Human Transferrin Detection Through a Mass-Sensitive Biosensor Utilizing ZnO Thin-Films via Atomic Layer Deposition

In this letter, we present the first example of a zinc oxide (ZnO) thin film grown by atomic layer deposition method (ALD) on a quartz crystal microbalance (QCM) for the detection of human transferrin (hTF) molecule. Morphological, structural, and optical properties of ZnO thin film were investigated by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction spectroscopy, ultraviolet–visible spectroscopy, and photoluminescence. For biosensor measurements, ZnO/QCM sensors were modified with antitransferrin to obtain selectivity against hTF. Mass-sensitive biosensor tests were carried out using two different measurement methods: dip–dry and flow-cell. It was observed that antitransferrin immobilized ZnO/QCM sensor detected hTF molecule in the range of 100–1000 ng. Moreover, the sensors exhibited better performance in the dip–dry method than the flow-cell method. ZnO-coated QCM exhibited good mass-sensitive performance, which make it a suitable sensor platform for biosensor applications.