Hydrogen Bond Organic Frameworks as a Novel Electrochemiluminescence Luminophore: Simple Synthesis and Ultrasensitive Biosensing

Nowadays, continuous efforts have
been devoted to searching highly
efficient electrochemiluminescence (ECL) emitters for applications
in clinical diagnosis and food safety. In this work, triazinyl-based
hydrogen bond organic frameworks (Tr-HOFs) were synthesized by N···H
hydrogen bond self-assembly aggregation,
where 6,6′-(1,4-phenylene)­bis­(1,3,5-triazine-2,4-diamine) (phenyDAT)
was prepared via the cyclization reaction and behaved
as a novel ligand. Impressively, the resulting Tr-HOFs showed strong
ECL responses with highly enhanced ECL efficiency (21.3%) relative
to the Ru­(bpy)32+ standard, while phenyDAT hardly
showed any ECL emission in aqueous phase. The Tr-HOFs innovatively
worked as a new ECL luminophore to construct a label-free biosensor
for assay of kanamycin (Kana). Specifically, the ECL response greatly
weakened upon assembly of captured DNA with ferrocene (cDNA-Fc) onto
the Tr-HOFs-modified electrode, while the ECL signals were adversely
recovered by releasing linked DNA (L-DNA) from double-stranded DNA
(dsDNA, hybridization of aptamer DNA (aptDNA) with L-DNA) due to the
specific recognition of Kana with the aptDNA combined by the linkage
of L-DNA and cDNA-Fc on the electrode. The as-built sensor showed
a broadened linear range (1 nM–10 μM) and a limit of
detection (LOD) down to 0.28 nM, which also displayed satisfactory
results in the analysis of Kana in the milk and diluted human serum
samples. This work offers a novel pathway to design an ECL emitter
with organic molecules, holding great promise in biomedical analysis
and food detection.