TY - JOUR
T1 - Defining mass transfer in a capillary wave micro-bioreactor for dose-response and other cell-based assays
AU - Frey, L.J.
AU - Vorländer, D.
AU - Rasch, D.
AU - Meinen, S.
AU - Müller, B.
AU - Mayr, Torsten
AU - Dietzel, A.
AU - Grosch, J.-H.
AU - Krull, R.
PY - 2020
Y1 - 2020
N2 - For high-throughput cell culture and associated analytics, droplet-based cultivation systems open up the opportunities for parallelization and rapid data generation. In contrast to microfluidics with continuous flow, sessile droplet approaches enhance the flexibility for fluid manipulation with less operational effort. Generating biologically favorable conditions and promoting cell growth in a droplet, however, is particularly challenging due to mass transfer limitations, which has to be solved by implementing an effective mixing technique. Here, capillary waves induced by vertical oscillation are used to mix inside a sessile droplet micro-bioreactor (MBR) avoiding additional moving parts inside the fluid. Depending on the excitation frequency, different patterns are formed on the oscillating liquid surface, which are described by a model of a vibrated sessile droplet. Analyzing mixing times and oxygen transport into the liquid, a strong dependency of mass transfer on the oscillation parameters, especially the excitation frequency, is demonstrated. Oscillations at distinct capillary wave resonant frequencies lead to rapid homogenization with mixing times of 2 s and volumetric liquid-phase mass transfer coefficients of more than 340 h
−1. This shows that the mass transfer in a droplet MBR can be specifically controlled via capillary waves, what is subsequently demonstrated for cultivations of Escherichia coli BL21 cells. Therefore, the presented MBR with vertical oscillation mixing is a promising analytical tool to perform cellular assays and experiments in parallel with intensified and tailored mass transfer.
AB - For high-throughput cell culture and associated analytics, droplet-based cultivation systems open up the opportunities for parallelization and rapid data generation. In contrast to microfluidics with continuous flow, sessile droplet approaches enhance the flexibility for fluid manipulation with less operational effort. Generating biologically favorable conditions and promoting cell growth in a droplet, however, is particularly challenging due to mass transfer limitations, which has to be solved by implementing an effective mixing technique. Here, capillary waves induced by vertical oscillation are used to mix inside a sessile droplet micro-bioreactor (MBR) avoiding additional moving parts inside the fluid. Depending on the excitation frequency, different patterns are formed on the oscillating liquid surface, which are described by a model of a vibrated sessile droplet. Analyzing mixing times and oxygen transport into the liquid, a strong dependency of mass transfer on the oscillation parameters, especially the excitation frequency, is demonstrated. Oscillations at distinct capillary wave resonant frequencies lead to rapid homogenization with mixing times of 2 s and volumetric liquid-phase mass transfer coefficients of more than 340 h
−1. This shows that the mass transfer in a droplet MBR can be specifically controlled via capillary waves, what is subsequently demonstrated for cultivations of Escherichia coli BL21 cells. Therefore, the presented MBR with vertical oscillation mixing is a promising analytical tool to perform cellular assays and experiments in parallel with intensified and tailored mass transfer.
KW - Capillary waves
KW - Droplets
KW - k a
KW - Micro-bioreactor
KW - Mixing
KW - Oscillation
UR - http://www.scopus.com/inward/record.url?scp=85086452629&partnerID=8YFLogxK
U2 - 10.1016/j.bej.2020.107667
DO - 10.1016/j.bej.2020.107667
M3 - Article
SN - 1369-703X
VL - 161
JO - Biochemical Engineering Journal
JF - Biochemical Engineering Journal
M1 - 107667
ER -