Highly fluorescent and stable 6,7-dimethoxy-2-oxoquinoline-4-carbonitriles (11) were synthesized starting from appropriate 4-hydroxyquinolones 3 via reactive 4-chloroquinolones 8 by using toluenesulfinates as catalysts. In contrast to the well-described 4-trifluoromethyl-substituted analogues 18, N-substituted derivatives 11 fluoresce in water, polar, and apolar solvents in a narrow 430-440-nm window with almost constant quantum yield of 0.5. Equal excitation is possible in the broad double maximum between 385 and 410 nm yield-

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Biological molecules such as enzymes, cells, antibodies, lectins, peptide aptamers, and cellular components in an immobilized form are extensively used in biotechnology, in biorecognition and in many medicinal applications. This review provides a comprehensive summary of the developments in new immobilization materials, techniques, and their practical applications previously developed by the authors. A detailed overview of several immobilization materials and technologies is given here, including bead cellulose, encapsulation in ionotropic gels and polyelectrolyte complexes, and various immobilization protocols applied onto surfaces. In addition, the review summarises the screening and design of an immobilization protocol, practical applications of immobilized biocatalysts in the industrial production of metabolites, monitoring, and control of fermentation processes, preparation of electrochemical/optical biosensors and biofuel cells.