# The magnetic beads-based sandwich-shaped immune complexes for rapid and sensitive amperometric detection of SOX2 protein

## TL;DR

This paper introduces a new magnetic bead-based immunosensor for quickly and accurately detecting the SOX2 protein, which is linked to cancer metastasis.

## Contribution

A novel magnetic disposable immunoplatform using sandwich-shaped immune complexes for rapid and sensitive SOX2 detection.

## Key findings

- The immunosensor achieved a high sensitivity with a limit of detection of 1.37 ng mL−1.
- The analysis time was reduced to 15 minutes, making it faster than traditional methods.
- The immunosensor showed good stability and comparable performance to ELISA.

## Abstract

Sex-Determining Region Y-box 2 (SOX2) is a transcription factor protein. SOX2 expression is related to lymph node metastasis and distant metastasis in colorectal carcinomas. SOX2 was determined with the first magnetic disposable immunoplatform. The designed sandwich-shaped immune complexes were formed by a capture antibody, SOX2 protein, and biotinylated secondary antibodies (dAb/HRP). The sandwich-shaped immune complex was linked to carboxylic acid functionalized magnetic beads (HOOC-MBs). This magnetic bioconjugate was dropped on the surface of the screen-printed carbon electrode (SPCE). The amperometric measurement was performed at –0.20 V in the presence of hydroquinone (HQ) and H2O2 against a silver pseudo-reference electrode. The optimization parameters affecting the immunoassay response were evaluated.

The analytical evaluation of the magnetic disposable immunoplatform for the amperometric detection of SOX2 standards was done. The developed immunosensor shows high sensitivity (LOD of 1.37 ng mL−1) and a short analysis time (15 min). Potential interfering compounds found in serum samples were tested. The storage stability of magnetic disposable immunoplatform was evaluated. The developed immunosensor was compared with the ELISA method.