosporin antibiotic, ceftazidime. No signs of aggregation or leaching of ceftazidime from GNP surface was observed upon its storage. Antibacterial testing showed dosedependent broad spectrum activity of Cef-GNPs against both Gram-positive (S. bovis and E. durans) and Gram-negative (P. aeruginosa and E. aerogenes) bacteria. A significant reduction in the minimum inhibition concentration (MIC) of Cef-GNPs was observed as compared to the ceftazidime by itself against Gram-negative bacteria. The MIC of Cef- GNPs were 0.1 mg mL-1 (P. aeruginosa and E. aerogenes) and 1.2 mg mL-1 (E. durans and S. bovis). Cef-GNPs exerted bactericidal action on both P. aeruginosa and E. durans by disrupting the cellular membrane resulting in leakage of cytoplasmic content and death of bacterial cell. Our investigation and results provides an additional step in the development of antibiotic capped GNP as potent next generation antibacterial agents.

Daktaro disertacijoje apibendrintų mokslinių tyrimų tikslas - pritaikyti aukso nanodaleles, skirtingas gliukozės oksidazes bei elektrai laidų polimerą polipirolą elektrodo modifikavimui bei gliukozės amperometriniam nustatymui biologiniais jutikliais. Aukso nanodalelės (AuND) imobilizuotos grafito elektrodo paviršiuje kartu su tirpiu elektronų pernašos tarpininku užtikrina efektyvesnę elektronų pernašą nuo gliukozės oksidazės (GOx) aktyvaus centro elektrodui fermentinės gliukozės oksidacijos metu. Naudojant AuND modifikuotus elektrodus amperometriniais biologiniais jutikliais registruojami apie 2 kartus didesni maksimalūs analiziniai signalai lyginant su elektrodu be AuND. Biologinių jutiklių tiesinės priklausomybės nuo substrato koncentracijos intervalas yra iki 10 mmol/L gliukozės ir aptikimo riba 0,08 mmol/L analitės. Po 66 dienų biologiniu jutikliu naudojančiu elektrodą modifikuotą GOx užregistruotas analizinis signalas sudarė 43 % pradinės signalo reikšmės, tuo tarpu naudojant 13,0 nm AuND ir GOx jutiklio analizinis signalas sudarė tik 22 % pradinės reikšmės. AuND esančios tiriamajame tirpale užtikrina efektyvesnę elektronų pernašą nuo gliukozės oksidazės aktyviojo centro elektrodui, kai jų koncentracija yra nuo 0,01 iki 0,60 nmol/L ir tirpale yra N-metilfenazino metosulfato. Naudojant 13,0 nm skersmens AuND, biologinio jutiklio aptikimo riba yra 0,05 mmol/L gliukozės, o tiesiškumo intervalas nuo 0,1 iki 10 mmol/L substrato. Taip pat nustatyta, kad kuo didesnė AuND... [toliau žr. visą tekstą] / The amperometric and voltammetric biosensors, based on gold nanoparticles, were designed and applied for biochemical, clinical and environment applications. Electrochemical biosensors are very selective, sensitive, fast and reusable. Gold, silver, platinum and SiO2 particles in the range 1–100 nm often provide an ideal remedy for immobilized enzymes with minimum diffusion limitations, promotion of electrochemical reaction, maximum surface area per mass unit and high effective achievement of enzymes direct wiring to electrode surface. Also, nanoparticles increase electron transfer rate between enzyme and an electrode surface. The aim of the work was to to apply different size nanoparticles, different glucose oxidases and electroconductive polymer polypyrrole for graphite electrode modification and determine the analytical characteristics of enzymatic biosensors for determination of glucose. It is established, that gold nanoparticles immobilized on graphite electrode with electron transfer mediator provide more effective electron transfer from glucose oxidase to electrode. Also, gold nanoparticles present in solution provide more effective electron transfer from enzyme to electrode when concentration of gold nanoparticles is ˂ 0.06 nmol/L and concentration of electron transfer mediator PMS is 2 mmol/L. The higher concentrations of nanoparticles in the solution make the electron transfer in the same system less efficient if compared with lower concentrations of nanoparticles... [to full text]

