A MOF-818-based nanozyme-linked aptasensor for microcystin-LR detection in edible algae powder

The development of simple, rapid, and sensitive detection methods for microcystin-leucine-arginine (MC-LR) is crucial for ensuring food safety. A novel nanozyme-linked colorimetric aptasensor was developed using metal-organic framework (MOF) material MOF-818. The aptamer and MOF-818 with complementary DNA (cDNA) on its surface (MOF-818/cDNA) served as bioreceptors and signal reporters, respectively. Without MC-LR, MOF-818/cDNA bound to the aptamer, catalyzing the oxidation of 3,5-Di-tert-butylcatechol (3,5-DTBC) and producing yellow-colored products. While in the presence of MC-LR, it bound to the aptamers competitively, inhibited MOF-818/cDNA capture and reduced catalytic activity, enabling colorimetric quantification. The method achieved a linear detection range of 1-200 ng/mL and a limit of detection of 0.849 ng/mL. It successfully quantified MC-LR in spiked lake water and tap water, as well as MC-LR-contaminated edible algae (Spirulina platensis and Chlorella pyrenoidosa) powders, with recovery rates ranging from 81.45 % to 136.67 %. This research provided a cost-effective, efficient and portable method for MC-LR screening in food and environmental samples.