The enzyme-catalyzed resolution of racemic naproxen 2,2,2-trifluoroethyl thioester was performed by the immobilization of lipase on silica nanoparticles using a covalent bonding method. To increase the conversion and reaction rate of this resolution, we investigated the effect of non-ionic surfactants (M-SA 1025 and SM 20). The optimal reaction conditions such as temperature and loading amount of immobilized lipase were also determined. The addition of M-SA 1025 resulted in the increase in reaction rate (V-S), conversion (X-S) and enantioselectivity (E value) comparison with SM 20 and the control. The reaction performed in a mixture containing M-SA 1025 at 50 degrees C with 80 U/mL of immobilized lipase markedly improved the resolution of racemic naproxen 2,2,2-trifluoroethyl thioester compared to other conditions. (C) 2010 Elsevier Ltd. All rights reserved.