Daktaro disertacijoje apibendrintų mokslinių tyrimų tikslas - pritaikyti aukso nanodaleles, skirtingas gliukozės oksidazes bei elektrai laidų polimerą polipirolą elektrodo modifikavimui bei gliukozės amperometriniam nustatymui biologiniais jutikliais. Aukso nanodalelės (AuND) imobilizuotos grafito elektrodo paviršiuje kartu su tirpiu elektronų pernašos tarpininku užtikrina efektyvesnę elektronų pernašą nuo gliukozės oksidazės (GOx) aktyvaus centro elektrodui fermentinės gliukozės oksidacijos metu. Naudojant AuND modifikuotus elektrodus amperometriniais biologiniais jutikliais registruojami apie 2 kartus didesni maksimalūs analiziniai signalai lyginant su elektrodu be AuND. Biologinių jutiklių tiesinės priklausomybės nuo substrato koncentracijos intervalas yra iki 10 mmol/L gliukozės ir aptikimo riba 0,08 mmol/L analitės. Po 66 dienų biologiniu jutikliu naudojančiu elektrodą modifikuotą GOx užregistruotas analizinis signalas sudarė 43 % pradinės signalo reikšmės, tuo tarpu naudojant 13,0 nm AuND ir GOx jutiklio analizinis signalas sudarė tik 22 % pradinės reikšmės. AuND esančios tiriamajame tirpale užtikrina efektyvesnę elektronų pernašą nuo gliukozės oksidazės aktyviojo centro elektrodui, kai jų koncentracija yra nuo 0,01 iki 0,60 nmol/L ir tirpale yra N-metilfenazino metosulfato. Naudojant 13,0 nm skersmens AuND, biologinio jutiklio aptikimo riba yra 0,05 mmol/L gliukozės, o tiesiškumo intervalas nuo 0,1 iki 10 mmol/L substrato. Taip pat nustatyta, kad kuo didesnė AuND... [toliau žr. visą tekstą] / The amperometric and voltammetric biosensors, based on gold nanoparticles, were designed and applied for biochemical, clinical and environment applications. Electrochemical biosensors are very selective, sensitive, fast and reusable. Gold, silver, platinum and SiO2 particles in the range 1–100 nm often provide an ideal remedy for immobilized enzymes with minimum diffusion limitations, promotion of electrochemical reaction, maximum surface area per mass unit and high effective achievement of enzymes direct wiring to electrode surface. Also, nanoparticles increase electron transfer rate between enzyme and an electrode surface. The aim of the work was to to apply different size nanoparticles, different glucose oxidases and electroconductive polymer polypyrrole for graphite electrode modification and determine the analytical characteristics of enzymatic biosensors for determination of glucose. It is established, that gold nanoparticles immobilized on graphite electrode with electron transfer mediator provide more effective electron transfer from glucose oxidase to electrode. Also, gold nanoparticles present in solution provide more effective electron transfer from enzyme to electrode when concentration of gold nanoparticles is ˂ 0.06 nmol/L and concentration of electron transfer mediator PMS is 2 mmol/L. The higher concentrations of nanoparticles in the solution make the electron transfer in the same system less efficient if compared with lower concentrations of nanoparticles... [to full text]

