Scientist​/Senior Scientist, Assay Development - Molecular Assay Chemistry and Biophysics

Spear Bio, founded in 2021, is a well‑funded and rapidly growing biotech start‑up headquartered in Woburn, Massachusetts. Our proprietary technology,
Successive Proximity Extension Amplification Reaction (SPEAR), is a novel wash‑free immunoassay platform, offering unprecedented sensitivity. We are dedicated to revolutionizing early disease diagnosis and monitoring by providing scalable, ultrasensitive solutions that deliver unparalleled accuracy in measuring low‑abundant biomarkers, enabling clinicians and researchers to improve patient outcomes and advance global health.

Our Assay Development team builds assays for low‑abundant protein biomarkers that are challenging to measure using conventional approaches. We are seeking a creative, hands‑on scientist with strong fundamentals in chemistry, biophysics, and molecular interactions who enjoys solving difficult technical problems from first principles.

The Scientist / Senior Scientist will design, optimize, and troubleshoot innovative protein‑detection assays that integrate antibody‑based recognition, nucleic‑acid interactions, conjugation chemistry, reaction kinetics, and quantitative analytical methods.

We are looking for a scientist who genuinely enjoys troubleshooting. The ideal candidate is persistent, analytical, creative, and comfortable working through uncertainty. This person should be motivated by understanding the underlying mechanism and should thrive in a fast‑moving startup environment with high scientific standards.

The successful candidate will be comfortable investigating why an assay behaves unexpectedly, developing mechanistic hypotheses, designing discriminating experiments, and systematically improving assay sensitivity, specificity, robustness, and reproducibility.

We welcome applications from exceptional recent Ph.D. graduates and postdoctoral fellows with strong hands‑on research ownership, as well as startup and industry scientists who have demonstrated rapid growth in technical scope and responsibility. This role is based onsite in our lab in Woburn, MA 5 days/week.

• Design and develop ultrasensitive protein‑detection assays from concept through feasibility, optimization, analytical characterization, verification, and transfer.
• Develop and optimize antibody and protein‑reagent to maximize analytical and clinical performance, including antibody selection, protein structural properties, epitope‑pair assessment, conjugation chemistry, reagent purification, and stability evaluation.
• Troubleshoot assay‑performance issues, including low signal, nonspecific background, limited sensitivity, poor reproducibility, matrix effects, instability, and lot‑to‑lot variability, using a mechanistic understanding of binding kinetics, affinity, avidity, thermodynamics, steric effects, and molecular interactions.
• Design efficient experiments and use structured approaches, including design of experiments where appropriate, to identify root causes and optimize performance.
• Collaborate closely with Platform, Product Development, Operations, and Business Development teams to transition assays from feasibility through verification and transfer.
• Prepare clear scientific presentations, technical reports, study summaries, abstracts, and publications.

• Ph.D. in Chemistry, Analytical Chemistry, Biophysics, Chemical Engineering, Biochemistry, Bioengineering, Molecular Engineering, or a closely related field.
• Strong fundamental understanding of molecular interactions involving nucleic acids, proteins, or both.
• Experience with protein–protein and antigen–antibody interactions, including affinity, avidity, kinetics, and thermodynamics.
• Demonstrated hands‑on experience creating and designing immunoassays, protein‑detection methods, molecular‑diagnostics assays, or an innovative life‑science analytical platform.
• Strong experimental‑design and troubleshooting skills, with the ability to develop mechanistic hypotheses and test them efficiently.
• Demonstrated ability to work independently, analyze complex data, and make sound technical decisions. Evidence of…