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Advanced antimicrobial biomaterials for wound healing applications are an active field of research for their potential in addressing severe and infected wounds and overcoming the threat of antimicrobial resistance. Beta-glucans have been used in the preparation of these materials for their bioactive properties, but very little progress has been made so far in producing biomedical devices entirely made of beta-glucans and in their integration with effective antimicrobial agents. In this work, a simple and eco-friendly method is used to produce flexible beta-glucan/nanostructured zinc oxide films, using glucans derived from the yeast Saccharomyces cerevisiae. The properties of the films are characterized through scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, infrared and UV–visible spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and water absorption tests. Finally, the antibacterial properties of the nanostructured zinc oxide and of the composite films are assessed against Staphylococcus epidermidis and Escherichia coli, showing a marked effectiveness against the former. Overall, this study demonstrates how a novel bionanocomposite can be obtained towards the development of advanced wound healing devices.

In this work, the surface of nanostructured fluorine-doped ZnO (nZnO&middot, F) is functionalized with protein A (PrA), and used as a model biomolecule. The chemical procedure is characterized by several analytical techniques such as Fourier Transform Infrared Spectroscopy, water contact angle analysis, and fluorescence microscopy. The surface modification of nZnO&middot, F by binding increasing concentrations of PrA is also investigated by two label-free optical techniques, i.e., the spectroscopic reflectometry and the steady-state photoluminescence. The results are compared with those obtained using undoped nZnO substrates in order to highlight the better performances of nZnO&middot, F due to the fluorine doping. The results of this study pave the way for the design and realization of a ZnO-based nanostructured platform for label-free optical sensing.

Дисертація присвячена розробленню фізико-технологічних засад створення та дослідженню чутливості сенсорів на акустичних хвилях на основі наноструктурованого оксиду цинку. Проведено моделювання п’єзоелектричних властивостей наноструктурованого шару ZnO та показано можливість підвищення ефективності перетворення енергії та зменшення товщини активного шару у порівнянні з полікристалічним. Проведено аналіз чутливості сенсорів на ОАХ та ПАХ з наноструктурованим шаром різноманітної морфології та підтверджено значне покращення чутливості сенсорів до масового навантаження як результат використання наноструктурованого шару за рахунок збільшення площі поверхні чутливого елемента. Встановлено закономірності між параметрами синтезу та структурними властивостями ZnO у формі нанострижнів на підкладках різних типів, що дозволило удосконалити технологію синтезу, досягнути стабільності та повторюваності результатів формування матеріалу. Продемонстровано можливість застосування технології низькотемпературного синтезу наноструктурованого ZnO у поєднанні з класичними мікроелектронними технологіями для виготовлення пристроїв електроніки. Розроблено та досліджено високочутливі макетні зразки сенсорів УФ випромінювання на основі резонатора на ПАХ на підкладці 128°YX – LiNbO3 з аподизованими ЗШП та RMSC і чутливим шаром на основі наноструктурованого ZnO та ZnO:Al. За допомогою методу вимірювання за зсувом частоти резонатора досягнуто більший у порівнянні з існуючими аналогами зсув частоти (138±1,9 кГц) при меншій інтенсивності випромінювання (46 мкВт/см2) з довжиною хвилі 365±3 нм. Запропоновано метод зменшення до 45 с часу відновлення сенсора на основі наноструктурованого ZnO та ZnO:Al шляхом обробки плазмою газового розряду поверхні сенсора. The dissertation is devoted to the development of physical and technological bases of design and study of the sensitivity of the acoustic wave sensors based on nanostructured zinc oxide. The simulation of the piezoelectric properties of nanostructured ZnO layer was carried out in the multilayered structure by the solving of electrostatics equation by the finite element method. It was shown that the simultaneous increase in the length, the distance between rods and the diameter reduction of nanostructured ZnO in the shape of nanorods had increased the energy-conversion efficiency and reduced the thickness of the active layer as compared with polycrystalline ZnO. The sensitivity of the sensors based on thin-film bulk resonators and surface acoustic wave sensors in the structure of delay line with nanostructured layers with different morphologies, sensitive to the mass and electrical load, were analyzed. It was confirmed a significant improvement in the mass sensor sensitivity of both types of sensors resulting from the application of nanostructured layer due to the increasing of the sensitive element’s surface area. The relationships between the parameters of synthesis (such as solution components, concentration, process time, temperature and post-growth treatment) and structural properties of nanostructured ZnO and Al-doped ZnO in the shape of nanorods on conductive, single-crystal and amorphous substrates were established. The synthesis technology of nanostructured ZnO was improved on the basis of the defined mechanisms. Stability and repeatability of the material formation at the certain process parameters were achieved, in particular on singlecrystal piezoelectric substrates of 128°YX – LiNbO3 and metal films, that allowed the formation of sensing elements on the top electrode of thin-film bulk resonators and surface acoustic wave sensor substrate between the interdigital transducers. The possibility of the application of the improved low-temperature synthesis technology of nanostructured ZnO in combination with conventional microelectronic technology for electronic devices manufacturing, in particular multilayer structures for energy conversion and harvesting and sensitive areas for acoustic wave sensors, including the sensing elements modified with other materials for gas analyzers, was shown. The high-sensitive prototypes of UV radiation sensors based on SAW resonator on the substrate of 128°YX–LiNbO3 with apodized interdigital transducers and reversing multistrip coupler and the sensitive layer based on nanostructured ZnO and ZnO:Al were developed and investigated. The major, as compared with existing sensors, frequency shift of 138±1,9 kHz at a lower radiation power of 46 mW/cm2 with a wavelength of 365±3 nm for the SAW sensor with nanostructured ZnO sensing layer was obtained by the method for measuring of resonator frequency shift. The frequency shift of 110±2,1 kHz at the same parameters of radiation was obtained for the SAW sensor with nanostructured ZnO:Al sensing layer. A method of reducing the recovery time of the sensors based on nanostructured ZnO and ZnO:Al up to 45 s after UV exposure by application of the gas discharge plasma on sensor surface was introduced to provide the fast discharge. The method avoids the sample heating and the defects formation. The results of the research were applied during implementation of the research and development activities including international co-operation of Research Institute of Applied Electronics, National Technical University of Ukraine “Kyiv Polytechnic Institute”. Диссертация посвящена разработке физико-технологических основ создания и исследованию чувствительности сенсоров на акустических волнах на основе наноструктурированного оксида цинка. Проведено моделирование пьезоэлектрических свойств наноструктури- рованного слоя ZnO и показана возможность повышения эффективности преобразования энергии и уменьшения толщины активного слоя по сравнению с поликристаллическим. Проведен анализ чувствительности сенсоров на ОАВ и ПАВ с наноструктурированным слоем различной морфологии и подтверждено значительное улучшение чувствительности сенсоров к массовой нагрузке в результате использования наноструктурированного слоя за счет увеличения площади поверхности чувствительного элемента. Установлены закономерности между параметрами синтеза и структурными свойствами ZnO в форме наностержней на подложках разных типов, что позволило усовершенствовать технологию синтеза, достигнуть стабильности и повторяемости результатов формирования материала. Продемонстрирована возможность применения технологии низкотемпературного синтеза наноструктурированного ZnO в сочетании с классическими микроэлектронными технологиями для изготовления устройств электроники. Разработаны и исследованы высокочувствительные макетные образцы сенсоров УФ излучения на основе резонатора на ПАВ на подложке 128°YX–LiNbO3 с аподизоваными ВШП и RMSC и чувствительным слоем на основе наноструктурированного ZnO и ZnO:Al. С помощью метода измерения по сдвигу частоты резонатора достигнут больший по сравнению с существующими аналогами сдвиг частоты (138±1,9 кГц) при меньшей интенсивности излучения (46 мкВт/см2) с длиной волны 365±3 нм. Предложен метод уменьшения до 45 с времени восстановления сенсора на основе наноструктурированного ZnO и ZnO:Al путем обработки плазмой газового разряда поверхности сенсора.

