Press Room

UNIDYM, INC. APPOINTS SEMICONDUCTOR INDUSTRY EXECUTIVE AS VICE PRESIDENT OF BUSINESS DEVELOPMENT & MARKETING

Menlo Park, CA, August 13, 2007

Unidym Incorporated, a majority-owned subsidiary of Arrowhead Research Corporation (NASDAQ:ARWR), announced today that Robert Bismuth has been appointed Vice President of Business Development & Marketing. Unidym Inc. is a leader in the development and manufacture of carbon nanotubes for applications in the electronics industry. Unidym, which recently merged with Carbon Nanotechnologies, Incorporated (CNI), possesses a foundational patent portfolio that covers nearly every aspect of carbon nanotube manufacturing and processing.

"Robert has a track record of innovative business success in both building strategic relationships and in bringing to market new applications for a wide range of technologies," said Art Swift, Unidymˇ¦s President & CEO. "The depth and breadth of his strategic business experience and intuitive understanding of technology will be of enormous benefit to Unidym as we expand our business."

"The combination of Unidym's application technology and carbon nanotube production capabilities clearly position the company strongly in many segments of the overall nanotechnology market," commented Bismuth. "For example Unidym's transparent, conductive films are poised to enable robust, innovative solutions in areas such as display technology, touch sensors, high performance solar cells, and may even make flexible electronics truly practical. In addition, the company's IP portfolio and materials production capabilities provide attractive licensing and partnership opportunities within a wide variety of industries. Thus, I am extremely excited to join the Unidym team at this point in time."

Robert's versatile experience includes executive leadership within the software, hardware, Internet and semiconductor industries. Most recently, Robert held the position of Vice President of Strategic Alliances at Transmeta Corporation, an innovative semiconductor company in the Silicon Valley. Prior to Transmeta, Robert led several startup technology companies, following his long tenure at Digital Equipment Corporation where he served as the companyˇ¦s Corporate Vice President for Strategic Alliances, holding responsibility for all major global business and technology alliances.

Educated in the US, Europe and Canada, Robert earned a B.Sc. in Pure Mathematics at the University of Wales, followed by an M.Sc. at McMaster University in Canada. More recently Robert attended the Stanford Graduate School of Business, completing the Executive Program for Growing Companies.

About Unidym, Inc.
Unidym, Inc. is developing low-cost, carbon-based materials, processes, and devices for the electronics industry. The Company's initial product is a thin, transparent film of carbon nanotubes that replaces the expensive, failure-prone materials currently employed by manufacturers of devices such as touch screens, flat panel displays, and solid state lighting. Unidym is also developing novel carbon nanotube-based transistors and conductive inks for the printable electronics industry to replace todayˇ¦s complex and capital intensive semiconductor manufacturing processes with inexpensive, solution-based printing processes. Unidym differentiates itself through its emphasis on low-cost materials and processes, in-house carbon nanotube production, aggressive partnership strategy, and significant intellectual property portfolio that includes foundational IP in both of its initial applications.

About Arrowhead Research Corp.
Arrowhead Research Corporation (www.arrowheadresearch.com) is a publicly-traded nanotechnology company commercializing new technologies in the areas of life sciences, electronics, and energy. Arrowhead is building value for shareholders through the progress of majority owned subsidiaries founded on nanotechnologies originally developed at universities. The company works closely with universities to source early stage deals and to generate rights to intellectual property covering promising new nanotechnologies. Currently, Arrowhead has four subsidiaries commercializing nanotech products and applications, including anti-cancer drugs, RNAi therapeutics, carbon-based electronics and compound semiconductor materials.

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 factorsand uncertainties, including the recent economic slowdown affecting technology companies, the future success of our scientific studies, 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 filingsdiscuss 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.