Understanding the process of self-organization within living cells is crucial for unraveling the mysteries of living matter. To study cellular self-assembly, researchers often employ water/oil or water/water droplets as prototypes that mimic cells. These models offer valuable insights, particularly in the field of biomedical research. However, the methods used to generate cell mimetics are complex, expensive, and time-consuming.
In a significant breakthrough, a team of researchers from Doshisha University recently developed a simplified one-step method for producing uniform gelatin-based cell mimetics known as "microgels." The results of their study were published in Small last month.
The microgel formation process begins by generating domain structures composed of polyethylene glycol (PEG) and gelatin, both commonly used synthetic crosslinkers. Lowering the temperature to 24°C facilitates the selective transition of the gelatin-rich domains into a gel phase. Under specific experimental conditions, the PEG-rich phase preferentially migrates to the glass surface of a capillary tube due to its higher affinity for glass and lower affinity for the gelatin-rich domains. As a result, the gelatin-rich droplets are enveloped by the PEG-rich phase. The researchers validated these findings through theoretical and numerical modeling studies using glass capillary experiments, which confirmed that the wettability of the inner surface of the glass capillary played a crucial role in the water/water phase separation.
Furthermore, the addition of DNA enabled the gelatin-rich droplets to spontaneously trap DNA molecules through the phase separation of PEG and gelatin, creating cell-mimicking microgels. The study also demonstrated that the incorporation of negatively charged DNA molecules stabilized the droplets, preventing their fusion even above the sol/gel transition temperature. By employing a fluorescent dye to label and track the encapsulated DNA, the researchers observed round microgel structures containing the illuminated DNA molecules through fluorescence microscopy. The authors anticipate that this novel approach can confine, store, and transport large DNA molecules within cell-sized droplets.
The study presents a novel and simplified method for producing gelatin-based cell mimetics, offering flexibility to tailor the technique according to specific applications. According to senior author Prof. Akihisa Shioi, "The method proposed in our study, which does not require special equipment, organic solvents, or surfactants, may prove useful for producing microgels used in food, medicines, cosmetics, and various materials."