Объектом исследования являются бактерии Staphylococcus aureus в модельных суспензиях. Цель работы— апробация разработанных алгоритмов определения Staphylococcus aureus с использованием электрохимической системы на основе бесферментных электрохимических иммуносенсоров в модельных суспензиях. Определение чувствительности микробной флоры к антибактериальному препарату.В процессе работы должны быть проведены исследования синтезированных наночастиц магнетита, изучен характер электропревращений модифицированных наночастиц. Должен быть осуществлен выбор рабочего электрода и оптимальных условий анализа для количественного определения Staphylococcus aureus в модельных суспензиях. Должна быть проведена апробация разработанных алгоритмов по определению Staphylococcus aureus в модельных образцах. Определена чувствительность микробной микрофлоры к антибактериальному препарату мазь «Новокомб – 50%». В результате исследования были синтезированы наночастицы магнетита (Fe3O4), наличие полимерного покрытия подтверждено методом ИК - спектроскопии. В результате проведенных экспериментов был получен электрохимический аналитический отклик от модифицированных наночастиц магнетита. Были выбраны оптимальные условия регистрации аналитического сигнала. В качестве рабочего электрода был выбран планарный платиновый электрод, в качестве метода иммобилизации - метод физической сорбции антител на рабочую зону электрода. Был получен электрохимический отклик от иммунокомплекса антитело-бактерия, меченая наночастицами магнетита. Были выбраны оптимальные условия проведения количественного определения Staphylococcus aureus в модельных суспензиях. При данных условиях была выполнена оценка результатов в отношении таких показателей, как воспроизводимость и специфичность. По результатам апробации алгоритмов на модельных образцах было выявлено, что результаты данного метода коррелируют с методами ИФА и бактериального посева. Точность метода с использованием электрохимического иммуносенсора удовлетворительная. Данный метод может быть рекомендован для определения чувствительности микробной флоры к антибактериальным препаратам при их разработке, исследовании и на этапах серийного производства и обращения Основные конструктивные и технико-эксплуатационные показатели: предел обнаружения для бактерий Staphylococcus aureus составил 8.7 КОЕ/мл. Относительное стандартное отклонение не превышает 10%.Эффективность метода определяется возможностью его применения для определения чувствительности микробной флоры к антибактериальным препаратам при их разработке, исследовании и на этапах серийного производства и обращения. / Object of research are the bacteria Staphylococcus aureus in model suspensions. The purpose of testing the developed algorithms work- determining Staphylococcus aureus using electrochemical systems based on electrochemical besfermentnyh immunosensors in model suspensions. Determination of the sensitivity of the microbial flora to antibacterial preparatu.V during operation should be studied synthesized nanoparticles of magnetite, studied character elektroprevrascheny modified nanoparticles. Selection is to be made the working electrode and optimal assay conditions for quantitative determination of Staphylococcus aureus in model suspensions. It must be carried out testing of the developed algorithms to identify Staphylococcus aureus in model samples. Determine the sensitivity of the microbial microflora antimicrobial ointment "Novokomb - 50%." The study nanoparticles of magnetite (Fe3O4) were synthesized, the presence of the polymer coating was confirmed by IR - spectroscopy. As a result of the experiments was obtained from the electrochemical analytical response modified magnetite nanoparticles. optimal conditions for the registration of the analytical signal were selected. The working electrode was selected planar platinum electrode, as a method of immobilization - the method of physical adsorption of antibodies to the working electrode area. electrochemical response by the bacterium-antibody immunocomplex, labeled magnetite nanoparticles was obtained. the optimal conditions were selected quantitative determination of Staphylococcus aureus in model suspensions. Under these conditions, evaluation of the results was carried out in relation to indicators such as reproducibility and specificity. According to the results of testing of algorithms to model samples it was found that the results of this method correlate with the ELISA and bacterial seeding. Accuracy of the method using an electrochemical immunosensor satisfactory. This method can be recommended for the determination of the sensitivity of the microbial flora to antibiotics when they are developing, researching and on the stages of mass production and circulation of basic design and technical and operational parameters: detection limit for bacteria Staphylococcus aureus was 8.7 CFU / ml. The relative standard deviation does not exceed 10% g? O FIG method determined by the possibility of its application for the determination of the sensitivity of the microbial flora to antibiotics when they are developing, researching and on the stages of mass production and circulation.

