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Proceedings ArticleDOI

Bio-Nanobattery Development and Characterization

15 Aug 2005-

Abstract: A bio-nanobattery is an electrical energy storage device that utilizes organic materials and processes on an atomic, or nanometer-scale. The bio-nanobattery under development at NASA s Langley Research Center provides new capabilities for electrical power generation, storage, and distribution as compared to conventional power storage systems. Most currently available electronic systems and devices rely on a single, centralized power source to supply electrical power to a specified location in the circuit. As electronic devices and associated components continue to shrink in size towards the nanometer-scale, a single centralized power source becomes impractical. Small systems, such as these, will require distributed power elements to reduce Joule heating, to minimize wiring quantities, and to allow autonomous operation of the various functions performed by the circuit. Our research involves the development and characterization of a bio-nanobattery using ferritins reconstituted with both an iron core (Fe-ferritin) and a cobalt core (Co-ferritin). Synthesis and characterization of the Co-ferritin and Fe-ferritin electrodes were performed, including reducing capability and the half-cell electrical potentials. Electrical output of nearly 0.5 V for the battery cell was measured. Ferritin utilizing other metallic cores were also considered to increase the overall electrical output. Two dimensional ferritin arrays were produced on various substrates to demonstrate the feasibility of a thin-film nano-scaled power storage system for distributed power storage applications. The bio-nanobattery will be ideal for nanometerscaled electronic applications, due to the small size, high energy density, and flexible thin-film structure. A five-cell demonstration article was produced for concept verification and bio-nanobattery characterization. Challenges to be addressed include the development of a multi-layered thin-film, increasing the energy density, dry-cell bionanobattery development, and selection of ferritin core materials to allow the broadest range of applications. The potential applications for the distributed power system include autonomously-operating intelligent chips, flexible thin-film electronic circuits, nanoelectromechanical systems (NEMS), ultra-high density data storage devices, nanoelectromagnetics, quantum electronic devices, biochips, nanorobots for medical applications and mechanical nano-fabrication, etc.
Topics: Power module (63%), Electronics (57%), Electric power (56%), Nanoelectromechanical systems (54%), Distributed power (53%)

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Bio-Nanobattery Development and Characterization
Glen C. King
1
, Sang H. Choi
1
, Sang-Hyon Chu
2
, Jae-Woo Kim
3
, Gerald D. Watt
4
, Peter
T. Lillehei
1
, Yeonjoon Park
3
, and James R. Elliott
1
1
NASA Langley Research Center, Hampton, VA 23681
2
National Institute of Aerospace, Hampton, VA 23666
3
Science and Technology Corp., Hampton, VA 23666
4
Brigham Young University, Provo, UT 84601
Abstract
A bio-nanobattery is an electrical energy storage device that utilizes organic materials
and processes on an atomic, or nanometer-scale. The bio-nanobattery under development
at NASA’s Langley Research Center provides new capabilities for electrical power
generation, storage, and distribution as compared to conventional power storage systems.
Most currently available electronic systems and devices rely on a single, centralized
power source to supply electrical power to a specified location in the circuit. As
electronic devices and associated components continue to shrink in size towards the
nanometer-scale, a single centralized power source becomes impractical. Small systems,
such as these, will require distributed power elements to reduce Joule heating, to
minimize wiring quantities, and to allow autonomous operation of the various functions
performed by the circuit. Our research involves the development and characterization of
a bio-nanobattery using ferritins reconstituted with both an iron core (Fe-ferritin) and a
cobalt core (Co-ferritin). Synthesis and characterization of the Co-ferritin and Fe-ferritin
electrodes were performed, including reducing capability and the half-cell electrical
potentials. Electrical output of nearly 0.5 V for the battery cell was measured. Ferritin
utilizing other metallic cores were also considered to increase the overall electrical
output. Two dimensional ferritin arrays were produced on various substrates to
demonstrate the feasibility of a thin-film nano-scaled power storage system for
distributed power storage applications. The bio-nanobattery will be ideal for nanometer-
scaled electronic applications, due to the small size, high energy density, and flexible
thin-film structure. A five-cell demonstration article was produced for concept
verification and bio-nanobattery characterization. Challenges to be addressed include the
development of a multi-layered thin-film, increasing the energy density, dry-cell bio-
nanobattery development, and selection of ferritin core materials to allow the broadest
range of applications. The potential applications for the distributed power system include
autonomously-operating intelligent chips, flexible thin-film electronic circuits,
nanoelectromechanical systems (NEMS), ultra-high density data storage devices,
nanoelectromagnetics, quantum electronic devices, biochips, nanorobots for medical
applications and mechanical nano-fabrication, etc.

