Ultra-wide, attomolar-level limit detection of CD44 biomarker with a silanized optical fiber biosensor

Measuring cancer biomarkers at ultralow detection limit and high sensitivity could be a promising tool for early diagnosis, monitoring treatment and post-treatment recurrence. Soluble CD44 is a promising diagnostic and prognostic biomarker in several types of cancer including gastric, colon and breast cancer. Several highly sen-sitive biosensors have been built to measure this important biomarker. However, they did not reach attomolar level of detection. The aim of this work was to build a biosensor capable of detecting CD44 concentrations down to attomolar (aM) level while measuring it in a wide concentration range. Herein, we demonstrate a biosensor that offers 4 key advantages over existing platforms for CD44 detection: 1) detection of CD44 was carried out in a diluted serum down to attomolar level (4.68 aM) which is about 6 orders of magnitude lower than that of a traditional ELISA; 2) fabrication of the sensor is done in a fast way using inexpensive materials making it a disposable fiber optic biosensor; 3) detection of CD44 was performed in a wide dynamic range previously not shown in other similar biosensors; 4) a proof-of-concept experiment was per -formed using the biosensor to embed it in a catheter to measure the protein in flow conditions.

Automated summary

This study has successfully developed a biosensor capable of detecting CD44 at attomolar levels. It has advantages of low detection limit, simple fabrication, wide dynamic range, and usability in flow conditions.