Atualmente, aplicações de nanopartículas de magnetita (NPs-Fe3O4) têm sido comumente reportadas em inúmeros trabalhos descritos na literatura. Catálise, ferrofluidos e dispositivos de armazenamento de dados são algumas delas. Além disso, aplicações biomédicas têm sido demonstradas. Para esse último, têm-se os exemplos de magneto-hipertermia, liberação controlada de fármacos, agente de contraste em imagens de ressonância magnética e o controle de reações bioeletrocatalíticas envolvendo enzimas redox. Nesta tese, NPs-Fe3O4 foram aplicadas em duas vertentes inéditas. Dessa forma, tendo em vista uma melhor compreensão, a sua escrita foi dividida em dois capítulos, nos quais abordam separadamente cada uma dessas vertentes. O primeiro capítulo descreve a obtenção, modificação e funcionalização de NPs-Fe3O4 a afim de usá-las como uma plataforma para a imobilização do citocromo c (Cyt c); uma proteína redox de comportamento modelo dotada de um grupo prostético heme em sua estrutura terciária. Em seguida, após um efetivo processo de imobilização do Cyt c sobre as NPs-Fe3O4 com superfície modificada, o uso de um campo magnético externo possibilitou a deposição do mesmo na interface eletródica, estabelecendo a reação de transferência direta de elétrons entre o grupo heme e a superfície metálica do eletrodo de trabalho. Além disso, por meio da permuta entre os estados comutáveis switch on e switch off, obteve-se o controle magnético comutável da reação de transferência direta de elétrons do Cyt c quando imobilizado na superfície das NPs-Fe3O4 com superfície modificada. Já para o segundo capítulo, NPs-Fe3O4 foram utilizadas como adesivo magnético a fim de capturar nanoestruturas metálicas hollow (nanocages bimetálicos de Au/Ag) dispersas em suspensão aquosa. Dessa forma, por meio da influência de um campo magnético constante, os aglomerados formados entre esses dois nanomateriais foram depositados sobre uma máscara litográfica, levando a formação de padrões de litografia magnética dispostos sobre a superfície de um substrato de ITO (vidro recoberto com óxido de estanho dopado com índio). Imagens de microscopia eletrônica de varredura (MEV) comprovaram que a metodologia utilizada para o preparo dos padrões litográficos foi eficaz, apresentando um alto rendimento na obtenção dos mesmos. Além disso, realizou-se com sucesso o mapeamento químico de infravermelho dos padrões litográficos dispostos sobre o ITO. Para isso, empregou-se como alvo os modos vibracionais do polímero polivinilpirrolidona (PVP) utilizado na funcionalização dos nanocages bimetálicos de Au/Ag. Por fim, acredita-se que os padrões litográficos arranjados em macroescala, juntamente com os aglomerados de nanocages bimetálicos alinhados na forma de microfios, possuem potencial aplicação em estudos de espectroscopia de absorção no infravermelho intensificado por superfície (SEIRA). / Currently, applications of magnetite nanoparticles (Fe3O4-NPs) have been commonly reported in many studies in the literature. Catalysis, ferrofluids and data storage devices are some of them. Moreover, biomedical applications have been demonstrated. For the latter, there are the following examples, such as magneto-hyperthermia, controlled release of drugs and the control of bioelectrocatalysis of the enzymatic reactions. In this thesis, Fe3O4-NPs were used in two new applications. Therefore, towards a better understanding its writing was divided into two chapters, which each one of them reports separately these two applications. The first chapter describes the synthesis, modification and functionalization of Fe3O4-NPs in order to use them as a platform for the immobilization of cytochrome c (Cyt c); model redox protein which possess a heme prosthetic group in its tertiary structure. Then, after an effective immobilization of Cyt c on surface-modified Fe3O4-NPs, the use of an external magnetic field permitted the deposition of this redox protein on the electrode interface, establishing the reaction of direct electron transfer between heme prosthetic group and the metallic surface of the working electrode. Furthermore, by the exchange between ON and OFF switch modes was obtained the magnetic control of the direct electron transfer of Cyt c when immobilized on the surface-modified Fe3O4-NPs. For the second chapter, Fe3O4-NPs were used as magnetic adhesive to capture hollow metallic nanostructures (Au-Ag bimetallic nanocages) dispersed in aqueous suspension. Thus, by use of a constant magnetic field, the agglomerates formed between these two nanomaterials were deposited on a lithographic mask, leading to formation of magnetolithograph patterns on the surface of ITO substrate (glass coated with oxide tin-doped indium). Scanning electron microscopy images (SEM) showed that the methodology used for the high-yield preparation of lithographicpatterns was effective. Furthermore, the FTIR chemical mapping of the lithographic patterns arranged on the ITO\'s surface was successfully performed. For this, the CH2 and C-N, C=O vibrational modes of the polyvinylpyrrolidone polymer (PVP) used for the functionalization of Au-Ag bimetallic nanocages were employed as target. Finally, we believed that magnetolithograph patterns arranged in microscale on the ITO surface, and also the clusters of the bimetallic nanocages aligned as micro-wires show potential application in surface-enhanced infrared absorption (SEIRA).

