Nitrilotriacetate (NTA) Oligo Conjugate

The ability to conjugate selectively through chemical modification is vital to biomedical research.  Nitrilotriacetic acid (NTA) is a chelating agent that forms a coordination complex with various metal ions including Co2+ and Cu2+.  The capacity of modified NTA to coordinate with Ni2+, allowing it to bind to His-tag, opened up opportunity in multiple biological applications (replacing the previously used iminodiacetic acid).  It greatly simplified the purification process of recombinant proteins with His-tag expressed in prokaryotic or other contexts (Li et al., 2012).  Using nanoparticles with immobilized NTAs, selective purification of His-tagged proteins was achieved (Kim et al., 2007).  To observe specific proteins in living cells, a membrane-permeable NTA-based fluorescent probe was developed that labeled His-tagged proteins in vivo to allow real-time visualization (Lai et al., 2015).  In the arena of DNA nanotechnology, which employs nucleic acids to self-assemble nanoparticles (Robert, 2011; Rothemund et al., 2006), His-tagged recombinant proteins were linked by functionalizing DNA with NTA groups (Goodman et al 2009).  For the diagnosis of thrombin, a microplate with immobilized DNA aptamers was developed, which was terminally hybridized to a NTA-oligonucleotide linked to a His-tagged reporter; upon binding of thrombin to the aptamer, the reporter is released, dampening the signals generated (Shimada et al, 2012).  Thus, NTA-modified oligonucleotides can be used for a wide range of applications.

Nitrilotriacetate (NTA) modified oligonucleotide has high affinity to His-tag on recombinant protein via the complexation of Ni2+. NTA modified oligo can be achieve by post-synthetic conjugation using a thiol functional group, dual HPLC purification is require. This modificaiton can be place at 5', 3' and internally using a DTSPA thiol modified base.