(Invited) Detection of Cancer Biomarkers By Scanning Electrochemical Microscopy

Abstract

Scanning electrochemical microscopy (SECM) is a scanning probe technique that is composed of a micro- or nanoelectrode that can be scanned in close proximity to an interface. Faradaic current signals can be recorded due to the flux of redox active species between the sample and an amperometric SECM probe. SECM can be used to image the topography and reactivity of biological specimens for mapping localized biochemical activity. Although SECM has been applied to different biological systems, SECM studies of tissues are still under exploration. The reason is due to the shape and high roughness of such real samples and requires overcoming major drawbacks in conventional SECM instrumentation when scanning large, i.e. square centimeter sized, areas with irregular surface keeping a constant working distance.My research aims to develop various reliable SECM bioimaging techniques for the study of the distribution of biomarkers in tape-stripping cancer samples and human melanoma tumor samples. Melanoma is the most lethal form of skin cancer striking thousands of people around the world. The survival rate depends on the stage of the cancer when it is diagnosed. SECM could improve the diagnosis and understanding of different melanoma stages based on highly resolved maps of the tyrosinase distribution in tumor sections. [1]Furthermore, the increasing levels of tyrosinase were recorded in cells that were collected from the skin of melanoma mouse models representing three different stages of tumor growth. [2] Additionally, SECM results of tape-stripped different human melanoma cell lines were confirmed by previous studies based on traditionally fixed and permeabilized cells. The presented electrochemical tyrosinase detection approach can potentially be integrated into point of-care testing (POCT) devices. SECM scanning parameters, such as microelectrode size and step size can be used to determine experimentally the best design before fabricating microelectrode array prototypes. [1] 1. Lin TE, Lu YJ, Sun CL, Pick H, Chen JP, Lesch A, Girault H. Soft electrochemical probes for mapping the distribution of biomarkers and injected nanomaterials in animal and human tissues Angew. Chem. Int. Ed. 2017;56:16498–16502.2. Darvishi S, Pick H, Lin TE, Zhu Y, Li X, Ho PC, Girault HG, Lesch A. Tape-Stripping Electrochemical Detection of Melanoma Anal. Chem. 2019, 91, 12900–12908