Medical advances in nanotechnology

Materials World magazine
,
1 Dec 2015

Rhiannon Garth Jones takes a look at some of the latest nanotechnology research that could improve our health.

Thomas Carlyle, the long-lived Victorian polymath, once said, ‘Health alone is victory’. As the pace of technology speeds up, we are starting to turn our eyes towards the benefits it could have on health, and the areas of research being conducted in the field of nanomedicine promise significant improvements. From drug delivery to cancer treatment and the long-promised 3D printing of organs, this is a field where, increasingly, it seems anything could be possible.

In Materials World August 2015, Simon Frost reported that, while bioprinting is a field very much still developing, there are reasons to be excited. It might be possible, for instance, to bioprint tissue constructs, rather than wait for entire organs, or to print and embed cells in a matrix before allowing them to mature and form a complete vascularised system in a bioreactor, avoiding the obstacle of vascularisation. In the meantime, skin and cartilage substitutes have been successfully printed, as well as a bioreabsorbable tracheal splint that was transplanted into a baby by a research team from the universities of Sydney, Harvard and Stanford, while MIT have managed to bioprint a perfusable network of capillaries.

Building on the past

Although the possibilities of bioprinting perhaps receive the most coverage, it is in the area of drug delivery that nanotechnology might have the most impact on health. Much of this field is building on techniques that were already in use before the explosion of nanotechnology as a field, such as liposomes, polymeric micelles and dendrimers. For instance, liposomes have been used in drug delivery since the 1960s. Their membranes are made from lipids, the same material that comprises the cell wall, and it is often engineered to pair with proteins in the membrane of the target cell. Liposomes can have a low rate of success, however – those carrying toxic chemotherapy drugs have sometimes ended up in the correct cells less than 10% of the time.

Recently, a team of researchers from Carnegie Mellon, the University of California and the Colorado School of Mines published a paper in ACS Nano suggesting that more stable liposomes would improve delivery accuracy. They used computer modelling to show that a nanoparticle core made of gold or iron, connected by polymer tethers to the membrane would help the liposome absorb the pressures of travelling through the body.

Combating cancer

Another way of improving the effectiveness of existing methods of drug delivery was proposed by a team from the National Cancer Institute, USA. The blood vessels around a cancerous tumour in the body are unusually porous, allowing nanoparticles to accumulate at the site. This has previously been more effective than other methods but still inefficient. The team discovered that the porosity of the vessels could be increased with photo-immunotherapy, which uses an antibody linked to a light-sensitive compound or photosensitiser. This increased the number of drug-delivering nanoparticles able to accumulate at the site, leading to a reduction in the size of the tumours treated.

Elsewhere, targeted therapies are being developed to treat more difficult cancers, where surgery or other treatments cannot remove all the mutated cells. A research team from Oregon University is investigating the compound naphthalocyanine, believing it might be able to insert itself into cancer cells and enable surgeons to better identify them during surgery, as well as kill any remaining cells afterwards using phototherapy. Naphthalocyanine reacts to infrared light, and the team's research shows that it can be used to makes cells glow, as well as kill them. By adjusting the intensity of the light, the compound can be controlled to only target the cancerous cells. Associate Professor Oleh Taratula, who leads the project, explained to the American Association of Pharmaceutical Sciences that they hoped to 'create a useful tool for surgeons. Certain compounds are not cancer-specific, demonstrate low fluorescence and phototherapeutic efficiency and gradually fade under light, leading to false negative results. Our nanoparticles are overcoming these issues, acting as an extra pair of eyes and scissors by providing real-time imaging and phototherapy treatment during surgery.'

Other scientists are seeking to identify cancerous tumours before they become dangerous by hyperpolarising synthetic nanodiamonds so they light up early tumours in Magnetic Resonance Imaging (MRI) scans. The research team from the University of Sydney's School of Physics have attached the magnetised nanodiamonds to chemicals that target cancers and injected into the body. If a tumour is present, the chemicals will target it and the nanodiamonds will light up on the MRI scan.

Another area where nanodiamonds are employed is in root canal treatment. Research from UCLA Dentistry shows that nanodiamonds can strengthen the compound used to fill teeth and ward off infection post-surgery. Some root canal processes don’t completely remove the infection, and residual infections can lead to tooth loss. The polymer currently used to fill teeth during root canal, gutta percha, has a limited ability to ward off infection. When reinforced with antibiotic-loaded nanodiamonds, it is much more effective at preventing the growth of bacteria within the tooth, removing the need for further surgery.

While much of the progress being made by nanotechnology in the field of health is in the earliest stages, it is not just consigned to the lab. Savyon Diagnostics has been using its NanoChip technology – a tiny, bio-compatible silicon chip capable of rapid identification and precise multiplexed analysis of nucleic acids – for clinical molecular diagnostics since 2006, and it is not alone. Nanotechnology is improving our health in the here and now, as well as promising great advancements for the future.