17th July 2019

Small molecules present an ongoing challenge for antibody production and detection. Development of biosensors for the detection of small molecules is difficult due to the lack of suitable antibodies and the relatively small signals. Tools to detect and quantify them are therefore in high demand.

At Aptamer Group we select aptamers that bind to small molecules with high specificity and undergo a substantial conformational change that can be applicable for a variety of sensor platforms. These aptamers can also be adapted for a rapid, gain of signal assay that can be used to discover, deduce and quantify sample compounds which can reduce the heavy reliance on antibodies and mass spec. The ‘gain-of-signal’ response can be achieved by capturing displaced aptamers to allow straightforward immobilisation of the aptamer onto the appropriate sensor; thus converting a generic sensor platform into a target specific biosensor. This allows simplified downstream assay development and makes them useful as alternatives in ELISA-like assays, Lateral Flow Devices, Molecular Beacons, Biosensors, etc.

For ELISA-like assays, aptamers can be labelled with fluorophores to allow direct reading or with traditional moieties (such as biotin) to facilitate more sensitive assays. Aptamer based ELISA like assays have been used to detect small molecules such as pathogens, microbial toxins and other hazardous environmental toxicants in order to ensure human health and safety.

Similarly, lateral flow assays (LFAs) are typically set up as sandwich or competitive formats, comparable to an ELISA where a simple paper-based platform are used for the detection of targets. The readout of the assays is in a ‘gain of signal’ format and no ‘sandwich pair’ is required. This simple format has gained considerable interest due to its potential to provide results in a matter of minutes, with the only required end-user intervention being sample addition.

Figure 1. Schematic representation of LFD assay based on ‘Displacement selection’ approach. 1. Aptamers are displaced by a specific target binding 2. Displaced aptamers are carried along the LFD pad in the sample matrix. 3. Displaced aptamers are re-captured by a re-capture molecule at the end of the LFD

 

Advantages include no multiple capture and detection reagents, reduced assay costs and increased stability compared to the antibody-based assay. LFAs are used in diverse fields including biomedicine, quality control, food safety, as well as environmental health.

At Aptamer Group, aptamers used on LFA device can be applied to a range of biological samples including urine, saliva, sweat, serum, plasma and blood. If you would like more information on how our aptamers can be used in your research, please contact using the form below.

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