Arrowhead Announces Expansion of Nanotech Intellectual Property Portfolio.

PASADENA, Calif. -- Arrowhead Research Corporation (NASDAQ:ARWR) (NASDAQ:ARWRW) announced today that it has exclusively licensed new technology in dip pen nanolithography (DPN) from the California Institute of Technology (Caltech). In addition, Arrowhead acquired a 12-month option to exclusively license additional patent applications from Caltech covering nanotube-based scanning probes, lipid membrane fabrication, nanotube-based memory devices, and nanotube strain sensors, which technology could potentially be used as mechanically tunable light emitting diodes (LEDs). During the option period, the Company expects to craft commercialization plans for these technologies.

"It's great to see our strategy of funding research in exchange for rights to intellectual property come full circle," said R. Bruce Stewart, President of Arrowhead. "Arrowhead and its subsidiaries now own or have licensed over 240 patents and patent applications to a range of different materials, devices, and systems and are looking to strategically add more patents to our portfolio in the near future."

The licensed technology (covered by patent applications) relate to the use of DPN to write different biological molecules on previously inaccessible, or difficult to pattern, surfaces. DPN potentially could be used as a research tool for understanding biomolecular interactions, as well as in developing and manufacturing nanoscale diagnostic devices, data storage systems, and molecular-cascade logic devices. The technology was developed at Caltech in the labs of Professor C. Patrick Collier, whose research Arrowhead has been funding since 2003.

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 IP 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, Inc. is developing nanostructures for delivery and therapeutic use of RNA interference.

Arrowhead is funding three research efforts in nanotechnology at the California Institute of Technology in the areas of nanomaterials, nanoelectronics, and nanobiomolecular tools.

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.