Introduction
Bio-nanobatteries will function as distributed power sources within an electrical circuit,
unlike currently utilized central power storage systems. The bio-nanobattery can be
made as a flexible thin film and incorporated into a fabric or made to conform to various
applications, even incorporating power harvesting devices for recharging the bio-
nanobattery. The ferritin-based bio-nanobattery may also be biocompatible, depending
on the core materials. They are lightweight, have a high energy density, and because of
their size, can function as a chip scale power source. This characteristic will make
possible a smart chip, able to operate autonomously. Bio-nanobatteries will have
numerous applications, including flexible thin-film electronic circuits, ultra-high density
data storage devices,
4
nanoelectromagnetics,
5
quantum electronic devices,
6
biochips,
nanorobots for medical applications and mechanical nano-fabrication, nanomechanical
devices, etc.
Ferritins, naturally occurring iron storage proteins, are necessary for the biological
mechanisms of humans, animals, and even bacteria, and may contain up to 4,500 Fe
+3
atoms. Ferritins consist of 24 monomer subunits arranged in a spherical shell with an
outer diameter of about 12.5 nanometers and an inner diameter of around 7.5 nanometers
(Figure 1).
7
They form a stable and robust structure able to withstand biologically
extremes of high temperature (up to 80 °C) and pH variations (2.0-10.0).
8
Both 3-fold
and 4-fold channels in the organic shell allow for the transport of ions and molecules,
making electron conduction through the ferritin shell possible. Research conducted at
Brigham Young University indicates that naturally occurring HEME groups of
bacterioferritins should facilitate electron transport through shell.
Using the reconstitution process of site-specific biomineralization, ferritins may be
loaded with different core materials within the protein shell.
8
Core materials are
incorporated into the ferritin shell with the addition of an oxidant (see Figure 2).
Replacing the naturally occurring iron core using this reversible reaction, ferritins for the
bio-nanobattery can be tailored according to redox capability. Ferritins with cobalt and
manganese cores have already been made for the bio-nanobattery, as well as ferritins with
other core materials for extended applications.
Fe-ferritins and Co-ferritins were used for a unit cell of the bio-nanobattery. In the
absence of chelators at pH = 7.0, the Fe(OH)
3
iron core of ferritins undergoes reversible
reduction to produce a stable Fe(OH)
2
core, while all 4500 iron atoms remain within the
ferritin interior. Redox reactions between ferritin with different core materials involve the
transfer of an electron from a donor to an acceptor ferritin (Figure 3). We have found
that the half-cell potential of Fe-cored ferritins, -400 mV, and the Co-cored ferritins, 1000
mV, indicates that a cell having a 1.4V potential is possible. The charge density per gram
exceeds that of both the “D cell” and “button battery.”
2

Spin coating, dipping, and LangmuirBlodgett deposition were utilized in producing
ferritin arrays for incorporating into the bio-nanobattery. Spin coating, a quick and
simple process for producing a flat and uniform layer, relies on air drag and centrifugal
force, the layer thickness controlled by viscosity and spinning speed. The dipping
method also produces a thin ferritin layer by physical adsorption on substrates, the
thickness controlled by process time and solution concentration. LangmuirBlodgett
deposition is accomplished through monolayer adsorption at the air/water interface.
9,10
With proper surfactant selection, it can form highly ordered ferritin monolayers. The
surface pressure of the protein layer controls the film thickness. Figure 4 shows
integration of the thin-film bio-nanobattery with a photovoltaic component for high
capacity, high efficiency, compact size, and flexible applications.
Experimental and Result
Ferritins were purified through size exclusion chromatography and de-mineralized
through a reduction process to make apo-ferritin, ferritins without a core material. Co
ferritin was synthesized by adding Co
2+
to apo-ferritin in the presence of H
2
O
2
.
11
Similarly, ferritins can be reconstituted with other metallic cores. Ferritin arrays were
fabricated using cationized Ferritin, enabling a strong electrostatic attraction to the
negatively charged Si substrate.
The spin self-assembly (SSA) deposition method
12
was used to produce Ferritin arrays on
various substrates. Depositing successive layers of ferritins on silicon substrates formed
the arrays, redox charge transfer chains. The total output current and voltage can be
tailored by selecting either serial or parallel connection of the pairs. Examination of the
layer structure was accomplished using scanning probe microscopy (SPM), while the
magnetic properties of the ferritin with metallic cores allowed a magnetic force
microscopy (MFM) tip to be used. SPM images show the 2-D ferritin arrays to be
smooth and uniform, suggesting that the SSA deposition method will produce fast,
reliable arrays for the bio-nanobattery.
Stability tests of Co-ferritin indicate that most of the cobalt(II) remains bound to Co-
ferritin (>90%) for extended time periods, demonstrating the stability of the Co(OH)
2
mineral phase within the ferritin interior. Figure 5 shows the reduction of Co
3+
to Co
2+
in
Co-ferritin at 350 nm. The absorbance decreases with the reduction of the cobalt core as
ascorbic acid (a 2 electron donor) is added, until it becomes stable when all Co
3+
-ferritin
is reduced to Co
2+
-ferritin. This result shows that 1.85 Co
3+
are reduced per ascorbic acid
added. An electrochemical cell was also used for coulometric reduction measurements,
showing that 1.10 e/Co was taken up during the electrolysis of Co
3+
-ferritin. The
reduction equilibrium and the reduction kinetics of both Co-ferritin and Mn-ferritin were
also examined. Preliminary results showed that an equilibrium condition between the M
II
and M
III
core material was achieved. The reduction kinetics show a reduction of core
material with time. Results indicate that the manganese reduces much faster than the
cobalt.
3

