The singlet oxygen produced by the activation of the PpIX molecule was significantly enhanced through the FRET process from negatively and positively charged QDs with emission wavelengths of 550 nm and 580 nm, respectively, to the PpIX molecules. The activation of the QDs using LEDs at 410 nm and 470 nm, significantly contributed to the FRET process, as well as to the production of singlet oxygen. The singlet oxygen produced by the QDs and PpIX in this work could be used in the treatment of Escherichia coli. The entrapment of the QDs and PpIX into the sol-gel matrix GA produced sol-gel membranes with high efficiency of singlet oxygen production. (C) 2010 Elsevier B. V. All rights reserved.