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Postdoctoral Fellow, Expanded Aptamer Technology

San Diego, California



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"At Sanofi, We are guided by a deep appreciation and understanding of what it means to live with a rare blood disorder, and we learn by listening to the community – patients, caregivers physicians, and other healthcare professionals."

Shannon Resetich US Head Rare Diseases & Blood Disorders

"Patients are at the center of all that we do at Sanofi. Our teams are focused on advancing transformational therapies that can address serious unmet needs for people living with rare blood disorders, and expanding global patient access to our medicines."

Mouhamed Gueye US Head Medical Rare Blood Disorders


Sanofi is pioneering the development of novel biological therapeutics. Aptamers are promising as candidate therapeutics, but their composite natural nucleotides restrict their physicochemical properties. As a member of the Synthorx Platform Innovation team, the successful postdoctoral researcher will work towards using the Synthorx expanded genetic alphabet (unnatural base pair) to evolve aptamers and aptamer-drug conjugates with desired properties beyond those available with the four natural nucleotides. Efforts will include the exploration of aptamers conjugated to therapeutic proteins to modify receptor recognition or to target the proteins to specific cells or environments. The position to which the aptamers are conjugated will be controlled by expressing the protein in the Synthorx semi-synthetic organism. The semi-synthetic organism harbors the unnatural base pair in its DNA and transcribes it into RNA and then uses it to translate proteins with non-canonical amino acids that enable biorthogonal coupling. Efforts will also include evolving aptamers with unnatural nucleotides that are used to site-specifically conjugate moieties of interest such that they are included in the evolution process itself. The postdoctoral researcher will also aid in the coordination, planning, and execution of existing and new collaborations with other groups within Sanofi to deploy the technology. Publication of results will be a priority.

Key Responsibilities:

  • Use the Synthorx semi-synthetic organism to express proteins with non-canonical amino acids at different positions.

  • Optimize biorthogonal reactions to site-specifically couple aptamers to the proteins.

  • Collaboratively evaluate the effects of targeting the therapeutic protein using in vitro assays and mouse models.

  • Design and create libraries of DNA where the unnatural base pair is used to attach small molecules, including drugs or ligands that bind a therapeutically interesting target, and then subject the library to multiple rounds of SELEX to evolve the aptamer-drug conjugate for optimal activity (specificity and affinity).

  • Collaboratively evaluate the aptamer-drug conjugates using in vitro assays and mouse models.

Basic Qualifications:

  • PhD in appropriate field

  • Experience with protein expression and/or biorthogonal chemistry beneficial.

  • Ability to work both independently and within a team.


  • Experience with SELEX (aptamer evolution)-preferred but not required

At Sanofi R&D North America, we deliver meaningful solutions for patients. We transform science into breakthrough, best-in-class and first-in-class medicines and vaccines. We believe in creating a diverse and inclusive workforce – and workplace – which brings together the collective brainpower of over 2,000 colleagues and provides you with an exciting place to grow and develop. We set the bar high, and we deliver. Join us and together we will build on our trusted legacy of breakthroughs for society. 

Sanofi Inc. and its U.S. affiliates are Equal Opportunity and Affirmative Action employers committed to a culturally diverse workforce. All qualified applicants will receive consideration for employment without regard to race; color; creed; religion; national origin; age; ancestry; nationality; marital, domestic partnership or civil union status; sex, gender, gender identity or expression; affectional or sexual orientation; disability; veteran or military status or liability for military status; domestic violence victim status; atypical cellular or blood trait; genetic information (including the refusal to submit to genetic testing) or any other characteristic protected by law.

As a healthcare company and a vaccine manufacturer, Sanofi has an important responsibility to protect individual and public health. All US based roles require individuals to be fully vaccinated against COVID-19 as part of your job responsibilities.

According to the CDC, an individual is considered to be “fully vaccinated” fourteen (14) days after receiving (a) the second dose of the Moderna or Pfizer vaccine, or (b) the single dose of the J&J vaccine. Fully vaccinated, for new Sanofi employees, is to be fully vaccinated 14 DAYS PRIOR TO START DATE.  



At Sanofi diversity and inclusion is foundational to how we operate and embedded in our Core Values. We recognize to truly tap into the richness diversity brings we must lead with inclusion and have a workplace where those differences can thrive and be leveraged to empower the lives of our colleagues, patients and customers. We respect and celebrate the diversity of our people, their backgrounds and experiences and provide equal opportunity for all.

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