Heteroaptamer recognition mediated strand displacement amplification for efficient electrochemical analysis of...

The human milk protein beta-2-microglobulin (B2M) plays a vital role as a diagnostic biomarker for infants, with conventional detection methods frequently relying on intricate instruments that have constraints in sensitivity and selectivity. Here, an innovative heteroaptamer recognition-mediated strand displacement amplification for electrochemical analysis of B2M in breast milk is described. Two heteroaptamers associating with distinct sites on B2M kickstart the toehold-mediated strand displacement on the magnetic bead, facilitating the reuse of heteroaptamer/B2M complexes. The molecular machine's operation induced the formation of numerous G-quadruplex structures on the sensing interface, which could bind with hemin and produce a significantly increased current for the detection of B2M, with a detection limit of 0.2 fg/mL. With its unique capabilities, the sensor can differentiate the target B2M from other non-target proteins, guaranteeing the specific detection of B2M in milk samples. This system could be modified to detect different targets by using the correct aptamer/ligand combinations.