MOF-based tri electrode aptasensor platform for effective detection of sepsis markers with minimal cross interference

Abstract

In recent years, several multiplexed point-of-care platforms have been developed as diagnostic aids for sepsis. However, the current versions suffer from poor electrode consistency, analyte interference, and complicated production challenges. Herein, we report a polymethyl methacrylate (PMMA) based three-in-one (triad) multiplex sensor for the concurrent detection of three sepsis biomarkers: procalcitonin (PCT), C-reactive protein (CRP), and interleukin-6 (IL-6). The device has three active sensing areas. Each area contains a conductive paste of trypan blue (TB) linked metal organic framework (MOF), which acts as a transduction layer and is modified with aptamers specific to each analyte. The design includes barriers, optimized shapes, and capillary stops to keep electrolytes separate, preventing cross contamination and off target binding. The TB-MOF material, with its extended π conjugation, allows direct electron transfer, which is amplified by surface modification with 3-phosphonopropionic acid (3-PPA). This phenomenon reduces charge transfer resistance (Rct), lowers redox potential, and increases peak currents by ~ 5-10 fold compared to the unmodified MOF paste. The increased density and orientation of aptamers, caused by the phosphonic acid groups of 3-PPA, also increased the number of binding sites, resulting in noticeable changes in reversible electrode behavior after immobilization. With such arrangements, the subsequent aptasensors achieved detection limits of approximately 0.025 ng mL⁻¹ (PCT), 0.50 μg mL⁻¹ (CRP), and 0.15 pg mL -1 (IL-6), with cross reactivity below 5%. Overall, this single-paste, single-step platform does not rely on graphene, shows good baseline stability, and provides a cost-effective approach to produce disposable diagnostic cartridges for sepsis with high specificity.