The objectives of the doctoral thesis are following: (i) to design carbohydrate/oxygen enzymatic biofuel cells (EBFCs); (ii) to determine the factors limiting the performance of EBFCs; (iii) to characterise the bioelectrochemical properties of the enzymes adsorbed at conductive nanostructures and evaluate the viscoelasticity of these nanostructures. In this work 5-amino-1,10-phenanthroline (5AP) has been found to be the best redox mediator for glucose oxidase (GOx) enzyme among five studied phenanthroline derivatives with different functional groups. Later the 5AP cross-linked with GOx enzyme on a graphite rod electrode (GRE) was employed as an anode while GRE with co-immobilised horseradish peroxidase (HRP) and GOx was exploited as a cathode in order to design a glucose powered EBFC. A positively charged bi-functional thiol, N-(6-mercapto)hexylpyridinium (MHP), was exploited to electrostatically attach the cellobiose dehydrogenase (CDH) enzymes from Corynascus thermophilus (CtCDH) and Humicola insolens (HiCDH) to the gold nanoparticle (AuNP) surface. This coupling enabled a sufficient direct electron transfer between the enzymes and the AuNP-modified gold surface. Therefore, the HiCDH enzyme, showing better performance characteristics, was employed as an anodic biocatalyst in the designing of a mediatorless carbohydrate (glucose or lactose)/oxygen EBFC. The biocathode of the EBFC was based on bilirubin oxidase from Myrothecium verrucaria directly immobilised on the surface... [to full text] / Disertacinio darbo tikslai: (i) sukonstruoti fermentinius angliavandenių/deguonies biokuro elementus (FBKE); (ii) nustatyti FBKE veikimą ribojančius faktorius; (iii) apibūdinti fermentų, adsorbuotų laidžiose nanostruktūrose, bioelektrokatalizines charakteristikas ir įvertinti šių nanostruktūrų viskoelastines savybes. 5-amino-1,10-fenantrolino (5AF) junginys, iš penkių šiame darbe tirtų fenantrolinų junginių besiskiriančių funkcinėmis grupėmis, įvertintas kaip geriausias elektronų pernašos (EP) tarpininkas gliukozės oksidazės (GO) katalizuojamoje heterogeninėje reakcijoje. 5AF junginys kartu su GO fermentu (5AF/GO) buvo panaudotas anodinio elektrodo konstrukcijoje, o atitinkamai bifermentinė krienų peroksidazės (KP) ir GO sistema (KP/GO) – katodinio elektrodo konstrukcijoje. Šie elektrodai panaudoti gliukozės FBKE kūrimui. Teigiamą krūvį turintis bifunkcinis tiolinis N-(6-merkapto)heksilopiridinio (MHP) junginys panaudotas fermentų imobilizacijai aukso nanodalelių (AuND) paviršiuje elektrostatinės sąveikos būdu. AuND paviršiuje imobilizuoti celiobiozės dehidrogenazės (CDH) fermentai, išskirti iš Corynascus thermophilus (CtCDH) ir Humicola insolens (HiCDH) kamienų, sudarė fermentas-AuND sąsają įgalinančią tiesioginę EP. HiCDH fermentas kaip biokatalizatorius pritaikytas anodinio elektrodo konstrukcijoje AuND/MHP/HiCDH kuriant tiesiogine EP paremtus angliavandenių (gliukozės, laktozės)/deguonies FBKE. Bilirubino oksidazė (BO), tiesiogiai imobilizuota AuND paviršiuje (AuND/BO)... [toliau žr. visą tekstą]

Disertacinio darbo tikslai: (i) sukonstruoti fermentinius angliavandenių/deguonies biokuro elementus (FBKE); (ii) nustatyti FBKE veikimą ribojančius veiksnius; (iii) apibūdinti fermentų, adsorbuotų laidžiose nanostruktūrose, bioelektrokatalizines charakteristikas ir įvertinti šių nanostruktūrų viskoelastines savybes. 5-amino-1,10-fenantrolino (5AF) junginys, iš penkių šiame darbe tirtų fenantrolinų junginių besiskiriančių funkcinėmis grupėmis, įvertintas kaip geriausias elektronų pernašos (EP) tarpininkas gliukozės oksidazės (GO) katalizuojamoje heterogeninėje reakcijoje. 