Senior Scientist - Platform Development

Position Overview: We are seeking a Senior Scientist to help build and advance our peptide- and protein-based deliveryplatform. This is a hands-on platform development position with technical responsibilities acrossmolecular design, recombinant shuttle production, bioconjugation, and biophysical, biochemical, invitro, and in vivo characterization. The scientist will develop new capabilities, solve technicalproblems, and generate data that guides platform and program decisions. The ideal candidate is a creative, scientifically curious thinker who questions assumptions, proposesnew approaches, and adapts methods to unfamiliar problems. They enjoy working across disciplinesand will contribute wherever technical support is needed as the platform evolves. Responsibilitiesextend beyond biochemistry and assay development.

Key Responsibilities: Platform Development and Technical Problem Solving

• Identify technical gaps and develop experimental approaches, workflows, and tools that improvethe platform across discovery, molecule production, characterization, and delivery.
• Design hypothesis-driven experiments, test alternative approaches, and recommend practicalnext steps when results challenge current assumptions. Recombinant Shuttle Production
• Design expression constructs and produce, purify, and characterize recombinant shuttles, including VHHs, Fc fusion proteins, and recombinant peptide constructs, using appropriatemicrobial and/or mammalian expression systems.
• Optimize expression, folding, recovery, and purification workflows; assess protein quality, purity, aggregation, and stability using appropriate analytical methods. Small Scale Bioconjugation
• Perform and optimize small-scale conjugation of peptide or protein shuttles to oligonucleotidesor other payloads, including reaction setup, purification, and recovery.
• Characterize conjugates for purity, conjugation stoichiometry, residual free components, andretained binding and activity, using in-house methods and external analytical support asneeded.3210 MerryfieldSan Diego, CA 9212 Diaxis Therapeutics, Assay Development and Execution
• Develop, optimize, and run biochemical and biophysical assays to evaluate shuttle andconjugate binding, affinity, kinetics, selectivity, competition, and activity, using methods such asBLI, SPR, and plate-based assays.
• Develop flow cytometry assays to quantify cell-surface binding and internalization of shuttlesand conjugates, with controls and methods that distinguish surface-bound material frominternalized material. Develop cell-based functional assays to assess payload activity, including oligonucleotidemediated gene knockdown, and relate functional results to binding and internalization data. Establish assay conditions, controls, and performance criteria for screening, hit confirmation, and lead optimization. Troubleshoot assay variability, interference, and other technical challenges. Document methods and results clearly so assays can be reproduced and used acrossprograms. In Vivo Studies and Translation
• Provide technical support for the design, execution, and interpretation of in vivo studies withbiology colleagues and external partners, including pharmacokinetics, biodistribution, tissuedelivery, and functional activity.
• Support bioanalytical methods for shuttles and payloads in biological samples, and integrate invivo findings with biochemical, biophysical, and cell-based data to guide optimization. Screening and Hit Validation
• Support peptide and protein screening campaigns and follow-up testing of selected hits, including hits from display-based discovery programs. Confirm promising hits using orthogonal assays and appropriate counter-screens. Generate concentration-response, binding, competition, and selectivity data to support shuttleand conjugate optimization.
• Work with peptide chemistry and protein engineering colleagues to evaluate how sequencechanges, linkers, and conjugation affect molecular performance. Collaboration and Data Interpretation Analyze results, identify limitations, and recommend follow-up experiments. Partner with peptide chemistry, protein engineering, biology, and platform colleagues to ensureexperiments address key program questions.
• Coordinate with external partners on specialized conjugation and analytical characterizationneeds.