The mechanism of electron conduction through the protein shell is a key factor to
determine power density, maximum discharge rate, and duty cycle life of bio-nanobattery
cell units. Figure 6 illustrates the results of a dynamic redox reaction between Fe
2+
-
ferritin and Co
3+
-ferritin. A chelating agent was added to the solution containing ferrous
ions. The remaining Fe
2+
is indicated by the decrease in absorbance at 511 nm as the
redox reaction takes place, corresponding to the remaining Fe
2+
in the solution. The
reaction reached an equilibrium state after 4 min, with the absorbance around 0.07. The
initial reaction increased significantly when a piece of gold foil was added to Fe-Co
solution, with a corresponding decrease in the absorbance. This result indicates that the
presence of gold expedites electron transport from Fe
2+
to Co
3+
, and that the mechanism
of electron conduction through the protein shell is a key factor to determine power
density, maximum discharge rate, and the duty cycle life of bio-nanobattery cell units.
Two methods may be employed to determine electron transport in ferritins. The first
involves conductivity measurement of a single ferritin cell using an AFM tip (Figure 7).
A single ferritin cell element is isolated on a positively charged gold substrate. Electrical
current applied through the ferritin cell with the AFM tip is then measured. The
mechanism of electron transport may be either electrons hopping over the cell surface
(electron avalanche?) or electron tunneling through the ferritin cell. The current-voltage
(I-V) curves for holo-ferritin (with core material) and apo-ferritin (without core material)
indicate that Fowler Nordheim tunneling may be the mechanism of electron transport in
the ferritin cell unit. As Figure 8 depicts, the tunneling barrier height is larger for apo
than holo ferritin. Note that the apo-ferritin has no current flow when 0.5 volts is applied,
while the holo-ferritin begins to conduct electrons. The electron conduction is influenced
by the presence of a core material, suggesting that electron tunneling may be the
mechanism of electron transport. Another possible method for conductivity measurement
involves measuring a DC current through a nonconductive substrate, both with and
without a 2-D ferritin array. The number of ferritins sandwiched between electrodes can
be approximated to estimate the conductivity of a single ferritin.
Summary
The bio-nanobattery will enable distributed power storage systems, making more
flexibility in circuit design. Characterization of Fe-ferritin and Co-ferritin indicate that
they would be good candidates for the bio-nanobattery half cell units. Reconstituting
ferritins with other metallic core materials having a higher redox potential may improve
the power density of the bio-nanobattery. Two-dimensional arrays of ferritins were
successfully fabricated on silicon substrates using the spin self-assembly deposition
method. Improving the electron transport and using multilayered ferritin arrays and
ferritins with other core materials may improve the bio-nanobattery performance.
Acknowledgement
This work was partially supported under NASA grants NCC-1-02005 and NCC-1-02043
to the National Institute of Aerospace and Brigham Young University. Related research
4

performed under contract to Science and Technology Corporation was also utilized in this
work.
Figures
Figure 2. Ferritin reconstitution
Fi
g
ure 3. Bio-nanobatter
y
unit cell
Figure 1. Ferritin protein shell
Figure 4. Integration of bio-nanobattery cell
Time (min)
024681012141618
Absorbance (at 511 nm)
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
0.22
With gold
Without gold
Figure 6. Absorbance change of Fe
2+
-
chelates as a function of reaction time.
Figure 5. Reducing power of Co-ferritin
5

