2nd July 2019

Detecting and quantifying small molecule analytes can be difficult. Our specially designed displacement approach allows us to select aptamers which can directly be used in various biosensor platforms for the detection of small molecules. Binding of the aptamer to the analyte gives a ‘signal amplification’ effect which can be used as a basis for small molecule detection.

Two such examples are shown below, demonstrating aptamer discrimination between anti-cancer chemotherapy drug and its metabolites using BLI (BioLayer Interferometry) and an ELISA-like assay (fluorescent plate reader assay in plasma). Results from both the assays demonstrate that the aptamer binds specifically to the chemotherapeutic target as compared to the metabolite competitors and the negative target.

Small Molecule detection using our displacement approach via BLI

We immobilise our aptamers onto commercially available biosensor platforms such as BLI adapting a simple ‘Dip and Read’ biosensor format. Using this principle, we have demonstrated that our aptamers are able to discriminate between a chemotherapeutic target and its metabolites and negative target (Figure 1).

Figure 1. Binding of the aptamer to the chemotherapeutic target (red), it’s metabolites (green and yellow) and the negative target (blue) using BLI assay.

Small molecule detection using our displacement approach via ELISA-like assay

The following data demonstrates concentration dependent binding of the aptamer to its respective target using an ELISA-like assay. The results were comparable with BLI assay showing increased aptamer binding to the target as compared to its metabolite and the negative targets (Figure 2).

Figure 2. Binding of the aptamer to the chemotherapeutic target, it’s metabolite and the negative targets using an ELISA-like assay.

Small molecule detection in plasma via ELISA-like assay

As with other Aptamer Group selection methodologies; we isolate and design our small molecule targeting aptamers using selection conditions tailored to the end application. The data presented below demonstrates concentration dependent binding of the aptamer to the target in various concentrations of buffered plasma (0, 10, 20 and 25%) using an ELISA-like assay (Figure 3).

Figure 3. Binding of the aptamer to the target in different plasma concentration using an ELISA-like assay.

Overall, the data suggests that our aptamers can be readily incorporated into BLI assay and existing ELISA platforms showing target specific responses even in crude sample matrices.

At Aptamer Group, we have developed and validated numerous small molecule specific aptamers in many such biosensor and assay formats. To find out more about our small molecule aptamer detection methods, please contact us using the form below.

We also have test aptamers available which you can try so let us know if you would like to learn more.

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