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Posted: October 12, 2007
Nanomedicine - copying Nature to solve problems
(Nanowerk News) Some 3500 visitors attended the NanoEurope event in St.Gallen in mid-September to familiarize themselves with promising future applications of nanotechnology. Nanomedicine was one of the focal subjects discussed at the NanoEurope 2007.
If we intend to take advantage of nanomedicine, we must observe Nature to see how she organizes herself in superstructures at the molecular level. That was the message conveyed by David W. Grainger, who opened the series of papers on "Medical Devices" at the NanoEurope in St.Gallen. For Grainger, who is professor of Pharmaceutics & Pharmaceutical Chemistry at the University of Utah, this product development is based on the bottom-up principle rather than the top-down system applied up to now. He said it was as if we were to take car body components and shake them so cleverly that this would produce what we wanted – a car. And indeed, nanomedicine has evolved thanks to the insights gained in genomics and proteomics. The knowledge of how genes and proteins function in cells was a prerequisite for understanding the molecular causes of diseases.
Nanomedicine – five strategic goals
Nanomedicine aims at five main applications. Nanoparticles and large molecules are suitable as novel active substances and therapy methods. One example of this is the dendrimer molecule family. These molecules can be synthesized for specific therapies or be applied to surfaces, where they will – say – prevent malignant viruses from entering cells.
A downright revolutionary application is molecular imaging for performing in vivo diagnostics, which allow early diagnoses. For example, defined nanoparticles are injected into patients suspected of having cancer, which accumulate in the afflicted tissue. Exposed to light of a certain wavelength, any tumors can be clearly detected. This process also serves as a lethal weapon against cancer. Researchers from the Medical Faculty of the Charité University in Berlin developed nanoparticles containing iron oxide. They injected them into a tumor and then heated the relevant part of the body with a magnetic alternating field, killing the tumor cells with high precision. The physicians in Berlin successfully tested the therapy in clinical studies on brain tumors and prostatic carcinoma. The interesting thing about this is that cancer cells absorb the nanoparticles in a selective manner. At the NanoEurope, Professor Georg Duda from the "Centrum für Muskuloskeletale Chirurgie" at the Charité hospital showed how he and his team apply nanoparticles in order to enhance the contrast in magnetic resonance images (MRI) and to track structures such as blood vessels and marked cells in vivo.
Start-ups as engines propelling nanotechnology Nanoparticles are opening up new possibilities in the field of in-vitro diagnostics, namely as markers for molecules or for new measurement concepts. One such concept concerns cantilever sensors – microtechnically produced spring poles with a length of up to 100 micrometers and a thickness in the nanometer to micrometer range. Coated with special molecules, they will react selectively and rapidly with the desired biomolecules in a sample, thereby serving for medical diagnostics, the discovery of new medicines, and environmental monitoring.
Nanotechnology offers high potential in the area of implants and biomaterials. As humans live longer, degenerative diseases increase. What is required are implants that can remain inside the body for a long time. Today, some ten percent of all knee and hip implants fail after one dozen years due to the inadequate integration of the "foreign object" in the tissue. Implants with a nanotextured surface will enable proteins to attach, improving the interaction with the bone cells and thus significantly increasing the life expectancy of the implants.
The fascinating thing about nanotechnology is that properties, interactions, and the compatibility of materials may change drastically at the nanometer scale. But this also poses a risk, says Cornelia Camara, the regulatory affairs manager of Medipol SA Lausanne, a start-up founded in 2003. She says that from the regulatory viewpoint, the greatest challenge existing in the medical application of nanomaterials resides in the identification and evaluation of new risks and hazards created by nanoscale materials. For market approval, accurate safety assessments and a risk management system are required. This presents unknown risks for highly innovative start-ups and calls for adequate problem solutions. She continues that legislation must ensure maximum safety in medical nanotechnology applications. This, in turn, requires guidance of producers and the international harmonization of standards.
Striking out for new frontiers
One promising field is that of crystalline nanomaterials for making bone-like cements as bone substitutes or as components for tooth fillings with excellent mechanical properties. The production of such nanodispersions is a true challenge. Hans Näf, chairman of the supervisory board of Bühler PARTEC GmbH (PARticle TEChnology), explains that the goal is to prevent the nanoparticles in such dispersions from reagglomerating. This is accomplished by means of a specific surface treatment of the individual particles. Such nanoscale dispersions are manufactured using chemomechanical systems. This effort was supported by the Leibniz Institute for New Materials (INM) in Saarbrücken, an internationally leading research center for chemical nanotechnology. Today, Bühler PARTEC GmbH – an affiliate of the global Buhler Technology Group – has established itself as the first name in the development and production of tailor-made nanoparticle dispersions. Together with partners such as the Swiss Federal Institute of Technology (ETH) in Zurich, the company searches for new applications, including components for tooth filling materials. Hans Näf explains that the control of the surface chemistry of nanoscale matrix interfaces is the prerequisite for using nanoparticles in such applications. Only then will novel nanoproperties become effective. He says that the company develops and produces formulations and components tailored to the specific area in which customers’ products are used.
Suppliers of active substances for producing well-tolerated drugs
One of the fields with currently the most intense activity is drug delivery. Today, over 50 percent of all companies worldwide engaged in nanomedicine are working on it. Active substances can be enveloped in specially designed nanoparticles which will deliver their valuable contents to precisely the correct part of the body by adhering to protein structures. This signifies a technological leap in medication therapy considering that drugs today often cause side effects because they are spread throughout the organism in an unspecific manner. But it is not easy to smuggle such Trojan horses into the body. They must be skillfully disguised if they are not to be detected as intruders by guard cells. In this case, they would be flushed away with the blood stream, or spleen and liver cells would absorb the transporter before it reaches the target tissue. Fredrik Tiberg, CEO of Camurus AB, says that a substance is required to dissolve the active agent plus a suitable encapsulation. The carrier system must overcome biological barriers such as the skin, deliver the active agent in a selective manner and on an intracellular basis, and moreover have an acceptable shelf life and good stability. Camurus AB, located in the Swedish Ideon Science Park, was distinguished in June 2007 among Danish and Swedish contestants as the best biotech company in Medicon Valley. Camurus specializes in carrier systems for peptides, proteins, and non-soluble small molecules. With its Fluid Crystal® nanoparticles, the company focuses on self-organizing active agent transporters, liquid lipid crystals with three-dimensional structures. Though no results from clinical studies are yet available, the tests do show that the substances are delivered to the body over a substantially longer period of time. Tiberg says that this means better effectiveness and less side effects, and it is also easier to administer the medication. He believes that this would boost the quality of life especially of people who have to continuously swallow or inject medicines, for example diabetes patients. At the same time, it reduces the medical care requirement.
Is nanomedicine a problem solver for our health management system? David Tapolczay, a former researcher with GlaxoSmithKline, believes it is. He says that in Western societies the number of aging persons requiring care is on the rise while that of young people still working is shrinking. He continues that nanomedicine presents the potential opportunity of offering high-quality medical care at reduced cost. It would be a pity if we forfeited this chance.