Implantable medical devices bolstered by next-gen surface modification

January 24, 2018, University of Sydney
Control of peptide orientation by electric field. Charge separation on one end of the peptide creates a dipole moment (indicated by ellipses) that aligns with the electric field and rotates the entire molecule. When the peptide makes contact with the radical-functionalized surface it becomes irreversibly anchored in this orientation. Credit: University of Sydney

A discovery by University of Sydney researchers could underpin a new class of implantable devices that provide biological signals to surrounding tissue for better integration with the body and reduced risk of infection.

Modern medicine increasingly relies on implantable biomedical devices but their effectiveness is often limited because of unsuccessful integration with or the development of untreatable infections, necessitating replacement of the device through revision surgery.

The team at the Applied Plasma Physics and Surface Engineering Laboratory has developed practical techniques to guide and attach peptides to surfaces; computer simulations and experiments demonstrated control of both peptide orientation and surface concentration, which can be achieved by applying an electric field like that delivered by a small household-sized battery.

The findings are published today in Nature Communications.

Corresponding author Professor of Applied Physics and Surface Engineering Marcela Bilek said biomaterial coatings can mask the implanted devices and mimic surrounding tissue.

"The holy grail is a surface that interacts seamlessly and naturally with host tissue through biomolecular signalling," said Professor Bilek, who is a member of the University of Sydney Nano Institute and the Charles Perkins Centre.

Robust attachment of biological molecules to the bio-device surface is required to achieve this, as enabled by unique surface modification processes developed by Professor Bilek.

"Although proteins have successfully been used in a number of applications, they don't always survive harsh sterilisation treatments - and introduce the risk of pathogen transfer due to their production in micro-organisms," Professor Bilek said.

Professor Bilek - together with Dr Behnam Akhavan from the School of Aerospace, Mechanical and Mechatronic Engineering and the School of Physics and lead author PhD candidate, Lewis Martin from the School of Physics - are exploring the use of short protein segments called peptides that, when strategically designed, can recapitulate the function of the protein.

Mr Martin said the team was able to tune the orientation of extremely small biomolecules (less than 10 nanometres in size) on the . "We used specialised equipment to perform the experiments, but the electric fields could be applied by anyone using a home electronics kit," he said.

Dr Akhavan said that assuming industry support and funding for clinical trials, improved implants could be available to patients within five years.

"The application of our approach ranges from bone-implants to cardiovascular stents and artificial blood vessels," Dr Akhavan said.

"For the bone , for example, such modern bio-compatible surfaces will directly benefit patients suffering from bone fracture, osteoporosis, and bone cancer."

Because of their small size, the peptides can be produced synthetically and they are resilient during sterilisation. The main difficulty in using peptides is ensuring they are attached at appropriate densities and in orientations that effectively expose their active sites.

Using applied electric fields and buffer chemistry, the researchers discovered several new levers that control peptide attachment. Charge separation on peptides creates permanent dipole moments that can be aligned with an electric field to provide optimal orientation of the molecules and the amount of peptide immobilised can also be tuned by the electrostatic interactions when the peptides have an overall charge.

The paper said this knowledge is being used to design strategies to create a new generation of synthetic biomolecules.

"Our findings shed light on mechanisms of biomolecule immobilisation that are extremely important for the design of synthetic and biofunctionalisation of advanced implantable materials," the paper states.

Explore further: Surfaces that communicate in bio-chemical Braille

More information: Lewis J. Martin et al, Electric fields control the orientation of peptides irreversibly immobilized on radical-functionalized surfaces, Nature Communications (2018). DOI: 10.1038/s41467-017-02545-6

Related Stories

Surfaces that communicate in bio-chemical Braille

October 1, 2014

A Braille-like method that enables medical implants to communicate with a patient's cells could help reduce biomedical and prosthetic device failure rates, according to University of Sydney researchers.

Modified peptides could boost plant growth and development

October 5, 2017

A new Australian study of peptide hormones critical for plant development could result in wide-ranging benefits for agriculture, tissue culture, and related industries, and even improve knowledge of peptides in humans.

Technology tethers free radicals

August 17, 2011

The science world is abuzz with news of a new platform technology developed by physicists at the University of Sydney - technology that can be used in areas as diverse as disease detection through to biofuel production.

Simple one-pot synthesis of druggable tricyclic peptides

December 19, 2017

Chemists at the University of Amsterdam's Van 't Hoff Institute for Molecular Sciences (HIMS) and Pepscan (Lelystad) have developed a new methodology for locking linear peptides into highly rigidified tricyclic structures ...

Recommended for you

Research gives new ray of hope for solar fuel

April 24, 2018

A team of Renewable Energy experts from the University of Exeter has pioneered a new technique to produce hydrogen from sunlight to create a clean, cheap and widely-available fuel.

Scientists have tracked down an elusive 'tangled knot' of DNA

April 23, 2018

It's DNA, but not as we know it. In a world first, Australian researchers have identified a new DNA structure—called the i-motif—inside cells. A twisted 'knot' of DNA, the i-motif has never before been directly seen inside ...

New theory shows how strain makes for better catalysts

April 20, 2018

Brown University researchers have developed a new theory to explain why stretching or compressing metal catalysts can make them perform better. The theory, described in the journal Nature Catalysis, could open new design ...

Machine-learning software predicts behavior of bacteria

April 19, 2018

In a first for machine-learning algorithms, a new piece of software developed at Caltech can predict behavior of bacteria by reading the content of a gene. The breakthrough could have significant implications for our understanding ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.