SPR sensing of small molecules with modified RNA aptamers: Detection of neomycin B

We have studied how the modification of the RNA aptamer evolved against neomycin B at 2' position of ribose with a methyl group influences the affinity of the interaction. Using surface plasmon resonance (SPR) and faraclaic impedance spectroscopy (FIS) an affinity constant in the mu M range was calculated. The results showed that the modification of the aptamer does not significantly alter the affinity of the aptamer for the antibiotic. This finding opens up the possibility of designing modified RNA aptamers resistant to endonucleases without variation of the analytical features. In addition to this, we propose a competitive assay for the detection of neomycin B using SPR as a transduction technique. A range of quantification between 10 nM and 100 mu M was obtained, which shows the feasibility of detecting small molecules using aptamers with high sensitivity. (c) 2009 Elsevier B.V. All rights reserved.