<p> Research in the field of sol-gel derived materials has evolved dramatically over the past forty years. The developments in the past decade, in the field of bioanalytical chemistry, have revolutionized this field. Early research, as well as that done by our group, has confirmed that the commonly used alkoxysilane precursors (tetraethylorthosilicate - TEOS or tetramethylorthosilicate - TMOS) are not ideal for entrapment of biomolecules. They produce materials that are brittle, often undergo cracking due to hydration stresses and in some cases, can block the accessibility of the analyte to the entrapped biomolecules. My research project therefore focuses on the development of new sol-gel processing methods through the use of an additive-glycerol, which will produce new "second generation" glasses. I have focused on obtaining a basic understanding of glycerol-doped sol-gel derived materials and the effect they have on the entrapped biomolecules. Glycerol-doped sol-gel materials display larger pore size, decreased shrinkage and cracking as compared to the TEOS-based materials. Biocatalysts entrapped in glycerol-doped materials showed significantly smaller decreases in activity over a period of one month relative to enzyme entrapped in TEOS. Also, to gain further insight into the effects of glycerol doping on the properties of entrapped proteins, both steady-state and time-resolved fluorescence of Trp 214 was used to examine the conformation, dynamics, accessibility, thermal/chemical stability and the degree of ligand binding of human serum albumin (HSA) in solution and after entrapment of the protein in glycerol-doped TEOS-based materials.</p> / Thesis / Master of Science (MSc)

The present thesis is devoted to synthesis, through the environmentally friendly citrate sol-gel route, of YIn0.9O3 −ZnO near infrared reflective based pigments, having different chromophore elements (Mn, Cu, Fe), with the aim to add in binder and obtaining cool coatings. A “cool” coating for roofing consists of paint (or glaze) containing color pigments, which do not absorb the infrared portion of the solar spectrum. Cool coatings applied over buildings surface provide an effective solution for passive cooling of building indoors and influencing local outdoor microclimate, mitigating urban heat islands effect (UHIE). The primary purpose is to produce pigments according to an environmentally friendly route, using non-toxic raw materials, as well as short times and low temperatures for synthesis, and without residual waste. The resulting pigments must have high reflectance in the near-infrared so that they can be used in the field of cold paints. To realize the corresponding coatings, pigments were dispersed in two different binders (standard PMMA and industrial binder). For the most interesting pigments, in terms of NIR reflectance, other property, was decided to explore, which define these NIR reflective pigments as smart pigments for building application: the photocatalytic ability.

An optical fiber humidity sensor has been devised using a porous sol-gel silica (PSGS) coating as a transducer. Evanescent wave scattering (EWS) in the PSGS coating. PSGS particles are highly hydrophilic and have a strong tendency to absorb water molecules from the surrounding environment. The absorbed water molecules form a thin layer on the inner surface of the pores inside the porous silica and enhance EWS, from which an indicatory signal can be obtained. The humidity sensor presented in this thesis has a fast response, is reversible, low cost, and has a broad dynamic relative humidity range from 3.6?0-6% to 100% or humidity range from 1.2ppm to 30000ppm. Because of its multiple advantages, including immunity to electromagnetic interference, resistance to corrosive environments, and high sensitivity, this humidity sensor has various applications. In soil moisture sensing, this humidity sensor can avoid the interference caused by compounds in soil water. For electrical transformer moisture sensing, this humidity sensor can avoid the effect of electromagnetic fields.

A scintillating optical fiber sensor of this work consists of a scintillating optical fiber, connected to a photomultiplier tube (PMT) via a conventional silica optical fiber. When a gamma ray impinges on the scintillating optical fiber, photons are generated inside the fiber. The photons are trapped inside the fiber and guided through the PMT. The PMT output signal is acquired by a computer. Two types of scintillating optical fibers sensors were developed for gamma ray detection. The first one is a silica optical fiber doped with an inorganic scintillating agent. The second one is a liquid core waveguide optical fiber filled with a solution of a nanostructured core shell CdSe/ZnS quantum dot. Test results indicate that the scintillating optical fibers developed in this work are sensitive for detecting gamma radiation. These scintillating fibers offer more flexibility for applications in nuclear energy industry as well as in nuclear medical research.

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