A novel fluorescent aptasensor based on mesoporous silica nanoparticles for the selective detection of sulfadiazine in edible tissue

Sulfadiazine (SDZ) is a broad-spectrum antibiotic used to treat bacterial infections in animals, and SDZ residues in food can be harmful to human health. As a result, an aptasensor based on silica nanoparticles was developed for the rapid detection of SDZ. An aptamer that specifically binds to SDZ was obtained using graphene oxide-SELEX and further truncated to a 13 nt sequence (SDZ30-1:5'-AACCCAATGGGAT-3'), which has a high affinity (K-d = 65.72 nM). In addition, it was found by molecular simulation that a steric hindrance could prevent the target molecule from entering the binding pocket formed by the key base TGG, which affects the total binding free energy of SDZ30-1 and the target molecule, thereby affecting the affinity of SDZ30-1 to the target. The SDZ30-1 was selected as the fluorescent probe to establish an aptasensor for the detection of SDZ residues in milk and honey. The aptasensor exhibited a wide dynamic linear range (3.125 - 100 ng/mL) and a limit of detection (LOD = 1.68 ng/mL). The aptasensor in spiked samples recovered at a rate of 95.12 - 105.47%, with a coefficient of variation of less than 13.18 %. The results of aptasensor were positively correlated with those of HPLC (R-2 > 0.8687). Based on the above results, it could be inferred that the aptasensor can be used sensitively and rapidly for the detection of SDZ residues in edible tissue. (C) 2022 The Author(s). Published by Elsevier B.V. on behalf of King Saud University.

Automated summary

An aptasensor based on silica nanoparticles was developed for the rapid detection of sulfadiazine (SDZ) residues in food. The aptasensor exhibited a wide dynamic linear range and a low limit of detection, and showed good recovery efficiency and reliability. The study suggests that the aptasensor has potential application value for the sensitive and rapid detection of SDZ residues in edible tissue.