Monthly Archives: September 2018

Medical applications of light and fibre optics

20 September 2018:

A class of Year 11 Physics students from Loreto College, Marryatville, South Australia were visited by CNBP researcher Dr Jiawen Li, September 20th, 2018.

During the outreach visit Dr Li spoke on the medical uses of fibre optics technology and answered questions from the class, helping shed light on the life of a scientist and explaining the wide-range of career options open to STEM students.

“I really enjoyed visiting the school and found the session an extremely rewarding experience,” said Dr Li.

“Student questions following the presentation were well thought through and hopefully I helped in some small way to encourage the girls to continue their study of physics and other STEM related subjects.”

“Higher education potentially opens up a wide range of exciting career opportunities right across the science, engineering and medical disciplines,” said Dr Li. “And it would be great to see these enthusiastic students get to University.”

Feedback from the school post-event noted that the students had found Dr Li to be a fantastic role model and that her presentation session had been particularly inspiring.

Below: Students from Loreto College at the outreach session.

Amperometric sensing device to detect cytokines

10 September 2018:

A new paper with CNBP co-authors Prof Mark Hutchinson, Prof Ewa Goldys and Dr Guozhen Liu demonstrates an amperometric sensing device based on graphene oxide (GO) and structure-switching aptamers for long-term detection of cytokines in a living organism.

Journal: ACS Applied Materials and Interfaces.

Publication title: Graphene Oxide Based Recyclable in Vivo Device for Amperometric Monitoring of Interferon-γ in Inflammatory Mice.

Authors: Chaomin Cao, Ronghua Jin, Hui Wei, Wenchao Yang, Ewa M. Goldys, Mark R. Hutchinson, Shiyu Liu, Xin Chen, Guangfu Yang, and Guozhen Liu.

Abstract: Cytokine sensing is challenging due to their typically low abundances in physiological conditions. Nanomaterial fabricated interfaces demonstrated unique advantages in ultrasensitive sensing. Here, we demonstrate an amperometric sensing device based on graphene oxide (GO) and structure-switching aptamers for long-term detection of cytokines in a living organism. The device incorporates a single layer of GO acting as a signal amplifier on glassy carbon electrodes. The hairpin aptamers specific to interferon-γ (IFN-γ), which were loaded with redox probes, are covalently attached to GO to serve as biorecognition moieties. IFN-γ was able to trigger the configuration change of aptamers while releasing the trapped redox probes to introduce the electrochemical signal. This in vivo device was capable of quantitatively and dynamically detecting IFN-γ down to 1.3 pg mL–1 secreted by immune cells in cell culture medium with no baseline drift even at a high concentration of other nonspecific proteins. The biocompatible devices were also implanted into subcutaneous tissue of enteritis mice, where they performed precise detection of IFN-γ over 48 h without using physical barriers or active drift correction algorithms. Moreover, the device could be reused even after multiple rounds of regeneration of the sensing interface.

Optical fibre innovation via trans-disciplinary approach!

10 September 2018:

CNBP researchers have published a new  trans-disciplinary review that reports on the Centre’s development of advanced optical fibre probes for use in biomedical sensing and imaging. The paper examines CNBP innovation through convergence of multiple science disciplines to generate opportunities for the fibre probes to address key challenges in real-time in vivo diagnostics. The lead author on the paper is Dr Jiawen Li (pictured).

Journal: APL Photonics.

Publication title: Perspective: Biomedical sensing and imaging with optical fibers—Innovation through convergence of science disciplines.

Authors: Jiawen Li, Heike Ebendorff-Heidepriem, Brant C. Gibson,  Andrew D. Greentree, Mark R. Hutchinson, Peipei Jia, Roman Kostecki, Guozhen Liu, Antony Orth, Martin Ploschner, Erik P. Schartner,   Stephen C. Warren-Smith, Kaixin Zhang, Georgios Tsiminis, and Ewa M. Goldys.

Abstract: The probing of physiological processes in living organisms is a grand challenge that requires bespoke analytical tools. Optical fiber probes offer a minimally invasive approach to report physiological signals from specific locations inside the body. This perspective article discusses a wide range of such fiber probes developed at the Australian Research Council Centre of Excellence for Nanoscale BioPhotonics. Our fiber platforms use a range of sensing modalities, including embedded nanodiamonds for magnetometry, interferometric fiber cavities for refractive index sensing, and tailored metal coatings for surface plasmon resonance sensing. Other fiber probes exploit molecularly sensitive Raman scattering or fluorescence where optical fibers have been combined with chemical and immunosensors. Fiber imaging probes based on interferometry and computational imaging are also discussed as emerging in vivo diagnostic devices. We provide examples to illustrate how the convergence of multiple scientific disciplines generates opportunities for the fiber probes to address key challenges in real-time in vivo diagnostics. These future fiber probes will enable the asking and answering of scientific questions that were never possible before.

