Glow-type luminol chemiluminescence based on a supramolecular enhancer of cyclodextrin

Chemiluminescence (CL) bioassay is one of the most advanced and used detection method in clinical diagnosis and biomedical research because of the advantages of low background, easy operation, and wide-field imaging without a light source or microscope. The luminol/hydrogen peroxide/horseradish peroxidase (luminol/H₂O₂/HRP) system is the most popular CL system, but its application in high-throughput imaging detection is challenged due to its low luminescence efficiency and flash-type emission which is difficult in ensuring the reproducibility and consistency of detection results.

We reported a glow-type CL system of luminol@CD/H₂O₂/HRP by using a supramolecular enhancer of cyclodextrin (CD). This luminol@CD/H₂O₂/HRP system exhibited a luminescence lifetime of 41 min for sensitive and accurate imaging analysis. The long-lasting CL emission was attributed to the formation of a 1:1 host-guest complex between luminol and CD, which could stabilize the emitter and effectively reduce nonradiative relaxation. The formation of luminol@CD complex was determined through NMR experiments and theoretical analysis. Under optimum conditions, the luminol@CD/H₂O₂/HRP system showed higher sensitivity and much better precision than classical luminol/H₂O₂/HRP system for imaging detection of HRP. Especially, this glow-type luminol@CD/H₂O₂/HRP system realized CL imaging of microwell arrays on microfluidic chips. In addition, the luminol@CD/H₂O₂/HRP system was successfully applied for point-of-care detection of 17β-estradiol based on a competitive mechanism of host-guest recognition.

An efficient CL system is crucial for obtaining reproducible and consistent results for accurate detection. Our luminol@CD/H₂O₂/HRP system emitted strong and persistent luminescence, resulting in reliability and efficiency at both CL macroscopic and microscopic imaging detection. We expected the luminol@CD/H₂O₂/HRP CL system to be applied in various detection fields.