Short Communication Reflectance-based detection of oxidizers in ambient air

This study used two types of paper supported materials with a prototype, reflectance-based detector for indication of hydrogen peroxide vapor under ambient laboratory conditions. Titanyl based indicators provide detection through reaction of the indicator resulting in a dosimeter type sensor, while porphyrin based indicators provide a reversible interaction more suitable to continuous monitoring applications. These indicators provide the basis for discussion of characteristics important to design of a sensor system including the application environment and duration, desired reporting frequency, and target specificity

Short Communication Reflectance-based detection of oxidizers in ambient air

This study used two types of paper supported materials with a prototype, reflectance-based detector for indication of hydrogen peroxide vapor under ambient laboratory conditions. Titanyl based indicators provide detection through reaction of the indicator resulting in a dosimeter type sensor, while porphyrin based indicators provide a reversible interaction more suitable to continuous monitoring applications. These indicators provide the basis for discussion of characteristics important to design of a sensor system including the application environment and duration, desired reporting frequency, and target specificity

지속 가능한 이산화탄소 순환을 위한 광합성 모방의 하이브리드 시스템 개발

학위논문 (박사)-- 서울대학교 대학원 : 공과대학 재료공학부, 2019. 2. 남기태.자연계의 모든 자유에너지들은 태양에너지로부터 얻어지며 이는 광합성을 통해 흡수된다. 매년 4.2"×" 1017 kJ 의 에너지가 광합성을 통해 흡수되며 이는 물과 이산화탄소를 산소와 포도당으로 전환하는데 사용된다. 이러한 과정을 통해 대기중의 이산화탄소는 지상에서 탄소화합물을 형성하는 구성 요소로 사용되며, 이로 인해 지구상의 탄소 순환이 그 균형을 유지할 수 있다. 그러나 인류의 산업 시대 이후 무분별한 화석 연료의 사용은 대기 중으로 과량의 탄소를 배출시켰으며 이는 지구 탄소 순환을 깨뜨리는 결과를 야기하였다. 따라서 이를 해소하기 위해서는 새로운 인공적인 탄소 고정 경로가 개발되어야 한다. 본 학위 연구에서는 자연계의 광합성을 모델로 한 인공 에너지 전환 시스템을 개발하였다. 각각의 시스템은 광합성에서 연속적으로 일어나는 에너지 전환 과정들, 빛 에너지의 흡수 / 전자 전달 / 탄소의 고정, 을 모사하였다. 자연계가 이미 정교한 디자인과 훌륭한 기능들을 보유하고 있음에도 불구하고, 이를 인공 장치에 적용하기 위해서는 개선이 필요하다. 먼저 단백질과 같이 안정성이 떨어지는 생체 재료들을 보완하기 위해 안정한 합성 물질들을 추가적인 지지체 혹은 대체제로 사용해야 한다. 또한 광합성 반응에 의해 생성된 에너지 혹은 연료는 유기물의 신진대사가 아닌 엔진을 작동시키는데 사용될 수 있어야 한다. 본 학위 연구에서는 이들을 해결하기 위한 새로운 전략을 세우기 위해 먼저 인공광합성 개발에 대한 선행 연구들을 조사하였다. Chapter 2 에서는 지금까지 연구되었던 인공적인 광합성 시스템들인 인공 집광복합체 개발, 인공 전자전달계 개발, 전기화학적 이산화탄소 고정에 대해 다루었다. 선행 연구들로부터 얻은 교훈을 발판 삼아 본 학위 연구에서는 유용한 연료 개발을 위한 세 가지의 에너지 전환 경로를 개발하였다. 광합성은 광활성 단백질인 광계가 태양빛을 흡수하며 그 반응이 개시된다. 광계는 집광복합체와 반응중심체로 그 구조가 이루어지며, 집광복합체는 태양빛을 흡수하고 흡수된 광 에너지를 반응중심체로 전달하는 역할을 수행한다. 이때, 색소 분자들의 효율적인 배열이 전체 집광복합체의 광-흡수, 광-에너지 전달 특성을 좌우하게 된다. 본 학위 연구에서는 이러한 광계 내의 정교한 색소 분자 배열을 모사하여 포르피린 색소 분자를 기반으로 하고 금 나노입자를 지지체로 사용한 인공 집광복합체를 개발하였다. 이때 색소 분자들 간의 배열을 정밀하게 조절하기 위해 펩토이드를 사용하여 나노 입자의 가지 지지체로 사용하였다. 포르피린 분자들 간의 거리는 6 Å 에서 12 Å 으로 조절하였으며 이는 실제 광계 단백질에서 엽록소 분자들이 배열되어 있는 거리와 같은 범위이다. 더불어 금 나노입자의 플라즈몬 효과로 인해 색소 분자의 형광을 증폭시킬 수 있다. 그 결과, 색소의 형광 신호가 최대 20배까지 증가하였으며 이로써 집광복합체의 광특성을 더욱 정밀하게 분석할 수 있었다. 구체적으로, 서로 다른 색소 분자의 배열로부터 구분되는 형광 스펙트럼이 얻어졌다. 이는 본 연구에서 개발된 집광복합체가 색소 집합체의 분자간 에너지 전달 특성을 조사할 수 있는 플랫폼으로 사용될 수 있음을 보여준다. 빛 흡수에 의해 모아진 광-에너지는 반응 중심체에서 전자를 여기시키는 과정에 사용된다. 여기된 전자는 두 개의 광계로 이루어진 Z-체계의 전자전달계로 전달되어 광계II 에서의 물 산화반응과 광계I 에서의 NADP 환원 반응에 참여한다. 두 번의 연속적인 전자 여기를 통해 전체 산화 환원 과정은 가시광선-적외선 영역의 작은 에너지만을 이용해 이루어진다. 인공적인 Z-체계에서는 광계를 대신하여 광활성 반응체의 역할을 대체할 수 있는 반도체 물질을 사용한다. 반도체 물질은 구현하고자 하는 산화 환원 반응과 최적 전자 전달 효율을 달성할 수 있는 에너지 준위를 고려하여 선정되고 제작된다. 본 학위 연구에서는 광계I 과 반도체 물질을 결합한 새로운 하이브리드 Z-체계를 개발하였다. 본 시스템에서는 광계I과 반도체가 금 또는 은 금속 중간체 물질로 직접 연결되어 합쳐진 구조를 이루고 있으며, 가시광선 영역의 빛을 받아 물로부터 수소를 생산한다. 이때 수소 발생 반응의 효율과 안정성은 광계I을 화학 환원제를 사용하여 수소를 생산한 경우에 비하여 모두 증가하였다. 