Methods for Analysis of Oligonucleotide Drugs

Written by Carl Ascoli, PhD
May 28, 2026

Sequence-Independent Detection Workflows for ASO, siRNA, and mRNA Therapeutics

ModDetect® monoclonal antibodies provide sequence-independent tools for visualization, quantification, localization, and analysis of chemically modified oligonucleotide therapeutics across standard immunoassay workflows. This methods guide presents validated protocols for detecting antisense oligonucleotides (ASOs), siRNA, and related modalities in cell culture, tissue, and in vivo applications.


Overview

The rapid growth of RNA therapeutics has created increasing demand for analytical methods capable of accurately measuring oligonucleotide uptake, distribution, localization, metabolism, and pharmacodynamic activity across biological systems.

Traditional approaches such as LC-MS/MS, ligand binding assays (LBA), hybridization assays, qPCR, and radiolabeling remain foundational technologies for oligonucleotide characterization. These methods each offer distinct advantages in sensitivity or specificity, but are often constrained by sequence dependence, limited spatial resolution, workflow complexity, or challenges associated with probe design and labeling.

In many imaging workflows, fluorescent labeling strategies may alter oligonucleotide uptake or intracellular behavior, complicating interpretation of biological activity. Likewise, custom antibodies developed against individual ASO sequences are frequently limited to specific drug constructs and may not translate across broader therapeutic platforms.

ModDetect® antibodies were developed to address these limitations through sequence-independent recognition of chemically modified oligonucleotides.

 

Sequence-Independent Recognition of Therapeutic Oligonucleotides

Unlike sequence-specific detection methods, ModDetect® monoclonal antibodies recognize defined nucleic acid chemistries independently of oligonucleotide sequence. Individual antibody panels target common therapeutic modifications including:

  • Phosphorothioate (PS)
  • 2′-MOE
  • 2′-OMe
  • 2′-F

Because these modifications are broadly incorporated across oligonucleotide therapeutics, ModDetect® antibodies can detect multiple ASO, siRNA, and mRNA constructs sharing common chemical architectures.

This modification-specific approach enables:

  • Cross-platform detection capabilities
  • Reduced dependence on custom probe design
  • Compatibility with diverse oligonucleotide sequences
  • Multiplexed assay configurations
  • Visualization and quantification using standard immunoassay workflows

Applications in RNA Therapeutics Research

ModDetect® antibodies support a broad range of applications for oligonucleotide drug development and translational research, including:

  • ASO uptake studies Intracellular trafficking analysis
  • Tissue biodistribution
  • Comparative chemistry evaluation
  • Drug localization studies
  • Quantitative oligonucleotide analysis
  • Multiplexed detection workflows Sequence-independent screening assays