Tailored ZnO nanoplatforms as hybrid biosensor substrates for fluorescence based biosensing

Advanced biosensor targets for biomolecular fluorescence detection are characterized by multitasking capability, sensitivity and high specificity. In this work we have investigated the optical properties change of ultrathin hybrid ZnO-SiO2 films upon interaction with model analyte biomolecule, e.g., fluorescein-labeled albumin. The ultrathin ZnO-SiO2 films have been prepared by an integrated approach of metallorganic chemical vapor deposition (MOCVD) at unusual mild conditions of time duration and temperature during deposition, polystyrene (PS) colloidal lithography and film growth through wet chemistry. The newly deposited films, nanostructured either as ordered and dense ZnO nanoring arrays surrounding SiO2 pit areas or organic inorganic PS-ZnO core-shells spheres distributed as monolayer on the SiO2 substrate, exhibit different thicknesses - ranging from few nanometers up to about 50 nm –morphologies and surface chemical composition, as determined by X-ray photoelectron spectroscopy and scanning electron microscopy. By laser scanning microscopy observations we demonstrated that such films have great potential as innovative fluorescence sensing substrates, with individual addressability and tuning of the biomolecular detection capability. Indeed, the green emission of the different ZnO-based films is significantly affected by the protein immobilization process. Moreover, the fluorescence recovery after photobleaching technique provides evidence that the protein mobility and fluorescence detection capability are tunable by proper patterning of the ZnO-SiO2 films