이러한 뛰어난 활성은 안정한 반도체 물질과 단백질의 하이브리드 구조에서 기인한 것으로 보여진다. 자연계의 광합성에서는 광반응으로부터 생산된 전기화학 에너지를 이용하여 최종적으로 이산화탄소로부터 포도당을 합성한다. 인공적인 전기화학 장치에서 이산화탄소는 가해준 전위에 의해 환원된다. 이로 인해, 이산화탄소는 고부가가치의 연료로 직접 전환될 수 있으며 또는 카르복실화 반응을 통해 탄화수소 반응물에 삽입 될 수 있다. 본 연구에서는 자연계의 탄소 고정 과정에서 영감을 받아 불포화 결합이 있는 탄화수소물질에 이산화탄소를 카르복실화 시키는 전기화학적 플랫폼을 새롭게 개발하였다. 본 플랫폼에서는 광합성에서 환원을 위해 화학 환원제인 NADPH를 사용하는 것을 대체하여 직접 전기에너지를 가해 환원 반응을 진행시키고자 하였으며 이를 통해 빠르고 안정적으로 대량의 연료를 생산하고자 하였다. 결론적으로 스타이렌, 다이엔, 알파 올레핀과 같은 불포화 탄화수소 원료로부터 이산화탄소와 물을 사용하여 카르복실산 연료를 생산하였다. 이러한 전기화학 플랫폼을 통해 유용한 탄화수소 연료를 이산화탄소와 물로부터 생산하는 새로운 탄소 고정 경로를 열어줄 수 있을 것으로 기대된다. 본 학위 연구에서는 지속가능한 탄소 순환을 위해 하이브리드 형태의 에너지 전환/전달 시스템을 개발하였다. 시스템의 디자인은 자연계의 광합성에 기반하였으나, 실제 구조는 생체 유기재료와 합성 재료들을 적절히 배합한 하이브리드 구조체를 사용하여 개선된 형태로 제작하였다. 이를 통해 자연계에 비해 향상된 특성과 안정성을 가지는 시너지 효과를 확인하였다. 본 연구는 광합성을 재료과학의 관점에서 깊이 이해할 뿐 아니라 이를 유용한 연료 생산 과정에 적용할 수 있는 방향을 제시하고 있다. 더 나아가 본 연구를 기반으로 광반응과 암반응을 결합한 진정한 인공 광합성을 개발할 수 있을 것으로 기대한다.In nature, all free energy utilized by biological systems comes from solar energy that is trapped by photosynthesis. Annually, 4.2"×" 1017 kJ of solar energy is harvested by photosynthesis and used in the production of oxygen and glucose from water and carbon dioxide (CO2). This enables to fix atmospheric CO2 on the ground as a carbon building block of hydrocarbon and therefore, contributes to sustain the equilibrium of the global carbon cycle. However, since the industrial revolution era, imprudent use of fossil fuel and the resulted CO2 emission has destroyed the balance in global carbon cycle. To restore the natural energy circulation, new artificial energy storage pathway should be developed. In this thesis, designating natural photosynthesis as a model system, artificial energy harvesting/conversion systems are newly developed. Each system is inspired from the sequential energy conversion steps in photosynthesis: (1) light harvesting, (2) electron transfer and (3) carbon fixation. Although the biological system has elaborate design and superior functionality for energy harvesting, it should be reformed to be adopted in artificial devices. First, due to the delicate nature of biomaterials such as proteins, stable synthetic materials should additionally support or replace the biomaterials. Moreover, the final energy or fuel produced from the photosynthetic reaction should be aimed to operate engines rather than metabolize organisms. To build up new strategy for these issues, we have firstly studied previous research on the development of artificial photosynthesis. The representative examples of artificial photosynthesis systems are presented in Chapter 2 which includes the development of artificial light harvesting complexes, artificial electron transfer system and electrochemical CO2 fixation. After learning lessons from the previous studies, we have designed three novel energy conversion pathways inspired from photosynthesis for the production of valuable fuels. The respective systems are specifically presented in Chapter 3, Chapter 4 and Chapter 5. Photosynthesis initiates by light absorption at photosynthetic proteins, photosystem. The protein is comprised of light harvesting complex and reaction center where light harvesting complex absorbs solar light and transfer the photon energy to reaction center. Here, the effective construction of dye assembly in photosystem determines the overall light absorption property and photo-energy transfer efficiency. Inspired from the elaborate alignment of these dye assembly, we newly developed porphyrin-dye based light harvesting complex on the silica-coated gold nanoparticle templates. To precisely align dyes in atomic