Senior Scientist, Organic & Oligonucleotide Chemistry

Sirius Therapeutics, Inc.; San Diego (CA); On-site; USD 120,000 - 180,000; Full time

Job summary

Sirius Therapeutics, Inc. in San Diego, CA, is seeking a Senior Scientist for Organic, Medicinal, and Oligonucleotide Chemistry to advance siRNA therapeutic programs.

You will design and synthesize modified nucleosides, phosphoramidites, linkers, and ligands, and integrate them into siRNA and related oligonucleotides for preclinical development. The role requires a PhD in a relevant chemistry field and hands-on expertise in synthetic organic chemistry, bioconjugation, and oligonucleotide

Qualifications

• PhD in organic, medicinal, pharmaceutical chemistry or related field with 3+ years of industry or postdoc experience.
• Strong hands-on expertise in synthetic organic chemistry and bioconjugation.
• Experience in building blocks for oligonucleotide modification or conjugation (modified nucleosides, phosphoramidites, linkers, conjugation handles).
• Understanding of oligonucleotide chemical modifications and their impact on nuclease stability, potency, PK, and safety.

Responsibilities

• Design and synthesize building blocks for novel oligonucleotide modifications (modified nucleosides, phosphoramidites, reagents for backbone modification).
• Design and synthesize lipids, targeting ligands, linkers, and conjugation handles.
• Incorporate modifications into siRNA and related oligonucleotides and assess nuclease stability, potency, pharmacokinetics, and safety.
• Synthesize, purify, and characterize siRNA and related oligonucleotides for discovery and preclinical development.
• Develop and optimize workflows for solid-phase oligonucleotide synthesis, bioconjugation, and purification; develop analytical methods (LC–MS, HPLC/UPLC, UV).
• Establish SAR for ligand-oligonucleotide conjugates; optimize ligand, linker, and conjugation to improve delivery.
• Contribute to platform development by exploring novel siRNA architectures and delivery approaches.
• Independently design experiments, troubleshoot, analyze data, and communicate findings to project teams.
• Maintain accurate records and contribute to reports, publications, and patent applications.
• Collaborate with cross-functional teams to advance programs toward candidate nomination.

Skills

Synthetic organic chemistry

Bioconjugation

Oligonucleotide modification

Analytical characterization

Independent experiment design

Education

PhD in organic/medicinal/pharmaceutical chemistry or related

Tools

Automated solid-phase oligonucleotide synthesis

Oligonucleotide bioconjugation

LC-MS

HPLC/UPLC

Job description

Sirius Therapeutics, Inc. in San Diego, CA, is seeking a Senior Scientist for Organic, Medicinal, and Oligonucleotide Chemistry to advance siRNA therapeutic programs.

You will design and synthesize modified nucleosides, phosphoramidites, linkers, and ligands, and integrate them into siRNA and related oligonucleotides for preclinical development. The role requires a PhD in a relevant chemistry field and hands-on expertise in synthetic organic chemistry, bioconjugation, and oligonucleotide