Concentric glucose/O2 biofuel cell

Enzymatic Biofuel Cells: A Review on Flow Designs

Because of environmental concerns, there is a growing interest in new ways to produce green energy. Among the several studied applications, enzymatic biofuel cells can be considered as a promising solution to generate electricity from biological catalytic reactions. Indeed, enzymes show very good results as biocatalysts thanks to their excellent intrinsic properties, such as specificity toward substrate, high catalytic activity with low overvoltage for substrate conversion, mild operating conditions like ambient temperature and near-neutral pH. Furthermore, enzymes present low cost, renewability and biodegradability. The wide range of applications moves from miniaturized portable electronic equipment and sensors to integrated lab-on-chip power supplies, advanced in vivo diagnostic medical devices to wearable devices. Nevertheless, enzymatic biofuel cells show great concerns in terms of long-term stability and high power output nowadays, highlighting that this particular technology is still at early stage of development. The main aim of this review concerns the performance assessment of enzymatic biofuel cells based on flow designs, considered to be of great interest for powering biosensors and wearable devices. Different enzymatic flow cell designs are presented and analyzed highlighting the achieved performances in terms of power output and long-term stability and emphasizing new promising fabrication methods both for electrodes and cells.

Air bio-battery with a gas/liquid porous diaphragm cell for medical and health care devices

Powering future generations of medical and health care devices mandates the transcutaneous transfer of energy or harvesting energy from the human body fluid. Glucose-driven bio fuel cells (bio-batteries) demonstrate promise as they produce electrical energy from glucose, which is a substrate presents in physiological fluids. Enzymatic biofuel cells can convert chemical energy into electrical energy using enzymes as catalysts. In this study, an air bio-battery was developed for healthcare and medical applications, consisting of a glucose-driven enzymatic biofuel cell using a direct gas-permeable membrane or a gas/liquid porous diaphragm. The power generation characteristics included a maximum current density of 285μA/cm² and maximum power density of 70.7μW/cm² in the presence of 5mmol/L of glucose in solution. In addition, high-performance, long-term-stabilized power generation was achieved using the gas/liquid porous diaphragm for the reactions between oxygen and enzyme. This system can be powered using 5mmol/L of glucose, the value of which is similar to that of the blood sugar range in humans.

Hybrid microfluidic fuel cell based on Laccase/C and AuAg/C electrodes

A hybrid glucose microfluidic fuel cell composed of an enzymatic cathode (Laccase/ABTS/C) and an inorganic anode (AuAg/C) was developed and tested. The enzymatic cathode was prepared by adsorption of 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and Laccase on Vulcan XC-72, which act as a redox mediator, enzymatic catalyst and support, respectively. The Laccase/ABTS/C composite was characterised by Fourier Transform Infrared (FTIR) Spectroscopy, streaming current measurements (Zeta potential) and cyclic voltammetry. The AuAg/C anode catalyst was characterised by Transmission electron microscopy (TEM) and cyclic voltammetry. The hybrid microfluidic fuel cell exhibited excellent performance with a maximum power density value (i.e., 0.45 mW cm(-2)) that is the highest reported to date. The cell also exhibited acceptable stability over the course of several days. In addition, a Mexican endemic Laccase was used as the biocathode electrode and evaluated in the hybrid microfluidic fuel cell generating 0.5 mW cm(-2) of maximum power density.

Electropolymerized carbonic anhydrase immobilization for carbon dioxide capture

Biomimetic carbonation carried out with carbonic anhydrase (CA) in CO2-absorbing solutions, such as methyldiethanolamine (MDEA), is one approach that has been developed to accelerate the capture of CO2. However, there are several practical issues, such as high cost and limited enzyme stability, that need to be overcome. In this study, the capacity of CA immobilization on a porous solid support was studied to improve the instability in the tertiary amine solvent. We have shown that a 63% porosity macroporous carbon foam support makes separation and reuse facile and allows for an efficient supply and presentation of CO2 to an aqueous solvent and the enzyme catalytic center. These enzymatic supports conserved 40% of their initial activity after 42 days at 70 °C in an amine solvent, whereas the free enzyme shows no activity after 1 h in the same conditions. In this work, we have overcome the technical barrier associated with the recovery of the biocatalyst after operation, and most of all, these electropolymerized enzymatic supports have shown a remarkable increase of thermal stability in an amine-based CO2 sequestration solvent.

Functional assembly of a multi-enzyme methanol oxidation cascade on a surface-displayed trifunctional scaffold for enhanced NADH production

We report a simple and low-cost strategy that allows the sequential and site-specific assembly of a dehydrogenase-based multi-enzyme cascade for methanol oxidation on the yeast surface using the high-affinity interactions between three orthogonal cohesin-dockerin pairs. The multi-enzyme cascade showed 5 times higher NADH production rate than the non-complexed enzyme mixture, a result of efficient substrate channeling.