In Situ Engineering of Intracellular Hemoglobin for Implantable High Performance Biofuel Cells.

The key challenge for the broad application of implantable biofuel cells (BFCs) is to achieve inorganic-organic composite biocompatibility while improving the activity and selectivity of the catalysts. We have fabricated nanoengineered red blood cells (NERBCs) by an environmentally friendly method by using red blood cells as the raw material and hemoglobin (Hb) embedded with ultrasmall hydroxyapatite (HAP, Ca-10(PO4)(6)(OH)(2)) as the functional BFC cathode material. The NERBCs showed greatly enhanced cell performance with high electrocatalytic activity, stability, and selectivity. The NERBCs maintained the original biological properties of the natural cell, while enhancing the catalytic oxygen reduction reaction (ORR) through the interaction between -OH groups in HAP and the Hb in RBCs. They also enabled direct electron transportation, eliminating the need for an electron-transfer mediator, and showed catalytic inactivity for glucose oxidation, thus potentially enabling the development of separator-free BFCs.