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JANUARY 2011 EXAMINATION IN CHEMISTRY
The attached text is a description of an invention that I just received from the
inventors.
Please draft a complete patent application based on the attached text. In case of lack
of unity you may specify in a footnote that certain group/groups of claims might be
subject of a restriction requirement once the examination will start. In such case
please explain in brief how you would take care of the restriction requirement.
This draft is to be sent to the inventor and may contain requests for additional data,
questions, clarifications etc.
As this is the inventor's first patent application, please write a short paragraph before
the claims explaining your protection strategy, what you attempt to achieve by the
claims. Although such a paragraph is not part of the formal application it will help the
inventor understand the reasoning of the protection.
GOOD LUCK
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LETTER FROM THE INVENTOR
As you are aware, we have substantial interests, through a joint venture, in energy
storage devices such as supercapacitors and batteries. Our present invention relates to
a new method of forming improved electrodes by the use of peptide raw materials.
The method was successfully applied to modification of carbon electrodes and the
capacitance of the modified electrodes is much higher than that for the unmodified
electrodes. Our method starts from cheap precursors and involves a minimum number
of steps. On the following pages we have described our process in more detail.
Please prepare a patent application based on this information. Copy of what we think
is the closest prior art is provided at the end of the description.
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DESCRIPTION
Our invention relates to a new method of manufacturing electrodes, and, more
specifically, to electrodes characterized by high surface area. The electrodes obtained
by our new method are especially useful in energy storage devices such as
supercapacitors and batteries.
The electrodes are formed by a new technological approach which is based on
coating of the electrodes (for example carbon electrodes) by elementary peptide
building blocks in the form of discrete nanocrystals (NC) of nanometer size using
various coating technologies.
The coating may be carried by known methods such as adhesion technology or
vapor deposition. In the adhesion technique, the adhesion occurs from a colloidal
solution of discrete peptide nanocrystals. For example, an electrode can be immersed
into a solution which contains the discrete nanocrystals thus allowing adherence of the
discrete nanocrystals to the surface of the electrode.
In another coating method, the coating employs vapor deposition of the
discrete peptide nanocrystals onto the surface of the electrode. Vapor deposition (VD)
refers to a process in which materials in a vapor state are condensed through
condensation, chemical reaction or conversion to form a solid material. VD is used to
form coatings to alter the mechanical, electrical, thermal, optical, corrosion resistance,
and wear properties of the coated substrates, as well as to form free-standing bodies,
films, and fibers and to infiltrate fabric to form composite materials. VD processes
typically take place within a vacuum chamber, and are classified into two process
categories: physical vapor deposition (PVD) and chemical vapor deposition (CVD).
Our surprising findings relate to the formation of high surface area electrodes
by the use of peptide nanocrystals e.g. peptide quantum dots. Our electrodes are
different from those obtained when peptide self-assembled nanostructures such as
nanotubes, nanospheres or nanowires are used. The following Fig. 1 shows the
difference between peptide quantum dots used in our experiments vs the known use
of peptide self-assembled nanostructures as described in US-2007-0138007. For your
convenience, the relevant parts of US-2007-0138007 are pasted at the end of the
description of the invention.
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Figure 1: Simple dipeptides are building blocks for quantum dots and
nanotubes.
a, Researchers recently reported that when they concentrated a solution of diphenylalanine
peptides in methanol, the molecules arrange into quantum dots. Each quantum dot was
composed of two diphenylalanines. b, When the researchers changed the solvent from
methanol to water, the peptides further self-assembled to form nanotubes, each. The
researchers also reported that the process of self-assembly and disassembly is reversible.
We have found that the use of discrete nanocrystals, e.g., quantum dots for
coating an electrode has several advantages. A first advantage is that it simplifies the
electrode modification process. A second advantage is that it provides much higher
effective electrode area of energy storage devices. We believe that such high surface
area is especially useful for supercapacitors devices. It was found by us that the use
of discrete nanocrystals increases the surface area of a conventional carbon electrode.
This allows increase of storage capability of the coated electrode by the same amount.
Discrete peptide nanocrystals for use in our method are provided as nonassembled particles. Alternatively, a top-down process can be employed for providing
the discrete nanocrystals, according to which supramolecular structures in solution are
disassembled into discrete nanocrystals.
