An Optically-Transparent Aptamer-Based Detection System for Colon Cancer Applications Using Gold Nanoparticles Electrodeposited on Indium Tin Oxide

In this paper, a label-free aptamer based detection system (apta-DS) was investigated for detecting colon cancer cells. For this purpose, we employed an aptamer specific to colon cancer cells like HCT116 expressing carcinoembryonic antigen (CEA) on their surfaces. Capture aptamers were covalently immobilized on the surface of gold nanoparticles (GNPs) through self-assembly monolayer of 11-mercaptoundecanoic acid (11-MUA) activated with EDC (1-Ethyl-3-[3-dimethylaminopropyl]carbodiimide)/N-hydroxysuccinimide (NHS). The cyclic voltammetry (CV) and chronopotentiometry (CP) methods were used for electrodeposition of GNPs on the surface of indium tin oxide (ITO). In this work, the CV method was also used to demonstrate the conjugation of GNPs and aptamers and identify the cancer cell capturing events. Additionally, Field Emission Scanning Electron Microscopy (FE-SEM) confirmed the deposition of GNPs on ITO and the immobilization of aptamer on the apta-DS. The electrodeposited GNPs played the role of nanoprobes for cancer cell targeting without losing the optical transparency of the ITO substrate. A conventional optical microscope also verified the detection of captured cancer cells. Based on this study’s results relying on electrochemical and optical microscopic methods, the proposed apta-DS is reliable and high sensitive with a LOD equal to 6 cell/mL for colon cancer detection

An Apta-Biosensor for Colon Cancer Diagnostics

This paper reports the design and implementation of an aptasensor using a modified KCHA10a aptamer. This aptasensor consists of a functionalized electrodes using various materials including 11-mercaptoandecanoic acid (11-MUA) and modified KCHA10a aptamer. The HCT 116, HT 29 and HEp-2 cell lines are used in this study to demonstrate the functionality of aptasensor for colon cancer detection purposes. Flow cytometry, fluorescence microscopy and electrochemical cyclic voltammetry are used to verify the binding between the target cells and aptamer. The limit of detection (LOD) of this aptasensor is equal to seven cancer cells. Based on the experimental results, the proposed sensor can be employed for point-of-care cancer disease diagnostics