Singh Seminar Series: Neha Srikumar and David Barth

Microsecond biochemical reactions via an integrated ESI-MS silicon and glass device

Speaker: Neha Srikumar

Abstract: Limitations in current microfluidic mixing technology typically allow for the sampling of protein hydrogen deuterium (H/D) exchanges only on millisecond to hour time scales. However, it has been well documented that select side chains and post-translational modifications on proteins undergo H/D exchanges on the microsecond scale. We have thus produced a microfluidic device capable of 1 𝜇s reagent mixing and 10 𝜇s to 1 ms post mix reaction times to study amino acids and peptides with fast exchanging sites. To account for back-exchange of deuterium for hydrogen in solution, we have also fabricated an in-built electrospray orifice to rapidly transition peptides to a gaseous, ionized state, thus preventing further reactions past specified exchange times and allowing for subsequent analysis via mass spectrometry.

About the Speaker: Neha Srikumar is a PhD candidate in the biochemistry, biophysics and chemical biology (BBCB) program here at the University of Pennsylvania, mentored by David Issadore and Benjamin Garcia (now at Washington University in St. Louis). Her past work prior to beginning her PhD has involved developing instrumentation and software for mass spectrometer based analysis of protein as well as tissue engineering work and microfluidics for organ-on-a-chip applications. For her PhD, she aimed to work at the intersection of microfluidics and proteomics to better sample preparation for structural proteomics assays. Separate from her thesis work, she has taken the time to teach and mentor students, training students in the Singh Center QNF cleanroom, as a teaching assistant, and helping out her lab mates doing interdisciplinary work. She hopes to expand her work in the future, using microfluidics to better improve other structural and dynamic proteomics techniques and has been awarded with a structural biophysics training grant fellowship and analytical chemistry fellowship for her work so far.

Choosing parameters for EBL

Speaker: David Barth

Abstract: Electron beam lithography (EBL) requires the optimization of many parameters including fracturing conditions, current, field size and traversal, shape handling, subfields, etc. Understanding how to begin managing all of these parameters to get the desired outcome can be daunting. In this talk, I will show how these decisions can be made as a process is developed and optimized, and how they might affect the lithographic results.

About the Speaker: David Barth is a Senior Manager in the QNF, responsible for lithography, process integration, and new process development. His background includes nanophotonic device fabrication, electron beam lithography, and process support on a variety of fabrication tools and techniques.
David has a Ph.D. from UC Berkeley and a B.E. and M.E. from Stevens Institute of Technology in Mechanical Engineering.