Nanotechnology for health: Facts and figures

Can developing countries use nanotechnology to improve health? Priya Shetty looks at nanomedicine's promise at a SciDev report.

Nanotechnology — the science of the extremely small — holds enormous potential for healthcare, from delivering drugs more effectively, diagnosing diseases more rapidly and sensitively, and delivering vaccines via aerosols and patches.

Nanotechnology is the science of materials at the molecular or subatomic level. It involves manipulation of particles smaller than 100 nanometres (one nanometre is one-billionth of a metre) and the technology involves developing materials or devices within that size — invisible to the human eye and often many hundred times thinner than the width of human hair. The physics and chemistry of materials are radically different when reduced to the nanoscale; they have different strengths, conductivity and reactivity, and exploiting this could revolutionise medicine.

For example, a major challenge of modern medicine is that the body doesn't absorb the entire drug dose given to a patient. Using nanotechnology, scientists can ensure drugs are delivered to specific areas in the body with greater precision, and the drugs can be formulated so that the active ingredient better permeates cell membranes, reducing the required dose.




Rich countries are investing heavily in nanotechnology for health. The first generation of cancer drugs delivered via nanoparticles, for example, has already been approved by the US Food and Drug Administration (FDA).

However, it is still early days for nanotechnology in healthcare and whether it will be of value to resource-poor countries is still hotly debated. Critics argue that when millions of people in countries like India or those in Sub-Saharan Africa are dying because of a lack of access to even basic healthcare, investing in cutting-edge technologies is a ludicrous waste of money. [1]

And experts are concerned that the toxicity of nanoparticles to human health and the environment has not been studied extensively enough. For instance, a 2004 report by the UK Royal Society and Royal Academy of Engineering recommended that nanoparticles and nanotubes — cylindrical carbon molecules that are better conductors than normal carbon molecules — be treated as hazardous waste. [2]

Many emerging economies such as Brazil, China, India, Iran, Malaysia, Mexico, Singapore and South Africa have ambitious research and development (R&D) plans for nanotechnology. Their governments need to balance short-term health needs with long-term technological investment.

Yet while poor countries have an ongoing responsibility to strengthen healthcare systems and provide wider access to medicine, nanotechnology could, in the long run, save lives by making diagnosis and treatment far more effective.

A group of scientists who have mapped out the uses of nanotechnology and the needs of global health argue that nanomedicine is relevant for the developing world. They surveyed researchers worldwide and concluded that nanotechnology could greatly contribute to meeting the Millennium Development Goals for health. Specifically, the goals to reduce child mortality, improve maternal mortality and combat HIV/AIDS, malaria and other diseases. [3]

Diagnostics and screening

There is an urgent need in the developing world for better disease diagnosis, and nanotechnology offers a multitude of options for detecting disease.

One way of doing this is by using quantum dots — nanosized semiconductors that can be used as biosensors to find disease and which can be made to fluoresce. Sometimes known as nanocrystals, quantum dots have significant advantages over traditional organic dyes as their luminescence can be tuned to a wide range of frequencies, and they degrade much more slowly in the body. Fluorescent quantum dots can be tagged to antibodies that target cancerous cells or cells infected with tuberculosis (TB) or HIV. [4, 5]

Fluorescent quantum dots could also be used to diagnose malaria by making them target the protein that forms a mesh in the blood cell's inner membrane. The shape of this protein network changes when cells are infected with malaria, so scientists are able to spot malaria infection from the shape produced by the dots. [6]

Similarly, carbon nanotubes, and other nanoparticles such as nanowires, have been used as biosensors to detect diseases such as HIV and cancer. Cancer biosensors can be made, for instance, by attaching nucleic acid probes to the ends of nanowires. These probes are specifically designed to bond to biomarkers that indicate cancer such as mutated RNA. When mutated RNA in a sample interacts with the probes, electric currents are induced along the nanowire, which is detected by the silicon chip in which the biosensor is embedded. [7]

Drug delivery

Nanotechnology could also revolutionise drug delivery by overcoming challenges such as how to sustain the release of drugs in the body and improving bioavailability — the amount of active ingredient per dose.

Some drugs can now be delivered through 'nanovehicles'. For example liposomes, which can deliver the drug payload by fusing with cell membranes, have been used to enscapsulate HIV drugs such as stavudine and zidovudine in vehicles ranging from 120 to 200 nanometres in size. [7] Since both these drugs have short half-lives, the liposome coating could potentially make them active for longer periods.

Other nanodrug delivery systems include using fullerene 'buckyball' cages, [8] and branched nanomolecules called dendrimers.

In the developed world, cancer is top of the list of diseases being targeted for nanomedical treatment. Cancer prevalence is rising fast in the developing world with 70 per cent of all cancer deaths, according to WHO. In developing nations, the use of nanotechnology is also being explored in the fight against infectious diseases such as HIV and TB.

Vaccines

Nanotechnology could herald a new era in immunisation by providing alternatives to injectable vaccines for diseases that affect the poor. Injectable vaccines need to be administered by healthcare professionals, who may be scarce in developing countries, particularly in rural areas. Vaccines also need reliable refrigeration along the delivery chain. Scientists are working on an aerosol TB vaccine. They are also investigating a nanotechnology-based skin patch against West Nile Virus and Chikungunya virus. [12]

Injectable vaccines can be useful if the inactive virus is bound up with nanoparticles to increase the immune response. This method is being used to devise a vaccine against pandemic influenza. [13]

Leaders of the pack

China is by far top of the leader board for nanotechnology research among developing countries, registering the most nanotechnology patents. It has had a national nanotechnology programme since the early 1990s, and a huge number of new nanotechnology companies are set up every year. [14]

India is also taking nanotechnology seriously, with over 30 institutions involved in research. South-East Asian countries are especially active, with Malaysia, the Philippines, Thailand and Vietnam all engaged in nanotechnology research.

