A novel electronic assay based on a sol-gel transition reaction and a thin-film transistor of supramolecular hydrogels to detect alkaline phosphatase activity

Abstract

Abstract Herein, we developed an extended floating-gate thin-film transistor (EFG-TFT) together with various sol-gel phases to determine alkaline phosphatase (ALP) activity. The EFG-TFT was fabricated with ZnO as the channel material and YOX as the dielectric layer, which provided an extended area for sensing the analyte interacting with the designed hydrogelator. A peptide-based supramolecular hydrogel material, i.e., 2-naphthylacetic acid- l -phenylalanine- l -phenylalanine- l -O-phosphor tyrosine (named Nap-FF-Yp) was synthesized as our sensing platform to detect ALP activity and the sol-gel state. Nap-FF-Yp could be cleaved by ALP during hydrolysis, leading to π-π stacking, and finally changed to a hydrogel. Due to the difference in the potential drop between the liquid phase and gel phase of the hydrogel, the sol-gel transition reaction could be monitored by the electrical signal. The greater the extent of hydrogelation, the smaller the threshold voltage (Vth) variation, and the threshold voltage shifted to the left. Under the device’s optimal conditions with oxygen plasma treatment, the limit of detection (LOD) reached 0.024 U/L. The development of this novel sol-gel state for a high-speed screening sensing platform with an excellent electrical response demonstrates the potential capabilities of future high-speed response sensors.