Preparation of Curcubit[6]uril functionalized CuO Nanoparticles: A New Nanosensing Scheme Based on Fluorescence recovery after FRET for the Label Free Determination of Dopamine

In this manuscript, the aim is to functionalize CuO nanoparticles with the supramolecular host molecule, in this case curcubit[6]uril to have a host guest interaction between the CuO nanoparticles and probe (guest) molecules. Acridine Orange (AO) is applied as a guest molecule. Acridine orange binds with curcubit[6]uril via its carbonyl rims. In the presence of curcubit[6]uril conjugated CuO nanoparticles, the fluorescence intensity of AO is quenched by the CuO NPs through fluorescence resonance energy transfer phenomenon. However, dopamine adsorbs on the surface of CuO nanoparticles by getting incorporated into CB[6] host molecules and kicks out AO from curcubit[6]uril pocket, thus, discouraging fluorescence resonance energy transfer phenomenon and thus enhancing fluorescence intensity of AO by a factor of 3. This fluorescence recovery has been utilized to design a new detection system for dopamine. The assay, measured at fluorescence excitation and emission wavelengths of 480 nm and 520 nm respectively, works in the 0-40 mu M concentration range of dopamine with 40 nM limit of detection. This method is not interfered by ascorbic acid, uric acid, glucose, tryptophan and acetaminophen. The proposed method provides a good recovery from synthetic samples and shows good stability.