For many years, aptamers were developed using one of several versions of the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) process. X-Aptamers are the next step in the evolution of aptamer technology. They are synthetic affinity reagents that incorporate natural and chemically-modified DNA or RNA nucleotides. Common modifications include amino acid functional groups, as well as small molecules in virtually any combination.
AM Biotech uses a proprietary bead-based technology to select X-Aptamers. Our single round discovery process has significant advantages relative to SELEX. AM Biotech’s selection eliminates the repeated rounds of PCR amplification, unlike SELEX who's many rounds lead to PCR bias – which disfavors recovery of the most structurally stable aptamers.
Improve Existing Aptamers & siRNA
AM Biotech uses chemical modifications to improve existing aptamer and siRNA performance. DNA or RNA aptamer binding affinity can improve dramatically without adversely affecting specificity by using just one or two modified nucleotides in a distinct sequence location.
Selections were performed using a bead-based X-Aptamer (XA) library containing several different amino acid functional groups attached to dU at the 5-position.
The well-characterized interaction between the MS2 coat protein and its cognate RNA hairpin was used to evaluate changes in affinity as a result of phosphorodithioate (PS2) replacing phosphate by biolayer interferometry (BLI).
X-Aptamers contain combinations of chemical modifications that cannot be amplified using PCR. A unique bead-based process is required to perform selections of X-Aptamers to protein and small molecule targets.
“Working in an aptamer research lab, I’m regularly approached by companies and researchers from all around the world for technical help with their aptamer selections. It seems to me that there has been a demand for aptamers-on-demand for quite some time and it is delightful to see it is finally becoming a reality!
“Compared to aptamers selected through SELEX protocol, X-Aptamers generated through this kit demonstrated much higher affinity to their target molecules on our platform.”
“Using the prototype kit we were able to select nanomolar affinity X-Aptamers to a target candidate biomarker of Tuberculosis disease…that we failed to raise DNA aptamers to via conventional SELEX procedures and we believe that the chemical modification of the X-Aptamer library was key to this success.”
“The ease of use [of the kit] allowed my undergraduate researchers to be able to skillfully perform the selection experiments, and we have since identified one of the putative aptamers identified as a success – this aptamer binds with low nanomolar affinity and is being used to generate an electrochemical biosensor platform for the detection of botulism.”