5AF junginys kartu su GO fermentu (5AF/GO) buvo panaudotas anodinio elektrodo konstrukcijoje, o atitinkamai bifermentinė krienų peroksidazės (KP) ir GO sistema (KP/GO) – katodinio elektrodo konstrukcijoje. Šie elektrodai panaudoti gliukozės FBKE kūrimui. Teigiamą krūvį turintis bifunkcinis tiolinis N-(6-merkapto)heksilopiridinio (MHP) junginys panaudotas fermentų imobilizacijai aukso nanodalelių (AuND) paviršiuje elektrostatinės sąveikos būdu. AuND paviršiuje imobilizuoti celiobiozės dehidrogenazės (CDH) fermentai, išskirti iš Corynascus thermophilus (CtCDH) ir Humicola insolens (HiCDH) kamienų, sudarė fermentas-AuND sąsają įgalinančią tiesioginę EP. HiCDH fermentas kaip biokatalizatorius pritaikytas anodinio elektrodo konstrukcijoje AuND/MHP/HiCDH kuriant tiesiogine EP paremtus angliavandenių (gliukozės, laktozės)/deguonies FBKE. Bilirubino oksidazė (BO, tiesiogiai imobilizuota AuND paviršiuje (AuND/BO)... [toliau žr. visą tekstą] / The objectives of the doctoral thesis are following: (i) to design carbohydrate/oxygen enzymatic biofuel cells (EBFCs); (ii) to determine the factors limiting the performance of EBFCs; (iii) to characterise the bioelectrochemical properties of the enzymes adsorbed at conductive nanostructures and evaluate the viscoelasticity of these nanostructures. In this work 5-amino-1,10-phenanthroline (5AP) has been found to be the best redox mediator for glucose oxidase (GOx) enzyme among five studied phenanthroline derivatives with different functional groups. Later the 5AP cross-linked with GOx enzyme on a graphite rod electrode (GRE) was employed as an anode while GRE with co-immobilised horseradish peroxidase (HRP) and GOx was exploited as a cathode in order to design a glucose powered EBFC. A positively charged bi-functional thiol, N-(6-mercapto)hexylpyridinium (MHP), was exploited to electrostatically attach the cellobiose dehydrogenase (CDH) enzymes from Corynascus thermophilus (CtCDH) and Humicola insolens (HiCDH) to the gold nanoparticle (AuNP) surface. This coupling enabled a sufficient direct electron transfer between the enzymes and the AuNP-modified gold surface. Therefore, the HiCDH enzyme, showing better performance characteristics, was employed as an anodic biocatalyst in the designing of a mediatorless carbohydrate (glucose or lactose)/oxygen EBFC. The biocathode of the EBFC was based on bilirubin oxidase from Myrothecium verrucaria directly immobilised on the surface... [to full text]

Histone deacetylase (HDAC) inhibition is an emerging novel therapeutic strategy in cancer therapy. HDAC inhibitors (HDACi) have shown ability to block angiogenesis and cell cycling, as well as initiate differentiation and apoptosis. In fact, suberoylanilide hydroxamic acid (SAHA) is the first in the class of HDACi approved by the FDA for the treatment of cutaneous T cell lymphoma. On the other hand, there is a sustained interest in the use of gold nanoparticles (AuNPs) for various cancer diagnostic and therapeutic applications - bioimaging, drug delivery, and binary therapy techniques such as photodynamic and photothermal therapies. This interest in AuNPs is facilitated by favorable attributes such as ease of fabrication, bioconjugation and biocompatibility, and unique optical and electronic properties. However, HDACi- and AuNPs- based antitumor agents are plagued with problems common to all chemotherapeutic agents such as lack of selectivity, which often results in systemic toxicity. Therefore, availability of a methodology to selectively deliver AuNPs and HDACi to cancer cells will significantly improve their therapeutic indices and lead to the identification of novel agents for use in diagnostic imaging and targeted cancer therapy applications.

