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 across molecular design, recombinant shuttle production, bioconjugation, and biophysical, biochemical, in vitro, and in vivo characterization. The scientist will develop new capabilities, solve technical problems, and generate data that guides platform and program decisions. The ideal candidate is a creative, scientifically curious thinker who questions assumptions, proposes new approaches, and adapts methods to unfamiliar problems. They enjoy working across disciplinesand will contribute wherever technical support is needed as the platform evolves. Responsibilities extend 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 practical next 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 appropriate microbial 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 oligonucleotides or other payloads, including reaction setup, purification, and recovery.
• Characterize conjugates for purity, conjugation stoichiometry, residual free components, and retained binding and activity, using in-house methods and external analytical support as needed.3210 Merryfield San Diego, CA 9212 Diaxis Therapeutics, Assay Development and Execution
• Develop, optimize, and run biochemical and biophysical assays to evaluate shuttle and conjugate binding, affinity, kinetics, selectivity, competition, and activity, using methods such as BLI, SPR, and plate-based assays.
• Develop flow cytometry assays to quantify cell-surface binding and internalization of shuttles and conjugates, with controls and methods that distinguish surface-bound material from internalized 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 across programs. In Vivo Studies and Translation
• Provide technical support for the design, execution, and interpretation of in vivo studies with biology colleagues and external partners, including pharmacokinetics, biodistribution, tissue delivery, and functional activity.
• Support bioanalytical methods for shuttles and payloads in biological samples, and integrate in vivo 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 shuttle and conjugate optimization.
• Work with peptide chemistry and protein engineering colleagues to evaluate how sequence changes, 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 ensure experiments address key program questions.
• Coordinate with external partners on specialized conjugation and analytical characterization needs.
• Present findings and recommendations in project meetings.
• Help improve shared assay workflows and mentor less experienced team members as appropriate.3210 Merryfield San Diego, CA 9212 Diaxis Therapeutics, Qualifications