Protection of Electroactive Biofilm from Extreme Acid Shock by Polydopamine Encapsulation

Electroactive biofilm has a low tolerance for accidental shocks, such as extreme acid shock, which is a potential limitation for the application of bioelectrochemical systems (BESs), especially as a sensor for water quality monitoring. In this work, we encapsulated electroactive biofilms with biocompatible polydopamine (PDA) to protect against extreme acid shock. The bacterial cells were completely encapsulated in ∼50 nm films formed by PDA spheres, which protected their viability and current recoverability even after pH 0.5 and 1.5 shocks. The limiting current density of the PDA-encapsulated anode was 0.20 ± 0.05 A/m2, which was 1900% higher than that of the unprotected control (0.01 ± 0.01 A/m2) after strong acid shock (pH 0.5, 30 min). Without PDA encapsulation, the biofilm partly disintegrated with a thickness decreased by 68% from 72 to 23 μm, where 92% of the cells were dead. Our findings reported a novel and effective method for protecting electroactive biofilm under extreme conditions, which will greatly extend the use of BESs in the future.