Visual Detection of Kanamycin by Poly-Adenine-based Diblock Oligonucleotide Probe
Adsorption of single-stranded DNA(ssDNA)onto unmodified gold nanoparticles(AuNPs)has been utilized as a common strategy for colorimetric assays,enabling facile detection of target analytes.In this study,a label-free,sensitive AuNP-based colorimetric biosensor was developed for visual detection of kanamycin(Kana)using a diblock oligonucleotide probe(dP)that included a poly-adenine(polyA20)tail.In the presence of Kana,the aptamer on the MBs@double-stranded DNA(dsDNA)complex specifically bound to Kana,leading to dissociation of dPs from complementary aptamer strands.The dP sequences were anchored to the surface of AuNPs due to the strong affinity between polyA20 tail and AuNPs,thus stabilizing the colloidal AuNPs against aggregation when high concentration level salt(NaCl)was introduced.Compared with random sequence(RS)with the same number of bases,AuNPs colorimetric strategy with polyA20 tail sequence significantly improved the detection sensitivity of Kana by two orders of magnitude.The results showed that the colorimetric sensor had good colorimetric performance when the concentration of Kana ranged from 0.01 to 1 nmol/L,and the detection limit(S/N=3)was 0.01 nmol/L.This sensing system did not require large instruments and other signal amplification technique,and was suitable for visualization and real-time detection of large quantities of samples with high sensitivity and specificity.This study provided a good idea for visual detection of other antibiotic drugs and chemical pollutants affecting food safety.
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