This thesis describes the development of microfluidic (MF) platforms for the study of biological and chemical processes. In particular the thesis is divided into two distinct parts: (i) development of a MF methodology to generate tunable cell-laden microenvironments for detailed studies of cell behavior, and (ii) the design and fabrication of MF reactors for studies of chemical reactions. First, this thesis presented the generation of biopolymer microenvironments for cell studies. In the first project we demonstrated a high-throughput MF system for generating cell-laden agarose microgels with a controllable ratio of two different types of cells. The MF co-encapsulation system was shown to be a robust method for identifying autocrine and/or paracrine dependence of specific cell subpopulations. In the second project we studied the effect of the mechanical properties on the behavior of acute myeloid leukemia (AML2) cancer cells. Cell-laden macroscopic agarose gels were prepared at varying agarose concentrations. A modest range of the elastic modulus of the agarose gels were achieved, ranging from 0.62 kPa to 20.21 kPa at room temperature. We observed a pronounced decrease in cell proliferation in stiffer gels when compared to the gels with lower elastic moduli. The second part of the thesis focuses on the development of MF platforms for studying chemical reactions. In the third project presented in this thesis, we exploited the temperature dependent solubility of CO2 in order to: (i) study the temperature mediated CO2 transfer between the gas and the various liquid phases on short time scales, and (ii) to generate bubbles with a dense layer of colloid particles (armoured bubbles). The fourth project involved the fabrication of a multi-modal MF device with integrated analytical probes. The MF device comprised a pH, temperature, and ATR-FTIR probes for in-situ analysis of chemical reactions in real-time. Furthermore, the MF reactor featured a temperature controlled feedback system capable of maintaining on-chip temperatures at flow rates up to 50 mL/hr.

This thesis presented a microfluidic preparation of bubbles-templated micro-size materials. In particular, this thesis focused on the microfluidic formation and dissolution of CO2 bubbles. First, this thesis described pH-regulated behaviours of CO2 bubbles in the microfluidic channel. This method opened a new way to generate small (<10 µm in diameter) with a narrow size distribution (CV<5%). Second, the microfluidic dissolution of CO2 bubbles possessed the important feature: the local change of pH on the bubble surface. This allowed us to encapsulate the bubbles with various colloidal particles. The bubbles coated with particles showed a high stability against coalescences and Ostwald ripening. The dimensions and shapes of bubbles with a shell of colloidal particle were manipulated by the hydrodynamic and chemical means, respectively. Third, we proposed a microfluidic method for the generation of small and stable bubbles coated with a lysozyme-alginate shell. The local pH decrease at the periphery of CO2 bubbles led to the electrostatic attraction between lysozyme on the bubble surface and alginate in the continuous phase. This produced the bubbles with a shell of biopolymers, which gave a long-term stability (up to a month, at least) against the dissolution and coalescence. Fourth, we presented a single-step method to functionalize bubbles with a variety of nanoparticles. The bubbles showed the corresponding properties of nanoparticles on their surface. Further, we explored the potential applications of these bubbles as contrast agents in ultrasound and magnetic resonance imaging.

