Schematic showing programmed expulsion of a selected population of urease-containing colloidosomes from a segregated binary community immobilized in Janus-like hydrogel microspheres with Ca2+-crosslinked RITC-alginate (1, red) and unlabelled Ca2+-crosslinked alginate (75 wt %)/tyramine-alginate (25 wt %) (2, grey) domains (Vin,1:Vin,2=3 : 1). Urease- (dark grey) or FITC-GOx (green)-containing colloidosomes are immobilized in hemispheres 1 and 2, respectively at a urease : GOx-colloidosome number ratio of 6 : 1. Addition of urea, glucose and HRP disassembles the ionic crosslinks (small black bars) in both hemispheres due to carbonate production in 1 and subsequent diffusion into 2; simultaneously, H2O2production in 2 establishes tyramine covalent crosslinks (purple curvy lines) in domain 2. Consequently, the urease-containing colloidosomes are expelled over 20 h as region 1 is disassembled while the GOx/colloidosome population is retained in intact hemispheres of 2. HRP is added in excess and is in direct contact with the tyramine-alginate groups after diffusion into the microspheres.
