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We report the use of cross-linked enzyme aggregates (CLEAs 1 ) to catalyse the kinetic resolution of tetralol and 1-phenylethanol in a continuous supercritical carbon dioxide (scCO 2 ) system. We describe the performance of the CLEA from Candida antarctica lipase B (CALB) and compare this to the catalytic activity of Novozym 435 (CALB immobilised on a macroporous acrylic resin). In addition, we report a two-stage reaction with the kinetic resolution of 1-phenylethanol performed in series with the metal (Pd) catalysed hydrogenation of acetophenone. Reactions performed in series have a potential economic advantage as the second, and subsequent reactions do not require additional expenditure of energy for re-pressurization of solvent.

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Fluorescent nanoparticles of zirconia doped with europium (ZrO 2 :Eu 3+ ) have been produced via the co-precipitation of simple metal salt precursors using continuous supercritical water hydrothermal synthesis. The effect of reaction temperature and residence time on both particle size and conversion were investigated. Increasing the reaction temperature from 200 to 400 • C increases the size of the particles: smaller diameters (<5 nm) were produced at lower temperatures and larger diameters (>20 nm) at higher temperatures. Varying residence time at constant temperatures (between 3.7 and 7 seconds) did not significantly affect the particle size. The structure of the nanoparticles synthesised at 400 • C was revealed to be cubic by X-ray diffraction. Conversion of the metal precursors to ZrO 2 :Eu 3+ was improved from 4 to 99% on increasing the temperature between 250 and 350 • C. The photoluminescent properties of the nanoparticles were also explored with respect to synthesis temperature. Fluorescence upon UV excitation at 255 nm, originating from Eu 3+ doped in ZrO 2 , was not significantly affected by the synthesis temperature. The emission spectra demonstrated characteristic f → f transitions of Eu 3+ ions and can be explained through an effective dispersion of these ions within the ZrO 2 nanoparticles. Initial cell toxicity studies suggest that ZrO 2 :Eu 3+ nanoparticles do not cause any significant increase in cell death in Chinese hamster ovary cells following an 18 hour incubation at 37 • C. This paper describes a 'green' and controlled method for the continuous production of research scale quantities of nanomaterials.