Miniaturized, disposable amperometric biosensors for determination of creatinine in human serum are described. The base electrodes are fabricated using micro-electronics techniques, to build a multilayer film structure on a polyimide foil. By using a thin electropolymerized film of poly(1,3-diaminobenzene), the electrochemical interferences from ascorbate, urate, acetaminophen, and other oxidizable species are greatly diminished. The multienzyme system (creatininase, creatinase, sarcosine oxidase) is immobilized on top of the permselective layer using cross-linking of the proteins with glutaraldehyde. The electropolymerization conditions for obtaining almost ideal permselectivity of the inner layer are defined, as well as the optimal enzyme layer preparation. A composite polymeric outer membrane [Nafion + poly-(2-hydroxy-ethyl methacrylate) is used for diffusion control and to protect the enzyme layer from fouling. The reagentless planar sensors for creatinine and creatine have fast response time (t95 = 1 min), linear response up to 1.2 mM in batch-type and 2.0 mM in flow injection analysis and a detection limit of 10-20 muM. They are applied in a differential setup for creatinine assay in control and hospital human serum samples and are suitable for incorporation in a portable analyzer.

A new class of coumarin-based iridium tris-cyclometalated complexes has been developed. These complexes are highly emissive, with emission colors ranging from green to orange-red. Besides modification of ligand structures, color tuning was realized by incorporation of ligands with different electrochemical properties in a heteroleptic structure. The organic light-emitting diodes (OLEDs) using these compounds as emissive dopants are highly efficient and stable. Unlike other Ir(III) phosphorescent dopants, these coumarin-based Ir(III) dopants can effectively trap and transport electrons in the emissive layer.

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Novel light-emitting organic materials comprising conjugated oligomers chemically attached via a flexible spacer to an electron-or hole-conducting core were designed for tunable charge injection and transport properties. Representative glassy-isotropic and glassy-liquid-crystalline (i.e., noncrystalline solid) materials were synthesized and characterized; they were found to exhibit a glass transition temperature and a clearing point close to 140 and 250°C, respectively; an orientational order parameter of 0.75; a photoluminescence quantum yield up to 51%; and HOMO and LUMO energy levels intermediate between those of blue-emitting oligofluorenes and the ITO and Mg/Ag electrodes commonly used in organic light-emitting diodes, OLEDs. This class of materials will help to balance charge injection and transport and to spread out the charge recombination zone, thereby significantly improving the device efficiency and lifetime of unpolarized and polarized OLEDs.