Atualmente, aplicações de nanopartículas de magnetita (NPs-Fe3O4) têm sido comumente reportadas em inúmeros trabalhos descritos na literatura. Catálise, ferrofluidos e dispositivos de armazenamento de dados são algumas delas. Além disso, aplicações biomédicas têm sido demonstradas. Para esse último, têm-se os exemplos de magneto-hipertermia, liberação controlada de fármacos, agente de contraste em imagens de ressonância magnética e o controle de reações bioeletrocatalíticas envolvendo enzimas redox. Nesta tese, NPs-Fe3O4 foram aplicadas em duas vertentes inéditas. Dessa forma, tendo em vista uma melhor compreensão, a sua escrita foi dividida em dois capítulos, nos quais abordam separadamente cada uma dessas vertentes. O primeiro capítulo descreve a obtenção, modificação e funcionalização de NPs-Fe3O4 a afim de usá-las como uma plataforma para a imobilização do citocromo c (Cyt c); uma proteína redox de comportamento modelo dotada de um grupo prostético heme em sua estrutura terciária. Em seguida, após um efetivo processo de imobilização do Cyt c sobre as NPs-Fe3O4 com superfície modificada, o uso de um campo magnético externo possibilitou a deposição do mesmo na interface eletródica, estabelecendo a reação de transferência direta de elétrons entre o grupo heme e a superfície metálica do eletrodo de trabalho. Além disso, por meio da permuta entre os estados comutáveis switch on e switch off, obteve-se o controle magnético comutável da reação de transferência direta de elétrons do Cyt c quando imobilizado na superfície das NPs-Fe3O4 com superfície modificada. Já para o segundo capítulo, NPs-Fe3O4 foram utilizadas como adesivo magnético a fim de capturar nanoestruturas metálicas hollow (nanocages bimetálicos de Au/Ag) dispersas em suspensão aquosa. Dessa forma, por meio da influência de um campo magnético constante, os aglomerados formados entre esses dois nanomateriais foram depositados sobre uma máscara litográfica, levando a formação de padrões de litografia magnética dispostos sobre a superfície de um substrato de ITO (vidro recoberto com óxido de estanho dopado com índio). Imagens de microscopia eletrônica de varredura (MEV) comprovaram que a metodologia utilizada para o preparo dos padrões litográficos foi eficaz, apresentando um alto rendimento na obtenção dos mesmos. Além disso, realizou-se com sucesso o mapeamento químico de infravermelho dos padrões litográficos dispostos sobre o ITO. Para isso, empregou-se como alvo os modos vibracionais do polímero polivinilpirrolidona (PVP) utilizado na funcionalização dos nanocages bimetálicos de Au/Ag. Por fim, acredita-se que os padrões litográficos arranjados em macroescala, juntamente com os aglomerados de nanocages bimetálicos alinhados na forma de microfios, possuem potencial aplicação em estudos de espectroscopia de absorção no infravermelho intensificado por superfície (SEIRA). / Currently, applications of magnetite nanoparticles (Fe3O4-NPs) have been commonly reported in many studies in the literature. Catalysis, ferrofluids and data storage devices are some of them. Moreover, biomedical applications have been demonstrated. For the latter, there are the following examples, such as magneto-hyperthermia, controlled release of drugs and the control of bioelectrocatalysis of the enzymatic reactions. In this thesis, Fe3O4-NPs were used in two new applications. Therefore, towards a better understanding its writing was divided into two chapters, which each one of them reports separately these two applications. The first chapter describes the synthesis, modification and functionalization of Fe3O4-NPs in order to use them as a platform for the immobilization of cytochrome c (Cyt c); model redox protein which possess a heme prosthetic group in its tertiary structure. Then, after an effective immobilization of Cyt c on surface-modified Fe3O4-NPs, the use of an external magnetic field permitted the