New synthetic routes to nitrogen- and phosphorus-containing polymers have been investigated. These routes rely on amine- and phosphine-containing monomers bearing pendant alkyne substituents, and subsequent hydroamination, oxidation, or hydrophosphination polymerization. A series of primary amines of the form H2NC6H2R2C≡CR’ (R = H or iPr; R’ = Ph, SiMe3, nBu, or p-C6H4Me) is reported. These amines are deprotonated with nBuLi to give lithium amides, which react with zirconocene compounds to provide amidozirconium complexes. Characterization is achieved by multinuclear NMR spectroscopy, IR spectroscopy, high-resolution mass spectrometry, elemental analysis, X ray crystallography, and DFT calculations. Three routes were attempted towards nitrogen-containing oligomers: (1) thermolysis of amidozirconium complexes to afford [2+2] cycloaddition polymers; (2) Ti(IV)-catalyzed hydroamination of H2NC6H4C≡CPh; (3) chemical oxidation of H2NC6H4C≡CPh. The latter two strategies resulted in distinct nitrogen-containing oligomers. The oligomer formed by Ti(NR2)4-catalyzed hydroamination (R = Me, Et) contains up to 15 repeat units in the chain, with both imine and enamine moieties, and is capped by a molecule of HNR2 (R = Me or Et) originating from the catalyst. The oligomer formed by chemical oxidation contains up to 9 repeat units in the chain. A series of phosphines of the form X2PC6H2R2C≡CR’ is reported (X = NEt2, Cl, H; R = Me, iPr; R’ = Ph, SiMe3). Characterization is achieved by multinuclear NMR spectroscopy, IR spectroscopy, high-resolution mass spectrometry, elemental analysis, and X-ray crystallography. The primary phosphines, H2PC6H2R2C≡CR’, are relatively “user-friendly” in that they are not particularly malodorous, they are isolated as solids or highly viscous liquids, and they are stable when stored under N2 in the solid state and in solution. The primary phosphine H2PC6H2iPr2C≡CPh serves as a precursor for a zirconium phosphinidene and for the secondary phosphines RP(H)C6H2iPr2C≡CPh (R = CH2iPr, CH2Ph). Hydrophosphination polymerization gives cyclic P(III)-containing oligomers, which are converted to P(V)-based macromolecules by treatment with sulfur. The oligomers contain ca. 5 to 10 repeat units, and heating to 800 °C gives rise to phosphorus-containing ceramics. The mechanism of hydrophosphination is discussed with the use of DFT calculations.

New synthetic routes to nitrogen- and phosphorus-containing polymers have been investigated. These routes rely on amine- and phosphine-containing monomers bearing pendant alkyne substituents, and subsequent hydroamination, oxidation, or hydrophosphination polymerization. A series of primary amines of the form H2NC6H2R2C≡CR’ (R = H or iPr; R’ = Ph, SiMe3, nBu, or p-C6H4Me) is reported. These amines are deprotonated with nBuLi to give lithium amides, which react with zirconocene compounds to provide amidozirconium complexes. Characterization is achieved by multinuclear NMR spectroscopy, IR spectroscopy, high-resolution mass spectrometry, elemental analysis, X ray crystallography, and DFT calculations. Three routes were attempted towards nitrogen-containing oligomers: (1) thermolysis of amidozirconium complexes to afford [2+2] cycloaddition polymers; (2) Ti(IV)-catalyzed hydroamination of H2NC6H4C≡CPh; (3) chemical oxidation of H2NC6H4C≡CPh. The latter two strategies resulted in distinct nitrogen-containing oligomers. The oligomer formed by Ti(NR2)4-catalyzed hydroamination (R = Me, Et) contains up to 15 repeat units in the chain, with both imine and enamine moieties, and is capped by a molecule of HNR2 (R = Me or Et) originating from the catalyst. The oligomer formed by chemical oxidation contains up to 9 repeat units in the chain. A series of phosphines of the form X2PC6H2R2C≡CR’ is reported (X = NEt2, Cl, H; R = Me, iPr; R’ = Ph, SiMe3). Characterization is achieved by multinuclear NMR spectroscopy, IR spectroscopy, high-resolution mass spectrometry, elemental analysis, and X-ray crystallography. The primary phosphines, H2PC6H2R2C≡CR’, are relatively “user-friendly” in that they are not particularly malodorous, they are isolated as solids or highly viscous liquids, and they are stable when stored under N2 in the solid state and in solution. The primary phosphine H2PC6H2iPr2C≡CPh serves as a precursor for a zirconium phosphinidene and for the secondary phosphines RP(H)C6H2iPr2C≡CPh (R = CH2iPr, CH2Ph). Hydrophosphination polymerization gives cyclic P(III)-containing oligomers, which are converted to P(V)-based macromolecules by treatment with sulfur. The oligomers contain ca. 5 to 10 repeat units, and heating to 800 °C gives rise to phosphorus-containing ceramics. The mechanism of hydrophosphination is discussed with the use of DFT calculations.

