Senior Scientist, Protein Sciences

Company Overview: Strand Therapeutics is a clinical-stage biotechnology company pioneering programmable mRNA therapeutics to unlock the full potential of genetic medicines. Strand is applying its proprietary Signal Stack platform, which integrates EverScript circular RNA, AmpliScript self-replicating RNA, SignalPath targeted delivery, and logic-driven SignalLock genetic circuits to enable precise control of therapeutic activity across tissues and cell types and overcome foundational limitations in targeting, durability, and safety. Strand is advancing a pipeline with an initial focus on oncology and autoimmune disease. Its initial program, STX-001, an intratumorally delivered LNP-encapsulated self-replicating RNA expressing IL-12, has demonstrated preliminary evidence of systemic immune activation and anti-tumor activity in patients with advanced solid tumors who have progressed on prior therapies. Building on this early clinical validation, intravenously delivered STX-003 is designed for tumor-targeted expression and avoidance of off-target expression. STX-003, which is expected to enter the clinic in mid-2026, has the potential to be a major step forward for the fields of genetic medicine and oncology. Strand is also advancing STX-005, an in vivo CAR-T program designed to enable controlled, durable expression and repeat dosing. Founded by MIT synthetic biology pioneers, Strand has raised over $250 million and is headquartered in Boston, MA. Become the next standout single strand! Job Summary: Strand is seeking a highly motivated and innovative Senior Scientist of Protein Sciences to join our Platform Enabling Technologies team. This founding role will establish and lead protein science capabilities that enable the discovery, engineering, and validation of protein payloads, binders, and reagents for Strand’s programmable RNA medicines. Reporting to the Associate Director of Platform Enabling Technologies, the ideal candidate combines deep expertise in nanobody or antibody engineering, computational protein design, high-throughput protein purification and characterization, and enthusiasm for building new scientific functions while remaining active on the bench. This role integrates experimental protein sciences with AI-enabled design to discover and optimize antibodies, nanobodies, and other therapeutic proteins. Working closely with our computational biology, RNA biology, delivery, and translational teams, the scientist will define protein design criteria, lead experimental validation, and connect molecular attributes, including expression, folding, secretion, stability, activity, and developability as recombinant protein and following RNA delivery. Primary Responsibilities: • Establish and lead the Protein Sciences function by defining the scientific priorities, managing external vendors, selecting technology and instrumentation, and building workflows for binder discovery, protein engineering, production, and characterization. • Build antibody, nanobody, or other binder modalities & discovery capabilities that integrate computational modeling, library design/construction, display-based high-throughput screening, and downstream validation to discover and optimize single domain and other antibody-derived binders • Partner with Computational biology to develop an AI-enabled protein design platform by defining experimentally relevant design criteria, generating high-quality training and validation datasets, and testing model-generated candidates. • Lead binder discovery projects against therapeutically relevant targets by leveraging external partners and internal platform capabilities • Develop fit-for-purpose recombinant protein expression and purification workflows in in mammalian, yeast, and bacterial systems to support rapid design-build-test-learn cycles. • Establish biochemical, biophysical, and cell-based assays to evaluate binding kinetics, specificity, purity, stability, aggregation, activity, and developability. • Partner with RNA biology teams and delivery teams to optimize RNA-encoded proteins for translation efficiency, folding, intracellular trafficking or secretion, functional activity, duration of expression, and compatibility with the intended delivery modality. • Design orthogonal assays that distinguish RNA, delivery, and protein-level drivers of performance and use the resulting data to guide construct and formulation optimization. • Communicate data, risks, and recommendations clearly to multidisciplinary project teams and contribute to portfolio and platform strategy. Qualifications: • PhD with 2-5 years of experience, or B.S/M.S. with 7-10 years of experience in Biochemical Engineering, Biotechnology, Biochemistry, Molecular Biology, or a related scientific discipline. • Demonstrated expertise in nanobody or antibody discovery and engineering including library design, screening and production, humanization, affinity maturation, and experimental validation. • Demonstrated expertise in high-throughput recombinant protein expression, purification, and characterization from mammalian, yeast, and bacterial systems including cell culture, chromatography-based separations, and affinity/developability assays. • Proven track record of developing biologics as therapeutics and delivering on projects to enable programs to progress toward IND submissions. • Experience with advanced protein characterizations methods such as LC-MS, SEC-MALS, and SPR/BLI. • Strong understanding of ML/AI enabled protein design methodologies and the experimental validation of resulting designs. Direct, hands-on experience in deploying methods preferred. • Strong understanding of protein structure-function relationships, sequence–function relationships, and principles governing properties related to successful drug development including protein stability, activity, specificity, immunogenicity, and developability. • Experience integrating yeast or phage display, high-throughput screening and computational library design. • Experience analyzing complex experimental datasets and using quantitative approaches to guide subsequent protein engineering cycles. • Experience with protein conjugation and downstream purification and characterization a plus but not required. • Experience with building laboratory capabilities, managing external partners, or translating research workflows into development preferred but not required. • Experience with RNA biology, RNA delivery, lipid nanoparticles, or related delivery technologies is a strong plus, but not required for candidates with exceptional protein engineering expertise. • Ability to work effectively in a highly interdisciplinary environment and collaborate with scientists across RNA biology, LNP formulation, cell biology, computational biology, and analytical sciences. • Strong track record of scientific communication, including presenting complex data and conclusions to multidisciplinary teams. • Experience mentoring junior scientists and contributing to experimental strategy and technical direction. • A track record of scientific contributions through peer-reviewed publications, patents, or other evidence of technical innovation. Strand offers a fast-paced, entrepreneurial, team-focused small company environment. We also offer a top-notch benefits package (health, dental, life, open PTO, onsite lunch catering, commuter support and more) and work/life flexibility and integration. Being part of the Strand team allows you to become part of a small team that supports professional development while working together to meet Strand’s goals. Strand Therapeutics is an equal opportunity employer. We do not discriminate on the basis of race, color, gender, gender identity, sexual orientation, age, religion, national or ethnic origin, disability, protected veteran status or any other basis protected by applicable law. Strand does not accept unsolicited resumes from any source other than directly from candidates. Job Type: Full-time Salary: $132,000 - $142,000 annually plus bonus and equity incentives Pay Transparency Base Salary Range $132,000—$142,000 USD