Figure 10.

(a) Demonstration of the transient acidic pH flip involving a tri‐layered system. While esterase embedded gel layer (middle) catalyzed the hydrolysis of ethyl acetate to acetic acid, urease encapsulated gel layer (bottom) converted urea to NH₃ and CO₂. (b) Change of pH with time in the supernatant layer (top) involving the tri‐layered system described in (a). (c) Change of pH with time in the supernatant layer when both the enzymes were encapsulated in a single gel layer. Reproduced with permission from Ref. [35]. Copyright © 2020 John Wiley and Sons.