Hydrogel-filled micropipette enables antifouling in vivo iontronic sensing

Iontronic sensors based on pipette-confined ion transport have attracted increasing interest, especially for single-cell and in vivo sensing. However, the design and construction of iontronic sensing interface to reduce non-specific adsorption of proteins remains a great challenge. Herein, we propose a hydrogel-filled micropipette strategy to develop the antifouling in vivo iontronic sensors. By rationally optimizing the species and mesh size of the hydrogel, the bovine serum albumin (BSA) hydrogel-filled micropipette exhibits excellent anti-swelling and antifouling performance towards multiple proteins with different charges. By combining the antifouling performance and pH responsiveness of BSA hydrogel, the pH iontronic sensor was developed, which shows excellent antifouling property for in vivo experiments. Based on these properties, the as-prepared sensor was successfully used for reliable pH sensing in the brain with physiological and pathological stimulation.