The first step towards the creation of artificial cells with bioPISA-derived micro-sized vesicles is to mimic the ability of cells to encapsulate macromolecules, particles and internal compartments 59 in order to create a complex environment in the lumen of the GUVs. In order to show that bio-PISA vesicles can encapsulate compounds with a range of different sizes, bioPISA reactions were run in the presence of 40 kDa FITC-labelled dextran, β-galactosidase (β-gal; 102 kDa), and fluorescent silica nanoparticles (Alexa405 SiO2 NP). The encapsulation efficiency (EE) of these cargoes, along with Mb that self-encapsulates, was ~85% for Mb, and decreased with the increase of the species' Rh to 60% for the silica nanoparticles (Figure ). CLSM imaging, which is limited by its resolution to the GUVs present in the mixture, showed that each of the fluorescent species was encapsulated into the GUVs (Figure ). Even fluorescent polystyrene microparticles (PS-μP FITC, Figure ) could be encapsulated, but they tended to clump together during bioPISA, some vesicles to be empty, and some to contain several particles. It should be noted that the GUV membrane was confirmed to be impermeable for macromolecules (Figure , Figure ), so that the GUVs would not lose their cargo once the vesicles have formed in bioPISA. The reaction also showed good compatibility with living cells (Figure , Figure ) and monomer consumption remained high regardless of the cargo in the reaction mixture, including bacteria (Figure ).