level, peptoid scaffolds were used which carry out a role of branch on the nanoparticle surface. The intermolecular distance between porphyrins were controlled from 6 Å to 12 Å which is in the range of chlorophyll distance in natural light harvesting complex. We also utilized surface plasmon effect of gold nanoparticle core to amplify the fluorescence of dye. As a result, the fluorescence could be enhanced up to ~20 times at the optimal condition which facilitated to analyze optical property of light harvesting complex more precisely. In detail, distinctive fluorescence spectra were observed from different porphyrin intermolecular alignments. This indicates the developed light harvesting complex can be used as platform for the investigation of intermolecular energy transfer in dye assemblies. Followed by light absorption, collected light energy is consumed in electron excitation at the reaction centers. The excited electrons are then transferred via Z-scheme which is composed of two photosystem proteins and participates in the water oxidation at photosystem II and NADP reduction at photosystem I. By using step-wise excitation of electrons, the overall redox process can be derived by low-energy light in visible-IR range. In artificial Z-scheme, semiconductors are used instead of photosystems which can replace the role of photocatalyst. The semiconductor materials are selected based on the energy level for the desired redox reaction and efficient electron transfer. In this thesis, newly developed hybrid Z-scheme of photosystem I and semiconductor is demonstrated. The hybrid Z-scheme was constructed in all-solid-system by using Au or Ag mediator to conjugate photosystem I and BiVO4. The system produced hydrogen from water under visible light. The hydrogen evolution activity and stability of the photocatalytic reaction was both enhanced significantly compared to the case of single excitation system of photosystem I using chemical reductant. We believed that our hybrid Z-scheme exhibited the high performance due to the stable hybrid structure between the inorganic template and protein. In photosynthesis, CO2 fixation for glucose synthesis occurs lastly by using electrochemical energy produced from light dependent reaction. In artificial electrochemical devices, CO2 can be directly reduced by applied potential. As a result, it can be directly converted into valuable fuels or inserted into hydrocarbon feedstocks by carboxylation to make value-added fuels. In this thesis, inspired from the carbon fixation in photosynthesis, new platform for the carboxylation of unsaturated hydrocarbon substrate using CO2 presented. Instead of using chemical reductant as natural system, electrochemical method was used for stable, fast and mass production of fuel. As a result, site-selective carboxylic acids were produced from the carboxylation of unsaturated hydrocarbons such as styrenes, dienes and α-olefins by using CO2 and water as carbon and proton source. We envision that the electrochemical platform will aid to open new carbon fixation pathway by producing valuable hydrocarbon fuels from CO2 and water. In conclusion, hybrid energy pathway for sustainable carbon fuel cycle was developed in this thesis. The design and concept of system is based on natural photosynthesis, but the virtual construction was modified and upgraded by using hybrid materials from both biological and synthetic materials. Consequently, we could achieve synergetic effect from the hybrid system in the aspect of amplified activity and stability of the complex or device compared to the biological system. This study will aid understanding the underlying material science in photosynthesis and further exploit the desired fuel production reactions. We also envision that this study will be extended to excellent artificial photosynthesis where the light reaction and dark reaction are combined together.Chapter 1. Introduction…………………………………….