Such disassembling can be chemical or
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mechanical. Chemical disassembling can be achieved by acidic solutions such as
sulfuric acid of low pH (1-2) or organic solution such as HFIP.
Mechanical
disassembling can be achieved by ultrasound treatment.
The electrodes obtained by us are characterized by increased surface area, high
wettability and enhanced electrical performance.
Experimental part
Peptide nanotubes for comparison tests (see Figure 3) were prepared by
dissolving the lyophilized form of the FF or FW building blocks in 1,1,1,3,3,3hexafluoro-2-propanol (HFIP) at a concentration of 100 mg/ml. The FF stock solution
was diluted to a final concentration of 2 mg/ml in ddH2O for the nanotubes selfassembly process to occur. To avoid any pre-aggregation and assembly, fresh stock
solutions were prepared for each experiment.
FF (Diphenylalanine)-peptide quantum dots (abbreviated below as FF-NC)
were prepared in two ways. The first one was to dissolve the prepared peptide
nanotubes in the methanol solution. The second way was to dilute the stock solution
(FF in HFIP) in methanol at different concentrations, 1-8 mg/ml. FW (PhenylalanineTryptophan)-peptide quantum dots (abbreviated below as FW-NC) were prepared by
dissolving the FW stock solution either in H2O or in methanol.
The method was successfully applied to modification of the carbon electrodes.
Aromatic FF and FW as well non-aromatic LL (leucine-leucine) raw dipeptide
materials were used. Figure 2 demonstrates cyclic voltammetry graphs of the carbon
and peptide modified electrodes (Fig. 2).
The data show that the geometric capacitance for the modified electrodes is much
higher that that for the carbon electrode which has the ground capacitance CDL ~20
μF/cm2.
The current density response found for FF-NC modified electrode is by ~60 times
higher than that for the background carbon electrode. FF-NC-modified carbon
electrodes led to significant growth of the electrical double-layer capacitance density
reaching CDL ~ 1200 μF/cm2.
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LL NC-modified electrode is by ~80 times higher than that for background carbon
electrode and it possesses electrical double-layer capacitance density reaching CDL ~
1600 μF/cm2.
FW NC -modified carbon electrode showed the electrical double-layer
capacitance density CDL ~ 2500 μF/cm2 for the geometric electrode area which by 125
times higher than that for the carbon electrode (Figure 2).
Figure 2. cyclic voltammetry (CV) graphs of an electrode coated by peptide
nanocrystals (NC). Measurements were carried in KCL electrolyte at a scan rate 100
mVs-1 for the carbon electrode (thick black line), FF NC modified carbon
electrode(black line), LL NC modified carbon electrode (thin black line), FW NC
modified carbon electrode (grey line).
Figure 3 below demonstrates CV data for vapor deposited peptide nanotubes in
the same KCL electrolyte at a scan rate 100 mVs-1 for the carbon electrode and FF
peptide nanotubes vapor deposited on the carbon electrode. The electrical doublelayer capacitance of the peptide nanotubes-modified carbon electrode is CDL ~ 480
μF/cm2. The data in Figure 2 show that the new technology provides by several times
higher double layer capacitance values. For example, FF-NC modified carbon
electrodes according to our invention led to much higher electrical double-layer
capacitance density reaching CDL ~ 1200 μF/cm2.
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Figure 3. CV measurements in KCL electrolyte at a scan rate 100 mVs-1 for the
carbon electrode and FF-nanotubes deposited by vapor deposition technology
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DOCUMENT
1 (Relevant
Prior
Art):
US20070138007A1:
Peptide
nanostructure-coated electrodes
Abstract
An electrode coated with peptide nanostructures, composed of self-assembled peptides, is
disclosed. The electrode is capable of conducting a response current resulting from an
electrochemical reaction. The electrode can form a part of an electrochemical cell, a detector
and a sensor array. Methods utilizing an electrochemical cell, a detector or a sensor array
comprising the electrode for detecting an Analyte in a sample and kits containing same are
also disclosed.
CLAIMS
1. An electrode comprising a plurality of peptide nanostructures, said peptide nanostructures
being composed of a plurality of peptides self-assembled into said peptide nano structures,
the electrode being capable of conducting a response current resulting from an
electrochemical reaction in a proximity thereof.
2. The electrode of claim 1, further comprising a support having a surface, said peptide
nanostructures being attached to said surface.