Citations
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01 Jan 1996
Abstract: A novel system has been used to manufacture nanoparticulate Cu:Pt with an average diameter of 8nm and very small standard deviation. The system uses a protein called ferritin that normally stores iron in viva, but this iron can be chemically removed. The hollow protein can then be used to grow Co:Pt nanopmicles which are subsequently heat treated to promote a particular crystalline phase. The femtin can be deposited onto a substrate where it naturally self assembles into an HCP monolayer under appropriate conditions. If the protein is then carbonised or otherwise removed, a regular HCP close packed array of 8nm Co:Pt particles is left. The theoretical storage densit of a thin film exploiting the patterned qualities of the HCP arrangement is 4.5 Tbitshu , Work is presented regarding the development of a magnetic thin film media based on these processes.

5 citations


References
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Journal ArticleDOI
Pauline M. Harrison1, Paolo Arosio2Institutions (2)
TL;DR: A great deal of research effort is now concentrated on two aspects of ferritin: its functional mechanisms and its regulation and the apparent links between iron and citrate metabolism through a single molecule with dual function are described.
Abstract: The iron storage protein, ferritin, plays a key role in iron metabolism. Its ability to sequester the element gives ferritin the dual functions of iron detoxification and iron reserve. The importance of these functions is emphasised by ferritin's ubiquitous distribution among living species. Ferritin's three-dimensional structure is highly conserved. All ferritins have 24 protein subunits arranged in 432 symmetry to give a hollow shell with an 80 A diameter cavity capable of storing up to 4500 Fe(III) atoms as an inorganic complex. Subunits are folded as 4-helix bundles each having a fifth short helix at roughly 60° to the bundle axis. Structural features of ferritins from humans, horse, bullfrog and bacteria are described: all have essentially the same architecture in spite of large variations in primary structure (amino acid sequence identities can be as low as 14%) and the presence in some bacterial ferritins of haem groups. Ferritin molecules isolated from vertebrates are composed of two types of subunit (H and L), whereas those from plants and bacteria contain only H-type chains, where ‘H-type’ is associated with the presence of centres catalysing the oxidation of two Fe(II) atoms. The similarity between the dinuclear iron centres of ferritin H-chains and those of ribonucleotide reductase and other proteins suggests a possible wider evolutionary linkage. A great deal of research effort is now concentrated on two aspects of fenitin: its functional mechanisms and its regulation. These form the major part of the review. Steps in iron storage within ferritin molecules consist of Fe(II) oxidation, FE(III) migration and the nucleation and growth of the iron core mineral. H-chains are important for Fe(II) oxidation and L-chains assist in core formation. Iron mobilisation, relevant to ferritin's role as iron reserve, is also discussed. Translational regulation of mammalian ferritin synthesis in response to iron and the apparent links between iron and citrate metabolism through a single molecule with dual function are described. The molecule, when binding a [4Fe-4S] cluster, is a functioning (cytoplasmic) aconitase. When cellular iron is low, loss of the [4Fe-4S] cluster allows the molecule to bind to the 5′-untranslated region (5′-UTR) of the ferritin m-RNA and thus to repress translation. In this form it is known as the iron regulatory protein (IRP) and the stem-loop RNA structure to which it binds is the iron regulatory element (IRE). IREs are found in the 3′-UTR of the transferrin receptor and in the 5′-UTR of erythroid aminolaevulinic acid synthase, enabling tight co-ordination between cellular iron uptake and the synthesis of ferritin and haem. Degradation of ferritin could potentially lead to an increase in toxicity due to uncontrolled release of iron. Degradation within membrane-encapsulated ‘secondary lysosomes’ may avoid this problem and this seems to be the origin of another form of storage iron known as haemosiderin. However, in certain pathological states, massive deposits of ‘haemosiderin’ are found which do not arise directly from ferritin breakdown. Understanding the numerous inter-relationships between the various intracellular iron complexes presents a major challenge.

2,311 citations


"Bio-Nanobattery Development and Cha..." refers background in this paper

  • ...5 nanometers (Figure 1).(7) They form a stable and robust structure able to withstand biologically extremes of high temperature (up to 80 °C) and pH variations (2....

    [...]


Journal ArticleDOI
Abstract: This work was supported by the Ministry of Education through the Brain Korea 21 Program at Seoul National University and by the National Program for Tera-level Nano-devices of the Ministry of Science and Technology as one of the 21st century Frontier Programs as well as by the Korean Ministry of Science and Technology (MOST) under Grant 99-07. X-ray reflectivity experiments performed at the Pohang Light Source (PLS) were supported in part by MOST and POSCO. We are very grateful to S.-H. Lee, H. Kang, J. Koo, and B. H. Seung for their assistance during the X-ray reflectivity experiments.

