Scientist, Bioconjugation / Chemical Biologist

GT Biosciences is a seed-stage techbio startup building Deliveromics, the first AI-powered, high-throughput, multiplexed in vivo data engine for cracking the design rules of drug delivery. Founded by MIT PhDs and an MIT professor, backed by top-tier investors, we’re creating next-generation, non-viral, cell-type-specific delivery vehicles. We’re a small, fast-moving, science-obsessed team on a mission to make routine in vivo cell reprogramming possible. We’re a small, fast-moving, science-obsessed team on a mission to make routine in vivo cell reprogramming possible. We value transparency and collaboration, and seek teammates who thrive in an open, cooperative environment and want to grow together with the team and the company. Job Description: GT Biosciences is seeking a mission-driven, multidisciplinary Scientist in Organic Chemistry and Bioconjugation to join our Deliveromics Platform Development team. In this role, you will lead the design, synthesis, and characterization of novel ligands, linkers, and conjugates for targeted delivery applications. You will develop and optimize multi-step synthetic routes and bioconjugation strategies across a broad range of molecular formats, including oligonucleotides, peptides, proteins, lipids, small molecules, and other therapeutic payloads. You will work end-to-end, from molecular design and synthesis through purification, analytical characterization, formulation integration, and evaluation in cellular, mouse, and non-human primate studies. You will independently plan and execute experiments, troubleshoot complex chemistry challenges, analyze data, and clearly communicate results. As one of the earliest scientific hires at an emerging biotech, you will help shape our chemistry capabilities, collaborate closely with biologists, formulation scientists, and engineers, and contribute directly to the development of transformative delivery technologies. This is a full-time, in-person position based in Cambridge, MA. What success looks like: You establish a reliable chemistry engine that rapidly turns targeting concepts into purified, fully characterized conjugates ready for formulation and in vivo testing. Responsibilities: Own chemistry strategy and execution. Design and synthesize ligands, linkers, activated lipids, lipid-ligand constructs, ligand-payload conjugates, labeled standards, and other platform-enabling molecules. Drive multi-step organic synthesis. Lead route scouting, reaction optimization, troubleshooting, purification, and scale-up from milligram quantities toward gram-scale material. Develop bioconjugation methods. Create robust, chemoselective workflows for coupling small molecules and targeting ligands to oligonucleotides, peptides, proteins, antibodies or nanobodies, lipids, polymers, and nanoparticle components. Engineer linker properties. Optimize spacer length, valency, polarity, stability, release mechanisms, and reactive handles to balance potency, manufacturability, formulation behavior, and in vivo performance. Purify and characterize materials. Use HPLC/UPLC, LC-MS, NMR, UV/Vis, chromatography, and other fit-for-purpose methods to confirm identity, purity, loading, conjugation efficiency, stability, and batch consistency. Translate chemistry into delivery systems. Partner with LNP scientists, protein engineers, oligonucleotide scientists, cell biologists, automation engineers, and in vivo teams to incorporate new conjugates into formulations and screens. Support in vitro and in vivo studies. Deliver high-quality test articles for cellular assays, mouse studies, and NHP studies, and connect chemical attributes to biodistribution, uptake, pharmacology, and safety. Build scalable workflows. Develop SOPs, specifications, analytical release criteria, and technology-transfer packages; improve throughput through parallel chemistry, automation, and data-driven experimentation. Manage external execution and documentation. Coordinate CROs and vendors, maintain complete experimental records, follow appropriate EHS practices, and communicate results clearly in a fast-moving startup environment. Qualifications: PhD in organic chemistry, medicinal chemistry, chemical biology, polymer chemistry, pharmaceutical sciences, or a related field; or an MS/BS with substantial directly relevant industry experience. Strong hands-on experience in multi-step organic synthesis, reaction development, route optimization, purification, and structural characterization. Demonstrated expertise in bioconjugation or linker chemistry, including selection of reactive handles and chemoselective coupling strategies. Experience with analytical and preparative methods such as LC-MS, HPLC/UPLC, NMR, and chromatography used to establish identity, purity, and stability. Ability to work with both small molecules and biomolecules, including aqueous or mixed-solvent conditions and sensitive functional groups. Excellent experimental judgment, troubleshooting ability, attention to detail, documentation, and scientific communication. Resourceful, collaborative, and comfortable taking ownership in a small company with evolving priorities. Ability to work onsite five days per week at our Cambridge, MA laboratory. Preferred Qualifications: Experience conjugating oligonucleotides, peptides, proteins, antibodies, nanobodies, lipids, polymers, or other macromolecular systems. Experience with lipid chemistry, ionizable lipids, PEG-lipids, LNP components, or other non-viral delivery systems. Familiarity with amine, thiol, maleimide, oxime, hydrazone, strain-promoted click, tetrazine, enzymatic, or cleavable linker approaches. Experience with multivalent constructs, targeted nanoparticles, ligand-density studies, or structure-activity relationship campaigns. Experience developing analytical methods for conjugates, including loading, free ligand, aggregation, degradation, or release kinetics. Exposure to automated or parallel synthesis, design-of-experiments, in vivo biodistribution studies, CRO management, or early-stage biotech. Nice to have: Prior experience working with non-human primate models will be a strong plus. Experiences with drug delivery systems (lipid nanoparticles, polymer nanoparticles, AAV, etc.). Hands-on experience troubleshooting liquid-handling platforms or automated lab systems. What We Offer Competitive salary, meaningful equity ownership, and flexible, generous health benefits. The opportunity to build a core chemistry capability and shape an emerging delivery platform from an early stage. Close collaboration across chemistry, AI, protein engineering, formulation, automation, and in vivo biology. A small, ambitious team that values rigorous science, candid discussion, and rapid learning. Equal Opportunity Employer: GT Biosciences is an Equal Opportunity Employer. We celebrate diversity and are committed to fostering an inclusive, supportive environment for all employees. All qualified applicants will be considered without regard to race, color, religion, national origin, age, sex, marital status, ancestry, physical or mental disability, veteran status, gender identity, or sexual orientation. We don't expect anyone to know everything. We learn together, support each other, and get better every day! If you are ready to make an impact, we would love to hear from you. #J-18808-Ljbffr GT.Bio