3. The electrode of claim 1, wherein each of said peptides in said plurality of peptides
comprises from 2 to 15 amino acid residues.
4. The electrode of claim 1, wherein each of said peptides in said plurality of peptides
comprises from 2 to 7 amino acid residues.
5. The electrode of claim 1, wherein each of said peptides in said plurality of peptides
comprises at least one aromatic amino acid residue.
6. The electrode of claim 1, wherein at least one peptide in said plurality of peptides is an
end-capping modified peptide.
7. The electrode of claim 5, wherein at least one peptide in said plurality of peptides
consists essentially of aromatic amino acid residues.
8. The electrode of claim 3, wherein at least one peptide in said plurality of peptides is a
dipeptide.
9. The electrode of claim 8, wherein each peptide in said plurality of peptides is a
phenylalanine-phenylalanine dipeptide.
10. The electrode of claim 2, wherein each of said peptide nanostructures is attached to
said surface via interactions selected from the group consisting of hydrogen bond
interactions, hydrophobic interactions, covalent interactions, coordinative interactions,
electrostatic interactions and surface interactions.
11. The electrode of claim 10, wherein at least one peptide in said plurality of peptides
forming said peptide nanostructures comprises a functional group for forming said interactions
with said surface.
12. The electrode of claim 1, further comprising a moiety being capable of generating an
electrochemically reactive molecule and/or capable of reacting with and/or capturing a
molecule generating an electrochemically reactive molecule upon said electrochemical
reaction.
13. The electrode of claim 12, wherein said moiety is an enzyme, said enzyme being
capable of catalyzing a reaction generating said electrochemically reactive molecule.
14. The electrode of claim 12, wherein said moiety is a ligand, said ligand being capable of
capturing said molecule generating said electrochemically reactive molecule.
15. A process of preparing the electrode of claim 1, the process comprising subjecting said
plurality of peptides to conditions which favor formation of said peptide nanostructures.
16. The process of claim 15, wherein said electrode further comprises a support having a
surface coated with said peptide nanostructures, the process further comprising:
attaching said peptide nanostructures to said surface.
17. The process of claim 16, further comprising, prior to said attaching:
modifying said peptide nanostructures to thereby generate a functional group thereon, said
functional group being for attaching said peptide nanostructures to said surface.
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18. The process of claim 15, further comprising, prior to, concomitant with or subsequent to
said subjecting, attaching to or encapsulating in said peptide nanostructures a moiety capable
of generating an electrochemically reactive molecule and/or capable of reacting with and/or
capturing a molecule generating said electrochemically reactive molecule upon said
electrochemical reaction.
19. An electrochemical cell comprising a working electrode and a reference electrode, said
working electrode being the electrode of claim 1.
20. The electrochemical cell of claim 19, further comprising an auxiliary electrode.
21. An electrochemical cell comprising a working electrode and a reference electrode, said
working electrode being the electrode of claim 12.
22. The electrochemical cell of claim 19, further comprising an auxiliary electrode.
23. The electrochemical cell of claim 19, further comprising a moiety being capable of
generating an electrochemically reactive molecule and/or capable of reacting with and/or
capturing a molecule generating said electrochemically reactive molecule upon said
electrochemical reaction.
24. The electrochemical cell of claim 23, wherein said moiety is attached to or
encapsulated in said peptide nanostructures.
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to novel, highly sensitive electrodes and to methods of
generating and using same in detection of a variety of molecules.
During the last few years much interest has been focused on the development of analytical
methods allowing rapid “on-the-spot” performances for medical diagnostics and to measure
environmental pollutants. A device operating in remote sites, such as an ambulance, an
agricultural farm, or in field testing of environmental pollutants, should provide fast, sensitive,
small and inexpensive measurements. Moreover, for measurements held in the field, the
device should be simple to operate by a non-qualified person.
In amperometric measurements a potential is applied between a working electrode and a
reference electrode and the resulting current is measured. Often a third electrode, an auxiliary
electrode, is used for current collection.
The response of a working electrode depends on the chemical (electrochemical) reaction
variables. These include the electrode surface where the reaction takes place, the mobile
phase (reaction medium), and the compound undergoing the reaction.
Measurements are performed either at constant or varying potential between the working
electrode and the reference electrode. In cyclic voltammetry the potential is changed linearly
from an initial potential to a final potential and then back to the initial value, and the resulting
current is measured. When an electroactive molecule is present in the tested solution, a peak
is observed. The scan rate (rate of potential changed) affect the peak height and the peak
position depends on kinetic constants of the electrochemical reaction.
