BACKGROUND: The NAD(P)H cofactor, which is the reduced form of nicotinamide adenine dinucleotide phosphate, plays the important role of electron donor in enzymatic metabolism. The primary drawback of metabolism reactions involving enzymes is the dependence on this highly expensive cofactor. RESULTS: Electron formation was effectively triggered by inducing Qdots with (UV) irradiation at 365 nm. The analytical potential of the Qdots-based electron-transfer system was demonstrated by examining two different types of cofactors, i.e. chemical (NADPH) and nanoparticle (Qdots). The Qdots-based method gave promising results in comparison with the NADPH-dependent system. A Qdots-based electron supply to a CYP2B4 and 7-pentoxyresorufin incubation mixture produced a resorufin metabolite. The kinetic rates of the cytochrome P450 reactions induced by photoactivated Qdots were determined CONCLUSIONS: The influence of electron formation from ultraviolet (UV)-induced quantum dots (Qdots) on the cytochrome P450 (CYP2B4) reaction was elucidated. The process comprised UV-induced electron formation by photoactivated Qdots and subsequent enzyme reactions mediated by the resultant electron supply. Copyright (c) 2012 Society of Chemical Industry