Scientists have shown that gold nanotubes have many applications, from fighting cancer to drug delivery and high-resolution imaging
Pulsed near infrared light (shown in red) is shone onto a tumour (shown in white) that is encased in blood vessels. The tumour is imaged by multispectral optoacoustic tomography via the ultrasound emission (shown in blue) from the gold nanotubes.
A study, published in Advanced Functional Materials, details the first successful demonstration of the biomedical use of gold nanotubes in a mouse model of human cancer.
Study lead author Dr Sunjie Ye from the School of Physics and Astronomy and the Leeds Institute for Biomedical and Clinical Sciences at the University of Leeds, said: ‘High recurrence rates of tumours after surgical removal remain a formidable challenge in cancer therapy. Chemo- or radiotherapy is often given following surgery to prevent this, but these treatments cause serious side-effects.
‘Gold nanotubes — that is, gold nanoparticles with tubular structures that resemble tiny drinking straws — have the potential to enhance the efficacy of these conventional treatments by integrating diagnosis and therapy in one single system.’
A new technique to control nanotube length underpins the research; by controlling the length, the researchers were able to produce gold nanotubes with the right dimensions to absorb near infrared light. The study’s corresponding author, Professor Steve Evans, from the School of Physics and Astronomy at the University of Leeds, said: ‘Human tissue is transparent for certain frequencies of light (in the red/infrared region). When the gold nanotubes travel through the body, if the right frequency light is shone on them, they absorb that light and convert it to heat. Using a pulsed laser beam, we were able to rapidly raise the temperature in the vicinity of the nanotubes so that it was high enough to destroy cancer cells.’
In cell-based studies, by adjusting the brightness of the laser pulse, the researchers were able to control whether the gold nanotubes were in cancer-destruction mode or ready to image tumours. To see the gold nanotubes in the body, a new type of imaging technique called multispectral optoacoustic tomography (MSOT) was used.
It is the first biomedical application of gold nanotubes in a living organism. It was also shown that gold nanotubes were excreted from the body and are therefore unlikely to cause problems in terms of toxicity, an important consideration when developing nanoparticles for clinical use.
Study co-author Dr James McLaughlan, from the School of Electronic & Electrical Engineering at the University of Leeds, said: 'The nanotubes can be tumour-targeted and have a central hollow core that can be loaded with a therapeutic payload. This combination of targeting and localised therapeutic release could, in this age of personalised medicine, be used to identify and treat cancer with minimal toxicity to patients.’