The downside to inhabiting one of the most sophisticated machines on earth is that when something goes wrong it's often very difficult to find out exactly what - and how to fix it.
The human body's intricate systems can make diagnosing and treating an illness a trying process, while behavioural factors may throw an extra spanner in the works. Fortunately, nanotechnology offers a way to address both hurdles, and holds great promise for medical applications that could change the nature of diagnosis and recovery.
Some of these innovative techniques are being explored at the National Centre for Nanostructure Materials, based at the Council for Scientific and Industrial Research (CSIR) in Pretoria. In a recent tour held by the National Research Foundation, in partnership with the South African Agency for Science and Technology Advancement and the Nanotechnology Public Engagement Initiative, scientists demonstrated a range of technologies that will impact our daily lives.
One of the most valuable aspects of nanotech is the ability to individually manipulate atoms and molecules. At this scale, researchers are working with components a millionth the size of a millimetre, allowing them to create materials with exciting new properties. Nanomaterials can exhibit vastly increased surface areas, better thermal or conductive qualities or super-strength. They can also move easily between and within biological structures, with a DNA molecule being about 2.5nm in diameter, while a red blood cell comes in at 8000nm.
Instead of dumping a dose of drugs into a random area of the body, customised nanoparticles could serve as nimble delivery vehicles, bringing exactly the right drug, in exactly the right quantity, to exactly the right place. This means medicine is administered earlier in the course of the disease, and with fewer side effects, making overall treatment far more effective.
Nano-sized drug carriers are also efficient mercenaries for pathogens, taking them out with a well-aimed shot rather than issuing a spray of bullets that hit both diseased and healthy cells. In future, it could be possible to coat insulin in nanoparticles which would be swallowed or absorbed through the skin, saving people with diabetes the trouble of frequent injections. Nanomedicine is a rapidly growing field of research, with a whole world of possibility waiting to be realised.
Worth its weight in gold
One application gaining interest in the medical community is the use of 'quantum dots' - light-sensitive nanoparticles that can serve as markers of disease. These phosphorescent particles could theoretically be injected into the body, attach themselves to the offending cell, and then emit a telltale glow when doctors shine, say, a UV light on the patient.
As CSIR candidate researcher Ntombizodwa Mathe explains, this will enable doctors to identify specific areas they need to target during radiation or surgery. She adds, however, that SA is still a long way off from advancing these methods. “We're only at the stage where scientists are synthesising these particles; we still have to collaborate with the medical fraternity to see how we can work together to push these capabilities forward.”
A particularly promising application is identifying and treating cancer cells, something gold nanoparticles have shown to be mighty effective at. These golden multi-taskers can be attached to target molecules that are drawn to cancer cells, which doctors can then identify by the cluster of gold particles huddled around it. Magnetic iron oxide nanoparticles are also good cancer identifiers, although they use magnetism to turn the cell they're clinging to into a magnet, which sticks to the biopsy needle.
One of the most heartbreaking aspects of cancer is the devastating effects treatment has on the person's physical, emotional and mental health. Nanoparticles could help make treatment less traumatic and more effective, providing relief to the approximately 12.6 million people diagnosed with various forms of cancer worldwide every year.
A gold nanoparticle, for example, can be heated up by radio frequency to essentially fry the cancer cell it's attached to, or hit it with a lethal chemical dose. These particles can also be loaded with molecules that counteract the tumour's internal defences, all without harming healthy neighbouring cells.
Extensive research on gold nanoparticles is being conducted at Mintek, one of SA's nanotech centres of innovation, and portable test kits for various diseases are now in the final stages of development. Aimed at combating some of the country's most common diseases, diagnostic test kits for TB and malaria have been designed to be fast, affordable and accurate. These gold nano-particle-based kits can be used by individuals at home, without the need for trained professionals.
Mr (nano) Delivery
Another growing field in nanomedicine is drug delivery, as nanoparticles are small enough to permeate cell membranes and could potentially be used to dispense medicines in the brain.
We still have to collaborate with the medical fraternity to see how we can work together to push these capabilities forward.
