Category Archives: UA

First reversible ‘turn-off’ sensor for Glutathione

6 September 2017:

The first reversible ‘turn-off’ sensor for Glutathione has been reported by CNBP researchers in a paper published in the science journal Biosensors.

The paper is accessible online (open access).

Dr Sabrina Heng notes:

γ-Glutamyl-cysteinyl-glycine (GSH) plays a critical role in maintaining redox homeostasis in biological systems and a decrease in its cellular levels is associated with disease. Many diseases including Parkinson’s, cancer, heart diseases and Alzheimer’s are indicated by a decrease in GSH levels. In this case, a ‘turn on’ sensor would result in reduced fluorescence relative to healthy cells. An important advance would come from the development of a sensor that is measurably turned off by GSH and back on by a lower level of GSH. This would then provide an opportunity to sense reduced GSH levels during the onset of important diseases.

With that in mind we have rationally designed, to the best of our knowledge, the first reversible, reaction-based ‘turn-off’ probe that is suitable for sensing decreasing levels of GSH, a situation known to occur at the onset of various diseases.  We have demonstrated that the sensor can be used to detect changes of intracellular GSH in live HEK 293 cells to provide a potentially regenerable sensor for monitoring lower levels of intracellular GSH as associated with the onset of important diseases.

Journal: Biosensors.

Publication title: A Rationally Designed Reversible ‘Turn-Off’ Sensor for Glutathione.

Authors: Sabrina Heng (pictured), Xiaozhou Zhang, Jinxin Pei and Andrew D. Abell.

Abstract: γ-Glutamyl-cysteinyl-glycine (GSH) plays a critical role in maintaining redox homeostasis in biological systems and a decrease in its cellular levels is associated with diseases. Existing fluorescence-based chemosensors for GSH acts as irreversible reaction-based probes that exhibit a maximum fluorescence (‘turn-on’) once the reaction is complete, regardless of the actual concentration of GSH. A reversible, reaction-based ‘turn-off’ probe (1) is reported here to sense the decreasing levels of GSH, a situation known to occur at the onset of various diseases. The more fluorescent merocyanine (MC) isomer of 1 exists in aqueous solution and this reacts with GSH to induce formation of the ring-closed spiropyran (SP) isomer, with a measurable decrease in absorbance and fluorescence (‘turn-off’). Sensor 1 has good aqueous solubility and shows an excellent selectivity for GSH over other biologically relevant metal ions and aminothiol analytes. The sensor permeates HEK 293 cells and an increase in fluorescence is observed on adding buthionine sulfoximine, an inhibitor of GSH synthesis.

Charge transfer in helical peptides

1 September 2017:

Understanding the electronic properties inherent to peptides is crucial for controlling charge transfer, and precursory to the design and fabrication of bio-inspired next generation electronic components.

However, to achieve this objective one must first be able to predict and control the associated charge transfer mechanisms.

Here CNBP researchers demonstrate for the first time a controllable mechanistic transition in peptides resulting directly from the introduction of a side-bridge.

Journal: RSC Advances.

Publication title: A controllable mechanistic transition of charge transfer in helical peptides: from hopping to superexchange.

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

For more information, access the paper here.

School tour of Braggs labs

31 August 2017:

Caritas College students visiting the University of Adelaide for a ‘science day’ were shown around laboratory spaces in the Braggs Building by CNBP PHD students Kathryn Palasis (pictured) and Georgina Sylvia.

The 23 Year 9 school students were given a tour through a synthetic chemistry lab and then spoke with both CNBP researchers about the work being done and their journeys through University. This was followed by a further tour through a fibre-optics laboratory.

According to Kathryn, “The students seemed engaged and interested, particularly with the fibre-optics tour. And feedback from Amy (who organised the day) was that the students enjoyed it and that the teachers were very appreciative. Personally I spoke to a girl who said she was interested in studying science at university which was very pleasing to hear, and hopefully we encouraged others to see it as an appealing career path as well.”

New technique to aid IVF embryo selection

28 August 2017:

Researchers at the ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP) have successfully developed an advanced new imaging technique, which can help assess the quality of early-stage embryos.

The research, reported in the journal ‘Human Reproduction’ has the potential to significantly benefit the IVF industry of the future, improving assisted reproduction outcomes for women.

“We use a special type of imaging to show differences in the metabolism and chemical make-up of embryos before they’ve been implanted,” says lead author Dr Mel Sutton-McDowall (pictured).

“This technique can give us an objective measure of which embryo to choose as part of the IVF process.”

This ‘hyperspectral imaging’ measures light that cells naturally produce during their normal activities. The light or ‘autoflorescence’ produced changes according to the chemical reactions or metabolism going on in the cell.

Being able to measure embryo metabolism is viewed by many researchers as one of the most important factors as to whether a particular IVF program will be successful.

