Microcarriers’ suspension and flow dynamics in orbitally shaken bioreactors

Abstract

In the present work an effort is made to determine the suspension speed of microcarriers in an orbitally shaken bioreactor of cylindrical geometry, and to assess the associated two-phase flow by means of Particle Image Velocimetry (PIV). Microcarrier technologies are commonly used in the bioprocess industry to culture adherent-dependent cells in three dimensional flow. Commercial GE Cytodex microcarriers were employed throughout this study to best mimic the flow conditions occurring in a bioreactor under standard operating conditions. Suspension speed measurements were obtained at different solid concentrations, that are typical for cell cultures, and for different combinations of orbital to cylinder diameters' ratio, d o /d i (c = 2.5-12.5 g/L; d o /d i = 0.2-0.7; N = 0-200 RPM). The current two-phase PIV results show that mean flow dynamics occurring in the cylindrical bioreactor are not significantly affected by the presence of the microcarriers, and that their suspension is directly associated to the flow transition reported by Weheliye et al. (2013). The flow scaling law included in their study can be successfully employed to predict the full suspension speed across bioreactors of different scales and working under different operating conditions (i.e. inner diameter of the cylinder, d i , orbital diameter, d o , and filling volume, V f).

Mixing Time in Intermediate‐Sized Orbitally Shaken Reactors with Small Orbital Diameters

“… for larger reactors ( d i = 10–125 cm) indicated that the Froude number ratio, Fr / Fr cr , is an effective scaling parameter for mixing time measurements in shaken cylinders under a wide range of operating conditions. The flow transition identified by the Froude number ratio was also found to accurately predict the full suspension speed of microcarriers across different bioreactor geometries (cylindrical vessels and flasks) and scales , . The two‐phase PIV study of Pieralisi et al.…”

“…The two‐phase PIV study of Pieralisi et al. demonstrated that the flow dynamics in the presence of GE Cytodex 3 microcarriers (∼400 μm after swelling) is only marginally affected by the solid phase with minimal slip velocity (≈ 0.02 πNd o ).…”

Towards modular bone tissue engineering using Ti–Co-doped phosphate glass microspheres: cytocompatibility and dynamic culture studies

“…In these preliminary studies, we sought to investigate whether mixing could enhance cell proliferation on the microspheres compared to static culture. In this work a microwell plate format reported, corresponding to a critical Froude number at which the transition occurs, and the analysis has been extended to two-phase flows in the presence of microcarriers 26 . While their work has been carried out using a well internal diameter d i = 10 cm (larger than the one employed in this study), the equations can be applied in first approximation to smaller systems to be able to calculate the critical speed at which transition occurs and predict the flow pattern inside the well.…”

CFD studies on hydrodynamic characteristics of shaking bioreactors with wide conical bottom

“…Rodriguez et al . and Pieralisi et al . designed orbital shaking bioreactors with conical bottoms aimed at maximizing microcarriers suspension, and their research showed that lower shaking frequency was required to achieve similar flow dynamics conditions in contrast with flat bottom bioreactors.…”

“…Li et al 11 and Liu et al 12 quantitatively investigated the key parameters of shake flasks and reported the advantages of efficient mass transfer and a distinctive shear property in baffled flasks compared with unbaffled flasks. Rodriguez et al 13 and Pieralisi et al 14 designed orbital shaking bioreactors with conical bottoms aimed at maximizing microcarriers suspension, and their research showed that lower shaking frequency was required to achieve similar flow dynamics conditions in contrast with flat bottom bioreactors.…”