Electrochemical immunosensor for the detection of CD133+ cancer cells using silica-platinum nanocomposite

Abstract

Introduction: In addition to the highly proliferating cells that make up the bulk of the tumor, a tumor has a small subset of cells with a slow, undifferentiated cell cycle called cancer stem cells (CSCs). These cells are of great diagnostic importance due to their involvement in factors such as tumorigenesis, therapeutic resistance, metastasis, and recurrence. Objective: In this poject, a sensitive electrochemical cytosensor was designed to identify CD133+ HT-29 colorectal cancer stem cells based on mesoporous silica nanoparticles (MSNs) and platinum nanoparticles (PtNPs). Materials and Methods: PtNPs/MSNs nanocomposite was co-electrodeposited by applying the optimal potential on a glassy carbon electrode (GCE). Streptavidin was then incubated at the optimal time and temperature. Then, CD133 biotinylated antibody was layered at the optimal time. Finally, after blocking the active sites of the modified electrode, the cytosensor was ready for detection of CD133+ cells isolated by magnetic activated cell sorting (MACS). After loading of the target cells, any changes in electrical current on the final modified electrode was recorded by differential pulse voltammetry (DPV) and square wave voltammetry (SWV) and quantified as a cells number. Result: Based on the calibration curve (number of the cells versus recorded electrical signals), the designed cytosensor was able to detect cells in the range of 5 to 20 cells/ml. The resulting nanobiocomposite was able to specifically detect CD133+ stem cells compared to HT-29 somatic cancer cells before and after the MACS stage. Discussion: The synthesized porous and biocompatible nanocomposite, in addition to increasing the surface-to-volume ratio, improves the local electron transfer rate and provides suitable sites for the efficient formation of Pt nanoparticles. As a result, direct and stable binding of biotinylated monoclonal antibody of CD133 to streptavidin enables access to active sites for cancer stem cell identification.