酵素修飾ナノチューブ電極を用いた発電デバイスに関する研究

要約のみTohoku University西澤松彦課

Glucose-based Biofuel Cells: Nanotechnology as a Vital Science in Biofuel Cells Performance

Nanotechnology has opened up new opportunities for the design of nanoscale electronic devices suitable for developing high-performance biofuel cells. Glucose-based biofuel cells as green energy sources can be a powerful tool in the service of small-scale power source technology as it provides a latent potential to supply power for various implantable medical electronic devices. By using physiologically produced glucose as a fuel, the living battery can recharge for continuous production of electricity. This review article presents how nanoscience, engineering and medicine are combined to assist in the development of renewable glucose-based biofuel cell systems. Here, we review recent advances and applications in both abiotic and enzymatic glucose biofuel cells with emphasis on their “implantable” and “implanted” types. Also the challenges facing the design and application of glucose-based biofuel cells to convert them to promising replacement candidates for non-rechargeable lithium-ion batteries are discussed. Nanotechnology could make glucose-based biofuel cells cheaper, lighter and more efficient and hence it can be a part of the solutions to these challenges

Enhancing Student Usability of 3D Bioprinting

3D bioprinting is an emerging technology that is changing the face of tissue engineering through the ability to print cells, scaffolding and matrix materials, and other bioactive reagents. 3D bioprinters are a culmination of various scientific and engineering disciplines with respect to their operation and bioprints, and as such, offer a prime case study on the convergence of the technical fields in research. In order to capitalize on this fact and make 3D bioprinting more accessible for interdisciplinary education applications, we sought to translate 3D bioprinting into the classroom environment as a tool for education. In collaboration with SE3D Education, a start-up that manufactures affordable desktop 3D bioprinters, we designed biological array experiments and software that allows students to easily design and bioprint their own experiments using the SE3D R3bel Classroom 3D Bioprinter. Through extending the utility of a desktop 3D bioprinter into the hands of students, we hope to assist schools in administering interdisciplinary, hands-on instruction, and empowering students to become proficient in the next generation of technological tools

Development of 3D printed enzymatic biofuel cells for powering implantable biomedical devices

The drive toward device miniaturisation in the field of enzyme-based bioelectronics established a need for multi-dimensional geometrically structured and highly effective microelectrodes, which are difficult to implement and manufacture in devices such as biofuel cells and sensors. Additive manufacturing coupled with electroless metal plating enables the production of three-dimensional (3D) conductive microarchitectures with high surface area for potential applications in such devices. However, interfacial delamination between the metal layer and the polymer structure is a major reliability concern, which results in device performance degradation and eventually device failure. This thesis demonstrates a method to produce a highly conductive and robust metal layer on a 3D printed polymer microstructure with strong adhesion by introducing an interfacial adhesion layer. Prior to 3D printing, multifunctional acrylate monomers with alkoxysilane (-Si-(OCH3)3) were synthesised via the Thiol-Michael addition reaction between pentaerythritol tetraacrylate (PETA) and 3-mercaptopropyltrimethoxysilane (MPTMS) with a 1:1 stoichiometric ratio. Alkoxysilane functionality remains intact during photopolymerisation in a projection micro-stereolithography (PµSLA) system and is utilised for the sol-gel reaction with MPTMS post-functionalisation of the 3D printed microstructure to build an interfacial adhesion layer. This functionalisation leads to the implementation of abundant thiol functional groups on the surface of the 3D printed microstructure, which can act as a strong binding site for gold during electroless plating to improve interfacial adhesion. The 3D conductive microelectrode prepared by this technique exhibited excellent conductivity of 2.2×107 S/m (53% of bulk gold) with strong adhesion between a gold layer and a polymer structure even after harsh sonication and adhesion tape test, which offers potential to build a robust 3D conductive microarchitecture for applications such as biosensors and biofuel cells. As a proof-of-concept, the microelectrode with gold-coated complex lattice geometry was employed as an enzymatic glucose anode, which showed a significant increase in the current output compared to the one in the simple cube form. As the first approach, glucose oxidase was used as an enzyme. To find the optimal protocol for the enzyme immobilisation, the enzyme was first immobilised on agarose to achieve the enzyme’s highest activity and stability. Then, this immobilisation protocol was applied to immobilise the enzyme on the gold electrode surface. Preliminary studies on the preparation of 3D gold diamond lattice microelectrode modified with cysteamine and glucose oxidase as a bioanode for single cell enzymatic biofuel cell (EFC) application were performed, which demonstrated high current density of 0.38 μA cm–2 at 0.35 V in glucose solutions. This method for fabrication of 3D conductive microelectrodes offers potential for several biological applications. Instead of using a thiol, the surface of the 3D-printed part can be functionalised with different other functional groups to create an appropriate surface for biomolecules and cell adhesion. Furthermore, the surface of thiol functionalised printed parts can be perfect for additional metal coatings, opening the door to the creation of highly efficient and customised implantable energy harvesters and biosensors