In Africa, meanwhile, South Africa has both its private and public sector working on nanotechnology R&D. Brazil, which is leading nanotechnology research in Latin America, has partnered with South Africa and India to promote South–South collaboration through the IBSA Nanotechnology Initiative.

Many other developing nations are hoping to catch up. A 2005 survey of global nanotechnology research activity classed countries as having national activities or funding (suggesting a clear national strategy or government funding), having at least one individual or research group engaged in nanotechnology research, or having the government expressing an interest in pursuing nanotechnology (see table 1, adapted from [14]).

Nanotechnology is an expensive science but the costs of setting up an institute seem to vary widely between countries. For instance, Mexico and Vietnam say it costs about US$5 million to establish a nanotechnology institute, but Costa Rica says it has done so for less than US$500,000. [14]

Public acceptance

What is technically possible and what is ethically appropriate is a matter of heated debate. In developing nations, nanomedicine evokes similar ethical issues to genetically modified foods. When people are desperately in need of food or medicine does it matter through what route it arrives? And whether illiterate or uneducated populations can be adequately involved in debates about the effects of these new technologies on society? [1]. The invisible nature of nanotechnology makes it easier to 'hide' nanotech products, and to invade privacy or carry out procedures that require consent, without the patient's knowledge. This may be particularly pertinent with regard to clinical trials of nanodrugs carried out in developing countries.

Developing country governments will need to tread carefully. The capacity to ensure ethical clinical trials is generally poor in the developed world and introducing health products based on nanotechnology may require an expertise that is lacking [2]. As with other health technologies, there is nothing intrinsically good or bad about nanotechnology. It will depend on how it is used.

In the field of health, advances in nanotechnology are combined with other technologies, including information technology and biotechnology, increasing nanotechnology's potential to 'displace' health measures and systems where regulation has been worked out over many years. One example is the development of computer-controlled molecular tools that may not require the direct intervention of a medical practitioner. Or, nanosensors that measure and store medical information about an individual where issues might arise over the storage, access and use of such information.

Even in the developed world the study of legal, ethical, environmental and equity issues are lagging behind scientific advances in nanotechnology for health. Nanotechnology may not be as advanced in the developing world as in countries like the United Kingdom or the United States, but it's only a matter of time before China and India catch up. Developing nations should not wait until the technology is on their doorstep before figuring out its ethical and societal implications.

This article is part of a spotlight on Nanotechnology for health.


SOURCES

[1] Court E. et al. Will Prince Charles et al diminish the opportunities of developing countries in nanotechnology? (2004) Accessed 23 October 2010.

[2]The Royal Society and Royal Academy of Engineering Nanoscience and Nanotechnologies: Opportunities and Uncertainties (2004)

[3] Salamanca-Buentello, F. et al. Nanotechnology and the Developing World. PLoS Medicine doi:10.1371/journal.pmed.0020097 (2005)

[4] Maclurcan, D.C. Nanotechnology and Developing Countries Part 1: What Possibilities? Online Journal of Nanotechnology doi:10.2240/azojono0103 (2005)

[5] Mathuria, J.P. Nanoparticles in tuberculosis diagnosis, treatment and prevention: a hope for the future. Digest Journal of Nanomaterials and Biostructures 4, 309-312 (2009)

[6] Tokumasu, F. et al. Band 3 modifications in Plasmodium falciparum-infected AA and CC erythrocytes assayed by autocorrelation analysis using quantum dots. Journal of Cell Science doi:10.1242/jcs.01662(2005)

[7] Mamo, T. et al. Emerging Nanotechnology Approaches for HIV/AIDS Treatment and Prevention.  Nanomedicine 5, 269-285 (2010)

[8]Partha, R. et al. Self assembly of amphiphilic C60 fullerene derivatives into nanoscale supramolecular structures. Journal of Nanobiotechnology doi:10.1186/1477-3155-5-6 (2007)

[9] Milane, L.J. et al. Development of EGFR-Targeted Polymer Blend Nanocarriers for Paclitaxel/Lonidamine Delivery to Treat Multi-Drug Resistance in Human Breast and Ovarian Tumor Cells. Molecular Pharmacology doi: 10.1021/mp1002653 (2010) [Epub ahead of print]

[10] Lee, H., et al. Rapid detection and profiling of cancer cells in fine-needle aspirates. Proceedings of the National Academy of Sciences doi:106(30):12459-64 (2009)

[11] Kam, N.W., et al. Carbon nanotubes as multifunctional biological transporters and near-infrared agents for selective cancer cell destruction. Proceedings of the National Academy of Sciences doi: 102(33):11600-5 (2009)

[12] Prow, T.W. et al. Nanopatch-Targeted Skin Vaccination against West Nile Virus and Chikungunya Virus in Mice. Small 6, 1776-84 (2010)

[13] Huang, M.H. Emulsified nanoparticles containing inactivated influenza virus and CpG oligodeoxynucleotides critically influences the host immune responses in mice. PLoS One doi:10.1371/journal.pone.0012279 (2010)

[14] Maclurcan, D.C. Nanotechnology and Developing Countries Part 1: What Realities? Online Journal of Nanotechnology doi:10.2240/azojono0104 (2005)

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Reference: Shetty, P. 2010, November. Nanotechnology for health: Facts and figures. Retrieved November 25, 2010. Accessed at http://www.scidev.net/en/south-east-asia/nanotechnology-for-health-facts-and-figures-1.html?utm_source=link&utm_medium=rss&utm_campaign=en_southeastasia.


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