An Aqueous‐Compatible On‐Column Approach for the Conjugation of Nucleic Acids Using Amino Modifiers
Bibliographic record
Abstract
Nucleic acid conjugation has emerged as a powerful strategy for enhancing the chemical and biological versatility of synthetic oligonucleotides. Solid-support synthesis of oligonucleotides provides an avenue for nucleic acid conjugation, so long as the method is inherently compatible with the synthesis cycle. Many methods exist, post-synthetically (i.e., after strand extension via the DNA synthesizer), to add ligands to the strand while it is still bound to the solid support. These, however, tend to require stringent reaction conditions (i.e., anhydrous, degassed solvents, special apparatus), making them sometimes impractical for routine use. This article describes a streamlined aqueous-compatible on-column conjugation strategy for preparing nucleic acids containing site-specific chemical modifications. This method utilizes commercially available or easily synthesized monophosphate or carboxylate-containing ligands and solid-phase synthesized oligonucleotides containing amino-modified termini. Coupling is enabled by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-methylimidazole (N-MeIm) chemistry in buffered aqueous-organic mixtures. The resulting conjugates are processed using typical deprotection and solid-support cleavage protocols, purified by standard techniques such as strong anion exchange high-performance liquid chromatography (SAX-HPLC), and are characterized by mass spectrometry (MS). © 2025 The Author(s). Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Synthesis of zidovudine 5'-O-monophosphate Basic Protocol 2: On-column phosphoramidate-mediated conjugation of 5'-O-phosphorylated AZT to 5'-amino DNA Basic Protocol 3: On-column amide-mediated conjugation of Fmoc-protected glycine to 5'-amino modified DNA Basic Protocol 4: On-column amide-mediated conjugation of potassium benzoate to 5'-amino modified RNA.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.008 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".