This research is focussed to quantify IGF1 by electroanalytical analysis on InterDigitated electrode surface and characterized by the microscopic observations. For the detection, antibody and aptamer were used to analyze the level of IGF1. The sandwich pattern (aptamer-IGF1-antibody) was designed on the chemically modified IDE surface and reached the limit of detection to 10 fM with 100 folds enhancement in the sensitivity. Different control experiments (absence of IGF1, binding with IGF2 and with non-complementary aptamer) were failed to show the current changes, discriminated the specific detection. A good detection strategy is to complement the currently following imaging systems for AAA.
An abdominal aortic aneurysm (AAA) is abnormal swelling in the abdominal aorta and a prevalent life-threatening disease. This research introduces a new interdigitated microelectrode (IDME)-sensing surface modified by iron oxide nanoworms (IONWs) for detecting the AAA biomarker insulin-like growth factor-1 (IGF1). A sandwich pattern was formulated with the IGF1 aptamer and IGFBP1 (IGF binding protein-1) on the IONW-constructed IDME hybrid to identify IGF1. The surface morphology of the IONWs revealed a uniform distribution of worm-like structures (80-100 nm) as confirmed by FESEM and FETEM analyses. Further, the presence of the major elements, Fe and O, was confirmed by EDX and XPS studies. The crystal planes that appeared in the IONW reflect cubic magnetite. IONW-modified IDME attained a limit of detection for IGF1 of 1 fM (3σ) with an aptamer-IGF1-IGFBP1 sandwich. This sandwich with IGFBP1 enhanced the current level at all concentrations of IGF1 and displayed linearity in the range 1 fM to 100 pM with a determination coefficient of R2 = 0.9373 [y = 3.38221x - 4.79]. Control experiments with complementary aptamer sequences, IGF2 and IGFBP3 did not show notable signal changes, indicating the specific detection of IGF1. This IONW constructed electrode helps to achieve the detection of low amounts of IGF1 and diagnose AAA at the stage prior to rupture.