A CoFe₂O₄ nanozyme mediated chemiluminescence imaging-colorimetric dual-mode sensor for monitoring ascorbic acid

Ascorbic acid (AA) participates in redox reactions in living organisms and scavenges free radicals to protect cells from oxidative damage. However, the conventional sensors for AA mainly rely on single-mode detection with insufficient accuracy. In this study, a CoFe₂O₄ nanozyme-mediated chemiluminescence (CL) imaging-colorimetric dual-mode sensor was proposed to monitor AA. CoFe PBA was utilized as a precursor to synthesize CoFe₂O₄ nanozymes through calcination, which shows high peroxidase-like activity. AA can efficiently scavenge ˙OH generated during CoFe₂O₄ nanozyme-catalyzed decomposition of H₂O₂. Due to the inhibitory effect of AA on the CoFe₂O₄ nanozyme-based catalytic system, the CL imaging-colorimetric dual-mode sensor was constructed to achieve rapid, accurate, and quantitative detection of AA. Experimental results demonstrate that as the AA concentration increases, the CL imaging intensity of the CoFe₂O₄-luminol-H₂O₂ system decreases, and the chromogenic reaction of the CoFe₂O₄-TMB-H₂O₂ system is significantly restrained (the blue coloration gradually fades). The detection ranges of AA are 20-200 μM (colorimetric) and 40-160 μM (CL imaging) with the detection limits of 18 μM and 25 μM, respectively. The developed dual-mode sensor features simple operation and a rapid signal response, and offers a promising approach for accurate determination of AA.