Senior Scientist, LNP Formulations

Company description

Serif Biomedicines is a privately held, early-stage biotechnology company developing a novel approach to gene therapy that can address currently untreatable diseases. It was founded by Flagship Pioneering, an innovation enterprise that conceives, creates, resources, and grows first-in-category life sciences companies.

Flagship Pioneering has created over 100 groundbreaking companies over the past twenty years, all of which are pioneering novel and proprietary biological, industrial, and engineering approaches to solve major needs in human health and sustainability. These companies include Moderna (MRNA), Syros Pharmaceuticals (SYRS), Seres Therapeutics (NASDAQ:MCRB), Generate Biomedicines, Tessera Tx, Evelo Biosciences (EVLO), and Indigo Agriculture.

The role

We are seeking a highly motivated Senior Scientist II with deep expertise in lipid chemistry to drive the design of novel ionizable lipids and the next generation of lipid nanoparticle (LNP) formulations for nucleic acid delivery. This role will focus on the rational design and synthesis of new ionizable lipids, the design of optimized LNP molar compositions, and the preparation of LNP formulations to screen and benchmark those new lipids.

This is an ideal opportunity for a chemist who wants to see their molecules move rapidly from the bench into functional LNPs, working at the interface of medicinal and organic chemistry, formulation science and delivery biology.

As a senior scientific contributor, this individual will be expected to operate with a high degree of independence, influence cross-functional program direction, and identify innovative solutions to advance platform capabilities. The role also includes mentoring junior scientists and contributing to the broader scientific strategy through internal leadership and external scientific engagement.

Key responsibilities

• Design and synthesize novel ionizable lipids, including head group, linker and tail variants, using structure-activity relationships and the pKa, biodegradability and tolerability profile of each series to guide design.
• Lead the design of LNP molar compositions, optimizing the ratios of ionizable lipid, helper lipid, cholesterol and PEG-lipid (and exploring alternative or novel excipients) for potency, stability and tolerability.
• Prepare LNP formulations at small scale (e.g., microfluidic or other mixing methods) to enable medium- to high-throughput screening of new lipids and compositions.
• Plan and conduct formulation screening studies, defining critical formulation parameters and building structure-property relationships across lipid libraries.
• Characterize lipids and LNPs using appropriate analytical methods (e.g., NMR, LC-MS, HPLC with CAD/ELSD, DLS, encapsulation and apparent pKa assays) and ensure lipid identity and purity.
• Collaborate with biology, analytical, process development and external partners to evaluate lead formulations in vitro and in vivo and feed results back into the next design cycle.
• Analyze and interpret experimental data, maintain detailed documentation, and communicate findings clearly to internal stakeholders.
• Mentor junior scientists and contribute to the scientific strategy and IP position of the delivery platform.
• Stay current with advancements in ionizable lipid chemistry, LNP technologies and nucleic acid delivery.

Professional experience and qualifications

• PhD. in Organic Chemistry, Medicinal Chemistry, Chemical Biology, Pharmaceutical Sciences or a related field, with 5+ years of relevant industry experience; or M.S. with 8+ years of experience.
• Strong background in multi-step organic synthesis, purification and structural characterization, ideally of lipids, amphiphiles or other delivery materials.
• Hands-on experience with LNP formulation (e.g., microfluidic mixing, nanoprecipitation) and an understanding of how lipid structure and molar composition drive potency, stability and tolerability.
• Experience designing and running formulation screens, including characterization by DLS, encapsulation assays and pKa determination.
• Experience with nucleic acid delivery (mRNA, DNA, siRNA) is highly preferred.
• Familiarity with lipid analytics (NMR, LC-MS, HPLC-CAD/ELSD) and with computational or data-driven approaches to lipid design is a plus.
• Demonstrated ability to design experiments, analyze data, and solve complex technical problems, with a record of innovation such as publications or patents.
• Strong communication and collaboration skills, and experience mentoring junior scientists.

What we offer

• Opportunity to work at the forefront of ionizable lipid and LNP innovation
• Collaborative, science-driven culture with high impact research
• Competitive compensation and benefits package

LOCATION: Cambridge, MA

ABOUT FLAGSHIP PIONEERING

Flagship Pioneering invents and builds platform companies, each with the potential for multiple products that transform human health, sustainability and beyond. Since its launch i