Highly sensitive electrochemical multimodal immunosensor for cluster of differentiation 5 (CD5) detection in human blood serum for early stage cancer detection based on laser-processed Ti/Au electrodes

In the rapidly evolving field of medical diagnostics, biomarkers play a pivotal role, particularly in the early detection of cancer. Cluster of differentiation 5 (CD5), a cell surface glycoprotein found on T cells and B-1a lymphocytes, is instrumental in immune regulation and is associated with both autoimmune diseases and malignancies. Despite its significant diagnostic and therapeutic potential, CD5 detection has been limited by modern methods in the pg/ml range. This study presents a novel multimodal electrochemical immunosensor that employs laser-processed Ti/Au electrodes for the ultra-sensitive detection of CD5 in human blood serum. The "multimodal" approach combines different analytical techniques- differential pulse volctammetry (DPV) and electrochemical impedance spectroscopy (EIS)- to ensure comprehensive analysis, enhancing both the accuracy and reliability of the sensor. This novel sensor significantly outperforms existing commercial ELISA kits, achieving a limit of detection (LOD) of 1.1 f 0.2 fg/mL with DPV and 3.9 f 0.5 fg/mL with EIS in phosphate- buffered saline (PBS) and 6.6 f 3.1 fg/mL and 15.6 f 3.1 fg/mL in human serum (HS), respectively. These results highlight the immunosensor's potential for improving early-stage cancer diagnosis and broader medical applications.