A nanostructured microfluidic device for plasmon-assisted electrochemical detection of hydrogen peroxide released from cancer cells

Non-invasive liquid biopsies offer hope for a rapid, risk-free, real-time glimpse into cancer diagnostics. Recently, hydrogen peroxide (H2O2) was identified as a cancer biomarker due to its continued release from cancer cells compared to normal cells. The precise monitoring and quantification of H2O2 are hindered by its low concentration and the limit of detection (LOD) in traditional sensing methods. Plasmon-assisted electrochemical sensors with their high sensitivity and low LOD make a suitable candidate for effective detection of H2O2, yet their electrical properties need to be improved. Here, we propose a new nanostructured microfluidic device for ultrasensitive, quantitative detection of H2O2 released from cancer cells in a portable fashion. The fluidic device features a series of self-organized gold nanocavities, enhanced with graphene nanosheets having optoelectrical properties, which facilitate the plasmon-assisted electrochemical detection of H2O2 released from human cells. Remarkably, the device can successfully measure the released H2O2 from breast cancer (MCF-7) and prostate cancer (PC3) cells in human plasma. Briefly, direct amperometric detection of H2O2 under simulated visible light illumination showed a superb LOD of 1 pM in a linear range of 1 pM-10 mu M. We thoroughly studied the formation of self-organized plasmonic nanocavities on gold electrodes via surface and photo-electrochemical characterization techniques. In addition, the finite-difference time domain (FDTD) simulation of the electric field demonstrates the intensity of charge distribution at the nanocavity structure edges under visible light illumination. The superb LOD of the proposed electrode combining gold plasmonic nanocavities and graphene sheets paves the way for the development of non-invasive plasmon-assisted electrochemical sensors that can effectively detect low concentrations of H2O2 released from cancer cells.

Automated summary

A new nanostructured microfluidic device was proposed for ultrasensitive, quantitative detection of H2O2 released from cancer cells, featuring self-organized gold nanocavities enhanced with graphene nanosheets. The device successfully measured released H2O2 from breast cancer and prostate cancer cells in human plasma with a superb LOD. The proposed electrode combining gold plasmonic nanocavities and graphene sheets paves the way for non-invasive plasmon-assisted electrochemical sensors that can effectively detect low concentrations of H2O2 released from cancer cells.