ZnO Nanobelts/wire for Electronic Detection of Enzymatic Hydrolysis of Starch

The hydrolysis of starch converting into glucose, cyclodextrins and other monomer products is very critical in food and pharmaceutical industries. The conventional methods of testing the hydrolysis products are cumbersome and time consuming. The single-crystal zinc oxide (ZnO) structures are quasi-one dimensional semiconducting nanostrucrures, and open a new field of biosensor technology for fabricating highly sensitive biosensors for the detection of protein, peptide, DNA/RNA, and enzyme-catalyst events in real-time mode. We synthesized ZnO nanobelts/wires, and modified surfaces by coating with silicon nitride (Si₃N₄) to protect nanostructure from process treatment. The nanostrucrures were coated with dilute aqueous starch solution, and electrical impedance measurements were recorded for both control and test samples. The test samples were hydrolyzed using amyloglucosidase enzyme (AMG). The SEM analysis showed degradation of the starch on the surface of ZnO nano-belts, whereas the starch remained intact on the control samples. The electrical impedance measurements showed shift in electrical impedance on test samples, whereas in control samples it remained static. The details of experimental results of electronic sensing of hydrolysis and advantages of the lab-on chip are discussed. This is the first report of electronic detection of starch hydrolysis using ZnO nanobelts/wires