deposition of this redox protein on the electrode interface, establishing the reaction of direct electron transfer between heme prosthetic group and the metallic surface of the working electrode. Furthermore, by the exchange between ON and OFF switch modes was obtained the magnetic control of the direct electron transfer of Cyt c when immobilized on the surface-modified Fe3O4-NPs. For the second chapter, Fe3O4-NPs were used as magnetic adhesive to capture hollow metallic nanostructures (Au-Ag bimetallic nanocages) dispersed in aqueous suspension. Thus, by use of a constant magnetic field, the agglomerates formed between these two nanomaterials were deposited on a lithographic mask, leading to formation of magnetolithograph patterns on the surface of ITO substrate (glass coated with oxide tin-doped indium). Scanning electron microscopy images (SEM) showed that the methodology used for the high-yield preparation of lithographicpatterns was effective. Furthermore, the FTIR chemical mapping of the lithographic patterns arranged on the ITO\'s surface was successfully performed. For this, the CH2 and C-N, C=O vibrational modes of the polyvinylpyrrolidone polymer (PVP) used for the functionalization of Au-Ag bimetallic nanocages were employed as target. Finally, we believed that magnetolithograph patterns arranged in microscale on the ITO surface, and also the clusters of the bimetallic nanocages aligned as micro-wires show potential application in surface-enhanced infrared absorption (SEIRA).

The poly(glycidyl methacrylate)-modified magnetite nanoparticles, Fe3O4-PGMA NPs, were investigated and applied in nondestructive flaw detection of polymeric materials in this research. The Fe3O4 endowed magnetic property to the materials for flaw detection while the PGMA promoted colloidal stability and prevented particle aggregation. The magnetite nanoparticles (Fe3O4 NPs) were successfully synthesized by coprecipitation and then surface-modified with PGMA to form PGMA-modified Fe3O4 NPs by both grafting-from and grafting-to approaches. For the grafting-from approach, the Fe3O4 NPs were surface-functionalized with α-bromo isobutyryl bromide (BIBB) to form BIB-modified Fe3O4 NPs (Fe3O4-BIB NPs) with covalent linkage. The resultant Fe3O4-BIB NPs were used as surface-initiators to grow PGMA by surface-initiated atom transfer radical polymerization (SI-ATRP). For the grafting-to approach, the Fe3O4 NP were surface-functionalized with (3-mercaptopropyl)triethoxysilane (MCTES) to form MCTES-modified Fe3O4 NPs (Fe3O4-MCTES NPs). The PGMA with Br-end group was pre-synthesized by ATRP and then was grafted to the surface of the Fe3O4-MCTES NPs by coupling reaction. Both bare and modified Fe3O4 NPs exhibited superparamagnetism and the existence of iron oxide in the form of Fe3O4 was confirmed. The particle size of individual Fe3O4 NPs was about 8 – 24 nm but they aggregated to form clusters. The PGMA-modified NPs formed stable dispersion in chloroform and had larger cluster sizes than the unmodified ones because of the PGMA polymer layer. However, the uniformity of the NP clusters could be improved with PGMA surface grafting. The PGMA surface layer of the grafting-from (Fe3O4-gf-PGMA) NPs was thin and dense while that of the grafting-to (Fe3O4-gt-PGMA) NPs was thick and loose. The hydrodynamic diameters (Zave) of Fe3O4-gf-PGMA NP clusters could be controlled between 176 to 643 nm, dependent on the PGMA contents and reaction conditions. During SI-ATRP, side reactions happened and caused NP aggregation as well as increase of size of NP clusters. However, the aggregation has been minimized through optimization of reaction conditions. Oppositely, Zave values of Fe3O4-gt-PGMA NPs had little variation of about 120 – 190 nm. And the PGMA content of the Fe3O4-gt-PGMA NPs was limited to 12.5% because of the spatial hindrance during grafting process. The saturation magnetization (Ms) of the unmodified Fe3O4 NPs was about 77 emu/g, while those of the grafting-from and grafting-to Fe3O4-PGMA NPs were 50 – 66 emu/g and 63 – 70 emu/g, respectively. For Fe3O4-PGMA NPs with similar Fe3O4 contents, the grafting-to NPs had slightly higher Ms than the grafting-from counterparts. In addition, the Ms of both kinds of the Fe3O4-PGMA NPs with higher Fe3O4 content (> 87%) were also higher than that of the fluidMAG-Amine, the commercially available amine-modified MNPs. Besides, both kinds of Fe3O4-PGMA NPs also had much higher Fe3O4 contents and Ms values than most of the reported PGMA-modified MNPs. The magnetic epoxy nanocomposites (MENCs) were prepared by blending the modified Fe3O4 NPs into bisphenol A diglycidyl ether (BADGE)-based epoxy system and the distributions of both kinds of the PGMA-modified NPs were much better than that of the oleic acid-modified Fe3O4 NPs. Similar to the NPs, the MENCs also exhibited superparamagnetism. By cross-section TEM observation, the grafting-to Fe3O4-PGMA NPs formed more homogeneous distributions with smaller cluster size than the grafting-from counterparts and gave higher Ms of the MENCs. Nondestructive flaw detection of surface and sub-surface defects could be successfully achieved by brightness contrast of images given through eddy current testing (ET) method, which is firstly reported. The mechanical properties of the materials were influenced very slightly when 2.5% or lower Fe3O4-gt-PGMA NPs were present while the presence of the Fe3O4-gf-PGMA NPs (1 – 2.5 %) gave mild improvement of the storage modulus and increase of the glass-rubber transition temperature(Tg) of the MENCs. Furthermore, the Fe3O4-PGMA NPs could be evenly coated onto the functionalized ultra-high molecular weight poly(ethylene) (UHMWPE) textiles. The Fe3O4-gt-PGMA NPs were coated on the textile in order to prepare NP-coated textile-reinforced composite. Preliminary result of ET measurement showed that the Fe3O4-gt-PGMA NPs coated on the textiles could visualize the structure of the textile hidden inside and their relative depth. Accordingly, the incorporation of MNPs to polymers opens a new pathway of damage-free structural health monitoring of polymeric materials.

The poly(glycidyl methacrylate)-modified magnetite nanoparticles, Fe3O4-PGMA NPs, were investigated and applied in nondestructive flaw detection of polymeric materials in this research. The Fe3O4 endowed magnetic property to the materials for flaw detection while the PGMA promoted colloidal stability and prevented particle aggregation. The magnetite nanoparticles (Fe3O4 NPs) were successfully synthesized by coprecipitation and then surface-modified with PGMA to form PGMA-modified Fe3O4 NPs by both grafting-from and grafting-to approaches. For the grafting-from approach, the Fe3O4 NPs were surface-functionalized with α-bromo isobutyryl bromide (BIBB) to form BIB-modified Fe3O4 NPs (Fe3O4-BIB NPs) with covalent linkage. The resultant Fe3O4-BIB NPs were used as surface-initiators to grow PGMA by surface-initiated atom transfer radical polymerization (SI-ATRP). For the grafting-to approach, the Fe3O4 NP were surface-functionalized with (3-mercaptopropyl)triethoxysilane (MCTES) to form MCTES-modified Fe3O4 NPs (Fe3O4-MCTES NPs). The PGMA with Br-end group was pre-synthesized by ATRP and then was grafted to the surface of the Fe3O4-MCTES NPs by coupling reaction. Both bare and modified Fe3O4 NPs exhibited superparamagnetism and the existence of iron oxide in the form of Fe3O4 was confirmed. The particle size of individual Fe3O4 NPs was about 8 – 24 nm but they aggregated to form clusters. The PGMA-modified NPs formed stable dispersion in chloroform and had larger cluster sizes than the unmodified ones because of the PGMA polymer layer. However, the uniformity of the NP clusters could be improved with PGMA surface grafting. The PGMA surface layer of the grafting-from (Fe3O4-gf-PGMA) NPs was thin and dense while that of the grafting-to (Fe3O4-gt-PGMA) NPs was thick and loose. The hydrodynamic diameters (Zave) of Fe3O4-gf-PGMA NP clusters could be controlled between 176 to 643 nm, dependent on the PGMA contents and reaction conditions. During SI-ATRP, side reactions happened and caused NP aggregation as well as increase of size of NP clusters. However, the aggregation has been minimized through optimization of reaction conditions. Oppositely, Zave values of Fe3O4-gt-PGMA NPs had little variation of about 120 – 190 nm. And the PGMA content of the Fe3O4-gt-PGMA NPs was limited to 12.5% because of the spatial hindrance during grafting process. The saturation magnetization (Ms) of the unmodified Fe3O4 NPs was about 77 emu/g, while those of the grafting-from and grafting-to Fe3O4-PGMA NPs were 50 – 66 emu/g and 63 – 70 emu/g, respectively. For Fe3O4-PGMA NPs with similar Fe3O4 contents, the grafting-to NPs had slightly higher Ms than the grafting-from counterparts. In addition, the Ms of both kinds of the Fe3O4-PGMA NPs with higher Fe3O4 content (> 87%) were also higher than that of the fluidMAG-Amine, the commercially available amine-modified MNPs. Besides, both kinds of Fe3O4-PGMA NPs also had much higher Fe3O4 contents and Ms values than most of the reported PGMA-modified MNPs. The magnetic epoxy nanocomposites (MENCs) were prepared by blending the modified Fe3O4 NPs into bisphenol A diglycidyl ether (BADGE)-based epoxy system and the distributions of both kinds of the PGMA-modified NPs were much better than that of the oleic acid-modified Fe3O4 NPs. Similar to the NPs, the MENCs also exhibited superparamagnetism. By cross-section TEM observation, the grafting-to Fe3O4-PGMA NPs formed more homogeneous distributions with smaller cluster size than the grafting-from counterparts and gave higher Ms of the MENCs. Nondestructive flaw detection of surface and sub-surface defects could be successfully achieved by brightness contrast of images given through eddy current testing (ET) method, which is firstly reported. The mechanical properties of the materials were influenced very slightly when 2.5% or lower Fe3O4-gt-PGMA NPs were present while the presence of the Fe3O4-gf-PGMA NPs (1 – 2.5 %) gave mild improvement of the storage modulus and increase of the glass-rubber transition temperature(Tg) of the MENCs. Furthermore, the Fe3O4-PGMA NPs could be evenly coated onto the functionalized ultra-high molecular weight poly(ethylene) (UHMWPE) textiles. The Fe3O4-gt-PGMA NPs were coated on the textile in order to prepare NP-coated textile-reinforced composite. Preliminary result of ET measurement showed that the Fe3O4-gt-PGMA NPs coated on the textiles could visualize the structure of the textile hidden inside and their relative depth. Accordingly, the incorporation of MNPs to polymers opens a new pathway of damage-free structural health monitoring of polymeric materials.:1. Introduction 2. Theoretical section 2.1. Magnetite Nanoparticles (MNPs) 2.2. Applications of MNPs 2.3. Atom transfer radical polymerization (ATRP) 2.4. Magnetic nanocomposites (MNCs) 2.5. Damage-free structural health monitoring (SHM) using MNPs 3. Objective of the work 4. Materials, methods and characterization 4.1. Materials 4.2. Methods 4.3. Formation of polymeric magnetic nanocomposites 4.4. Characterization 5. Results and discussions 5.1. Unmodified magnetite nanoparticles (Fe3O4 NPs) 5.2. Oleic acid-modified (Fe3O4–OA) NPs 5.3. PGMA-modified NPs by grafting-from approach (Fe3O4-gf-PGMA NPs) 5.4. PGMA-modified NP by grafting-to approach (Fe3O4-gt-PGMA NPs) 5.5. Comparison between grafting-from and grafting-to Fe3O4-PGMA NPs 5.6. Magnetic epoxy nanocomposites (MENCs) 5.7. Fiber-reinforced epoxy nanocomposites 6. Conclusions and outlook 7. Appendix 8. List of figures, schemes and tables 9. References Versicherung Erklaerung List of publications