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Home > Nanotechnology Columns > Magda Carvalho PhD, JD > Undue Experimentation: On DNA/Polyaniline Nano-Biosensors.

Magda Carvalho
Patent Attorney
Patent Law at M. Carvalho

Co-author Nice Shindo, Ph.D.
Bringing polyaniline into the chemical biosensor field was a major breakthrough for nanotechnology, but it is still a "nascent technology." Patent law requires that an artisan be capable of utilizing the invention without undue experimentation. Accordingly, a patent application only showing that the properties of DNA/polyaniline complexes can be used as biosensors—without showing exactly how—fails the enablement requirement.

February 20th, 2009

Undue Experimentation: On DNA/Polyaniline Nano-Biosensors.

This column discusses a patent application for an invention involving the "nascent technology" field of chemical biosensors comprising polyaniline.(i) Ex parte Samuelson is of interest because it is a good example of the applicability of the Section 2164.03 of the Manual of Patent Examining Procedure (MPEP), which states in part that, "if little is known in the prior art about the nature of the invention and the art is unpredictable, the specification would need more detail as to how to make and use the invention in order to be enabling."(ii) In this case, the patent applicants provided full detail on how to make DNA/polyaniline complexes but there was no teaching on "how to use" these complexes as a biosensor. The Examiner found a reference pointing to a "major challenge" in the control of morphology with nano-structured polyaniline. Given the state of the art, it would require the skilled artisan undue experimentation to utilize the invention. On appeal the Board of Patent Appeals and Interferences (BPAI) agreed.

Enablement: "How To Use" Prong.

The first paragraph of 35 U.S.C. § 112 reads as follows: The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention. As such, the enablement requirement obliges an inventor to describe "how to use" the claimed invention.(iii) All that an applicant need do is enable a person skilled in the art to duplicate his efforts. This is because the specification is written for a person of skill in the art, and such person comes to the patent with the knowledge which has come before. As such, it is unnecessary to spell out every detail of the invention in the specification; only enough must be included to enable a skilled one to make and use the invention without undue experimentation.(iv) In re Wands, the Court explained the factors to be considered in determining whether a disclosure would require undue experimentation: (1) the quantity of experimentation necessary, (2) the amount of direction or guidance presented, (3) the presence or absence of working examples, (4) the nature of the invention, (5) the state of the prior art, (6) the relative skill of those in the art, (7) the predictability or unpredictability of the art, and (8) the breadth of the claims.(v)


Chemical biosensors are nanodevices which have the potential to detect molecules ranging from glucose, DNA and proteins to chemical warfare agents. The sensors detect chemical and biological species based upon an interaction between two molecules; they change their conformation and/or properties in a controllable manner in response to an external stimulus. In particular, biosensors bearing double-stranded deoxyribonucleotide (DNA) might have genetic engineering applications, help in the diagnosis of genetic disease, and further the development and improvement of new drugs. In nature, the DNA exists almost exclusively in a double-stranded configuration. However, other configurations may exist (e.g., A-, B-, C- and Z-type duplexes). These variations in configuration may be responsible for the binding of certain molecular species, such as DNA, enzymes, proteins or chemicals. Therefore, methods of modulating the conformation of DNA are expected to have applications in the area of biosensors.

Ex Parte Samuelson et al. (February 10, 2009).

The invention relates to DNA biosensor technology. The conducting polymer was polyaniline. The biological element was double stranded DNA. Polyaniline and DNA were bound as a complex. The invention related to a method of modulating the conformation of DNA by changing the oxidation state of the polyaniline. Basically, when polyaniline is oxidized (e.g., increasing the positive charge on the polyaniline) it causes the double helix of the DNA to become more tightly wound (i.e., the double helix will have more base pairs per turn). Conversely, reducing the polyaniline will cause a double helix associated with it to become more loosely wound. Neutralization of polyaniline resulted in the uncoiling of DNA, back to its native state. The applicants explained that changing the oxidation state of polyaniline bound to a DNA duplex changes the linear length of a helical turn and, therefore, could be used to study the binding of proteins as well as hybridization.

The Examiner found that because the "dsDNA was encased within a shell of polyaniline" it was unpredictable whether any hybridization or protein binding could occur with the DNA. The Examiner cited a reference which discussed "challenges in polyaniline formation and use." As such, the Examiner required the applicants to explain how the DNA functions or reacts "to detect anything of interest." The specification identified two specific uses for the polyaniline/DNA complex as biosensor, one for hybridization and the other for binding to proteins. Still, the specification did not contain either a working example of nucleic acid hybridization or the application of any change in the oxidation state of polyaniline of dsDNA. Therefore, the Examiner rejected the claims on the "how to use" prong of the enablement requirement. That rejection was affirmed by the BPAI. The BPAI correctly pointed out that the patent applicants' arguments on "how to make" were misplaced because the Examiner focused on the "how to use" prong, a separate prong of the enablement requirement. The BPAI analyzed the Wands factors: the specification only taught methods for making complexes of DNA bound to polyaniline, there was scientific reasoning for the inability of such complexes to bind to molecules and that the state of the prior art was unpredictable. The BPAI concluded that in this case, where the inventors did not teach how to use the polyaniline/DNA complex as a biosensor, it would require undue experimentation to use the invention. As such, the invention had not blossomed into a complete invention.


Here, we have learned that as to inventions concerning "nascent technologies," while it would not be difficult to identify a utility for the invention, nonetheless those "uses" which have not yet been worked out in full detail, present a challenge when it comes providing the disclosure required to meet the enablement tests. Furthermore, in dealing with "nascent technologies" the working examples provided in the specification need to be accompanied with test data to demonstrate how the invention can be used without undue experimentation.

(i) Ex parte Samuelson et. al, No. 2008-5927 (Bd. Pat. App. & Int. February 10, 2009).
(ii) MPEP Sections dealing with enablement requirement:
MPEP 608 - Disclosure
MPEP 608.01 - Specification
MPEP 608.01(a) - Arrangement of Application
MPEP 608.01(g) - Detailed Description of Invention
MPEP 608.01(p) - Completeness
MPEP 2164 - The Enablement Requirement
MPEP 2164.01 - Test of Enablement
MPEP 2164.03- Relationship of Predictability of the Art and the Enablement Requirement
MPEP 2164.05(a) - Specification Must Be Enabling as of the Filing Date
MPEP 2164.05(b) - Specification Must Be Enabling to Persons Skilled in the Art
(iii) In re Storrs, 44 CCPA 981, 245 F.2d 474, 114 USPQ 293.
(iv) LizardTech. Inc. v. Earth Resource Mapping. PTY, Inc., 424 F.3d 1336, 1345 (Fed. Cir. 2005) (citing Union Oil Co. v. Atl. Richfield Co., 208 F.3d 989, 997 (Fed. Cir. 2000).
(v) In re Wands, 858 F.2d 731, 737 (Fed. Cir. 1988).

Nice Shindo, Ph.D.
Associate Project Leader
Infectious Disease Research/Drug Development Division
Southern Research Institute
2000, 9th Avenue South
Birmingham, AL, 35205
Phone: 205 581 2709

Please send your comments to Magda Carvalho at

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