Lateral flow biosensors for low abundance detection of brain natriuretic peptide with enzyme-free amplification

The diagnosis of heart failure in emergency settings requires rapid and sensitive detection of brain natriuretic peptide (BNP), a low-abundance biomarker of heart failure with a clinical rule-out threshold of 100 pg mL^-1 (0.03 nM). The current gold standards for BNP testing in clinical practice all rely on immunoassays that necessitate cold-chain storage for antibodies, limiting their utility at the point-of-care. We now propose an enzyme-free, isothermal amplification strategy employing a dual-aptamer system to measure BNP at clinically relevant levels. Upon simultaneous binding to the target BNP, both of the aptamers release their complementary DNAs, consequently triggering a cyclic amplification reaction. The resulting secondary DNA structures can be detected via a lateral flow test (LFT) format, providing visual readouts close to the patient in 30 min at room temperature. This work advances the field by combining the specificity of aptamers with the simplicity of LFTs, offering the sensitivity of conventional immunoassays while eliminating any enzymatic steps. This work bridges the gap between lab-based immunoassays and POC needs, offering a reliable, equipment-free alternative for heart failure diagnosis in resource-limited settings. Future studies will validate its performance with blood samples for clinical deployment.