…1 1.1 Global carbon cycle……………………………………………….1 1.2 Role of photosynthesis in sustainable energy storage………………5 1.3 Light dependent reaction……………………………………………8 1.4 Dark reaction…………………..…………………………………15 1.5 Scope of the thesis…………………..……………………………20 Chapter 2. Artificial photosynthesis mimetic system……….24 2.1 Introduction …………………..…………………………………24 2.2 Artificial antenna for light harvesting……………………………...26 2.2.1 Chromophore assembly………………………………………26 2.2.2 Antenna-reaction center hybridized light harvesting complex..31 2.3 Artificial electron transfer system for energy conversion…………34 2.3.1 Utilization of photosynthetic protein in hybrid system……….34 2.3.2 Photo-electrode for electrochemical reaction…………………39 2.3.3 Z-schematic fuel production system…………………………..42 2.4 Electrochemical carbon dioxide fixation…………………………45 2.4.1 Direct electrochemical reduction reaction of carbon dioxide…45 2.4.2 Carboxylation reaction using carbon dioxide…………………50 Chapter 3. Porphyrin decorated gold nanoparticle antenna complex……………………………………………………….65 3.1 Introduction………………………………………………………65 3.2 Experimental and analysis…………………………………………69 3.2.1 Materials……………………………………………………69 3.2.2 PPC synthesis………………………………………………69 3.2.3 Synthesis of silica nanoparticles………………………………74 3.2.4 Synthesis of AuNPs…………………………………………74 3.2.5 Silica coating on AuNPs………………………………………75 3.2.6 Carboxylation on silica surface………………………………76 3.2.7 EDC/NHS coupling…………………………………………76 3.2.8 Analytical methods…………………………………………77 3.3 Results and discussion……………………………………………78 3.3.1 Silica nanoparticle linked PPCs………………………………78 3.3.2 Silica coated gold nanoparticle linked PPCs…………………87 3.4 Conclusion……………………………………………………….104 Chapter 4. Hybrid Z-scheme of photosystem I and BiVO4 for hydrogen evolution………………….……………………….111 4.1 Introduction………………………………………………………111 4.2 Experimental and analysis………………………………………117 4.2.1 Materials…………………………………………………….117 4.2.2 Isolation of PSI………………………………………………117 4.2.3 Characterization of PSI…………………………………….118 4.2.4 Platinization of PSI……………………………………….119 4.2.5 Synthesis of BiVO4………………………………………….119 4.2.6 Photo-deposition of metal on BiVO4………………………...120 4.2.7 EDC/Sulfo-NHS coupling…………………………………..120 4.2.8 Analytical methods………………………………………….121 4.3 Results and discussion…………………………………………...123 4.3.1 Synthesis of Pt-PSI…………………………………………..123 4.3.2 Synthesis of metal deposited BiVO4…………………………127 4.3.3 Optical property analysis…………………………………….132 4.3.4 Synthesis of hybrid Z-scheme……………………………….134 4.3.5 Electron transfer study in the hybrid system by PL analysis…138 4.3.6 H2 evolution measurement by GC analysis…………………141 4.4 Conclusion……………………………………………………….149 Chapter 5. Electrochemical carboxylation of unsaturated hydrocarbons using CO2………………….…………………158 5.1 Introduction………………………………………………………158 5.2 Experimental and analysis………………………………………162 5.2.1 Materials…………………………………………………….162 5.2.2 Electrochemical analysis…………………………………….162 5.2.3 Analytical methods………………………………………….163 5.3 Results and discussion…………………………………………...165 5.3.1 Electrochemical carboxylation of styrene…………………165 5.3.2 Electrochemical carboxylation of aliphatic α-olefins………202 5.4 Conclusion………………………………………………………210 Chapter 6. Concluding remarks………………….…………219 국문 초록…………………………………………………………………223Docto

