Detection and simultaneous imaging of acrylamide, miR-21 and miR-221 based on multicolor aggregation-induced emission nanoparticles and DNAzyme walker

Acrylamide (AA) in heat-processed foods has emerged as a global health problem, mainly carcinogenic, neurotoxic, and reproductive toxicity, and an increasing number of researchers have delved into elucidating its toxicological mechanisms. Studies have demonstrated that exposure of HepG2 by AA in a range of concentrations can induce the upregulation of miR-21 and miR-221. Monitoring the response of intracellular miRNAs can play an important role in unraveling the mechanisms of AA toxicity. Here, multicolor aggregation induced emission nano particle (AIENP) probes were constructed from three AIE dyes for simultaneous imaging of intracellular AA and AA-induced miR-21/miR-221 by combining the recognition function of AA aptamers and the signal amplification of a DNAzyme walker. The surface of these nanoparticles contains carboxyl groups, facilitating their linkage to a substrate chain modified with a fluorescent quencher group via an amide reaction. Optimization experiments were conducted to determine the optimal substrate-to-DNAzyme ratio, confirming its efficacy as a walker for signal amplification. Sensitive detection of AA, miR-21 and miR-221 was achieved in extracellular medium, with detection limits of 0.112 nM for AA, 0.007 pM and 0.003 pM for miR-21 and miR-221, respectively, demonstrating excellent selectivity. Intracellularly, ZIF-8 structure collapsed, releasing Zn2+, activating DNAzyme cleavage activity, and the fluorescence of multicolor AIENPs within HepG2 cells gradually recovered with increasing stimulation time (0–12 h) and concentrations of AA (0–500 μM). This dynamic response unveiled the relationship between AA exposure and miR-21/miR-221 expression, further validating the carcinogenicity of AA.