Arrowhead Announces Patent Grant on Spintronic Technology for Use in Next-Generation Semiconductor Devices.

PASADENA, Calif. -- Arrowhead Research Corporation (NASDAQ:ARWR)(NASDAQ:ARWRW) announced today the U.S. Patent Office issued U.S. patent 6,879,012, Giant Planar Hall Effect in Epitaxial Ferromagnetic Semiconductor Devices. The patent is exclusively licensed to Nanotechnica, Inc., Arrowhead's majority-owned subsidiary, by the California Institute of Technology.

The patent covers ferromagnetic semiconductor-based methods, devices, and compositions. The technology enables measurements of magnetic spins and enhanced magnetic switching effects, which could play a key role in development of future semiconductor devices based on "spintronics."

Traditional semiconductor devices operate by storing information as charge - an electron's state represents 0 or 1. In contrast, spintronics taps into the spin of electrons to store or transmit information, which enables next-generation devices for memory, disk storage, magnetic sensors, and quantum computers to be smaller, more powerful, and have longer lives than today's products.

"This patent covers foundational technology for what we believe will be the next-generation of semiconductor devices," said R. Bruce Stewart, President of Arrowhead. "This patent further strengthens our diversified portfolio of patents in the nanotechnology space. Arrowhead and its subsidiaries now control 36 issued U.S. patents and have licensed over 240 U.S. and international patents and patent applications."

About Arrowhead Research Corporation

Arrowhead Research is a development-stage nanotechnology company structured to bring together a diverse and innovative mix of technologies, rights to a broad suite of intellectual property, and some of the most respected minds in this dynamic field. There are three strategic components to Arrowhead's business model:

--The Commercialization Program: Arrowhead forms or acquires majority-owned subsidiary companies pursuing products based on nanotechnology in high-growth technology markets.

--The Research Program: Arrowhead funds nanoscience research at universities in exchange for exclusive rights to license the technology.

--The Patent Toolbox: Arrowhead acquires, licenses, and sublicenses intellectual property in nanotechnology.

Arrowhead Research operates four majority-owned subsidiary companies:

--Aonex Technologies, Inc., developing and commercializing proprietary semiconductor nanomaterial technology.

--Insert Therapeutics, Inc., developing and commercializing a proprietary nanoscale drug delivery system.

--Nanotechnica, Inc., developing capabilities for mass-production of a variety of proprietary nanoscale devices, including laboratory on a chip.

--Calando Pharmaceuticals, Inc. is developing nanostructures for delivery and therapeutic use of RNA interference.

Arrowhead is funding three research and development efforts in nanotechnology at the California Institute of Technology.

Safe Harbor Statement under the Private Securities Litigation Reform Act of 1995:

This news release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. These statements are based upon our current expectations and speak only as of the date hereof. Our actual results may differ materially and adversely from those expressed in any forward-looking statements as a result of various factors and uncertainties, including the recent economic slowdown affecting technology companies, our ability to successfully develop products, rapid technological change in our markets, changes in demand for our future products, legislative, regulatory and competitive developments and general economic conditions. Our Annual Report on Form 10-K and 10-K/A, recent and forthcoming Quarterly Reports on Form 10-Q and 10-Q/A, recent Current Reports on Forms 8-K and 8-K/A, our Registration Statement on Form S-3, and other SEC filings discuss some of the important risk factors that may affect our business, results of operations and financial condition. We undertake no obligation to revise or update publicly any forward-looking statements for any reason.