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Nanomal Pharm Livestock and fish will also be affected by the nanotechnology revolution. While the great hopes of nanomedicine are disease detection and new pharmaceuticals for humans, veterinary appli- cations of nanotechnology may become the proving ground for untried and more controversial techniques—from nanocapsule vaccines to sex selection in breeding. particularly interested in using biochips and microfluidic devices to screen tissues for genetic differences so that they can design genetically targeted drugs (pharmacogenomics).'” Disease Detection Nanoparticles, which are able to move easily around the body, can be used for diagnosis. Of particular interest are quantum dots—cadmium selenide nanocrystals which fluoresce in different colours depending on their size. Quantum dots can be function- alised to tag different biological components, like proteins or DNA strands, with specific colours. In this way a blood sample can be quickly screened for certain proteins that may indicate a higher propensity for disease. Biochips colours depending on their size. Quantum dots can be function- Using biochips, biological samples such as blood, tissue and alised to tag different biological components, like proteins or semen can be instantaneously analysed and manipulated. In fewer DNA strands, with specific colours. In this way a blood sample than five years, biochips have become a standard technology for can be quickly screened for certain proteins that may indicate a genomics and drug discovery, and they are now moving into com- higher propensity for disease. mercial healthcare and food safety applications. A biochip (or microarray) is a device typically made of hun- New Delivery Mechanisms dreds or thousands of short strands of artificial DNA deposited Drugs themselves are set to shrink. Nano-sized structures have precisely on a silicon circuit. In DNA arrays, each DNA strand the advantage of being able to sneak past the immune system and acts as a selective probe and when it binds to material in a sample across barriers (e.g., the blood-brain barrier or the stomach wall) (e.g., blood) an electrical signal is recorded. the body uses to keep out unwanted sub- Rather like conducting a word search across a stances. piece of text, the biochip is able to report back Pharmaceutical compounds reformulated as on found genetic sequences based on the DNA nanoparticles not only reach parts of the body probes built into it. that today's formulations cannot, their large The best-known biochips are those pro- . surface area can also make them more biologi- duced by Affymetrix, the company that pio- Pharma companies are cally active. neered the technology and was first to produce A A Increased bioavailability means that lower a DNA chip that analyses an entire human particularly interested concentrations of expensive drug compounds genome on a single chip the size of a dime.''® in using biochips and would be required, with potentially fewer side In addition to DNA biochips there are other . . at . effects.'* Nanoparticles can also be used as variations that detect minute quantities of pro- microfluidic devices to carriers to smuggle attached compounds teins and chemicals in a sample, making them screen tissues for through the body. useful for detecting biowarfare agents or . . Leading nanopharma companies such disease. genetic differences so as SkyePharma and Powderject (now a Biochip analysis machines the size of that they can design wholly owned subsidiary of Chiron) have an inkjet printer are commercially avail- . developed methods of delivering genetically targeted drugs. able from companies such as Agilent nanoparticle pharmaceuticals across skin (Hewlett-Packard) and Motorola—each or via inhalation. Researchers in Florida able to process up to 50 samples in are working on nano-delivery systems around half an hour. that diffuse drugs across the eye from specially impregnated contact lenses. As with pesticide delivery, the big interest is in ‘controlled release.’ Many of the big pharma and animal Nano-Veterinary Medicine The field of nanomedicine offers ever more breathless promises of new diag- noses and cures as well as ways of pharma companies working on nano- improving human performance. The US drugs are using encapsulation technolo- National Science Foundation expects nanotechnology to account gies such as nanocapsules to smuggle active compounds into and for around half of all pharmaceutical industry sales by 2010. around the body. The capsules can be functionalised to bind at What is less hyped is that the same impact is likely to hit the ani- specific places in the body, or be activated by an external trigger, mal health market—either as nanotechnologies show their worth such as a magnetic pulse or ultrasound. The USDA compares in human medicine or as a proving ground for more controversial these functionalised drug nanocapsules, called "Smart Delivery approaches to nanomedicine, such as using DNA nanocapsules. Systems," to the postal system, where molecular-coded "address Companies such as SkyePharma, IDEXX and Probiomed are cur- labels" ensure that the packaged pharmaceutical reaches its rently developing nanoparticle veterinary applications. A full intended destination.'* assessment of how pharmaceutical companies are using nanotech- Besides capsules, other nanomaterials being used to deliver nology in drug development and delivery is beyond the scope of _—_ drugs include: this report. Briefly summarised below are some of the key tech- + BioSilicon—a highly porous silicon-based nanomaterial prod- nologies that are also relevant to animal pharmaceuticals: uct, which can release a medicine slowly over a period of time. Developed by Australian company pSivida, the company uses its Drug Discovery BioSilicon technology to fashion tiny capsules (to be swallowed) The ability to image and isolate biological molecules on the and also tiny needles that can be built into a patch to invisibly e opens the door for more precise drug design as well as__ pierce the skin and deliver drugs.'° genetic differences so that they can design genetically targeted drugs. Drug Discovery The ability to image and isolate biological molecules on the nano-scale opens the door for more precise drug design as well as much faster genomic screening and screening of compounds to assess their suitability as drugs. Pharma companies are 16 = NEXUS JUNE — JULY 2005 screen tissues for Continued on page 74 www.nexusmagazine.com