A sense-and-treat ELISA using zeolitic imidazolate framework-8 as carriers for dual-modal detection of carcinoembryonic antigen

Enzyme-linked immunosorbent assay (ELISA) has been widely used in the area of biological analysis, while there are still some challenges getting in the way to ensure both excellent sensitivity and reliable accuracy. To overcome these obstacles, we simulated the smart sense-and-treat carriers in a drug delivery system to fabricate an improved ELISA, employing zeolitic imidazolate framework-8 (ZIF-8) as the carrier to deliver the tracer agent carbon dots (CDs) and the drug thymolphthalein (TP), which was referred to as a sense-and-treat ELISA. In the sense part, the strong fluorescence intensity of CDs could be observed directly to achieve the sensitive detection of the target. In the treat part, after stimulation of alkaline solution, TP was released from ZIF-8 carriers and generated a color change with an obvious absorption, which was beneficial for increasing the sensitivity of this ELISA due to the high loading of the TP. Finally, we took carcinoembryonic antigen (CEA) as a model and performed dual-modal detection using this improved sense-and-treat ELISA to accomplish quantitative determinations sensitively and accurately. In addition, the results indicated by the two parts kept good concordance, which could demonstrate the reliable accuracy of this ELISA.