Custom Aptamer Services

Introduction to Aptamers

Often described as synthetic antibodies, aptamers are single stranded DNA or RNA molecules that fold into defined secondary structures and bind to targets with high affinity and specificity. In 1990, the first aptamer was developed against T4 DNA Polymerase using RNA1. The field of aptamer selection and the use of these aptamers has expanded significantly. Now aptamers are developed using both RNA and DNA, as well as non-natural bases, backbones, and small molecules. Aptamers have been used in a variety of applications; detection molecules in ELISA-like assays, protein-specific tissue staining, targeted drug delivery, and as an FDA-approved treatment for macular degeneration2. Aptamers are developed using a process known as SELEX (Systemic Evolution of Ligands by Exponential Enrichment). During SELEX, trillions of random DNA oligos are mixed with the target molecule; sequences that bind to the target are then collected and amplified. After multiple rounds of selection, the DNA is sequenced and individual sequences are evaluated for binding. Using SELEX aptamers with affinity for a variety of targets can be developed, including proteins, peptides, and small molecules.

Aptamer Chemical Structure

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If you’re interested in obtaining a quote for a custom aptamer, simply fill out a quote request form linked below or email our technical support department ( They will email you back a formal quote as soon as possible. To place an order, simply fill out the service form linked below and email to or include it with your shipment.

Aptamer Quote Request FormAptamer Service Form

The Aptamer Advantage

Due to their robust binding affinities for specific biomolecules, aptamers have been explored as an alternative to antibodies. Aptamers offer the following advantages:

  • Increased thermal stability and shelf life
  • Aptamers can undergo multiple freeze-thaw cycles and retain activity
  • Aptamers can be designed to increase enzyme resistance for in vivo and in vitro use.
  • Aptamers can be modified with fluorescent dyes or biotin for detection without post synthesis modification
  • Aptamers can be easily conjugated to proteins, peptides, drugs, and other small molecules using a variety of chemistries
  • Time to completion of custom aptamers is significantly faster than antibody development, generally 2-3 months
  • Eliminates need for hybridoma storage and maintenance
  • Easily scalable; can be generated and replenished without the use of animals

Our Selection Techniques

RayBiotech uses state of the art techniques in our SELEX process to generate high quality aptamers for our customers. Traditionally, the target must be bound to a solid support, altering the target the aptamer is selected for. However, at RayBiotech we use CE (Capillary Electrophoresis) to separate binding sequences, allowing the DNA to interact with the protein in free solution. While traditional SELEX can require 10 rounds of selection or more, CE is effective enough to identify aptamers in as few as 3 rounds, which helps to reduce the effects of PCR bias on the selection3. The use of CE also allows us to monitor the development of the aptamer library throughout the selection process.

In addition, RayBiotech uses NGS (Next Generation Sequencing) instead of plasmid cloning techniques to identify individual aptamers. We utilize the data gained in NGS to analyze the entire aptamer pool and identify common aptamer sequences, motifs, and other patterns in the library. Using this information allows us to identify better aptamer candidates than those identified by randomly selected clones.

Aptamer development has 3 primary phases:

  1. Selection: DNA that bind to the target are partitioned from sequences that do not. Binding sequences are amplified via PCR and brought forward for additional rounds of SELEX, generally 5-10
  2. Sequencing: RayBiotech uses NGS and data analysis to determine which aptamers to evaluate as opposed to randomly selecting individual clones.
  3. Candidate Aptamer Evaluation: Aptamers are evaluated for binding and the best aptamer is supplied to the customer
How Aptamer Development Works
  1. Bauer, Michelle, et al. "The Application of aptamers for immunohistochemistry." Nucleic acid therapeutics 26.3 (2016): 120-126.
  2. Stuart, Christopher H., et al. "Selection of a Novel Aptamer Against Vitronectin Using Capillary Electrophoresis and Next Generation Sequencing." Molecular Therapy—Nucleic Acids 5.11 (2016): e386.
  3. Mosing, Renee K., and Michael T. Bowser. "Isolating aptamers using capillary electrophoresis–SELEX (CE–SELEX)." Nucleic Acid and Peptide Aptamers: Methods and Protocols (2009): 33-43.
  4. Vinores, Stanley A. "Pegaptanib in the treatment of wet, age-related macular degeneration." International journal of nanomedicine 1.3 (2006): 263.
  5. Tuerk, Craig, and Larry Gold. "Systematic evolution of ligands by exponential enrichment: RNA ligands to bacteriophage T4 DNA polymerase." Science 249.4968 (1990): 505-510.