Poster Y14 - Eukaryotic Cell-Inspired Capsules with Smart Compartments

Introduction: Organelles within eukaryotic cells have distinct functions, including lipid synthesis, energy generation, protein degradation, etc. Inspired by this compartmentalized architecture of the cell, we have developed multi-compartment capsules (MCCs) based on biopolymers (Figure 1A). These microscale MCCs have internal compartments, each capable of encapsulating distinct components and thereby performing specific functions. Here, we show that individual compartments can respond to specific stimuli and thereby exhibit “smart” responses. Moreover, we further show that the overall MCC can exhibit an “emergent” response arising from the interactions between the smart compartments.

Materials and

Methods: The MCC as well as its inner compartments were made by a microfluidic method. Microdroplets of the anionic biopolymer alginate were introduced into a reservoir containing multivalent cations and/or the cationic biopolymer chitosan. Upon incubation, microcapsules were formed. Thereafter, these microcapsules were combined and used as the feed within the same microfluidic device to create MCCs.

Results, Conclusions, and Discussions: An example of an MCC with “smart” inner compartments is shown in Figure 1B. Here, the MCC contains two compartments, one cross-linked with Fe3+ and the other with Ca2+. Upon exposure to UV light, only the Fe3+ compartment gets degraded. Thus, the stimulus (light) can selectively act on one of the compartments.

Next, we create an MCC that can show an “emergent” response, i.e., one that requires the interaction between the inner “organelles” (Figure 1C). The response in this case is chemiluminescence (CL) and it can be induced by a cascade reaction between reactants in the MCC. First, hydrogen peroxide (H2O2) is encapsulated within one organelle, and this organelle is covered by a shell of paraffin wax. Other reagents needed for the CL (luminol and hemoglobin) remain in the lumen of the MCC. When a stimulus, in this case heat, is applied, the wax melts, releasing the encapsulated H2O2. The released H2O2 thereby interacts with the other reagents and the result is the emission of light. Thus, the overall MCC shows CL even though none of the original reagents have this property. Moreover, the property of CL can be generated on-demand, i.e., as and when desired.

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