Lipocalin-2 Determination on Multiwalled Carbon Nanotube Integrated Circular Electrodes for Diagnosing Ulcerative Colitis.

Ulcerative colitis affects the inner lining of the large intestine, causing discomfort, pain, and digestion issues, and sometimes leading to life-threatening complications. With proper medication, symptoms and inflammation can be reduced, improving the condition. In this research, a multiwalled carbon nanotube (MWCN)-modified circular interdigitated electrode (circular-IDE) biosensor was developed to detect the ulcerative colitis biomarker lipocalin-2 and measured at 0-2 V. A dual probing strategy with aptamer and antibody on gold nanoparticles was employed for the detection of lipocalin-2. Probe immobilization was optimized on MWCN-modified circular-IDE, and saturation of 800 nM of aptamer on the GNP-antibody facilitated the identification of lipocalin-2 at concentrations as low as 1 pg/mL, with an R2 value of 0.9716 [y = 2.1058x - 2.7351]. Furthermore, lipocalin-2 spiking in serum increased the current responses in correlation with the concentrations of lipocalin-2, indicating selective identification without interference. In addition, nonimmune antibody and GNP-conjugated complementary aptamer did not increase the current responses, affirming the specific detection of lipocalin-2. This MWCN-modified circular-IDE biosensor, utilizing aptamer-antibody interactions, aids in identifying the condition of ulcerative colitis.