published_or_final_version / Physics / Doctoral / Doctor of Philosophy

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The objectives of this efforts was to develop spectroscopic ellipsometry method for investigation of optical properties: (i) of multi-layered nanostructures used for Bovine leukaemia virus glycoprotein gp51 recognition, (ii) nanostructures consisting of monomeric (mGCSF) and dimeric (dGCSF) granulocyte colony stimulating factor and its receptor (GCSF-R) and (iii) Al2O3/ZnO nanolaminates designed by atomic layer deposition method. In particular, focusing on the investigation of: • biological recognition layers of immunosensors by means of comparison of analytical sensitivities of ellipsometric parameters Δ and Ψ in order to estimate differences in orientation of immobilized intact- and fragmented-antibodies against bovine leukemia virus antigen gp51; • the kinetics of biosensing layer formation, which was based on the immobilization of fragmented and intact antibodies, kinetics of antigen interaction with the immobilized antibodies and interactions of monomeric (mGCSF) and dimeric (dGCSF) granulocyte colony stimulating factor and its receptor (GCSF-R) immobilized on a thin gold layer; • kinetic coefficients of monomolecular biological layer formation process using model which takes into consideration partial reversibility (residence time) effect; • optical constants of Al2O3 and ZnO monolayer as well as Al2O3/ZnO nanolaminates prepared by atomic layer deposition method in order to investigate possibilities to apply these nanolaminates for optical biosensors. / Spektroskopinės elipsometrijos metodas išvystytas ir pritaikytas (i) daugiasluoksnių nanostruktūrų, skirtų galvijų leukemijos viruso (GLV) antigeno gp51 aptikimui, (ii) nanostruktūrų, sudarytų iš monomerinio ir dimerinio granuliocitų kolonijas stimuliuojančio faktoriaus bei jų receptoriaus ir (iii) Al2O3/ZnO nanolaminatų, pagamintų atominių sluoksnių nusodinimo metodu, optinių savybių tyrimams • Tiriant elipsometrinių parametrų Δ ir Ψ jautrumą biojutikliuose, sudarytuose iš biologiškai aktyvių sluoksnių, nustatyti biomolekulių orientacijos skirtumai tarp sluoksnių, sudarytų iš imobilizuotų skaldytų ir neskaldytų antikūnų prieš GLV antigeną. • Ištirti biologiškai aktyvūs sluoksniai, sudaryti iš imobilizuotų skaldytų ir neskaldytų antikūnų prieš GLV antigeną sąveikos su antigenu gp51 ir granuliocitų kolonijas stimuliuojančio faktoriaus (GCSF) receptoriaus imobilizuoto ant aukso paviršiaus, sąveikos su GCSF monomeru ir dimeru formavimosi kinetikos. • Pritaikant modelį, įskaitantį negrįžtamos imobilizacijos reiškinį, nustatytos monomolekulinių biologinių sluoksnių iš antikūnų prieš GLV ir antigeno gp51 bei GCSF ir jo receptoriaus formavimosi kinetinės konstantos. • Nustatytos Al2O3 ir ZnO sluoksnių bei Al2O3/ZnO nanolaminatų, suformuotų naudojant atominių sluoksnių nusodinimo metodą, optines konstantos ir ištirtos galimybes šias struktūras panaudoti biojutikliuose.

The thesis consists of four parts of which part 1 presents a brief overview of nanomaterials. Parts 2, 3 and 4 contain results of investigations of graphene, nanofilms of noble metal nanoparticles and ZnO nanostructures respectively. Investigations of graphene are described in Part 2 which consists of six chapters. In Chapter 2.1, changes in the electronic structure and properties of graphene induced by molecular charge-transfer have been discussed. Chapter 2.2 deals with the results of a study of the interaction of metal and metal oxide nanoparticles with graphene. Electrical and dielectric properties of graphene-polymer composites are presented in Chapter 2.3. Chapter 2.4 presents photo-thermal effects observed in laser-induced chemical transformations in graphene and other nanocarbons system. Chapter 2.5 describes the mechanical properties of polymer matrix composites reinforced by fewlayer graphene investigated by nano-indentation. The extraordinary synergy found in the mechanical properties of polymer matrix composites reinforced with two nanocarbons of different dimensionalities constitute the subject matter of Chapter 2.6. Investigations of noble metal nanoparticles have been described in Part 3. In Chapter 3.1, ferromagnetism exhibited by nanoparticles of noble metals is discussed in detail while Chapter 3.2 deals with surface-enhanced Raman scattering (SERS) of molecules adsorbed on nanocrystalline Au and Ag films formed at the organic–aqueous interface. Factors affecting laser-excited photoluminescence from ZnO nanostructures are examined in great detail in Part 4.

[Truncated abstract] An efficient synthesis of the p-phosphonic acid calix[n]arenes, (n = 4, 5, 6 and 8) in five steps and excellent yield has been developed. This includes the key use of an acetyl protecting group, which is straightforward to introduce and remove using acetic anhydride and potassium hydroxide respectively. The synthesized p-phosphonic acid calixarenes are water-soluble and the hydrogen bonding prowess of the acidic groups dominates its selfassembly processes. For p-phosphonic acid calix[4]arene these include the formation of nano-rafts in the gas phase (≤ 20 molecules) and nano-particles (3.0(3) and 20.0(2) nm) of the calixarene in water using spinning disc processing stabilized by acetonitrile. The larger p-phosphonic acid calix[5,6,8]arenes also show nano-raft formation in both solution and the gas phase. An extensive study of the supramolecular chemistry of calix[5]arene has also been undertaken to better understand its rich structural diversity. This includes the formation of chloromethane inclusion complexes of p-tert-butyl-calix[5]arene and p-H-calix[5]arene with dichloromethane, p-phenyl-calix[5]arene with chloroform and their potential application as gas storage materials. Along with these three investigated inclusion complexes are two sublimates of p-H-calix[5]arene (α and β) with only the β-polymorph active for sorption of carbon dioxide at room temperature and 1 atm. The α-polymorph adopts an inverted cone conformation and forms helical stacks in the extended structure whereas the β-polymorph adopts the usual cone conformation and packs in both 'self included' and 'back-to-back' helical arrangements. ... Complementary to this study involved the p-H-calix[5]arene inclusion complexes with fluoro-, chloro-, bromo- and iodobenzene. All but the iodobenzene complexes are isostructural forming columnar arrays in the extended packing comprised of 'tri-calix[5]arene' segments. Iodobenzene is too large to form the respective 'tri-calix[5]arene' segments and instead forms sheets in the extended packing. To better understand the type and nature of the intermolecular interactions present within the supermolecules and extended structures a detailed Hirshfeld surface analysis was performed. A detailed Hirshfeld surface analysis was also performed on O-octadecyl-calix[6]arene, which crystallizes in the inverted double cone conformation. Three alkyl chains on either side interplay to form one side of hexagon in an hexagonal close packed array of interdigitated alkyl chains. This was the first Hirshfeld surface analysis performed at variable temperatures and enhanced the description of such a large supramolecular system. The related compound O-octadecyl-calix[4]arene was found to crystallize from toluene or benzene as supramolecular bilayers, 32.2(4) and 32.7(2) Å thick respectively. The calixarenes adopt the cone conformation and the alkyl chains interplay to form a continuous hexagonal motif similar to that seen for O-octadecyl-calix[6]arene. The formation of stable bilayers using octadecyl chains leads to the possibility of inserting long chain calixarenes with suitable functionalization into biological membranes. Such functionalization could include upper rim phosphorylation as seen for the p-phosphonic acid calixarenes to produce phospholipid mimics.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Also available in print.