Nanomedicine

Advances in science have always fuelled innovation in medicine, and nanotechnology is no exception. Thanks to science fiction, most of you will have heard of nanotechnology; Dan Martin and Andrew McCaskie fill in the gaps.

Nanotechnology is the design and production of components with sizes of order nanometres (10−9m, one billionth of a metre), and nanomedicine is this technology applied to medicine. Conceptually, it is nothing new and is a natural progression towards design and study on a smaller scale—something that has been happening throughout science's history. A good example is the production of progressively smaller computers or mobile phones. But what excites people about nanotechnology is that it enables scientists to design and engineer at the molecular level, opening up a plethora of new medical possibilities.

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Many nano-objects have exquisite self assembling properties, in that they will construct themselves without external intervention—given the correct conditions. It is essentially this, and the fact that miniaturisation produces more cost effective and rapidly functioning components, that makes nanotechnology possible.¹ Self assembly is a fundamental principle in the natural world; viruses, for instance, self construct after manufacturing their component proteins in the host cell. Nature makes use of an array of ingenious nanomachines, such as the tiny molecular rotating motors that we know as ATP pumps. And since the discovery of DNA, scientists have tried to model structures that are found in real life, a trend that has led to the current development of nanoscaled devices. DNA molecules themselves are widely used as a fundamental building block of such components.² In practice, nanotechnology also represents an assimilation and integration of other technologies, including stem cell biology, molecular engineering, genomics, proteomics, tissue engineering, and materials science.¹

So what relevance does all this have to medicine? The theoretical possibilities of nanotechnology seem genuinely limitless. The idea of millions of tiny nanobots patrolling the body, however, spotting and cutting out cancerous strands of DNA and generally mopping up disease is a long way off. Various forms of nanotechnology are already employed in medicine, such as wound dressings that contain silver nanoparticles as a bactericide or the use of superparamagnetic iron oxide nanoparticles in magnetic resonance imaging.³ The near future looks to benefit from promising research being done in the fields of drug synthesis and targeted delivery.⁴ For instance, patients with diabetes could benefit from feedback controlled nanocapsules that can release insulin into the bloodstream in precisely the right concentrations, adjusted automatically according to blood sugar concentrations. Nanoparticles will be designed to deliver drugs to specific tissues and cell types while avoiding the immune system—a concept that has profound implications, not least for the treatment of tumours.⁴

Nanomedicine looks likely to have a considerable impact on medical imaging and diagnostics by means of nanosized biosensors.⁵ The physical sciences have provided nanotechnology with a new toolset, as innovative methods of nanoscale imaging are developed. This includes the use of atomic force microscopy, which measures force by touching a material's surface gently, and tunnelling microscopy, which measures the movement of charge through space. Quartz crystals can be used to generate the tiny controlled movements required for imaging on such a small scale.⁶

In orthopaedics, research is looking at developing biomimetic tissue surfaces for prostheses; surfaces that have been engineered at the nanoscale to mimic or interact with human tissue—in effect behaving as a living surface. Currently, joint surfaces are made with biocompatible materials that are tolerated by the body but eventually worn down. The new generation of nanoengineered materials are being designed—by means of appropriately placed proteins—to regenerate the surface tissue matrix of the prosthesis.⁷ Nanomedicine holds strong possibilities for the treatment of cancer, and in fact has been identified by the US National Cancer Institute as an “extraordinary opportunity for research investment.”⁸ In addition to advances in imaging, research in diagnostics holds promise for this specialty, involving identifying the internal chemistry and molecular markers of cancerous cells using nanoparticles.⁹ Innovative nanocomposites are also being developed that can initiate intracellular processes (such as programmed cell death) upon their introduction to the cell, for use in oncology.¹⁰

Aside from these impending developments in medical and surgical specialties, nanotechnology's passionate advocates are keen to draw attention to its more glamorous, albeit currently theoretical, possibilities. These include neuromorphic engineering, which involves enhancing the durability and recovery of injured neurons, and other forms of in vivo regenerative medicine, such as fully biological implants, including heart valves.¹¹ The futuristic concept of a nanobot does raise the possibility of individual cell surgery—minimal access surgery at its most minimal.⁵

At some point, technological possibility crosses the line into science fiction. As scientific reality changes almost daily, however, this line is steadily and rapidly moving closer and closer. Whether we are irritated, baffled, or fascinated by the idea of nanomedicine, it looks highly likely that the future is, in fact, small.