Ntombizodwa Mathe, CSIR
According to the Department of Health, SA has the seventh highest TB incidence in the world, a number aggravated by the prevalence of HIV. Treatment of tuberculosis is complicated by the fact that many patients fail to complete their course of medication, leading to multi-drug-resistant strains. Common reasons for this include the time, cost and inconvenience of having to take several antibiotics daily for months, as some patients have to travel long distances to health centres to take their drugs. New methods of delivering TB drugs could help alleviate these problems and provide treatment at a lower cost.
At the CSIR, researchers have developed a way to incorporate TB drugs into nanoparticles, which are then slowly released into the patient's blood stream. Dosage is only required every seven to 10 days, which should increase compliance and contribute to eradicating the disease.
The safety and uptake of nanoparticles is being tested in TB-infected mice, with human trials scheduled for future.
As Mathe mentioned, while SA isn't actively pushing nanomedicine, a team at Wits University is spearheading several drug-delivery platforms with exciting implications for the health sector.
Researchers in the department of pharmacy and pharmacology have developed technologies aimed at improving the efficacy of drugs used to treat conditions such as cancer, tuberculosis, HIV, and neurodegenerative disorders. Presently, taking medication isn't an exact science, as absorption isn't always optimal or accurate. The techniques developed at Wits are geared at improving accuracy by delivering drugs to specific parts of the body, in a controlled way.
The research team has found ways of delivering drugs to targeted areas of the body via the eye, nose, mouth, skin, and gastrointestinal tract; which may sound gory until one considers those who have to swallow handfuls of pills every day, or children who find taking medicine an ordeal.
In the latter case, the department's special wafer could do the trick, as they can be placed under the tongue or inside the cheek, dissolving instantly so the drug is absorbed almost immediately. This is also useful for patients like the elderly who can't take in liquids, tablets or capsules. Wafers trump pills in this regard as medicine isn't broken down by stomach acid or enzymes in the liver, so it acts faster and more effectively. One can also create a wafer 'sandwich' by layering the different drugs needed, so patients don't have to take several medications.
The department is also looking at implanting nanomaterials into specific areas of the brain, for the treatment of neuro-degenerative diseases like Alzheimer's and Parkinson's. These implants could deliver drugs to targeted sites for a period of six months to a year.
Bionic breed
Some may be surprised to find out they already come into contact with nanotechnology on a daily basis, as it's commonly used in sunscreens and other beauty products (you can thank those high absorption qualities for more powerful wrinkle-fighting). In sunscreen, nano-sized particles of zinc oxide or titanium dioxide are used to create a resilient but transparent film, to reduce the 'pasty' look.
But smearing nanoparticles onto skin is far cry from having them replace it, which is what some researchers hope to do in future. Using nano-based structures and materials to grow new skin, bones or teeth is a process called tissue engineering, and it could be revolutionary in replacing infected organs, repairing damaged nerves, and even building artificial limbs.
Building human-like tissue is no easy feat, however, and even working at the nanoscale, there are significant challenges. It involves creating a 3D framework of biomaterials as a structural support, and then adding biological components to surfaces to encourage cell growth. As an example, scientists have used nanofibre-based scaffolds to successfully grow bone tissue.
One of Wits' innovations is a nanodevice implanted into the eye for use in serious conditions affecting HIV-positive patients, or those in the advanced stages of Aids. It releases an anti-inflammatory agent in response to the level of inflammation in the eye, so the dosage is directly related to the severity of the irritation. This means patients aren't subjected to the continuous, indiscriminate release of drugs and the accompanying side effects.
Nanodevices like Wits' eye implant also negate the need for subsequent surgery to remove implanted systems, because they are made from biocompatible and biodegradable materials that dissolve naturally after a period of time.
While potentially groundbreaking, nano-based medical techniques are also undergoing considerable scrutiny, as there is a lack of accurate data when it comes to possible risks and long-term effects. The fact that nanoparticles are so small means they may not be detected by the body and remain there indefinitely, with no way of being eliminated. Ongoing tests are needed to more accurately establish nanotechnology's effects on human health.
Ultimately, we could see a future where miniature robots could travel through the bloodstream, tracking down viruses, repairing damaged tissues, and even performing surgery on individual cells. These are still visionary concepts, but a look at the technology advances of the past two decades suggests there are not only untold possibilities, but more than enough imagination and drive to see them realised.
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