Voltammetric aptamer based detection of HepG2 tumor cells by using an indium tin oxide electrode array and multifunctional nanoprobes

The authors describe a method for the detection and determination of human liver cancer cells in blood. The cytosensing system consists of a microfabricated chip-based electrochemical aptasensor that contains multifunctional hybrid electrochemical nanoprobes and an indium tin oxide (ITO) electrode array interface functionalized with celltargeting aptamer and gold nanoparticles (AuNPs). The thiolated cell targeting aptamer (referred to as TLS11a) was immobilized on the ITO electrode/AuNPs for specific adhesion of hepatocellular carcinoma cells (HepG2). The hybrid nanoprobe system consists of hydroquinone (HQ) as an electrochemical probe, horseradish peroxidase (HRP), and an aptamer/hemin/G-quadruplex aggregate that was immobilized on gold/palladium-functionalized ZnO nanorods (ZnO@ AuPd). The nanoprobes are capable of amplifying the voltammetric signal and capturing the target cells. Best operated at around -90 mV (vs Ag/AgCl), the electrode has a linear response that covers the 10 boolean AND 2 to 10 boolean AND 7 HepG2 cells per mL concentration range, with a 10 cell per mL detection limit. Captured cells may be released from the electrode via electrochemical desorption to break the Au-S bonds.