A sensor for detection of vapors of volatile organic compounds (VOCs) incorporating nanostructured zinc oxide film and silicon micromachining is reported. One of the key features of the sensor is the use of nanostructured ZnO material which has been synthesized using a novel low cost process. Considerable reduction in the operating temperature of the sensor has been achieved due to the use of nanostructured ZnO material as compared to a sensor having ZnO thin film as the sensing layer. The sensor is formed on a micromachined silicon platform thereby reducing the heat loss. This resulted in reduction in power consumption. The sensor has been tested for a variety of VOCs such as: ethanol, iso-propyl alcohol and acetone. The maximum sensitivity of sensor was observed for ethanol vapors.

Óxido de zinco (ZnO) nanoestruturado foi obtido por síntese de combustão em solução (SCS) utilizando nitrato de zinco como oxidante e ureia como combustível. O material foi caracterizado por difração de raios X (DRX); método Branauer, Emmet e Teller (BET); análises termogravimétricas (ATG) e termo diferencial (ATD) e microscopia eletrônica de varredura (MEV). A influência de diferentes razões molares combustível/oxidante na microestrutura do ZnO foi investigada. As amostras com maior razão molar apresentaram menor tamanho de cristalito e maior área superficial. As imagens de MEV mostraram placas irregulares e placas finas com pontas alongadas que se assemelham a flores. Nanostructured zinc oxide (ZnO) was obtained by combustion synthesis in solution (CSS) using zinc nitrate as oxidant and urea as fuel. The material was characterized by X-ray diffraction (XRD), Branauer, Emmet and Teller method (BET), thermal gravimetry (TGA) and thermal differential (DTA) analysis, and scanning electron microscopy (SEM). The influence of different fuel/oxidant molar ratios on the microstructure of ZnO was investigated. The ZnO powders produced using the highest molar ratio presented the lowest crystallite size and the highest surface area. The SEM images showed irregular plates and thin plates with elongated ends that resemble flowers.

