ELISA/ELONA

Aptamers are readily incorporated into existing ELISA platforms. The resulting assays benefit from advantages of aptamers over antibodies, which often present issues when trying to develop a rapid assay kit.

Aptamer benefits include:

  • Increased specificity– incorporation of counter-selection steps during aptamer selection means that aptamers can be isolated which do not recognise closely-related compounds.
  • Wider range of outputs– aptamers can be conjugated to multiple reporter molecules including fluorophores, biotin, enzymes (e.g. strep-HRP) and quencher molecules.
  • Virtually no target limitation– nearly any target can be used for aptamer selection; including low molecular weight targets in almost any buffer conditions or matrix.
  • No temperature control requirements-high stability of aptamers at various temperatures and their ability to refold, eliminates the need for cold-chain shipping and storage.
  • Robust Assays– aptamers show more resistance to different chemical buffers such as large ranges of pH, ionic strength etc.
  • Works in crude sample matrices – aptamers can be selected to function in a range of matrices e.g. plasma, milk, urine etc.
  • Low batch-to-batch variability – aptamers are prepared by simple chemical synthesis with very high fidelity once the sequence of the aptamers is known.
  • Cost effective – aptamers show cost advantages over antibodies as aptamers are produced synthetically.
  • Works with existing technology– can be used by all existing plate reader models and aptamers can be designed to work in tandem with high-quality monoclonal antibodies.

Aptamers can be easily incorporated into existing ELISA platforms

The example shows an prototype ELONA (Enzyme Linked OligoNucleotide Assay) in a ‘traditional ELISA-like format. The proteins were fixed at the microtiterplate surface; biotinylated aptamers Target binding aptamers could directly measured ;  aptamers ‘using aptamers labelled with gold nanoparticles for specific detection of a protein target.

ELISA-like Assays for small molecule detection

Our small molecule targeting aptamers are designed in such way that they can be used in a range of ‘ELISA-like’ formats. They can be labelled with fluorophores to allow direct reading or with traditional moieties (such as biotin) to facilitate more sensitive assays. The readout of the assays are in a ‘gain of signal’ format and no ‘sandwich pair’ is required. We have developed a number of ELISA-like assays for targeting small molecules and show specific and linear responses even in crude sample matrices.

Aptamers can easily incorporated into existing ELISA platforms

The figure shows the principle of an Enzyme Linked OligoNucleotide Assay (ELONA).

Aptamers recognise target in a variety of matrices

Aptamer based ‘ELISA-like’ assay can be used to detect small molecule targets in a variety of common sample matrices.

Assays are sensitive and show linear response

Aptamer based ‘ELISA-like’ assays are suitable for detection of small molecules at low concentrations, can be used in a ‘gain of signal’ format and show linear response.

Aptamer based assay plates are stable

Aptamer interaction with the small molecule gives a clear concentration dependant signal
Negative target is not recognised
Concentration dependant signal is seen for fresh plates and plates stored at 22°C or 37°C for 1 week