This thesis describes the synthesis and characterization of metal-encoded polystyrene microspheres with a narrow size distribution designed for mass cytometry-based immuno- and oligonucleotide-assays. These particles were prepared by multiple stage dispersion polymerization techniques using polyvinylpyrrolidone (PVP) as a steric stabilizer. As a cytometeric technique, mass cytometry necessitated metal-encoded microspheres to perform the same roles of fluorescent microspheres used in conventional flow cytometry. The first role of the microsphere was to be able to act as a platform (classifier microspheres) for bioassays. Secondly, the microspheres should be suitable for mass cytometry machine calibration as standards. To perform these roles, metal-encoded microspheres were required to have certain size, functionality and metal content criteria. Lanthanide elements were chosen as the metals for encoding the microspheres for their low natural abundance in biological systems and for their similar chemistry. My goal was to employ two-stage dispersion polymerization, of styrene in ethanol, to introduce the lanthanide salts along with excess acrylic acid in the second stage, one hour after the initiation. Acrylic acid deemed to serve as a ligand for the lanthanide ions, through its carbonyl group, so the lanthanide ions get incorporated into the microsphere while acrylic acid is copolymerizing with styrene. Using two-stage dispersion polymerization, I could synthesize lanthanide encoded microspheres with narrow size distribution and high lanthanide content. However the lanthanide content distributions were unexpectedly much broader than the size distribution obtained. In addition, I could not attach biomolecules to the surface of such particles. In an attempt to improve the characteristics of these microspheres, I employed modified versions of multiple stage dispersion polymerization and seeded emulsion polymerization to grow functional polymer shell on the surface of the particles prepared by dispersion polymerization. Moreover, I coated the lanthanide encoded microspheres with silica shell which enabled me to grow another layer of functional-silica. Consequently, I could use these particles as classifier microspheres for mass cytometry-based immunoassays as well as fluorescence-based oligonucleotide-assays.

Verdazyl radicals are a family of multicoloured stable free radicals. Aside from the defining backbone of four nitrogen atoms, these radicals contain multiple highly modifiable sites that grant them a high degree of derivatization. Despite having been discovered more than half a century ago, limited applications have been found for the verdazyl radicals and little is known about their chemistry. This thesis begins with an investigation to determine whether verdazyl radicals have a future as mediating agents in living radical polymerizations and progresses to their application as substrates for organic synthesis, an application that to date has not been pursued either with verdazyl or nitroxide stable radicals. The first part of this thesis describes the successful use of the 1,5-dimethyl-3-phenyl-6-oxoverdazyl radical as a mediating agent for styrene and n-butyl acrylate stable free radical polymerizations. The study of other verdazyl derivatives demonstrated the impact of steric and electronic properties of the verdazyl radicals on their ability to mediate polymerizations. The second part of this thesis outlines the initial discovery and the mechanistic elucidation of the transformation of the 1,5-dimethyl-3-phenyl-6-oxoverdazyl radical into an azomethine imine, which in the presence of dipolarophiles, undergoes a [3+2] 1,3-dipolar cycloaddition reaction to yield unique pyrazolotetrazinone structures. The reactivity of the azomethine imine and the scope of the reaction were also examined. The third part of this thesis describes the discovery and mechanistic determination of a base-induced rearrangement reaction that transforms the verdazyl-derived pyrazolotetrazinone cycloadducts into corresponding pyrazolotriazinones or triazole structures. The nucleophilicity, or the lack thereof, of the base employed leading to various rearrangement products was examined in detail. The final part of this thesis demonstrates the compatibility of the verdazyl-initiated cycloaddition and rearrangement reactions with the philosophy of diversity-oriented synthesis in generating libraries of heterocycles. A library of verdazyl-derived heterocycles was generated in a short amount of time and was tested non-specifically for biological activity against acute myeloid leukemia and multiple myeloma cell lines. One particular compound showed cell-killing activity at the 250 mM range, indicating future potential for this chemistry in the field of drug discovery.