Meteorites, Microfossils and Exobiology

The discovery of evidence for biogenic activity and possible microfossils in a Martian meteorite may have initiated a paradigm shift regarding the existence of extraterrestrial microbial life. Terrestrial extremophiles that live in deep granite and hydrothermal vents and nanofossils in volcanic tuffs have altered the premise that microbial life and microfossils are inconsistent with volcanic activity and igneous rocks. Evidence for biogenic activity and microfossils in meteorites can no longer be dismissed solely because the meteoritic rock matrix is not sedimentary. Meteorite impact-ejection and comets provide mechanisms for planetary cross-contamination of biogenic chemicals, microfossils, and living microorganisms. Hence, previously dismissed evidence for complex indigenous biochemicals and possible microfossils in carbonaceous chondrites must be re-examined. Many similar, unidentifiable, biological-like microstructures have been found in different carbonaceous chondrites and the prevailing terrestrial contaminant model is considered suspect. This paper reports the discovery of microfossils indigenous to the Murchison meteorite. These forms were found in-situ in freshly broken, interior surfaces of the meteorite. Environmental Scanning Electron Microscope (ESEM) and optical microscopy images indicate that a population of different biological-like forms are represented. Energy Dispersive Spectroscopy reveals these forms have high carbon content overlaying an elemental distribution similar to the matrix. Efforts at identification with terrestrial microfossils and microorganisms were negative. Some forms strongly resemble bodies previously isolated in the Orgueil meteorite and considered microfossils by prior researchers. The Murchison forms are interpreted to represent an indigenous population of the preserved and altered carbonized remains (microfossils) of microorganisms that lived in the parent body of this meteorite at diverse times during the past 4.5 billion years (Gy)

