Leeds University. UK: Scientists have shown that gold nanotubes have many applications in fighting cancer: internal nanoprobes for high-resolution imaging; drug delivery vehicles; and agents for destroying cancer cells.
The study, published today in
the journal 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, who is based in both 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.”
The researchers say that a new technique to control the
length of nanotubes underpins the research. By controlling the length, the
researchers were able to produce gold nanotubes with the right dimensions to absorb
a type of light called ‘near infrared’.
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. This is why parts of your hand appear red when a torch is shone through
it.
“When the gold nanotubes travel through the body, if light
of the right frequency is shone on them they absorb the light. This light
energy is converted to heat, rather like the warmth generated by the Sun on
skin. 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 say they were able to control whether the gold
nanotubes were in cancer-destruction mode, or ready to image tumours.
In order to see the gold nanotubes in the body, the
researchers used a new type of imaging technique called ‘multispectral
optoacoustic tomography’ (MSOT) to detect the gold nanotubes in mice, in which
gold nanotubes had been injected intravenously. It is the first biomedical
application of gold nanotubes within a living organism. It was also shown that
gold nanotubes were excreted from the body and therefore are 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: “This is the
first demonstration of the production, and use for imaging and cancer therapy,
of gold nanotubes that strongly absorb light within the ‘optical window’ of
biological tissue.
“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 release of a therapeutic agent could, in this age of
personalised medicine, be used to identify and treat cancer with minimal
toxicity to patients.”
The use of gold nanotubes in imaging and other biomedical
applications is currently progressing through trial stages towards early clinical
studies.
Further information
This work was supported by the Wellcome Trust, with
additional funding provided by the Engineering and Physical Sciences Research
Council (EPSRC).
The research paper, ‘Engineering Gold Nanotubes with
Controlled Length and Near-Infrared Absorption for Theranostic Applications’,
is published in the journal Advanced Functional Materials on 13
February 2015. The paper can be accessed here.
Dr Sunjie Ye, Professor Steve Evans and Dr James McLaughlan
are available for interview. Please contact Sarah Reed, Press Officer,
University of Leeds, on 0113 34 34196 or email s.j.reed@leeds.ac.uk