Defect Engineering Enhanced the Electrochemiluminescence of Bismuth-Based Metal-Organic Frameworks for Bioanalysis

Owing to their porous structures and highly tunable properties, metal-organic frameworks (MOFs) have emerged as a current research hotspot in the field of electrochemiluminescence (ECL). Nevertheless, research on main-group-metal-based MOFs in the ECL field remains limited and mainly focuses on aluminum-based MOFs and indium-based MOFs. This work developed bismuth-based MOFs (Bi-MOFs) as ECL luminophores and explored defect engineering to enhance their ECL efficiency. Using Bi3+ as the metal node and 4,4',4″-((1,3,5-triazine-2,4,6-triyl)tris(azanediyl))tribenzoic acid (H3TATAB) as the organic ligand, a series of Bi-MOFs with tunable defect states, namely, Bi-TATAB-X MOFs, were synthesized. Here, X represented the synthesis temperature. Research found that the synthesis temperature and synthesis time affected the defect level, and there was a clear correlation between the defect level and the ECL efficiency, which was similar to a volcanic eruption. In the Bi-TATAB-X MOF series, the Bi-TATAB-130 MOF, which was synthesized at 130 °C for 2 days, stood out for its excellent cathodic ECL performance due to the accelerated electron injection rate and improved electron-hole recombination efficiency by the defects. The Bi-TATAB-130 MOF integrated dual-locked Y-type DNAzyme-mediated catalytic hairpin self-assembly (CHA) to construct the ECL aptasensor for detecting dibutyl phthalate (DBP), which is a representative of plasticizers, with a limit of detection (LOD) of 3.31 fM. Bi-TATAB-130 not only expanded the ECL emitters of main-group-metal-based MOFs but also established a highly sensitive ECL platform for plasticizer detection.