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

Abstract

The key challenge for the broad application of implantable biofuel cells (BFCs) is to achieve inorganicorganic composite biocompatibility while improving the activity and selectivity of the catalysts.W eh ave 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,C a 10 (PO 4 ) 6 (OH) 2 )a st he functional BFC cathode material. The NERBCs showed greatly enhanced cell performance with high electrocatalytic activity,s tability, and selectivity.T he NERBCs maintained the original biological properties of the natural cell, while enhancing the catalytic oxygen reduction reaction (ORR) through the interaction between À OH groups in HAP and the Hb in RBCs.They also enabled direct electron transportation, eliminating the need for an electron-transfer mediator,a nd showed catalytic inactivity for glucose oxidation, thus potentially enabling the development of separator-free BFCs.Enzyme biofuel cells (EBFCs) [1] have attracted considerable attention as micro- [2] or even nanoscale power [3] sources for implantable biomedical devices,s uch as cardiac pacemakers, [4] implantable self-powered sensors, [5] and biosensors for monitoring physiological parameters. [6] There are two types of EBFCs,w hich differ in the operating mechanism;n amely, mediated electron transfer (MET) [7] and direct electron transfer (DET) [8] EBFCs.M ET EBFCs rely heavily on redox mediators to shuttle electrons between biocatalytic active sites and electrode surfaces,w hereas DET EBFCs enable electron transfer from the enzyme active sites directly to the electrode. [9] In either case,t he other electrode (cathode) requires an oxygen-reduction catalyst, such as laccase [10] or bilirubin oxide (BOD), [11] to facilitate the oxygen reduction reaction (ORR). Unfortunately,i ng eneral, the current catalysts under investigation show very low catalytic performance as well as poor adhesion to the electrode surface. Such drawbacks drastically limit the practical application of EBFCs. [12] Although approaches such as electrode nanomodification, [1b] enzyme immobilization, [13] and redox-mediator addition [14] have been intensively investigated to facilitate electron transfer between enzymes and electrodes,t hey usually face some challenges,s uch as avoiding the deformation and inactivation of enzymes, [15] preventing nanotoxicity, [16] or improving the stability of the cell. [17] As is well-known, the biosafety of nanomaterials synthesized in vitro for long-term operation in the body,i no ther words,t he use of invasive, external, and foreign (relative to the nature of the cell) nanomaterials,i sc ontroversial, for many reasons,i ncluding their unexpected migration and accumulation. [18] Nanobioengineering, [19] which has already seen great success in the fields of medicine,agriculture,environment, and electronic systems offers ap otential opportunity to tackle these challenges.I n situ biomineralization [20] processes...

Enzymatic Biofuel Cell: Opportunities and Intrinsic Challenges in Futuristic Applications

“…Therefore, how to modify or protect enzyme catalysts in situ to maintain high catalytic activity and stability in vivo will be an essential practical consideration in the future development of implantable EBFCs. [ 34 ]…”

Construction of a Cascade Catalyst of Nanocoupled Living Red Blood Cells for Implantable Biofuel Cell

“…Nevertheless, the combination of bienzymes may result in a decrease in their activity, as the enzymes are likely to interfere with each other, or the severe leakage of enzyme catalysts due to the weak immobilization between the objective materials and the enzymes. − To address these obstacles, the idea of this work is to couple the living cells possessing electrocatalytic activity with the redox nanomaterials so as to form the cascade catalyst, thereby replacing the current bienzymes to catalyze the reduction of O 2 –H 2 O 2 . Recent studies have shown that the use of nanomaterials can protect cells, and the use of nanomaterials can regulate the performance of cells, , which has attracted more and more attention.…”

“…Our previous research has shown that red blood cells (RBCs) had the property of favorable electrocatalytic oxygen reduction reaction (ORR) and the characteristics of direct electron transfer (DET) with the electrodes . Based on this finding, nanopolydopamine (NPDA) is selected to couple with living RBCs on account of its versatile adhesion, biocompatibility, and biodegradability. − More to the point, NPDA shows catalase-like catalytic activity for the decomposition of H 2 O 2 ; thus, it is feasible to substitute dual enzymes with RBCs and NPDA to catalyze the cascade reaction of O 2 –H 2 O 2 .…”

“…18−21 To address these obstacles, the idea of this work is to couple the living cells possessing electrocatalytic activity with the redox nanomaterials so as to form the cascade catalyst, thereby replacing the current bienzymes to catalyze the reduction of O 2 −H 2 O 2 . Recent studies have shown that the use of nanomaterials can protect cells, 22 and the use of nanomaterials can regulate the performance of cells, 23,24 which has attracted more and more attention.…”

Laser-Scribed N-Doped Graphene for Integrated Flexible Enzymatic Biofuel Cells

“…On this basis, various substrate materials have been designed, such as nanomaterials, , conductive polymers, − and liquid metals . However, the fabrication process generally required additional lithographic or coating treatment of materials on a substrate electrode. , In addition, the developed EBFCs always suffered from the introduction of electron mediators. − However, the mediated electron transfer would result in high overpotential losses and low stability. , Therefore, the performance of the flexible EBFCs will be greatly improved if the aforementioned challenges are addressed.…”