Cell-laden hydrogel microcarriers are widely used in diverse biomedical applications like three-dimensional (3D) cell culture, cellular therapy, and tissue engineering, where microcarriers were generally produced by oil, which is the common but not optimal choice, as oil may cause cytotoxicity or protein denaturation. Here, an all-aqueous-phase microfluidics is presented to achieve oil-free emulsification of cell-laden microcapsules and 3D cell culture. Aqueous solutions with different concentration gradients are used as an immiscible continuous phase and a dispersed phase, and oscillation from a solenoid valve facilitates the formation of microcapsules at the water–water interface. By adjusting aqueous-phase flow rates and oscillating frequencies, core–shell microcapsules with controllable structures can be stably and continuously generated. In further 3D cell culture, encapsulated cells maintained good viabilities and aggregated together. These features show that the oil-free microfluidic method may have broad prospects in many biomedical applications.

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Despite recent advances in controlling ice formation and growth, it remains a challenge to design anti‐icing materials in various fields from atmospheric to biological cryopreservation. Herein, tungsten diselenide (WSe2)‐polyvinyl pyrrolidone (PVP) nanoparticles (NPs) are synthesized through one‐step solvothermal route. The WSe2‐PVP NPs show synergetic ice regulation ability both in the freezing and thawing processes. Molecularly speaking, PVP containing amides group can form hydrogen bonds with water molecules. At a macro level, the WSe2‐PVP NPs show adsorption‐inhibition and photothermal conversation effects to synergistically restrict ice growth. Meanwhile, WSe2‐PVP NPs are for the first time used for the cryopreservation of human umbilical vein endothelial cell (HUVEC)‐laden constructs based on rapid freezing with low concentrations of cryoprotectants (CPAs), the experimental results indicate that a minimal concentration (0.5 mg mL−1) of WSe2‐PVP NPs can increase the viabilities of HUVECs in the constructs post cryopreservation (from 55.8% to 83.4%) and the cryopreserved constructs can also keep good condition in vivo within 7 days. Therefore, this work provides a novel strategy to synergistically suppress the formation and growth of the ice crystalsfor the cryopreservation of cells, tissues, or organs.

A microfluidic platform that integrates precise temperature control and multi-oocyte capture is proposed for investigation of oocyte osmotic responses.