18th June 2019

Kanamycin is an aminoglycoside antibiotic isolated from Streptomyces kanamyceticus and is widely used to treat various infectious diseases in humans and animals. However, like other aminoglycoside antibiotics, kanamycin exhibits comparatively narrow safety margin as high doses can cause ototoxicity, nephrotoxicity and allergic reactions.

The current methods used for analysis for detecting kanamycin levels in complex food matrix exhibit reasonable sensitivity, however, show various disadvantages in practical application. These include instrumental analysis such as capillary electrophoresis, HPLC, SPR and electrochemical immunosensor which provides high sensitivity, which requires expensive instrument, high operation skills, tedious pre-treatment and are relatively time consuming. Immunoassay which includes ELISA is fast and easy to operate, however, antibody requires high cost and harsh preservation condition along with batch to batch variation resulting in false positive results. Therefore, it is very meaningful to establish a convenient, sensitive and low – cost methods for rapid and efficient detection of kanamycin in complex food matrix.

As the aptamer exhibit higher affinity towards their target, aptasensor technology allows excellent performance such as high sensitivity, easy operation, low cost and rapid detection. Towards this goal, Ma et al. described a simple and reliable assay to detect kanamycin using a structure switching aptamer via fluorescence resonance energy transfer mechanism (Figure 1).

Figure 1: Structure switching aptamer assay for kanamycin detection based on the FRET

The structure switch was composed of kanamycin binding aptamers and the complementary strands, respectively labelled with a fluorophore (FDNA) and quencher (QDNA). In the absence of kanamycin, the FDNA and QDNA formed double helical structure through the complementary strands and the fluorescence from FDNA was quenched because of FRET mechanism. However, in the presence of kanamycin, the FDNA aptamer specifically bound to kanamycin due to high affinity exhibiting a structural change and disrupting the interaction of the QDNA. This resulted in fluorescence enhancement which relates directly to the presence of kanamycin. This paper was able to use this structure switching method in the detection of kanamycin in milk within 1h duration along with a detection limit of 13.52 nM which is below the maximum residue limit (MRL) of kanamycin in milk.

Aptamer Group has successfully selected aptamers with high affinity against various such antibiotics and have utilised more robust aptasensor based assays allowing rapid detection, good selectivity and high sensitivity for the target. If you would like more information on aptamers for your research, please contact us using the form below.

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References:

Ma X, Qiao S, Sun H, Su R, Sun C, Zhang M. Development of Structure-Switching Aptamers for Kanamycin Detection Based on Fluorescence Resonance Energy Transfer. Front Chem. 2019;7:29. Published 2019 Feb 7. doi:10.3389/fchem.2019.00029.