However, says Dr Sutton-McDowall, fertility specialists take a largely subjective approach in deciding which embryos should be used.

“Pre-implantation screening of embryos generally takes place under a normal optical microscope. Although it’s quite easy to discern poor embryos (due to differences in uniformity), it is far harder for the clinician to determine objectively, the viability of the other embryos,” she says.

“The challenge is how to choose the single healthiest embryo out of this group to maximise the chances of pregnancy.”

Dr Sutton-McDowall sees the use of hyperspectral imaging as a new tool that can be combined with other diagnostic methods to provide a more accurate and objective embryo viability assessment.

“The benefit of hyperspectral imaging is that it can capture information-rich content of inspected objects. It analyses every pixel in an image for its light intensity at differing wavelengths,” she says

“This lets us drill down and analyse the hyperspectral signature of each individual embryo, looking for known or anomalous characteristics. It lets us discriminate between embryos, but also measuring metabolic differences within individual embryos. We predict that embryos that have cells with homogeneous (uniform) metabolic profiles are the healthier ones.”

To date, this imaging technology has only been tested on cattle embryos but Dr Sutton-McDowall notes that the technique is extremely promising.

“It offers benefits of being a non-invasive imaging approach that provides real-time information to the clinician,” she says.

The paper is accessible online.

Journal: Human Reproduction.

Publication title: Hyperspectral microscopy can detect metabolic heterogeneity within bovine post-compaction embryos incubated under two oxygen concentrations (7% versus 20%).

Authors: Melanie L. Sutton-McDowall, Martin Gosnell, Ayad G. Anwer, Melissa White, Malcolm Purdey, Andrew D. Abell, Ewa M. Goldys, Jeremy G. Thompson.

Abstract: 

STUDY QUESTION
Can we separate embryos cultured under either 7% or 20% oxygen atmospheres by measuring their metabolic heterogeneity?

SUMMARY ANSWER
Metabolic heterogeneity and changes in metabolic profiles in morula exposed to two different oxygen concentrations were not detectable using traditional fluorophore and two-channel autofluorescence but were detectable using hyperspectral microscopy.

WHAT IS KNOWN ALREADY
Increased genetic and morphological blastomere heterogeneity is associated with compromised developmental competence of embryos and currently forms the basis for embryo scoring within the clinic. However, there remains uncertainty over the accuracy of current techniques, such as PGS and time-lapse microscopy, to predict subsequent pregnancy establishment.

STUDY DESIGN, SIZE, DURATION
The impact of two oxygen concentrations (7% = optimal and 20% = stressed) during post-fertilisation embryo culture was assessed. Cattle embryos were exposed to the different oxygen concentrations for 8 days (D8; embryo developmental competence) or 5 days (D5; metabolism measurements). Between 3 and 4 experimental replicates were performed, with 40–50 embryos per replicate used for the developmental competency experiment, 10–20 embryos per replicate for the fluorophore and two-channel autofluorescence experiments and a total of 21–22 embryos used for the hyperspectral microscopy study.

PARTICIPANTS/MATERIALS, SETTING, METHODS
In-vitro produced (IVP) cattle embryos were utilised for this study. Post-fertilisation, embryos were exposed to 7% or 20% oxygen. To determine impact of oxygen concentrations on embryo viability, blastocyst development was assessed on D8. On D5, metabolic heterogeneity was assessed in morula (on-time) embryos using fluorophores probes (active mitochondria, hydrogen peroxide and reduced glutathione), two-channel autofluorescence (FAD and NAD(P)H) and 18-channel hyperspectral microscopy.

MAIN RESULTS AND THE ROLE OF CHANCE
Exposure to 20% oxygen following fertilisation significantly reduced total blastocyst, expanded and hatched blastocyst rates by 1.4-, 1.9- and 2.8-fold, respectively, compared to 7% oxygen (P < 0.05), demonstrating that atmospheric oxygen was a viable model for studying mild metabolic stress. The metabolic profiles of D5 embryos was determined and although metabolic heterogeneity was evident within the cleavage stage (i.e. arrested) embryos exposed to fluorophores, there were no detectable difference in fluorescence intensity and pattern localisation in morula exposed to the two different oxygen concentrations (P > 0.05). While there were no significant differences in two-channel autofluorescent profiles of morula exposed to 7% and 20% oxygen (main effect, P > 0.05), morula that subsequently progressed to the blastocyst stage had significantly higher levels of FAD and NAD(P)H fluorescence compared to arrested morula (P < 0.05), with no change in the redox ratio. Hyperspectral autofluorescence imaging (in 18-spectral channels) of the D5 morula revealed highly significant differences in four features of the metabolic profiles of morula exposed to the two different oxygen concentrations (P < 0.001). These four features were weighted and their linear combination revealed clear discrimination between the two treatment groups.

