La0.6Sr0.4Co0.2Fe0.8O3-∝ (LSCF) biosensor for diagnosing colorectal cancer: A quaternary alloy on an interdigitated electrode

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Colorectal cancer (CRC) is a type of gastrointestinal cancer affecting the colon and rectum. It can metastasize to other parts of the body, making treatment more challenging. Early identification and treatment of CRC significantly enhance patient survival rates. Therefore, the development of a suitable biosensor to monitor CRC is crucial for early diagnosis. Interleukin-6 (IL-6) is recognized as a biomarker for CRC, with elevated levels correlating to tumor progression. A highly sensitive La0.6Sr0.4Co0.2Fe0.8O3-∝ (LSCF) based interdigitated microelectrode (IDME) sensor was developed to quantify IL-6 levels. This sensor utilizes an aptamer-conjugated gold nanoparticle (GNP), which is attached to the LSCF-modified IDME through an amine linker. This step facilitates IL-6 quantification using an anti-IL-6 aptamer and antibody. The combination of LSCF and GNP significantly enhanced aptamer immobilization on the IDME, enabling the detection of IL-6 at concentrations as low as 1 pg/mL. Furthermore, IL-6 was successfully detected in serum spiked with IL-6 without interference, demonstrating the sensor’s selectivity. The sensor showed no significant current responses when tested with complementary aptamers, CSE, or globulin, further confirming its specificity. Additionally, the same surface functionalization was successfully applied on an Ethylene diamine tetraacetic acid (ELISA) plate for IL-6 detection.