NanoSys Inc v. Board Of Trustees Of University Of Arkansas

1. Case Identification

• Case #: IPR2020-00503
• Patent #: 7,105,051
• Filed: February 4, 2020
• Petitioner(s): Nanosys, Inc.
• Patent Owner(s): The Board of Trustees of the University of Arkansas
• Challenged Claims: 1-11, 13-23

2. Patent Overview

• Title: High quality colloidal nanocrystals and methods of preparing the same in non-coordinating solvents
• Brief Description: The ’051 patent discloses a method for synthesizing substantially monodisperse colloidal nanocrystals. The method involves combining a cation precursor, a ligand, and a non-coordinating solvent to form a cation-ligand complex, and then admixing an anion precursor at a sufficient temperature to form the nanocrystals.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1–9, 11, 14, and 21 under §102

• Prior Art Relied Upon: Trentler (a 1999 journal article, "Synthesis of TiO₂ Nanocrystals by Nonhydrolytic Solution-Based Reactions").
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued Trentler disclosed all limitations of independent claim 1. Trentler described a procedure where a titanium halide (titanium iodide, TiI₄), serving as the cation precursor, was mixed with trioctylphosphine oxide (TOPO), a ligand, in heptadecane, a non-coordinating solvent. This mixture was heated to 300 °C, forming a cation-ligand complex. Subsequently, an anion precursor (titanium alkoxide) was rapidly injected into the hot solution, admixing at a temperature sufficient to form TiO₂ nanocrystals. Petitioner asserted that Trentler’s disclosure of specific reagents, temperatures, and resulting nanocrystal sizes (3.8 nm) directly mapped to the limitations of the challenged dependent claims.

Ground 2: Obviousness of Claims 2, 3, and 15–18 under §103

• Prior Art Relied Upon: Trentler (a 1999 journal article) and Murray 1993 (a 1993 journal article, "Synthesis and Characterization of Nearly Monodisperse CdE...").
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner contended that while Trentler taught the core method using a transition metal (titanium), it did not explicitly use a Group II metal like cadmium (Cd) as required by claims 2 and 3. Murray 1993, however, explicitly disclosed synthesizing Group II-VI semiconductor nanocrystals (CdS, CdSe, CdTe) using dimethyl cadmium as the cation precursor. The dependent claims 15-17, which require the formation of these specific nanocrystals, are also directly taught by Murray 1993.
  • Motivation to Combine: A POSITA would have been motivated to extend Trentler’s hot-injection method beyond metal oxides to synthesize high-quality II-VI semiconductor nanocrystals, which were known to be highly desirable for their size-tunable optical properties. Petitioner argued that the cation and anion precursors in Trentler and Murray 1993 were known to be interchangeable for their respective functions with predictable results, providing a strong motivation to substitute Murray 1993's precursors into Trentler's superior hot-injection synthesis method.
  • Expectation of Success: A POSITA would have had a reasonable expectation of success because the combination represented a simple substitution of known, interchangeable reagents. Trentler itself cited Murray 1993 as demonstrating the potential of the hot-injection method, suggesting the compatibility of the techniques and materials.

Ground 3: Obviousness of Claims 1–9, 11, 13, 14, and 19–21 under §103

• Prior Art Relied Upon: Alivisatos (Patent 5,505,928) and Trentler (a 1999 journal article).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner asserted that Alivisatos taught a similar method for synthesizing nanocrystals, disclosing the combination of a cation precursor (GaCl₃), a ligand (tributylphosphine), and a non-coordinating solvent (petroleum distillate) to form a complex. However, Alivisatos used a traditional "heat-up" method where precursors were combined at room temperature and then heated, rather than the "hot-injection" method of claim 1 where the anion precursor is admixed into an already hot solution. Trentler explicitly taught this missing hot-injection step.
  • Motivation to Combine: A POSITA would have been motivated to modify the older "heat-up" method of Alivisatos by incorporating the well-known and superior "hot-injection" method taught by Trentler. By 2001, the hot-injection technique was widely recognized as a versatile and easily adaptable method for yielding higher-quality nanocrystals compared to the heat-up approach. This provided a clear motivation to improve the Alivisatos process.
  • Expectation of Success: A POSITA would have expected success in applying Trentler's hot-injection technique to the Alivisatos system. The prior art demonstrated that hot-injection was generalizable to a wide variety of nanocrystalline materials with predictable results. Both references used similar reaction temperatures (~300 °C) and components, making the incorporation of the improved injection technique a routine and predictable optimization.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including combining Trentler with the Aldrich Catalog to teach the use of octadecene as a solvent (claim 10); combining Trentler with Alivisatos to teach using Group III metals (claims 4, 19, 20); and combining Trentler with general knowledge to teach premixing the anion precursor with a solvent (claim 13). Petitioner also asserted that Gao (a 1998 journal article) and Alivisatos each independently anticipated claims 22 and 23.

4. Key Claim Construction Positions

• "A method of synthesizing colloidal nanocrystals" (Preamble): Petitioner argued the preamble is not limiting because it does not provide an antecedent basis for any claim terms and does not affect the operation of the claimed method, which only requires forming "nanocrystals."
• "Colloidal" (If preamble is limiting): Should the Board find the preamble limiting, Petitioner proposed construing "colloidal nanocrystals" as "nanocrystals that are colloidal dispersions or capable of forming a colloid in a solvent." This construction is based on the specification and what a POSITA would have understood.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §325(d) would be inappropriate. While two references (Murray 1993 and Alivisatos) were listed on an Information Disclosure Statement (IDS) during prosecution, the Examiner never cited them in any substantive rejection or office action. Petitioner contended that mere citation in an IDS without substantive discussion by the Examiner is an insufficient reason to decline institution.

6. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1-11 and 13-23 of the ’051 patent as unpatentable.