## 3 Results  
A Mg\({}^{2+}\)-aided PILP process, as described in the methods section, was used to deposit smooth, continuous CaCO\({}_{3}\) shells onto the surface of oil-in-water emulsion droplets as well as aqueous liposomes. Light microscope images and polarized light microscopy (PLM) images of the core-shell microcapsules, created by PILP coating either oil-in-water emulsion droplets or liposomes, are shown in Figure 2A-D respectively. Coating the emulsion droplets resulted in products that were spherical CaCO\({}_{3}\) microcapsules with diameters of 2-10 \(\upmu\)m, which is slightly larger than the original, uncoated emulsion droplets (Figure 2A). Core-shell microcapsules created by coating liposome vesicles using the PILP process appear to be much smaller, with a diameter of less than 2 \(\upmu\)m (Figure 2C). This size is consistent with large liposomes, which are created by the ether-injection technique (-1 \(\upmu\)m in diameter), that have been coated with a mineral shell. As evidenced by the birefringent nature of the shells surrounding the emulsion droplets (Figure 2B) and liposomes (Figure 2D), the mineral shells appear to be crystalline. The presence of a \"Maltese Cross\" in the shell shown in Figure 2B, along with absence of birefringence in the center of the spheres, suggests a non-crystalline interior (presumably the n-dodecane fluid) with a surrounding shell composed of radially-oriented polycrystalline CaCO\({}_{3}\). Similarly, shells surrounding liposome-derived core-shells also display a birefringent coating surrounding a non-birefringent interior (Figure 2D), suggesting a crystalline core-shell structure. However, the presence of a \"Maltese Cross\" in the liposome-derived core-shells cannot be confirmed due to the resolution limit of the light microscopy technique. SEM images of the mineral coated particles are shown in Figure 3. Notably, these originally fluidic particles have been dried for SEM analysis. Microcapsules generated by emulsion coating and liposome coating, shown in Figure 3A,B, respectively, display smooth, continuous coatings. There is some polydispersity in diameter, indicating that the coating process appears to coat emulsion and liposome particles with different diameters. Although not a focus of the current work, one could presumably make use of syringe filters or centrifugation to isolate core-shells of a desired monodispersed diameter. Additionally, since variable diameter emulsions and liposomes appear to coat well, methods to generate monodispersed diameter emulsion or liposome substrates prior to coating may be a desirable approach to controlling the size of the core-shell product. A close-up image of a single emulsion microcapsule (Figure 4A) shows how smooth the surfaces of these particles are. Although there is a little bit of debris on the surface, we refer to this as smooth as compared to the alternative approach of nucleating crystals  
Figure 2: Light microscopy images of CaCO\({}_{3}\)-coated emulsion droplets and liposomes. (**A**) Brightfield light microscopy of coated emulsion droplets. (**B**) Polarized light microscopy (PLM) of the same particles shown in (**A**). The visible portion (due to birefringence) displays a “Maltese Cross” pattern, indicating the product is crystalline with radial alignment of the polycrystals. (**C**) Brightfield light microscopy of coated liposomes. (**D**) PLM of the product seen in (**C**). Although very small, the clear interiors of the particles can be seen, suggesting a crystalline core-shell structure has been achieved. on a Pickering template surface, which creates a surface composed of three-dimensional aggregates of rhombic calcite crystals [15]. The shell thickness of the coated emulsion microcapsules was determined by intentionally fracturing the microcapsules and obtaining SEM micrographs of the fractured shells.