Electroanalytical Immunotechnology for Minimally Invasive Assessment of Toll-Like Receptor 2, a Key Inflammatory Component in Colorectal Cancer Progression

Toll-like receptor 2 (TLR2) is involved in infectious diseases, inflammatory processes and carcinogenesis. Soluble TLR2 (sTLR2) can be released into circulation stream acting as an endogenous negative regulator of TLR2 signaling, essential for the prevention of chronic inflammation and tissue destruction. In this context, we propose pioneering electrochemical biotechnology for the determination of sTLR2 in plasma of colorectal cancer (CRC) patients. The method involves the use of magnetic particles as micro-supports for the implementation of a sandwich immunoassay using a pair of specific antibodies and horseradish peroxidase as enzymatic tracer to carry out the amperometric transduction on screen-printed carbon electrodes in the presence of H₂O₂ and hydroquinone. The proposed immunoplatform shows attractive operational and analytical characteristics, reaching a low limit of detection of 241 pg mL⁻¹ for TLR2 standards in buffered solutions, and showing an excellent reproducibility (RSD 1.4 %), and a wide dynamic range (804 to 25000 pg mL⁻¹). It has been applied to the analysis of a cohort of 21 plasma samples from healthy individuals and CRC patients at different stages of the disease, demonstrating precise quantitative determinations, in just 45 min and requiring minimal sample amount and pre-treatments. The results demonstrate the promising utility of TRL2 plasma levels for minimally invasive monitoring of CRC progression.