Low-triggering-potential electrochemiluminescence biosensor based on hydrogen-bonded organic framework and...

Low-triggering-potential can decrease electrochemical interference and cross talk of electrochemiluminescence (ECL), significantly improving long-term stability of working electrode. Herein, we develop a ratiometric ECL biosensor with hydrogen organic framework (HOF) and luminol derived carbon dots (Lu-CDs) as the emitters for sensitive detection of α-glucosidase (α-Glu) at a low positive potential range of 0.1-1.0 V. We synthesize the perylene-dicyandiamide-based HOF (PD-HOF) through the full imidization of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) with dicyandiamide (DCD) with an extended π-conjugated system and nitrogen-rich moieties. The PD-HOF exhibits a high cathodic ECL signal in the presence of K₂S₂O₈ at ultralow positive potentials (0.1-0.3 V) without damaging the target bioactivity. The π-π and hydrogen bonding stacking, nitrogen-rich units, and low impedance of PD-HOF can accelerate the charge transfer and lower the onset potential of K₂S₂O₈, greatly enhancing the ECL intensity. When target α-Glu is present, it catalyzes the hydrolysis of maltose into α-D-glucose that subsequently react with GO_x to produce H₂O₂ (a co-reactant of Lu-CDs), significantly amplifying the anodic ECL signal of Lu-CDs at 1.0 V, with the cathodic ECL intensity of PD-HOF at 0.1 V being remained unchanged. Based on the above reaction mechanism, we construct a ratiometric ECL biosensor for accurate detection of α-Glu. This ratiometric ECL biosensor exhibits a broad linear range from 0.01 to 1 U mL^-1 and high sensitivity with a detection limit of 0.0049 U mL^-1. Importantly, this ratiometric ECL biosensor can efficiently decrease background signals/systematic errors and improve the detection accuracy.