An interview with Emily Kempa, Analytical Scientist, AstraZeneca

Picodroplet microfluidics, based on the encapsulation of single cells into picolitre-volume aqueous droplet reactors, is an actively evolving area of research with a wide variety of applications. The miniaturized and high throughput nature of picodroplet microfluidics makes it an ideal tool for rapidly screening large libraries and performing single-cell or single-molecule analysis. Additionally, these versatile technologies are primed for automation, capable of integrating with established analytical methods, including optical detection, mass spectrometry, Raman spectroscopy, and nuclear magnetic resonance. This multi-device integration offers a viable alternative to traditional well plate screening methodologies commonly used for sample handling and high-throughput screening

Novel high throughput screening platforms, such as Sphere Fluidics' ESI-MINE, which couples droplet microfluidics with mass spectrometry, illustrate the advantages of such integration. By enabling the rapid, accurate and direct identification of chemical targets compartmentalized within droplet reactors, and facilitating high-resolution mass and structural analysis, the technology's advanced analytical screening capabilities overcome a critical bottleneck that can arise in many research areas.

To learn more, we spoke with Emily Kempa, whose PhD focused on coupling droplet microfluidics and lab-on-a-chip methods to a range of different mass spectrometers for the high throughput analysis of synthetic biology targets.

Please note, that although Emily is now under employment by AstraZeneca, they are not affiliated with this work. Emily’s involvement in this project spanned her PhD studies and a 3-month innovation placement, both in collaboration with the University of Manchester, Sphere Fluidics Ltd, Waters Corp. and SYNBIOCHEM with funding provided by BBSRC.

Advancements in picodroplet driven mass spectrometry analysis

While the coupling of droplet microfluidics with mass spectrometry (MS) is not new, our 2020 publication presented chip-based interfaces that improve the usability and ease of coupling droplet microfluidics with different commercially available mass spectrometers (1). The advantage of this flexibility is that it enables simple integration into existing laboratory setups without extensive modifications, representing an important advancement in the commercialization of picodroplet driven mass spectrometry technology (Figure 1).

Leveraging the fast scanning acquisition software for Waters instruments, we obtained a 33 Hz MS scan rate, higher than that of any other commercial offering. Our ongoing research efforts aim to achieve infusion at a rate of 100 Hz through additional performance enhancements. These enhancements include altering the microfluidic channel dimensions and emitter specifications while improving the scanning acquisition software to allow for greater data gathering per droplet.

Figure 1. Diagram of a droplet microfluidic chip interfaced with the (A) Agilent Nanospray ESI source (B) Waters z-spray source (C) Thermo Fisher Q Exactive nESI source. 

Image source: Kempa, E. et al, Analytical Chemistry 2020 92 (18), 12605 12612.

Ongoing research efforts using droplets for rapid analytical processing

Sphere Fluidics, The University of Manchester and Waters Corporation are now collaborating to extend the capabilities of these integrated devices and expand access to new users of microfluidics technology. In doing so, the optimized design will overcome limitations in data processing and transfer speed to improve analytical throughput, as well as address challenges in working with predefined droplets, by integrating copper mesh into the biochip design to prevent droplet coalescence.

Testing our experimental workflows with researchers at MIB is invaluable to the development process, enabling the capture of user insights and requirements to feed into the design and development of the platform. Subsequently, groups within MIB's interdisciplinary research lab have already demonstrated the enabling potential of this technology. High throughput picodroplet-based screening is being utilized as a tool for identifying novel biocatalysts generated via directed evolution and protein engineering, examining the aggregation of different peptides involved in Parkinson's disease, and understanding more about the antibiotic resistance of bacteria (2,3). These results are promising considering the infancy of this technology, reinforcing the spectrum of applications that will benefit from this technology's rapid information-rich analysis.

References

1. Kempa, E., Smith, C., Li, X., bellina, bruno, Richardson, K., Pringle, S., & Barran, P. (2020). Coupling droplet microfluidics with mass spectrometry for ultrahigh-throughput analysis up to and above 30Hz.
2. Kempa, E., Galman, J., Parmeggiani, F., Marshall, J., Malassis, J., Fontenelle, C., Vendeville, J., Linclau, B., Charnock, S., Flitsch, S., Turner, N., & Barran, P. (2021). Rapid Screening of Diverse Biotransformations for Enzyme Evolution. JACS Au, 1(4), 508–516.
3. Morsa, D., Kempa, E., Stroganova, I., Piruska, A., Huck, W., Nghe, P., Szathmáry, E., Hordijk, W., Commandeur, J., Otto, S., & Rijs, A. (2019). Emerging life (emlife). Retrieved September 22, 2021, from https://phase1.attract-eu.com/showroom/project/emerging-life-emlife/.