A number of diagnostic tests are routinely performed on humans to evaluate the amount or
existence of substances present in blood or other bodily fluids. These diagnostic tests
typically rely on physiological fluid samples removed from a subject, either using a syringe or
by pricking the skin.
Biological samples can be tested for the presence of a specific molecule by using a
detector electrode capable of electrochemically reacting with the detected molecule.
Amperometric biosensors combine the specificity and selectivity of biological interaction
reactions with the analytical power of electrochemistry. Many analytes are not intrinsically
electroactive and cannot be detected directly. The use of enzymes that catalyze biospecific
reactions facilitates the production of electroactive species which then can be determined
electrochemically.
Since their discovery in 1991, carbon nanotubes (CNTs) have been extensively studied
both theoretically and experimentally due to their unique physical and chemical properties.
Such nano-scale tubular structures have been suggested as potential functional elements in
nanotechnological devices and applications.
Kong et al. (2000) was the first to build a CNT based chemical sensor for detection of NH2
and NH3 gas. Chen et al. (2001) immobilized proteins on CNTs through a linking molecule
and Besteman et al. (2003), Lin et al. (2004) and Wang et al. (2003) demonstrated the use of
CNTs as biological sensors for detection of glucose. The unique electric properties together
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with significant surface enlargement made CNTs an important component in sensing
applications.
Studies also showed that bioorganic molecules can also self-assemble into well-ordered
structures at the nanometric level (Hartgerink et al. 2001; Ashkenasy et al., 2006).
Biomolecular nanostructures are an especially intriguing group of supramolecular assemblies
because they facilitate a wide range of chemical modifications. Moreover, such
nanostructures enable exploitation of the specificity of biological systems for biosensing,
catalytic activity, and highly specific molecular recognition processes.
Well-ordered and discrete peptide nanotubes that are self assembled from aromatic
peptides (e.g., diphenylalanine peptides) and uses thereof in numerous mechanical,
electrical, chemical, optical and biotechnological systems have recently been reported.
These peptide nanotubes are biocompatible and water soluble. They show notable
similarity to carbon nanotubes in their morphology and aspect ratio. Their assembly as
individual entities rather then bundles, makes them appealing for various nanotechnological
applications.
SUMMARY OF THE INVENTION
The present inventors have demonstrated that electrodes coated with peptide
nanostructures exhibit enhanced electrochemical sensitivity and thus are highly suitable for
use in electrochemical detection of various molecules and particularly as sensitive biosensors
in biomolecular diagnostics.
According to one aspect of the present invention there is provided an electrode comprising
a plurality of peptide nanostructures, the peptide nanostructures being composed of a plurality
of peptides self-assembled into the peptide nano structures, the electrode being capable of
conducting a response current resulting from an electrochemical reaction in a proximity
thereof.
According to further features, the electrode further comprising a support having a surface,
the peptide nanostructures being attached to the surface.
According to still further features in the described preferred embodiments the support
comprises a material selected from the group consisting of silicon oxide, carbon, graphite,
nickel, gold, silver, platinum and copper.
According to still further features in the described preferred embodiments each of the
peptides in the plurality of peptides comprises from 2 to 15 amino acid residues
According to still further features in the described preferred embodiments each of the
peptides in the plurality of peptides comprises from 2 to 7 amino acid residues.
According to still further features in the described preferred embodiments each of the
peptides in the plurality of peptides comprises at least one aromatic amino acid residue.
According to still further features in the described preferred embodiments at least one
peptide in the plurality of peptides is an end-capping modified peptide.
According to still further features in the described preferred embodiments at least one
peptide in the plurality of peptides consists essentially of aromatic amino acid residues.
According to still further features in the described preferred embodiments the aromatic
amino acid residue comprises an aromatic moiety selected from the group consisting of
substituted or unsubstituted naphthalenyl, substituted or unsubstituted phenanthrenyl,
substituted or unsubstituted anthracenyl, substituted or unsubstituted [1,10]phenanthrolinyl,
substituted or unsubstituted [2,2′]bipyridinyl, substituted or unsubstituted biphenyl and
substituted or unsubstituted phenyl.
According to still further features in the described preferred embodiments at least one
peptide in the plurality of peptides is a dipeptide.
