Fabrication of uniform-sized poly-ɛ-caprolactone microspheres and their applications in human embryonic stem cell culture

Abstract

The generation of liquefied poly-ɛ-caprolactone (PCL) droplets by means of a microfluidic device results in uniform-sized microspheres, which are validated as microcarriers for human embryonic stem cell culture. Formed droplet size and size distribution, as well as the resulting PCL microsphere size, are correlated with the viscosity and flow rate ratio of the dispersed (Q d) and continuous (Q c) phases. PCL in dichloromethane increases its viscosity with concentration and molecular weight. Higher viscosity and Q d/Q c lead to the formation of larger droplets, within two observed formation modes: dripping and jetting. At low viscosity of dispersed phase and Q d/Q c, the microfluidic device is operated in dripping mode, which generates droplets and microspheres with greater size uniformity. Solutions with lower molecular weight PCL have lower viscosity, resulting in a wider concentration range for the dripping mode. When coated with extracellular matrix (ECM) proteins, the fabricated PCL microspheres are demonstrated capable of supporting the expansion of human embryonic stem cells.

Tunable Volumetric Density and Porous Structure of Spherical Poly-ε-caprolactone Microcarriers, as Applied in Human Mesenchymal Stem Cell Expansion

“…Nonporous heavy PCL MCs (1.14 g/cm 3 ) were prepared as previously described. 36 36 consisted of a PTFE tubing and a 33G needle. These feeds were supplied with continuous and dispersed phases, using individual 20 mL syringes, mounted on a dual-rate syringe pump.…”

“…A previous study described the fabrication of solid PCL MCs using microfluidics to generate microspheres of uniform diameter. 36 These MCs bear some properties described above, with a smooth surface and a diameter in the optimal range of 100−200 μm. They are coated with a positive charge [poly-L-lysine (PLL)] to allow efficient cell attachment and an extracellular matrix (ECM) protein to allow efficient cell spreading.…”

“…49 These microspheres, fabricated using microfluidics, have a significant advantage of uniform size, ranging from microns to hundreds of microns. 36,51,52 The present article draws inspiration from earlier studies, 49,50 describing the fabrication of uniform-sized porous PCL microspheres from w/o/w emulsions formed using microfluidics and subsequently solidified by solvent extraction. The surface morphology and inner structure of the porous microspheres as well as their size, porosity, and overall density were probed as a function of process parameters: molecular weight of PCL, its concentration in dichloromethane (DCM) solvent, and the ethanol concentration during solvent extraction.…”

PLGA/chitosan–heparin composite microparticles prepared with microfluidics for the construction of hMSC aggregates

“…35 In droplet microfluidic technology, the design of the microchannels is important to the structure and stability of the generated microparticles. 36 Here, we applied a flow-focusing microchannel for the preparation of the P/C-h composite microparticles. The uniform P/C-h composite microparticles were fabricated due to the large shear stress of the microchannel (Fig.…”

Poly(α-hydroxy Acids)-Based Cell Microcarriers

“…for the homogenization of the particle size, and the batch-to-batch variation. An elegant method to overcome this problem is the use of microfluidic devices to generate polymer droplets that further solidify into uniform-sized microparticles [65][66][67]. Apart from synthetic polymers, this method has been satisfactorily exploited for the fabrication of natural polymer-based microparticles [68].…”