Self-Assembled Difunctional V Type DNA–Antibody Response Unit for Target-Driven Specific Amino Acid Analysis

Abstract Innovatively designing an amino acid–antibody recognition platform for specific analysis can avoid interferences from biological matrices in clinical detection and prevent signal drift, which is caused by the existing detection methods of adsorption differences and in-situ reactions. Meanwhile, unlike indirect signal responses, signal changes are directly linked to target concentrations can avoid errors caused by environmental factors and further improve detection sensitivity. Thus, in this work, a specific amino acid detection platform driven by target was developed using the self-assembled difunctional V type DNA-antibody response unit for glycine (Gly) ultrasensitive detection. Specifically, the specific recognition of Gly triggered the closure of V-shaped antibody–DNA tweezer nanodevice, shortening the distance between [Ag18H16(TPP)10]2+ (Ag NCs) and Fe11(μ4-O)4(μ-O) (Fcdc)8(μ2-OCH3)3•DMF (Fe11–Fcdc) to induce resonance energy transfer, thereby quenching the signal of Ag NCs. Meanwhile, the enzymatic reaction between Gly and its amino acid oxidase in situ generated H2O2, which was further catalyzed by Fe11–Fcdc via Fenton-like reaction to produce more •OH, significantly amplifying the signal of luminol. Benefiting from this target-driven direct response and dual-functional Fe11–Fcdc, the proposed ratio-sensor achieved sensitive detection of Gly in a wide concentration range from 5 fg/mL to 1 μg/mL with a detection limit of 3.28 fg/mL (S/N = 3). These realized the efficient diagnosis for breast cancer, and provided a feasible method to clinical analysis of other amino acids in complex biological environments.