Development of a microfluidic platform for the encapsulation of baker’s yeast Saccharomyces cerevisiae in alginate hydrogel microparticles

The encapsulation of cells in a semi-permeable polymer matrix enables the simulation of biochemical microenvironments for studying cellular response and interactions with minimal reagent use. Traditional methods often lack reproducibility, leading to variations in encapsulation quality. In contrast, microfluidic techniques can rapidly and consistently produce hydrogel microstructures encapsulating living cells. However, the fabrication of these devices remains challenging due to high initial costs and facility requirements. To address this, a microfluidic platform was developed using a CNC milling machine to enhance the accessibility of microfluidic-based cell encapsulation in hydrogel microstructures. A flow-focusing droplet generator was designed and employed to generate alginate-in-oil droplets containing baker’s yeast cells. The microfluidic device was fabricated from PMMA using CNC milling and sealed via solvent-assisted bonding, ensuring accessibility and ease of production compared to traditional lithography-based fabrication methods. The optimized system operated at a 400:4 oil-to-alginate phase flow rate, generating monodisperse alginate droplets at 10 Hz. The droplets were subsequently gelated in calcium chloride to form alginate microparticles. The resulting microparticles, averaging 164.14 ± 15.11 μm in the Feret diameter along the major axis, exhibited controlled morphology, with predominantly teardrop and oval shapes. Imaging confirmed the presence of multiple spherical-ovoid yeast cells within the resulting hydrogels, verifying successful encapsulation. The findings support the feasibility of using CNC-milled microfluidic platforms for controlled and reproducible yeast encapsulation in hydrogel matrices, demonstrating their potential for broader biological and biotechnological applications.