Colorimetric Detection of Kanamycin Residue in Foods Based on the Aptamer-Enhanced Peroxidase-Mimicking Activity of Layered WS₂ Nanosheets

Abstract

Although the colorimetric methods can easily meet the demands of point-of-care and ease-of-use for antibiotic detection, they still face many challenges in the accuracy and stability of assay. Herein, a facile and stable colorimetric aptasensor is first developed for kanamycin residue detection based on the aptamer-enhanced peroxidase-mimicking activity of layered WS2 nanosheets. The investigation confirmed that aptamer sequences can improve the affinity of nanosheets to the chromogenic substrate 3,3′’,5,5′’-tetramethylbenzidine, resulting in a significant increase of the peroxidase-mimicking activity. Under the optimal conditions, the limit of detection of the proposed colorimetric aptasensor for kanamycin was determined to be as low as 0.6 μM, and such an aptasensor displays excellent selectivity against other competitive antibiotics. Moreover, further studies have verified the applicability of the established colorimetric aptasensor in several actual samples, indicating that the aptasensor may have bright application prospects for kanamycin detection in livestock husbandry and agriculture samples.

Regulation Mechanism of ssDNA Aptamer in Nanozymes and Application of Nanozyme-Based Aptasensors in Food Safety

“…Protonated cytosine nucleotides in buffer at pH 4.0 increased the electrostatic repulsion between cytosine and positively charged TMB, resulting in a lower affinity of MoS 2 nanozymes [ 51 ]. Guanine (G) was also reported to significantly enhance the peroxidase-like activity of WS 2 nanosheets [ 57 ], iron-based MOFs modified with acidized carbon nanotubes (MOF/CNTs) [ 52 ], and MIL-53(Fe) [ 46 ]. Purine (A, G) modification demonstrated a remarkable enhancement of the peroxidase-like activity of AuNPs, while pyrimidine (T, C) modification enhanced it slightly, which was attributed to the difference in the interaction between TMB and the surface-adsorbed nucleobases [ 58 ].…”

“…Besides the intrinsic factors mentioned above, the reaction conditions were also very important for DNA to regulate the nanozyme activity. The buffer pH at 4.0 had been found to be the optimum condition for both the catalytic activity of nanozymes and the inhibition of nanozyme activity by ssDNA [ 45 , 46 , 56 , 57 ]. TMB was the most-used substrate in those literatures.…”

“…This was because phosphate could compete with ssDNA to bind to CeO 2 nanozymes and enhance their peroxidase-like activity. Low ionic strength increased the peroxidase-like activity of ssDNA-modified WS 2 nanosheets [ 57 ], while high ionic strength could shield the electrostatic reaction, which reduced the interaction among ssDNA, nanozymes, and TMB [ 61 ].…”

“…In a 10 mM H 2 O 2 reaction system, DNA inhibited the peroxidase-like activity of AuNPs in the first 10 min and enhanced the catalytic activity of AuNPs in the next 20 min of the reaction time, while at a lower concentration of H 2 O 2 (5 mM), it prolonged the inhibition time to 30 min and enhancement occurred after 30 min [ 58 ]. Moreover, by changing the substrate from the positively charged TMB to the negatively charged 2,2′-azino-bis (3-ethyl benzothiazoline-6-sulfonic acid) (ABTS), the enhanced ability of ssDNA disappeared, and the inhibiting ability of ssDNA appeared [ 45 , 57 ].…”

“…Thus, the detection signal was negatively correlated with the concentration of the target. Similar mechanisms were also applied for the detection of tetracycline [ 85 ], kanamycin [ 57 ], sulfadimethoxine [ 86 ], cocaine [ 87 ], abrin [ 88 ], malachite green [ 89 ], and Streptococcus pneumoniae [ 90 ]. In addition, Wang et al [ 50 ] developed a versatile ratiometric fluorescence platform for detecting Hg(II) and aflatoxin B1 (AFB1) based on the enhancement of peroxidase-like activity of Pg-C 3 N 4 nanosheets by ssDNA.…”