High Yield Solvothermal Synthesis of Hexaniobate Based Nanocomposites via the Capture of Preformed Nanoparticles in Scrolled Nanosheets

The ability to encapsulate linear nanoparticle (NP) chains in scrolled nanosheets is an important advance in the formation of nanocomposites.These nanopeapods (NPPs) exhibit interesting properties that may not be achieved by individual entities. Consequently, to fully exploit the potential of NPPs, the fabrication of NPPs must focus on producing composites with unique combinations of morphologically uniform nanomaterials. Various methods can produce NPPs, but expanding these methods to a wide variety of material combinations can be difficult. Recent work in our group has resulted in the in situ formation of peapod-like structures based on chains of cobalt NPs. Building on this initial success, a more versatile approach has been developed that allows for the capture of a series of preformed NPs in NPP composites. In the following chapters, various synthetic approaches for NPPs of various material combinations will be presented and the key roles of various reaction parameters will be discussed. Also, uniform hexaniobate nanoscrolls were fabricated via a solvothermal method induced by heating up a mixture of TBAOH, hexaniobate crystallites, and oleylamine in toluene. The interlayer spacing of the nanoscrolls was easily tuned by varying the relative amount and chain lengths of the primary alkylamines. To fabricate NPPs, as-synthesized NPs were treated with hexaniobate crystallite in organic mixtures via solvothermal method. During solvothermal treatment, exfoliated hexaniobate nanosheets scroll around highly ordered chains of NPs to produce the target NPP structures in high yield. Reaction mixtures were held at an aging temperature for a few hours to fabricate various new NPPs (Fe3O4@hexaniobate, Ag@hexaniobate, Au@hexaniobate, Au-Fe3O4@hexaniobate, TiO2@hexaniobate, CdS@hexaniobate, CdSe@hexaniobate, and ZnS@hexaniobate). This versatile method was first developed for the fabrication of magnetic peapod nanocomposites with preformed nanoparticles (NPs). This approach is effectively demonstrated on a series of ferrite NPs (≤ 14 nm) where Fe3O4@hexaniobate NPPs are rapidly (~ 6 h) generated in high yield. When NP samples with different sizes are reacted, clear evidence for size selectivity is seen. Magnetic dipolar interactions between ferrite NPs within the Fe3O4@hexaniobate samples leads to a significant rise in coercivity, increasing almost four-fold relative to free particles. Other magnetic ferrites NPPs, MFe2O4@hexaniobate (M = Mn, Co, Ni), can also be prepared. This synthetic approach to nanopeapods is quite versatile and should be readily extendable to other, non-ferrite NPs or NP combinations so that cooperative properties can be exploited while the integrity of the NP assemblies is maintained. Further, this approach demonstrated selectivity by encapsulating NPs according to their size. The use of polydispersed NP systems is also possible and in this case, evidence for size and shape selectivity was observed. This behavior is significant in that it could be exploited in the purification of inhomogeneous NP samples. Other composite materials containing silver and gold NPs are accessible. Partially filled Fe3O4@hexaniobate NPPs were used as templates for the in situ growth of gold to produce the bi-functional Au- Fe3O4@hexaniobate NPPs. Encapsulation of Ag and Au NP chains with a hexaniobate nanoscroll was shifted the surface plasmon resonance to higher wavelengths. In these composites NPs can be incorporated to form NPP structures, decorated on nanosheets before scrolling, or attached to the surfaces of the nanoscrolls. The importance of this advancement is the promise it holds for the design and assembly of active nanocomposites. One can create important combinations of nanomaterials for potential applications in a variety of areas including catalysis, solar conversion, thermoelectrics, and multiferroics