Development of 3D printed enzymatic biofuel cells for powering implantable biomedical devices

The drive toward device miniaturisation in the field of enzyme-based bioelectronics established a need for multi-dimensional geometrically structured and highly effective microelectrodes, which are difficult to implement and manufacture in devices such as biofuel cells and sensors. Additive manufacturing coupled with electroless metal plating enables the production of three-dimensional (3D) conductive microarchitectures with high surface area for potential applications in such devices. However, interfacial delamination between the metal layer and the polymer structure is a major reliability concern, which results in device performance degradation and eventually device failure. This thesis demonstrates a method to produce a highly conductive and robust metal layer on a 3D printed polymer microstructure with strong adhesion by introducing an interfacial adhesion layer. Prior to 3D printing, multifunctional acrylate monomers with alkoxysilane (-Si-(OCH3)3) were synthesised via the Thiol-Michael addition reaction between pentaerythritol tetraacrylate (PETA) and 3-mercaptopropyltrimethoxysilane (MPTMS) with a 1:1 stoichiometric ratio. Alkoxysilane functionality remains intact during photopolymerisation in a projection micro-stereolithography (PµSLA) system and is utilised for the sol-gel reaction with MPTMS post-functionalisation of the 3D printed microstructure to build an interfacial adhesion layer. This functionalisation leads to the implementation of abundant thiol functional groups on the surface of the 3D printed microstructure, which can act as a strong binding site for gold during electroless plating to improve interfacial adhesion. The 3D conductive microelectrode prepared by this technique exhibited excellent conductivity of 2.2×107 S/m (53% of bulk gold) with strong adhesion between a gold layer and a polymer structure even after harsh sonication and adhesion tape test, which offers potential to build a robust 3D conductive microarchitecture for applications such as biosensors and biofuel cells. As a proof-of-concept, the microelectrode with gold-coated complex lattice geometry was employed as an enzymatic glucose anode, which showed a significant increase in the current output compared to the one in the simple cube form. As the first approach, glucose oxidase was used as an enzyme. To find the optimal protocol for the enzyme immobilisation, the enzyme was first immobilised on agarose to achieve the enzyme’s highest activity and stability. Then, this immobilisation protocol was applied to immobilise the enzyme on the gold electrode surface. Preliminary studies on the preparation of 3D gold diamond lattice microelectrode modified with cysteamine and glucose oxidase as a bioanode for single cell enzymatic biofuel cell (EFC) application were performed, which demonstrated high current density of 0.38 μA cm–2 at 0.35 V in glucose solutions. This method for fabrication of 3D conductive microelectrodes offers potential for several biological applications. Instead of using a thiol, the surface of the 3D-printed part can be functionalised with different other functional groups to create an appropriate surface for biomolecules and cell adhesion. Furthermore, the surface of thiol functionalised printed parts can be perfect for additional metal coatings, opening the door to the creation of highly efficient and customised implantable energy harvesters and biosensors

Applications and immobilization strategies of the copper-centred laccase enzyme : a review

DATA AVAILABILITY STATEMENT: No data was used for the research described in the article.Laccase is a multi-copper enzyme widely expressed in fungi, higher plants, and bacteria which facilitates the direct reduction of molecular oxygen to water (without hydrogen peroxide production) accompanied by the oxidation of an electron donor. Laccase has attracted attention in biotechnological applications due to its non-specificity and use of molecular oxygen as secondary substrate. This review discusses different applications of laccase in various sectors of food, paper and pulp, waste water treatment, pharmaceuticals, sensors, and fuel cells. Despite the many advantages of laccase, challenges such as high cost due to its non-reusability, instability in harsh environmental conditions, and proteolysis are often encountered in its application. One of the approaches used to minimize these challenges is immobilization. The various methods used to immobilize laccase and the different supports used are further extensively discussed in this review.The National Research Foundation (NRF) of South Africa.https://www.cell.com/heliyonChemical Engineerin

