Analysis of nanotextured ZnO surfaces for biosensing applications

In this study, we show the modulation to the performance of a nanotextured zinc oxide biosensor by varying the deposition conditions of the metal oxide thin film as well as the choice of cross-linking material used for conjugation of the recognition biomolecule. ZnO surfaces were functionalized using dithiobis succinimidyl propionate and 3-aminopropyl triethoxysilane cross-linkers and the associated binding effects to the zinc and oxygen surfaces were characterized. This characterization was first accomplished optically by utilizing fluorescent tags on the linker molecules. Electrical impedance spectroscopy was then used to demonstrate the connection between the fluorescent data and the performance of the biosensor through detection of the established cardiac biomarker, troponin-T. The results of this work indicate that films sputtered with O₂ have fewer numbers of zinc terminated ends throughout the film compared to films sputtered without O₂. It was also found that the most effective biosensor was created using the thiol-based linker molecules and ZnO films deposited without the presence of oxygen, concluded based on the largest changes in impedance and the 10 fg/mL limit of detection.