Розроблено конструкцію комбінованої системи перетворення енергії сонячного випромінювання та енергії механічних коливань на основі наноструктурованого оксиду цинку. Представлено експериментальні результати створення комірки перетворення енергії механічних коливань та тестування. Показано, що розроблена комірка на основі наноструктурованого оксиду цинку може бути успішно використана для створення системи перетворення енергії з широкими потенційними можливостями застосування у системах енергоживлення та управління. The combined system of solar radiation and mechanical vibrations energy conversion based on nanostructured zinc oxide was developed. Experimental results of mechanical vibrations energy conversion cell design and testing were performed. It was shown that the developed cell based on nanostructured zinc oxide can be successfully applied for energy conversion system development with a wide range of applications in the power systems and management. Разработана конструкция комбинированной системы преобразования энергии солнечного излучения и энергии механических колебаний на основе наноструктурированного оксида цинка. Представлены экспериментальные результаты создания ячейки преобразования энергии механических колебаний и тестирования. Показано, что разработанная ячейка на основе наноструктурированного оксида цинка может быть успешно использована для создания системы преобразования энергии с широкими возможностями применения в системах энергопитания и управления.

Made available in DSpace on 2014-06-11T19:23:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-07-31Bitstream added on 2014-06-13T18:09:34Z : No. of bitstreams: 1 zanatta_cs_me_bauru.pdf: 2567546 bytes, checksum: b92343b4c48fcdf306ed6a95bf902804 (MD5) Materiais nanoestruturados vêm sendo amplamente estudados pela comunidade científica, devido às suas propriedades únicas obtidas com o controle da síntese dos materiais. Por meio do controle experimental, esses materiais podem ser utilizados em numerosas áreas, tais como na eletrônica e na fotônica. Dentre os vários métodos químicos, o processo poliol vem sendo utilizado devido à fácil obtenção de nanopartículas de óxidos e metais na sua forma elementar. O presente trabalho teve como objetivo a síntese do óxido de zinco nanoestruturado por meio do método poliol. Diferentes precursores metálicos, tais como acetato de zinco dihidratado, nitrato de zinco hexahidratado, sulfato de zinco monohidratado e cloreto de zinco anidro e diferentes tempos de permanência da síntese foram utilizados para verificar possíveis interferências dos ânions precursores na síntese e na morfologia do óxido de zinco quando obtido. Os materiais obtidos das sínteses foram caracterizados por difração de raios X (DRX), análises térmicas (TG/DTA), medidas de adsorção de gás nitrogênio, microscopia eletrônica de varredura (MEV), microscopia eletrônica de varredura de alta resolução (MEV-FEG) e cronopotenciometria. Por meio destas técnias mostrou-se a viabilidade da obtenção do óxido de zinco nanoestruturado dd maneira direta a partir do acetato de zinco, através de refluxo em etilenoglicol por 2, 4 e 8 horas seguido de lavagem e centrifugação. A menor nanoestrutura encontrada apresentou partículas com dimensão de aproximadamente 25 nm e formato poliédrico, as quais foram observadas pelo FEG. A técnica de cronopotenciometria, representada por meio das curvas de carga/descarga mostraram que a utilização do compósito contendo o óxido de zinco sintetizado apresenta melhores resultados quando comparados ao uso... Nanostructered materials have been extensively studied by the scientific community due to their unique properties obtained by controlled synthesis of materials. By means of the control of parameters, this new materials can be used in a number of applications in electronic and photonic technology. Among the several methods to obtain nanoparticles or nanostructured materials, the polyol method has been applied because it shows easy procedures to produce nanostructured oxides and elemental metals. The aim of this work is the synthesis of nanostructured zinc oxide, one of the most multifunctional oxides, by the polyol method. Different precursors salts like zinc acetate dihydrate, zinc nitrate hexahydrate, zinc sulfate monohydrate and zinc chloride anhydrate, as well as several times of reflux, were used to investigate the influence of the precursos anions on the synthesis and on the morphology of the crystals of zinc oxide whenever produced. The obtained powders were characterized by X-ray diffraction (DRX), thermal analyses (TG/DTA), and measurements of 'N IND. 2' gas adsorption, scanning electronic and field emission microscopy (MEV and FEG) and chronopotentiometry. These techniques showed the possibility of producing nanostructured zinc oxide in direct way from the reflux in etylenglycol for 2, 4 and 8 hours, followed by washing and centrifugation. The smallest nanostructure observed by FEG presented around 25 nm polyhedral particles. The chronopotentiometry, present charge/discharge curves showing better results for the electrode made of polimer composite containing ZnO nanoparticles than the obtaining results for the oxide alone. The best results showed reversibility of the lithium-ion cell upon 20 cycles, applying 3 μΑ electric current and showing a charge potential up to 4.2 V.