1. Emerich DF, Thanos CG. Nanotechnology and medicine. Expert Opin Biol Ther 2003;3:655-63.
2. Bogunia-Kubik K, Sugisaka M. From molecular biology to nanotechnology and nanomedicine. Biosystems 2002;65:123-38.
3. Jordan A. [Nanotechnology and consequences for surgical oncology] Kongressbd Dtsch Ges Chir Kongr 2002;119:821-8. (German.)
4. Akerman ME, Chan WC, Laakkonen P, Bhatia SN, Ruoslahti E. Nanocrystal targeting in vivo. Proc Natl Acad Sci USA 2002;99:12617-21.
5. Freitas RA Jr. The future of nanofabrication and molecular scale devices in nanomedicine. Stud Health Technol Inform 2002;80:45-59.
6. Lee Y, Ding Z, Bard AJ. Combined scanning electrochemical/optical microscopy with shear force and current feedback. Anal Chem 2002;74:3634-43.
7. Beauregard GP, James SP. Synthesis and characterization of a novel UHMWPE interpenetrating polymer network. Biomed Sci Instrum 1999;35:415-9.
8. Coleman CN. Linking radiation oncology and imaging through molecular biology (or now that therapy and diagnosis have separated, it's time to get together again!). Radiology 2003;228:29-35.
9. Ananthaswamy A. Nanotech spy eyes life inside the cell. New Scientist 2004 Jan 31:22.
10. Paunesku T, Rajh T, Wiederrecht G, Maser J, Vogt S, Stojievi N, et al. Biology of TiO2-oligonucleotide nanocomposites. Nat Mater 2003;2:343-6.
11. Bader A. Intersections of reconstructive surgery in the area of regenerative medicine. Chirurgie 2002;75:428-34. (In German.)

   

           

Responses published this month Articles Responses EDITORIALS Nanomedicine       Dan Martin and Andrew McCaskie (March, 2005) Fatma Makame (March 11, 2005) Read this response EDITORIALS Nanomedicine       Dan Martin and Andrew McCaskie (March, 2005) Fatma Makame (March 11, 2005)       Student, MD2, Hubert Kairuki Memorial University fatmahhamzah@hotmail.com "But what excites people about nanotechnology is that it enables scientists to design and engineer at the molecular level, opening up a plethora of new medical possibilities." Amazing indeed! The idea of having such technology at hand is breath taking to someone interested in technology and molecular biology as I am. I would doubtlessly say, "that is some scientific advancement there!" It is what the medical world should look at because it represents numerous possibility and because it works at a molecular level it should be able to minimise risk and provide appreciable outcome in terms of treatment. Atleast so I think. It then comes as no surprise that the US cancer research has identified this field of study as an 'extraordinary opportunity for research investment.' Admist all it's capabilities I see but one problem... How practical and beneficial is this technology to third world countries where pooverty is clearly sweeping away the little health that we have? Probably not much! Why? Well, I can generally say we have soo many problems that need to be addressed and an unproportionate research fund to mind this little but sophiscated technology that theoretically and perharps practically would have great positive impacts in medicine. "In practice, nanotechnology also represents an assimilation and integration of other technologies, including stem cell biology, molecular engineering, genomics, proteomics, tissue engineering, and materials science.1" Molecular research labs in general involve expensive technology and given the great rate of burden of disease (BOD) of diseases such as malaria, TB, leprosy and HIV/AIDS our priority setting is far away from investing in any area other than the problem at hand. Besides nanomedicine would probably solve problems that are a main concern of developed worlds than our world because in my opinion uninfectious diseases such as cancer and diabetes, are not our big problem at the moment. So despite its fascination and open possibilities nanomedicine is not the talk of the town in this part of the world and may not be for the next God knows how many years to come. In short interesting as it may be, nanomedicine can be a feature article or news higlight but not our focus of interest at present. We simply can't afford to be interested!