Scientist II – Cell Biology

Proteintech is a fast-growing Biotech company located in the greater Chicago area. Our Mission is to support our customers in all their endeavors, be it accelerating life sciences research and/or clinical diagnostics and therapies.

Proteintech is an international biotechnology company that manufactures antibodies, ELISA kits, and proteins for use in life science research. Proteintech makes all its own products to the highest standards possible, with complete control over the whole manufacturing, validation, and QC process. 200,000+ citations of Proteintech products demonstrates what matters most to the company: the success of its reagents in the hands of scientists, helping them make discoveries to change and explain the world around us.

We are seeking a Scientist II with proven expertise in large-scale mammalian cell culture and transient transfections to join our upstream protein production team. This role will support the expansion and optimization of scalable protein expression systems and will involve working with various cell lines under sterile conditions at both research and production scales. The ideal candidate will be highly organized, hands-on, and able to thrive in a collaborative, fast-paced environment.

• Execute and scale mammalian cell culture processes in shake flasks, spinner flasks, and bioreactors (up to 200L)
• Perform large-scale transient transfections (e.g., PEI, lipid-based) in suspension cell systems
• Monitor, maintain, and optimize cell growth, viability, and productivity
• Collaborate with downstream, assay development, and quality teams to support integrated project goals
• Maintain detailed records of experimental data, protocols, and process improvements
• Ensure compliance with lab safety, aseptic technique, and quality control standards
• Perform routine maintenance and calibration of bioreactors and other lab equipment
• Contribute to process documentation and assist with SOP development

• B.S. in Cell Biology, Biotechnology, Biochemical Engineering, or related field with 3–5 years of relevant experience in an academic or industry lab or M.S. with 2–4 years of experience working with mammalian cell culture and protein expression or PhD with experience in cell culture

• Demonstrated expertise in mammalian cell culture scale-up and transient transfection techniques
• Familiarity with HEK
  293 cell lines in suspension culture
• Experience with single-use bioreactor systems is highly desirable
• Strong foundation in cell biology, sterile technique, and protein production workflows
• Working knowledge of GMP guidelines and international quality standards
• Excellent organizational and documentation skills
• Strong communication skills, both verbal and written
• Proficiency in data analysis tools such as Excel; familiarity with Graph Pad Prism or equivalent statistical software is a plus
• Highly motivated, adaptable, and able to work independently as well as collaboratively

Proteintech group is an EEO/Affirmative Action Employer and does not discriminate on the basis of race, color, religion, sex, sexual orientation, gender identity, national origin, protected veteran status, disability or any other legally protected status.