The research based on the use of GUVs as microreactors for synthesis of inorganic nanoparticles inside GUVs was firstly initiated in 2006, and reported officially in 2009 (Yang et al, 2009). To the best of our knowledge, the studies introducing similar approaches are scarce. Namely, a proposal concerning the possibility of using electroporation of GUVs in order to synthesize inorganic nanoparticles in the vicinity of the lipid membrane was made by Schelly (Schelly 2007). Thus, the breakthrough reported in 2009 is the first report on the use of GUVs as confined containers for performing the synthesis of inorganic semiconductor nanocrystals. Briefly, we succeeded in inducing, controlling and directly observing the formation of CdS quantum dots and nanoparticles in GUV, an artificial cell system whereby the membrane container remains intact. Our study, for the first time, extended confined vesicular reactions to micrometer-scale cell-size reactors for the synthesis of nanomaterials. Differently from the drastic experimental conditions used previously for the synthesis of nanoparticles in vesicles, the processes we employed in this report are quite simple and mild, and effectively mimic intracellular mixing and membrane fusion, which naturally occur in cells.