Zeolite-assisted Silica Substrate for Sensing Abdominal Aortic Aneurysms by Aptamer-C-reactive Protein-antibody Sandwich

Introduction: Identifying abdominal aortic aneurysm (AAA) and its condition is crucial for providing better treatment before rupture. Since AAA is often asymptomatic, regular monitoring is necessary for elderly individuals to detect changes in the aorta. Methods: Although imaging techniques are commonly used to diagnose AAA, they are expensive and can cause discomfort to patients. C-reactive protein (CRP) is an acute-phase protein, and its concentration is highly correlated with the size of the abdominal aortic aneurysm (AAA) diameter. It was found that patients with elevated CRP levels above 1.4 mg/mL had an AAA expansion rate of 4.8 mM, compared to 3.9 mM in those with levels below 1.4 mg/mL. In addition, CRP helps to identify AAA in asymptomatic patients. Compared to other biomarkers, CRP levels are useful in assessing the size of AAA. Results: Therefore, quantifying CRP levels aids in identifying and monitoring AAA size. This research focuses on developing a CRP biosensor on a zeolite-modified electrode with a silica substrate for diagnosing AAA. An anti-CRP aptamer serves as the capture molecule, while an anti-CRP antibody functions as the detection molecule. The aptamer is conjugated with gold nanoparticles and linked to the electrode via an amine-modified zeolite to enhance aptamer immobilization. Conclusion: Using an aptamer-antibody sandwich assay, a detection limit of 1 pg/mL of CRP was achieved on this surface. Furthermore, CRP-spiked serum samples showed a noticeable increase in current responses, while control proteins and complementary aptamers failed to elevate the current level, indicating the selective and specific detection of CRP.