Seanbiron Johnson

Seanbiron Johnson

Biography

Seanbiron Johnson is a rising junior at UC Berkeley studying Mechanical Engineering
with a minor in Global Poverty & Practice. This is his second summer in MIT’s Summer
Research Program (MSRP), working in Professor Ritu Raman’s lab. His current project
functionalizes PDMS as a substrate to replace fibrin, improving optical clarity for the lab’s cell
imaging. In his first MSRP project, he built an optogenetic stimulator for 2D cantilever muscle
tissue and developed a MATLAB based displacement tracking pipeline. At Berkeley, he also
works with O’Connell’s lab. Seanbiron’s drive to pursue biomechanics stems from family
members who live with physical disabilities, shaping his commitment to restoring function for
people. That belief in STEM and social impact drives his work as founder of Defining Ghetto,
a storytelling platform amplifying untraditional paths to higher education, and as a Student
Observer representing students on the UC Regents Public Engagement Committee.

Functionalized PDMS as a Tunable Substrate for Skeletal Muscle
Tissue Engineering
Seanbiron Johnson1, Brandon Rios2, and Professor Ritu Raman2
1Department of Mechanical Engineering, University of California, Berkeley
2Department of Mechanical Engineering, Massachusetts Institute of Technology

Engineered skeletal muscle monolayers are commonly grown on fibrin, a protein gel valued
for supporting cell attachment. However, fibrin is mechanically weak. Imaging it well requires
removing the gel from its well plate and flipping it over, risking tissue damage. A substrate that
is transparent and sturdy enough to withstand handling would greatly improve how engineered
muscle is imaged and tracked over time. This project explores polydimethylsiloxane (PDMS),
a transparent, durable silicone, as an alternative to fibrin. PDMS was tuned to approximate the
stiffness of native muscle tissue. It was then coated with two surface treatments, polydopamine
plus matrigel and benzophenone plus matrigel, to support C2C12 myoblast growth, with fibrin
used as a comparison. PDMS is clear and stable enough to be imaged directly in place, without
removal or flipping. Mechanical testing confirmed the target PDMS stiffness. Cell viability
and imaging tests then compared the two coatings against fibrin to identify which best supports
muscle cell growth and alignment. When successful, this approach would offer a sturdier, more
easily imaged, tunable substrate for engineered muscle research. It could also support future
studies on muscle development, aging, and disease within the Raman Lab.