EBF: ELEMENTS OF ROBUST MODIFIED OLIGONUCLEOTIDE EXTRACTION THROUGH SPE

Importance of the Topic

Therapeutic oligonucleotides require reliable extraction and quantification to support drug development and pharmacokinetic studies. Robust sample preparation ensures accurate measurement of both modified and unmodified sequences, guiding dosage optimization and safety assessment.

Study Objectives and Overview

This work evaluates a selective solid-phase extraction (SPE) approach for oligonucleotide recovery using mixed-mode ion-exchange sorbents. Key aims include screening sorbent batches, optimizing SPE conditions, and demonstrating reproducible extraction of reference oligos, including a 20-mer ssDNA and a lipid-conjugated antisense oligonucleotide (ASO).

Methodology

• Sorbent Screening and Sample Preparation

• Mixed-mode weak anion-exchange/reversed-phase cartridges tested with tyrosine, ssDNA 20-mer, and lipid-conjugated ASO standards.
• Rat plasma proteins digested under denaturing conditions using a proteinase K module to facilitate analyte release.

• Chromatographic Analysis

• Ion-pair reversed-phase UPLC-UV used to evaluate recovery before and after SPE (TEAA mobile phases, C18 column, 60 °C).
• IP-RP-LC-UV-MS on a BioAccord system for detailed mass confirmation of lipid-conjugated ASO (negative ion mode).
• Size exclusion chromatography (SEC) to verify complete plasma protein digestion.

Used Instrumentation

• Waters ACQUITY UPLC and Premier systems
• Oligonucleotide BEH C18 and SEC columns
• BioAccord with RDa detector
• RapiZyme Proteinase K digestion module

Key Results and Discussion

Batch screenings identified Oasis WAX sorbent lots delivering consistent six-analyte recoveries and high oligonucleotide extraction efficiency. UV profiles showed negligible matrix interference post-SPE. Mass spectra of lipid-conjugated ASO confirmed intact molecular mass (6047 Da) and minor oxidized species. SEC profiles demonstrated complete protein digestion within 40 minutes, ensuring clean extracts.

Benefits and Practical Applications

• Certified sorbent performance supports reproducible bioanalysis workflows.
• Reference standards (20-mer ssDNA and lipid ASO) enable method validation across laboratories.
• Applicable to pharmacokinetic and DMPK studies of emerging oligonucleotide therapies.

Future Trends and Opportunities

Advances may include tailoring sorbent chemistries for novel backbone modifications and expanding automation compatibility. Integration with high-resolution mass spectrometry and microfluidic platforms will further streamline oligonucleotide bioanalysis.

Conclusion

Selective mixed-mode SPE using certified Oasis WAX sorbent provides robust extraction of therapeutic oligonucleotides from biological matrices. Combined with UPLC-UV-MS and SEC assays, this workflow delivers reproducible results critical for drug development and regulatory compliance.

Reference

No references provided.