MEMBRANE-INTEGRATED AND MEMBRANE-FREE MICRO AND NANOFLUIDICS FOR ACCURATE MOLECULAR TRANSPORT IN BIOLOGICAL ASSAYS

Department of Mechanical EngineeringNanofluidics has a comparable characteristic length to the size of ions and biomolecules, so that it can be used as an efficient platform to conduct accurate biochemical assays/analyses. In particular, the nanofluidic elements are often embedded into microfluidics, forming integrated micro/nanofluidic networks for even more complex and systematic applications such as electrokinetic pumps, transistors, and energy convertors. Such innovative applications using unique mass-transport phenomena in micro/nanofluidic devices become available with the development of novel and precise nanofabrication techniques. For example, conventional nanolithography techniques such as electron or focused-ion beam lithography are used widely because of high degree of precision and accuracy of patterning. Another general nanofabrication method is micro-electromechanical system (MEMS)-based techniques that include both top-down (e.g., silicon etching) and bottom-up (e.g., thin-film deposition) approaches. However, it has been a challenge to fabricate the mixed-scale micro/nanofluidic devices by using either the conventional nanolithography utilizing the high-energy beams or the conventional MEMS-based nanofabrication because of the cost, time, throughput, and incompatibility issues of the methods. In particular, the limitations become more critical when both the microfabrication and the nanofabrication techniques need to be used in series to make micro/nano multi-scale structures. Therefore, an innovative alternate technique is specifically required to address the current weaknesses of both the conventional nanolithography and the MEMS-based nanofabrications. This dissertation describes novel and unconventional methods to fabricate mixed-scale micro/nanofluidic devices by integrating nanoporous hydrogels and ion selective membranes (ISMs) into microfluidic devices (membrane-integrated micro/nanofluidics). On the other hand, the micro/nanofluidic devices can be also fabricated by employing microfabricated ratchet structures that perform the same functions of a membrane, and by intentionally creating nanoscale cracks to produce nanochannels (membrane-free micro/nanofluidics). The dissertation???s early chapters deal with the development of novel nanomaterial-integrating methods to accurately control mass-transport phenomena at the micro/nanofluidic interfaces. A variety of hydrogel membranes are employed to enable pure diffusive or pure electrophoretic transport for accurate and active controls of chemical environments. In addition, ISMs are used to perform permselective ion transport for electrokinetic applications. The late chapters of this dissertation introduce membrane-free mixed-scale micro/nanofluidic devices that possess enhanced capabilities compared to the membrane-based devices, including higher precision and robustness in mass-transport controls, and higher compatibility with existing microfluidic components. First, an arrowhead-shaped ratchet microstructure in a microfluidic device physically compartmentalizes micron-sized bacterial cells but allows diffusion-controlled chemical environments without convective drag to the cells, which is commonly performed by a nanoporous membrane or a nanochannel. That is, the microfabricated ratchet structure acts the same function of a nanofluidic element without nanofabrication. Second, nanochannels and microchannels are fabricated simultaneously by an unprecedented cracking-assisted nanofabrication technique (called crack-photolithography) that relies only on a standard photolithography process. The crack-photolithography produces well-controlled micro/nanochannels in any desired shapes and in a variety of geometric dimensions, over large areas and with a high-throughput. Hence, mixed-scale micro/nanofluidic devices can be fabricated by the same technique that is used to fabricate a microchannel without additional nanofabrication processes and expensive equipment. Basically, the membrane-integrated and membrane-free micro/nanofluidic devices in this dissertation have the same mission, the transport control of biomolecules and chemical species to conduct biological assays in an accurate and high-throughput manner. As practical applications, the mixed-scale micro/nanofluidic devices are used for performing electrokinetic biosample pretreatments such as concentration and separation for ultra-sensitive and ultra-selective detection of target analytes such as proteins, particles and bacterial cells. In addition to the electrokinetic biomolecular/bacterial handling, the devices are also used for accurate characterizations of bacterial behavior such as chemotaxis and gene expression under convection-free and diffusion-controlled chemical stimulations. The role of a nanofluidic element such as a nanoporous membrane and a nanochannel array in microfluidics is essential to enable accurate and permselective transports of ions and molecules in various bioassays. In this context, the proposed membrane-based or membrane-free micro/nanofluidic devices play both microfluidic and nanofluidic functions without complicated nanofabrications, resulting in time-/cost-efficient and high-throughput fabrication. Thus, the research achievements in this dissertation substantially contribute to popularize and revolutionize the micro/nanofluidic systems and technologies, which have been hindered due to expensive and time-consuming conventional nanofabrications.ope

Engineering cytocompatible conducting polymers for bio-related energy applications

Portable, wearable and implantable medical devices (IMDs) can be used to solve various clinical problems such as monitoring of chronic diseases or artificial organ transplantation. Current available IMDs are generally powered by an energy source with a strong case for absolute encapsulation. It would be ideal to minimise the size and volume of the power source for users’ comfort by removing the strong case if the employed materials and by-products are safe for the body. In this thesis, two types of cytocompatible conducting polymers have been fabricated via facial chemical synthesis methods for use in bio-related energy sources that are capable of providing energy with the use of simulated body fluids. They are polypyrrole/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PPy/PEDOT) hydrogel and asymmetric polypyrrole (PPy) membrane. The demonstrated bio-related energy systems include a bioelectric battery and an energy harvesting system