Serif Biomedicines | Cambridge, MA Senior Scientist, LNP Formulations

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 in 2000, Flagship has originated more than 100 companies. Many of these companies have addressed humanity most urgent challenges: vaccinating billions of people against COVID-19, curing intractable diseases, improving human health, preempting illness, and feeding the world by improving the resiliency and sustainability of agriculture. Flagship has been recognized twice on FORTUNE Change the World list, an annual ranking of companies that have made a positive social and environmental impact through activities that are part of their core business strategies and has been twice named to Fast Company annual list of the World Most Innovative Companies. Learn more about Flagship At Flagship, we accept impossible missions to enable bigger leaps. Our core values guide us through uncertainty and toward lasting impact. We are an equal opportunity employer. All qualified applicants will be considered for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability, protected veteran status, or any other characteristic protected by law. Privacy Notice for Applicants: When you apply for a role at Flagship Pioneering or one of its portfolio companies, we collect and use personal information you provide (such as your name, contact details, work history, and application materials) to evaluate your application, communicate with you, and comply with legal obligations. Your application data is processed through Greenhouse, our applicant tracking system, and may also be reviewed using AI-assisted screening tools. We do not sell your personal information. California residents have rights under the CCPA/CPRA including to know, delete, and opt out of the sharing of their personal information. If you are located in the EU or UK, we process your data under GDPR and you have rights to access, rectify, and erase your data. To exercise your rights or for questions, contact View email address on click.appcast.io. The salary range for this role is $126,000 - $181,500. Compensation for the role will depend on a number of factors, including a candidate’s qualifications, skills, competencies, and experience. Serif Biomedicines currently offers healthcare coverage, annual incentive program, retirement benefits and a broad range of other benefits. Compensation and benefits information is based on Serif Biomedicines's good faith estimate as of the date of publication and may be modified in the future. Privacy Notice for Applicants: When you apply for a role at Flagship Pioneering or one of its portfolio companies, we collect and use personal information you provide (such as your name, contact details, work history, and application materials) to evaluate your application, communicate with you, and comply with legal obligations. Your application data is processed through Greenhouse, our applicant tracking system, and may also be reviewed using AI-assisted screening tools. We do not sell your personal information. California residents have rights under the CCPA/CPRA including to know, delete, and opt out of the sharing of their personal information. If you are located in the EU or UK, we process your data under GDPR and you have rights to access, rectify, and erase your data. To exercise your rights or for questions, contact View email address on click.appcast.io. #J-18808-Ljbffr Flagship Pioneering, Inc.