402 citations


Journal ArticleDOI
Ichiro Yamashita1Institutions (1)
Abstract: A new process is proposed which exploits protein-supramolecules as scaffolds for producing inorganic, functional nano-structures on a flat surface, and its feasibility is studied. A two-dimensional array of iron-oxide loaded ferritin molecules formed by self-assembly at an air/water interface is transferred onto a hydrophobic Si surface and the protein shell of the ferritin molecule is eliminated by 1 h heat-treatment at 500°C under nitrogen. Scanning electron microscopy (SEM) shows a well-ordered array of nanometer size dots on the Si surface. Atomic force microscopy (AFM) in contact mode indicates that the protein shell is eliminated by the heat-treatment, leaving only the iron cores. Fourier transform IR spectrophotometer (FTIR) analysis and weight measurements also indicate that the protein is selectively removed. From this result, together with the fact that ferritin molecules have the ability to accommodate various kinds of metals and metal complexes, it is feasible that nano-dot arrays suitable for quantum electronic devices can be fabricated by this method, which, in this paper, is called a ‘Bio Nano Process’. This newly proposed method will provide more economic mass-production than any other method.

286 citations


"Bio-Nanobattery Development and Cha..." refers background in this paper

  • ...LangmuirBlodgett deposition is accomplished through monolayer adsorption at the air/water interface.(9,10)...

    [...]


Journal ArticleDOI
Trevor Douglas1, Victoria T. Stark1Institutions (1)
TL;DR: The empty protein cage of ferritin has been used to synthesize and entrap nanoscale particles of a green cobalt oxide via oxidative hydrolysis of Co(II) by H2O2, and the resulting composite material retains the properties of the protein while incorporating the characteristics of the encapsulated mineral.
Abstract: The empty protein cage of ferritin has been used to synthesize and entrap nanoscale particles of a green cobalt oxide via oxidative hydrolysis of Co(II) by H2O2. The resulting composite material retains the properties of the protein while incorporating the characteristics of the encapsulated mineral. The visible absorption spectrum has a broad band at 350 nm and the IR spectrum shows a band at 587 cm-1 characteristic of the cobalt oxyhydroxide Co(O)OH.

266 citations


"Bio-Nanobattery Development and Cha..." refers background in this paper

  • ...Co ferritin was synthesized by adding Co to apo-ferritin in the presence of H2O2.(11) Similarly, ferritins can be reconstituted with other metallic cores....

    [...]

  • ...Co ferritin was synthesized by adding Co2+ to apo-ferritin in the presence of H2O2....

    [...]


BookDOI
01 Jan 1999
Abstract: Nanostructure science and technology now forms a common thread that runs through all physical and materials sciences and is emerging in industrial applications as nanotechnology. The breadth of the subject material is demonstrated by the fact that it covers and intertwines many of the traditional areas of physics, chemistry, biology, and medicine. Within each main topic in this field there can be many subfields. For example, the electrical properties of nanostructured materials is a topic that can cover electron transport in semiconductor quantum dots, self-assembled molecular nanostructures, carbon nanotubes, chemically tailored hybrid magnetic-semiconductor nanostructures, colloidal quantum dots, nanostructured superconductors, nanocrystalline electronic junctions, etc. Obviously, no one book can cope with such a diversity of subject matter. The nanostructured material system is, however, of increasing significance in our technology-dominated economy and this suggests the need for a series of books to cover recent developments. The scope of the series is designed to cover as much of the subject matter as possible – from physics and chemistry to biology and medicine, and from basic science to applications. At present, the most significant subject areas are concentrated in basic science and mainly within physics and chemistry, but as time goes by more importance will inevitably be given to subjects in applied science and will also include biology and medicine. The series will naturally accommodate this flow of developments in the sciences and technology of nanostructures and maintain its topicality by virtue of its broad emphasis. It is important that emerging areas in the biological and medical sciences, for example, not be ignored as, despite their diversity, developments in this field are often interlinked. The series will maintain the required cohesiveness from a judicious mix of edited volumes and monographs that while covering subfields in depth will also contain more general and interdisciplinary texts. Thus the series is planned to cover in a coherent fashion the developments in basic research from the distinct viewpoints of physics, chemistry, biology, and materials science and also the engineering technologies emerging from this research. Each volume will also reflect this flow from science to technology. As time goes by, the earlier series volumes will then serve as reference texts to subsequent volumes.

251 citations


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