Well-Established Long-Lasting Chemiluminescence Platform Based on Deep Eutectic Solvents

Long-lasting chemiluminescence (CL) has garnered substantial attention due to its superior controllability and minimal instrumentation requirements compared with conventional flash-type CL systems. However, most existing long-lasting CL systems still rely on the fabrication of complex microreactors to retard mass diffusion. In this study, we propose a facile "all-in-one" mixing platform for triggering long-lasting CL emission using deep eutectic solvents (DESs) as microreactors. Systematic screening identified choline chloride-urea (ChCl-urea) as the optimal DES, owing to its appropriate viscosity and favorable melting temperature. The CL coreactant accelerator of Co²⁺ was preincorporated into the DES via coordination bonds, where it exhibited high catalytic activity and excellent dispersibility (denoted as Co@DES). The DES functioned as a controlled-release reservoir, gradually delivering Co²⁺ to the overlying CL aqueous phase while simultaneously enriching luminol at the aqueous-Co@DES interface. The retarded diffusion of Co²⁺ facilitated the decomposition of H₂O₂ to continuously generate reactive oxygen species, which in turn reacted with luminol to produce sustained CL emission. Under optimized conditions, the developed system maintained a stable CL for up to 72 h, whereas the CL in the single aqueous phase decayed within 5 min. DES-modulated slow diffusion enabled a generalizable strategy for long-lasting CL and can be readily extended to diverse reactant combinations, including various coreactant accelerators and CL emitters. With regard to intensity, duration time, and catalytic characteristics, sensitive detection of H₂O₂ and alkaline phosphatase (ALP) was constructed based on the integrated intensity, indicating its great potential in immunoassays.