Electrospun nanofibers : an alternative sorbent material for solid phase extraction

The work described in the thesis seeks to lay a foundation for a better understanding of the use of electrospun nanofibers as a sorbent material. Three miniaturised electrospun nanofiber based solid phase extraction devices were fabricated. For the first two, 10 mg of electrospun polystyrene fibers were used as a sorbent bed for a micro column SPE device (8 mm bed height in a 200 μl pipette tip) and a disk (I) SPE device (5 mm 1 mm sorbent bed in a 1000 μl SPE barrel). While for the third, 4.6 mg of electrospun nylon nanofibers were used as a sorbent bed for a disk (II) SPE device, (sorbent bed consisting of 5 5 mm 350 μm stacked disks in a 500 μl SPE barrel). Corticosteroids were employed as model analytes for performance evaluation of the fabricated SPE devices. Quantitative recoveries (45.5-124.29 percent) were achieved for all SPE devices at a loading volume of 100 μl and analyte concentration of 500 ng ml-1. Three mathematical models; the Boltzmann, Weibull five parameter and the Sigmoid three parameter were employed to describe the break through profiles of each of the sorbent beds. The micro column SPE device exhibited a breakthrough volume of 1400 μl, and theoretical plates (7.98-9.1) while disk (I) SPE device exhibited 400-500 μl and 1.39-2.82 respectively. Disk (II) SPE device exhibited a breakthrough volume of 200 μl and theoretical plates 0.38-1.15. It was proposed that the formats of future electrospun nanofiber sorbent based SPE devices will be guided by mechanical strength of the polymer. The study classified electrospun polymer fibers into two as polystyrene type (relatively low mechanical strength) and nylon type (relatively high mechanical strength)

Biomimetic Based Applications

The interaction between cells, tissues and biomaterial surfaces are the highlights of the book "Biomimetic Based Applications". In this regard the effect of nanostructures and nanotopographies and their effect on the development of a new generation of biomaterials including advanced multifunctional scaffolds for tissue engineering are discussed. The 2 volumes contain articles that cover a wide spectrum of subject matter such as different aspects of the development of scaffolds and coatings with enhanced performance and bioactivity, including investigations of material surface-cell interactions

Photoactive tools for biomedical applications. From supramolecules to micro-objects

The research work within the wide field of nanomedicine that is presented in this thesis is centred on the development of new nanostructured multifunctional materials for future theranostic applications. In Chapter 2, is presented a new luminescent chemosensor for Mg2+ detection in mitochondria based on a diaza-18-crown-6 appended with two 8-hydroxyquinoline(8-HQ) derivative. In Chapter 3 is reported a new synthetic strategy, to prepare silica core/PEG shell nanoparticles doped with phosphorescent emitters such as organic molecules called “asterisks” and metal-phorphyrins. In Chapter 4 will be shown the study carried out at the New York University, centred on the synthesis of microstructures suitable to mimic invading microbial pathogens. There were also prepared other active colloids able to be propelled by the oxygen bubbles formed by a chemical reaction that is UV-light activated in the presence of hydrogen peroxide. Chapter 5 will deal with bioresorbable electrospun nanofiber mat that, if doped with theranostic agents can be used to the release the active species, during their degradation after post-surgical implantation. Photophysical characterization is reported together with a study of the PLGA fibers degradation that proves that the nanoparticle release correlates very well with the degradation profile in physiological conditions. Chapter 6 merged some research works on different species that could have, interesting properties to be exploited in building block moieties for the design of multifunctional platforms. The attention has been focused on NIR emitters. It has been discussed the results obtained with rhenium(I) and lanthanide metal complex from a photophysical point of view both in solution and in the solid state. Is also presented a basic study that aims to assess the possible pro-oxidant or antioxidant effects induced by gold nanoparticles