Essential oils to fight bacterial infections


June 7, 2018


James Cook University


Scientists have discovered a technique to
apply natural plant extracts such as Tea Tree Oil as a coating for medical
devices, a process which could prevent millions of infections every year.

James Cook University
scientists have discovered a technique to apply natural plant extracts such as
Tea Tree Oil as a coating for medical devices, a process which could prevent
millions of infections every year.

Professor Mohan Jacob,
Head of Electrical and Electronics Engineering at JCU, leads a team
investigating the problem. He said an increasing number of unplanned surgeries
are being performed to fight infections — mostly caused by bacterial activity
on medical devices and a subsequent ‘biofilm’ forming on them.

“Just in the US,
about 17 million new biofilm-related infections are reported annually, leading
to approximately 550,000 fatalities each year. It’s thought about 80% of
worldwide surgery-associated infections may relate to biofilm formation,”
he said.

Professor Jacob said the
team converted plant-based products — known as Plant Secondary Metabolites
(PSMs) — into polymer coatings for medical devices, including implants.

“They’re derived
from such things as essential oils and herb extracts and they have relatively
powerful broad-spectrum antibacterial activities. PSMs are a low-cost renewable
resource available in commercial quantities, with limited toxicity, and
potentially, different mechanisms for fighting bacteria than synthetic

Professor Jacob said the
group’s research tackled the persistent problem of how to convert the plant
extracts from a liquid to a solid state as a coating for medical devices,
without a significant loss of effectiveness.

Dr Katia Bazaka is an
Adjunct Senior Research Fellow and team member. “We used plasma-enhanced
techniques within a reactor containing the essential oil vapours. When the
vapours are exposed to a glow discharge, they are transformed and settle on the
surface of an implant as a solid biologically-active coating. These have shown
good antibacterial properties,” she said.

“The main advantage
of this approach is that we are not using other chemicals, such as solvents,
during the fabrication process. As such, there is no threat of potentially
harmful chemicals being retained in the coating or them damaging the surface of
the material onto which the coating is applied. It also makes the fabrication
process more environmentally friendly,” said Dr Bazaka.

Professor Jacob said the
JCU group are currently the global pioneers in the development of plant-derived
polymer thin films — publishing over 70 research articles and six PhD theses
in the field.

Professor Ian Atkinson,
Director of JCU’s eResearch unit and a collaborator on the project, said the
work had recently been extended to target marine organisms, to prevent the
growth of biofilms on aquatic sensors and their subsequent failure.

“Another attractive
feature of these coatings is their optical transparency, which may be quite
important if you are using them to coat contact lenses, or optical windows in
aquatic sensors,” he said.

Professor Jacob and his
PhD students are now collaborating with the Dr Peter Mulvey and Associate
Professor Jeff Warner at the JCU-based Australian Institute of Tropical Health
and Medicine to study the activity of different types of bacteria on the plant-
based coatings.


Even though synthetic
antibiotics have been the best weapon for eradicating microbial infections since
the arrival of penicillin, the overuse of these medications is gradually
rendering them ineffective. Scientists think that if new strategies are not
developed soon, medical treatments could retreat to the era where slight
injuries and common infections develop into serious medical problems.

Most plants produce
organic molecules as antimicrobial agents to combat harmful microorganisms. In
the past few decades, progress in the synthesis of nanoscale materials, in
particular plasma-assisted fabrication, has provided the means to retain the
antimicrobial activities of plant secondary metabolites within bioactive

Though the JCU team
investigated many natural precursors, their main focus was on the Australian
based essential oil, Tea Tree Oil (Melaleuca alternifolia) and its components.
As part of a PhD project, Dr Katia Bazaka developed antibacterial coatings from
terpene-4-ol, which is a major component of Tea Tree Oil.


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