TiO2 nanoparticles were synthesized by hydrolysis of tetralsopropyl orthotitanate in an aqueous solution of cyclodextrin The beta-cyclodextrin modified spherical TiO2 nanoparticles were water-dispersible and had an average particle diameter of 44 +/- 1 nm Pyrene fluorescence was enhanced by increasing the con centration of beta cyclodextrin-modified TiO2 nanoparticle and the sensitization effect was triply stronger than the case of the beta-cyclodextrin only The increase in a concentration of host (beta-cyclodextrin) changes its microenvironment for guest (pyrene) that is the interaction of pyrene with apolar cavity of beta-cyclodextrin increases resulting in enhancement of fluorescence The sensitization behavior of pyrene fluorescence in the presence of TiO2 nanoparticles occurs from the Increase in the extinction coefficient of pyrene demonstrating the charge transfer between pyrene and metal oxide nanoparticle Crown Copyright (C) 2010 Published by Elsevier Inc All rights reserved