According to still further features in the described preferred embodiments at least one of
the dipeptides is a homodipeptide.
According to still further features in the described preferred embodiments the
homodipeptide is selected from the group consisting of naphthylalanine-naphthylalanine
dipeptide, phenanthrenylalanine-phenanthrenylalanine dipeptide, anthracenylalanineanthracenylalanine dipeptide, [1,10]phenanthrolinylalanine-[1,10]phenanthrolinylalanine
dipeptide, [2,2′]bipyridinylalanine-[2,2′]bipyridinylalanine dipeptide, (pentahalo-phenylalanine)(pentahalo-phenylalanine) dipeptide, phenylalanine-phenylalanine dipeptide, (aminophenylalanine)-(amino-phenylalanine) dipeptide, (dialkylamino-phenylalanine)-(dialkylaminophenylalanine) dipeptide, (halophenylalanine)-(halophenylalanine) dipeptide, (alkoxy-
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phenylalanine)-(alkoxy-phenylalanine) dipeptide, (trihalomethyl-phenylalanine)-(trihalomethylphenylalanine) dipeptide, (4-phenyl-phenylalanine)-(4-phenyl-phenylalanine) dipeptide and
(nitro-phenylalanine)-(nitro-phenylalanine) dipeptide.
According to still further features in the described preferred embodiments each peptide in
the plurality of peptides is a phenylalanine-phenylalanine dipeptide.
According to still further features in the described preferred embodiments each of the
peptide nanostructures is attached to the surface via interactions selected from the group
consisting of hydrogen bond interactions, hydrophobic interactions, covalent interactions,
coordinative interactions, electrostatic interactions and surface interactions.
According to still further features in the described preferred embodiments at least one
peptide in the plurality of peptides forming the peptide nanostructures comprises a functional
group for forming the interactions with the surface.
According to still further features in the described preferred embodiments the electrode
further comprising a moiety being capable of generating an electrochemically reactive
molecule and/or capable of reacting with and/or capturing a molecule generating an
electrochemically reactive molecule upon the electrochemical reaction.
According to still further features in the described preferred embodiments the moiety is
attached to or encapsulated in the peptide nanostructures.
According to still further features in the described preferred embodiments the moiety is an
enzyme, the enzyme being capable of catalyzing a reaction generating the electrochemically
reactive molecule.
According to still further features in the described preferred embodiments the moiety is a
ligand, the ligand being capable of capturing the molecule generating the electrochemically
reactive molecule.
According to another aspect of the present invention there is provided a process of
preparing the electrode described herein, the process comprising subjecting the plurality of
peptides to conditions which favor formation of the peptide nanostructures.
According to further features in preferred embodiments of the invention described below,
the electrode further comprises a support having a surface coated with the peptide
nanostructures, the process further comprising: attaching the peptide nanostructures to the
surface.
According to still further features in the described preferred embodiments the attaching is
performed concomitant with or subsequent to the subjecting.
According to still further features in the described preferred embodiments the process
further comprising, prior to the attaching: modifying the peptide nanostructures to thereby
generate a fumctional group thereon, the functional group being for attaching the peptide
nanostructures to the surface.
According to still further features in the described preferred embodiments the process
further comprising, prior to, concomitant with or subsequent to the subjecting, attaching to or
encapsulating in the peptide nanostructures a moiety capable of generating an
electrochemically reactive molecule and/or capable of reacting with and/or capturing a
molecule generating the electrochemically reactive molecule upon the electrochemical
reaction.
According to an additional aspect of the present invention there is provided an
electrochemical cell comprising a working electrode and a reference electrode, the working
electrode being any of the electrodes described herein.
According to further features in preferred embodiments of the invention described below,
the electrochemical cell further comprising an auxiliary electrode.
According to still further features in the described preferred embodiments the
electrochemical cell further comprising a moiety being capable of generating an
electrochemically reactive molecule and/or capable of reacting with and/or capturing a
molecule generating the electrochemically reactive molecule upon the electrochemical
reaction.
According to still further features in the described preferred embodiments the moiety is
attached to or encapsulated in the peptide nanostructures.
According to yet an additional aspect of the present invention there is provided a detector
comprising: any of the electrodes described herein; and a detecting unit attached to the
electrode and being capable of detecting a response current resulting from the
electrochemical reaction.