LIMITATIONS, REASONS FOR CAUTION
Metabolic profiles were assessed at a single time point (morula), and as such further investigation is required to determine if differences in hyperspectral signatures can be detected in pre-compaction embryos and oocytes, using both cattle and subsequently human models. Furthermore, embryo transfers should be performed to determine the relationship between metabolic profiles and pregnancy success.

WIDER IMPLICATIONS OF THE FINDINGS
Advanced autofluorescence imaging techniques, such as hyperspectral microscopy, may provide clinics with additional tools to improve the assessment of embryos prior to transfer.

Talking science at UoA Open Day

20 August 2017:

CNBP volunteers at the University of Adelaide Open Day took the opportunity to set-up a stand and to demonstrate Centre related science, Sunday 20th August, 2017.

The Open Day, showcasing programs, facilities, and options for student study at the University, saw many thousands of visitors to Campus and the CNBP team was ready!

CNBP experiments and demonstrations were on offer, ranging from the opportunity to play with lasers, through to checking out spinal-cord cells through a microscope.

And for those visitors to the stand who really wanted to know more about the innovative biophotonics science that the CNBP undertakes, there were giveaway goodies including t-shirts, drink bottles, pens and brochures.

Below: CNBP researcher Vicky Staikopoulos encouraging members of the public to ‘Ask about science.’

Outreach at Concordia College

16 August 2017:

Students from Concordia College got the low-down on STEM careers—as well as learnt more about lasers, laboratories and the life of a scientist at a school outreach event organised and run by CNBP researchers from the University of Adelaide.

The event, celebrating National Science Week, saw a team of CNBP scientists and researchers visit Concordia College and present a variety of talks, DIY laboratory videos and science demonstrations, to over 150 Year 9 students with an interest in science, technology, engineering and maths (STEM).

CNBP’s Dr Hannah Brown, present on the day, sees outreach as a key responsibility for the science community.

“Getting high school students interested and engaged in STEM subjects is critical—not only to inspire future generations of young scientists but also in supporting the Australian economy more generally. What we hope to do with our outreach efforts is to show that science and technology can be fun and exciting, and potentially rewarding as a future career choice as well.”

Following the event, feedback from both students and teachers present was hugely positive with the CNBP team also gaining a great deal of satisfaction from their interactions and demonstration efforts.

Below: CNBP researchers Hannah Brown, Georgios Tsiminis, Patrick Capon and Aimee Horsfall with students, at the conclusion of a successful session of science outreach at Concordia College.

New CNBP research assistant

16 August 2017:

CNBP would like to welcome Robyn Kievit to the team. Located at the University of Adelaide, Robyn has joined the CNBP as a research assistant. She will primarily work within the Origins of Sensing biological challenges group (understanding the role of brain immune signals in the creation of chronic pain) with Dr Sanam Mustafa. Robyn will also set-up standard sensor validation protocols for testing of novel sensors being developed by Prof Andrew Abell’s team.

It’s great to have you on board Robyn!

Cambridge visit furthers research

10 August 2017:

After successfully receiving an ANN Overseas Travel Fellowship, CNBP researcher Dr Peipei Jia has arrived back at the University of Adelaide after a two month visit to the MRC Laboratory of Molecular Biology (LMB) in Cambridge, UK.

While there, Peipei had the opportunity to test both techniques and potential application for his work on the fabrication of large-area freestanding gold nanomembranes.

More specifically, tests undertaken while at Cambridge showed that the gold membrane had the size, quality and robustness  for the critical application of resolving molecular structures in Cryo-electron microscopy (cryo-EM).

Work continues but the nanophotonics structure is expected to have significant impact on both structural biology and electron microscopy.

Australian-French Entrepreneur Challenge

13 July 2017:

PhD team ‘ReMind’, which includes CNBP researcher Vicky Staikopoulos as CFO, has won the  Australian-French Entrepreneur Challenge held in Adelaide over two days, 11th-12th July, 2017.

The challenge (with 49 invited PhD students from all over Australia) required students to work continuously for 24 hours in teams of six, to come up with an idea and to then pitch it to a panel of judges containing some of Australia’s top entrepreneurs.

Team ‘ReMind’ presented their idea for a tactile gaming device for helping the elderly improve their balance and co-ordination to help prevent falls. The device utilised ultrasound waves to create a holographic touch screen.

Sixteen judges, including Susan Close MP (The Minister for Education & Child Development and Higher Education & Skills) as well as the new French Ambassador to Australia (His Excellency Mr Christophe Penot) were all part of the judging panel.

As winning team, ‘ReMind’ members have won a trip to France for two weeks with the opportunity to be mentored by experienced entrepreneurs.

Further information on the award and the team’s success can be found in an article on the ABC website.

Below – The ReMind Team hard at work during the challenge.