Synthesis of micro-polymer capsules encasing living cells

Abstract

Many organisms have evolved to protect themselves from external stress by particular defensive sys-tem such as eggshells and bacterial endospore. Previous research has examined the formation of artificial shells which have resistance to adverse change. Living cells in artificial shells can behave depending on their innate character because artificial shells play a role of protector. There are several methods widely used to encapsulate cells such as Layer-by-Layer (LbL) techniques, microfluidic techniques, and mineralization. However, they have mainly focused on the single cell encapsulation. Otherwise, cells couldn’t move freely because they were immobilized in case of research about multicell encapsulation, Accordingly, it is necessary to encapsulate several living cells with free space in which individual cells move freely. In this study, we propose synthesis method of micro polyelectrolyte capsules encasing multiple living cells using both LbL assembly and mineralization. The combination of these two techniques enables living cells to be enveloped with sufficient free space. Through mineralization of $CaCO_3$, several living cells could be entrapped in $CaCO_3$. Negatively charged cell surface acted as the site of nucleation and growth of $CaCO_3$. Layer-by-Layer assembly performed onto $CaCO_3$ as sacrificial templates. The dissolution of $CaCO_3$ core resulted in the synthesis of polyelectrolyte shells containing several living cells with sufficient empty spaces. As a result, cell embedded $CaCO_3$ and polymer capsules encasing living cells were successfully synthesized. Through control of the concentration of $CaCO_3$ source and microalgae, the number of algae in the polymer shell and free space could be adjusted. In addition, different cells could be successfully encapsulated. Moreover, these capsules could be easily functionalized to respond to specific external stimuli by using nanomaterials. Consequently, cell could behave and prolife in the newly suggested capsules. These capsules also act as microenvironment to observe cell behaviors.