Novel Biosensor Selectively Measures Cancer Patient p53 Autoantibodies

By LabMedica International staff writers
Posted on 24 Jan 2017

A team of Spanish cancer researchers has developed a disposable electrochemical biosensor for the specific and sensitive determination of p53-specific autoantibodies, which are biomarkers for certain types of cancers with p53 gene mutations.

The 10 to 40% of all cancer patients with aberrantly mutated p53 have cancer cells that multiply without control, and their immune systems generate autoantibodies against the p53 protein.

Image: A micrograph showing cells with abnormal p53 expression (brown) in a brain tumor (Photo courtesy of Wikimedia Commons).

To more effectively determine levels of p53 autoantibodies, investigators at Universidad Complutense de Madrid developed a disposable electrochemical biosensor. This specific and sensitive biosensor was based on magnetic microcarriers (MBs) modified with covalently immobilized HaloTag fusion p53 protein as solid supports for the selective capture of specific autoantibodies. HaloTag is a modified bacterial enzyme designed to covalently bind to a synthetic ligand of choice and fuse to a protein of interest.

After magnetic capture of the modified MBs onto screen-printed carbon working electrodes, the electronic signal generated by the hydroquinone/H2O2 system was correlated to the levels of p53-autoantibodies in the sample.

The biosensor was used to analyze sera from 24 patients with high-risk of developing colorectal cancer and six from patients already diagnosed with colorectal (four) and ovarian (two) cancer. The biosensor was able to determine p53 autoantibodies with sensitivity higher than that of a commercial standard ELISA using a simpler protocol with less sample volume. The biosensor can be easily miniaturized and developed into a cost-effective diagnostic tool.

"Our immune system produces these cancer autoantibodies even three years before the first symptoms appear," said contributing author Dr. Susana Campuzano, associate researcher in analytical chemistry at Universidad Complutense de Madrid. "Its simplicity of handling, portability, and time to complete the full procedure make it suitable for application in clinical routine."

The biosensor was described in the November 26, 2016, online edition of the journal Analytical Chemistry.