Endowing chloroplasts with artificial "cell walls" using metal-organic frameworks.

Biological photosynthesis via chloroplasts (CHs) is widely recognized as the most appropriate and effective way to convert solar energy and simultaneously supply nutrition to maintain life on earth. It of great interest to prepare CHs-based biohybrids which not only can artificially simulate photocatalytic functionality of CHs-containing plants and bacteria, but also can be easily prepared, long-term restored and conveniently utilized when needed. In this work, for the first time CHs were encapsulated into Metal-Organic Frameworks (MOFs), namely zeolitic imidazolate frameworks (ZIF-8), under very gentle reaction conditions, i.e. in aqueous solution and at room temperature. Without negative effects of organic solvent and high temperature in synthesis, the obtained CH@ZIF-8 biohybrids not only have shells maintaining the porous structure of ZIF-8, but also well preserve the biological activity of CHs inside. The porous ZIF-8 coating on CHs acts as a “cell wall” to allow mass and energy exchanges between CHs and environment, and protect CHs from microbiological degradation, which significantly prolong the lifetime of CHs in vitro (raised from several days to >300 days). The CH@ZIF-8biohybrids may have promising applications in “living” artificial leaves and even artificial trees capable of photosynthesis in the future.