For many cellular activities including escaping from toxins or acquiring nutrition, mobility is of significant importance. To mimic and study cellular motion, many strategies have been proposed. However, most reported motile systems cannot be applied to biological environments as either the moving objects or the environment media is not biocompatible, which confines their further applications. In this thesis, droplet-based cell-mimics were produced, of which the ability to acquire mobility and act as micro-reactors were separately demonstrated, shedding light in applying these cell-mimics to target delivery.
Firstly, a polyethylene glycol/dextran aqueous two-phase system and liposomes were used to produce liposome-stabilized droplets, i.e., droplet-based cell-mimics. The morphology and stability of these droplets were then studied systematically. It shows that liposomes locate at the droplet surface to form a coating preventing droplet coalescence. The stability of emulsion droplets are both influenced by liposome concentration and size, and higher concentration/larger size leads to better stability.
Secondly, a polymer gradient was introduced to the emulsion, which led to a concomitant interfacial tension gradient, inducing the Marangoni effect. Propelled by the Marangoni flow, droplets can achieve directional movement with the desorption of liposomes from droplet surface. These phenomena were explained by theoretical analysis.
Finally, photo-responsive liposomes were incorporated into the emulsion system to achieve the controllable release of substrate molecules from liposome lumen to droplet lumen, which enables the enzymatic reactions to occur in a controllable way within droplets. This result proves that the emulsion droplets hold the potential to work as functional carriers for biomolecules.