Le mercure est un élément reconnu pour sa toxicité pour les êtres humains, pouvant être notamment la cause de maladies neurologiques ou rénales une fois absorbé dans l'organisme. Il est rejeté dans l'environnement, et en particulier dans les eaux de surface, par des phénomènes naturels comme le volcanisme, mais également par le biais des activités humaines liées à l'industrie. Une fois rejeté, il est ingéré par la faune et la flore marine et bioaccumule tout le long de la chaîne alimentaire. Il est alors présent dans les espèces marines prédatrices dans des proportions importantes, mettant en danger la santé de ces espèces animales et exposant les êtres humains à des quantités importantes de mercure dans l'alimentation. La législation Européenne est très stricte en ce qui concerne les taux de mercure autorisés dans les eaux et se base sur des valeurs relevant de la trace voir de l'ultra trace. Les techniques actuelles permettant de détecter de si faibles doses sont efficaces mais possèdent de nombreux inconvénients tel que leur coût ou l'impossibilité de faire des mesures in situ. Les capteurs électrochimiques sont actuellement l'une des alternatives les plus prometteuses pour la détection de ce métal lourd en solution. L'objectif de ces travaux a donc été de mettre au point un capteur électrochimique basé sur la fonctionnalisation d'une électrode en carbone vitreux par des couches organiques et des nanoparticules d'or pour la détection du mercure. Deux types de couches organiques ont été utilisées et les interfaces ainsi développées caractérisées par voltammétrie cyclique et Microscopie Électronique à Balayage. Deux protocoles d'activation des nanoparticules ont été testés. Les performances des interfaces ont été évaluées au regard de la détection de traces de mercure, ainsi que leur stabilité au stockage. / Mercury is known for its toxicity on human beings, causing neurological and kidney diseases when absorbed in the body. It is rejected in the environment, and especially in surface waters, through natural processes like volcanism and human industrial activities. When present in water, it is ingested by marine plants and wildlife and bioaccumulates all along the food chain. It is then present in high proportions in marine predators, jeopardizing their health and exposing human beings to important mercury quantities in the food supply. The European legislation is very strict regarding to allowed mercury levels in waters, and is based on very low values, from traces to ultra traces. Current techniques able to detect such small doses are efficient but suffer from numerous drawbacks like their cost or the impossibility to use them for in situ measurements. Electrochemical sensors appear to be one of the most interesting alternatives for detection of this heavy metal in aqueous solution. The aim of this work was then to develop an electrochemical sensor based on the functionalization of a glassy carbon electrode with organic layers and gold nanoparticles for mercury detection. Two types of organic layers were used and the interfaces were characterised by using cyclic voltammetry and Scanning Electron Microscopy. Two different gold nanoparticles activation processes were tested. The interfaces performances were evaluated for detection of traces of mercury, as well as their storage stability.

Title: Optimization of surface-enhanced Raman scattering spectroscopy for study of biologically important biomolecules and their interactions Author: Natália Šmídová Department: Institute of Physics of Charles University Supervisor of the doctoral thesis: Doc. RNDr. Marek Procházka, PhD. Abstract: The main goal of this thesis was to optimize surface-enhanced Raman scattering (SERS) spectroscopy for study of biologically important biomolecules. For that purpose we focused on substrates based on gold colloidal nanoparticles immobilized to silanized glass plates. Stable, uniform and highly reproducible SERS-active substrates have been prepared by using aminopropyltrimethoxysilane and citrate- reduced gold nanoparticles thermally stabilized after their immobilization. Model biomolecules 5,10,15,20-tetrakis(1-methyl-4-pyridyl)porphyrin (TMPyP) and 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TSPP) were studied on these substrates by using a classical Raman spectrometer in macro-mode and a confocal Raman microspectrometer. Conditions for SERS spectroscopy of porphyrins were optimized with respect to sensitivity and reproducibility. SERS microspectroscopy showed several advantages over SERS measurements in macromode: possibility of surface spectral mapping, easier manipulation with samples, shorter...