25th June 2019
Small molecule targets (such as antibiotics, many drugs, toxins, food additives etc) are often perceived as difficult targets to obtain a suitable affinity ligand. They represent a challenge for traditional aptamer selection approaches which rely on immobilisation of the target molecule for efficient partitioning. Modification of the small molecule to facilitate immobilisation often uses one of a limited number of functional sites available for aptamer binding. The linker used may also affect the properties of the small molecule and may also interfere with aptamer binding.
Aptamer Group use a proprietary method to address these issues. Using a special automated approach, we select aptamers against small molecules in solution (in their natural structure) with all reactive groups available for aptamer binding. This displacement method relies on a conformational change of the aptamer that occurs upon binding with small molecule targets.
This conformational change leads to the release of the aptamer from the surface. The displaced aptamers are recovered, amplified and used in the next round of our selection process. We also include counter-selection steps to ensure that the aptamers are specific to the target of interest. This gives aptamers greater specificity than can be achieved by other affinity ligands. Automated parallel processing allows multiple targets and variables thus increasing throughput.
As with other Aptamer Group selection methodologies; we isolate our small molecule targeting aptamers using selection conditions tailored to the end application. Standard functional groups (biotin, thiol, amine etc) are readily incorporated into aptamers during their synthesis. This allows straightforward immobilisation of the aptamer onto the appropriate sensor; 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.
At Aptamer Group, we have developed and validated numerous small molecule specific aptamers in many biosensor and assay formats. If you would like to try aptamers or require more information on aptamers for your research, please contact us using the form below.