Film permeability triggered afterglow electrochemiluminescence for lipase detection

Abstract

Afterglow electrochemiluminescence (ECL), persistent luminescence observed after cessation of electric excitation, has attracted great attention but remains unexplored in sensing application. Here we present a solid-state afterglow ECL biosensor leveraging enzyme-responsive polymer nanoarchitectonics for lipase quantification. The sensor is constructed by covalently grafting amphiphilic block copolymers (PCL-PEG) onto nitrogen-deficient carbon nitride nanosheets (CNxNS) deposited on electrodes. Hydrophobic PCL segments self-assemble into a compact barrier under aqueous conditions, blocking S2O82- diffusion and suppressing CNxNS’s afterglow ECL. Lipase-triggered hydrolysis of PCL dynamically increases film permeability, enabling recovery of afterglow ECL proportional to enzyme activity. The sensor achieves a detection limit (3σ) of 1 μU mL-1 with a broad linear rang of 1 μU mL-1 to 10 mU mL-1, and shows high specificity against interferents (e.g. α-amylase, trypsin). Real-sample validation in toners demonstrates practical applicability. This work establishes a paradigm for afterglow ECL based biosensing.