Lighting up AstroLight 2018

8 September, 2018:

It was a fantastic evening of outreach by the CNBP-RMIT team at the annual AstroLight Festival, at Scienceworks in Melbourne, 8th September, 2018.

A wide range of demonstrations, talks and hands-on activities from volunteers from Observatories, Universities and Research Centres brought science to life to over 600 members of the public at this annual astronomy and optics event.

CNBP highlights included public talks from Center Chief Investigator Prof Andrew Greentree (The wonders and delights of bees and how they see colour) and Centre Associate Investigator Dr Kate Fox (Fluorescent Implants: 3D printing for the future).

Also  popular was the CNBP interactive stall where there was a number of light based giveaways as well as a room of CNBP light experiments showcasing the properties of lasers, fluorescence, imaging and more.

“Taking science to the public is always extremely satisfying,” said CNBP Node Leader at RMIT University, A/Prof Brant Gibson.

“It’s great to be able to excite and enthuse people about what we do and to explain the relevance that science has in our community more generally.”

“The team came together with a huge amount of energy and positivity which helped make the evening a great success!”

Below – Big smiles from the CNBP-RMIT team at AstroLight 2018!

Peptides as bio-inspired electronic materials

7 September 2018:

A new paper with CNBP authors Jingxian Yu, John Horsley and Andrew Abell extends fundamental knowledge of charge transfer dynamics and kinetics in peptides and also open up new avenues to design and develop functional bio-inspired electronic devices, such as on/off switches and quantum interferometers, for practical applications in molecular electronics.

Journal: Accounts of Chemical Research.

Publication title: Peptides as Bio-Inspired Electronic Materials: An Electrochemical and First-Principles Perspective.

Authors: Jingxian Yu, John R. Horsley, and Andrew D. Abell.

Abstract: Molecular electronics is at the forefront of interdisciplinary research, offering a significant extension of the capabilities of conventional silicon-based technology as well as providing a possible stand-alone alternative. Bio-inspired molecular electronics is a particularly intriguing paradigm, as charge transfer in proteins/peptides, for example, plays a critical role in the energy storage and conversion processes for all living organisms. However, the structure and conformation of even the simplest protein is extremely complex, and therefore, synthetic model peptides comprising well-defined geometry and predetermined functionality are ideal platforms to mimic nature for the elucidation of fundamental biological processes while also enhancing the design and development of single-peptide electronic components.

In this Account, we first present intramolecular electron transfer within two synthetic peptides, one with a well-defined helical conformation and the other with a random geometry, using electrochemical techniques and computational simulations. This study reveals two definitive electron transfer pathways (mechanisms), the natures of which are dependent on secondary structure. Following on from this, electron transfer within a series of well-defined helical peptides, constrained by either Huisgen cycloaddition, ring-closing metathesis, or a lactam bridge, was determined. The electrochemical results indicate that each constrained peptide, in contrast to a linear counterpart, exhibits a remarkable shift of the formal potential to the positive (>460 mV) and a significant reduction of the electron transfer rate constant (up to 15-fold), which represent two distinct electronic “on/off” states. High-level calculations demonstrate that the additional backbone rigidity provided by the side-bridge constraints leads to an increased reorganization energy barrier, which impedes the vibrational fluctuations necessary for efficient intramolecular electron transfer through the peptide backbone. Further calculations reveal a clear mechanistic transition from hopping to superexchange (tunneling) stemming from side-bridge gating. We then extended our research to fine-tuning of the electronic properties of peptides through both structural and chemical manipulation, to reveal an interplay between electron-rich side chains and backbone rigidity on electron transfer. Further to this, we explored the possibility that the side-bridge constraints present in our synthetic peptides provide an additional electronic transport pathway, which led to the discovery of two distinct forms of quantum interferometer. The effects of destructive quantum interference appear essentially through both the backbone and an alternative tunneling pathway provided by the side bridge in the constrained β-strand peptide, as evidenced by a correlation between electrochemical measurements and conductance simulations for both linear and constrained β-strand peptides. In contrast, an interplay between quantum interference effects and vibrational fluctuations is revealed in the linear and constrained 310-helical peptides.