Tag Archives: Sabrina Heng

New med-tech zinc sensor developed

29 September 2017:

A new zinc sensor has been developed by CNBP researchers, which will allow for a deeper understanding of the dynamic roles that metal ions play in regulating health and disease in the living body.

The research, published in the journal ACS Omega reports that the newly designed chemical sensor can detect and measure zinc levels in cells. It also has the functionality and portability to take continuous or repeated measurements within a single biological sample.

“This makes the sensor potentially suitable for use in future diagnostic tools that could open up entirely new windows into the body,” says lead author of the research Dr Sabrina Heng (pictured), Research Fellow at the ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), at the University of Adelaide.

Read more at PHYS.ORG.

New med-tech zinc sensor developed

27 September 2017:

A new zinc sensor has been developed and reported by CNBP researchers, which will allow for a deeper understanding of the dynamic roles that metal ions play in regulating health and disease in the living body.

The research, published in the journal ‘ACS Omega’ reports that the newly designed chemical sensor can detect and measure zinc levels in cells. It also has the functionality and portability to take continuous or repeated measurements within a single biological sample.

“This makes the sensor potentially suitable for use in future diagnostic tools that could open up entirely new windows into the body,” says lead author of the research Dr Sabrina Heng (pictured), Research Fellow at the ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP), at the University of Adelaide.

Read the full CNBP media release here and the publication here.

Journal: ACS Omega.

Publication title: A Rationally Designed Probe for Reversible Sensing of Zinc and Application in Endothelial Cells.

Authors: Sabrina Heng, Philipp Reineck, Achini K. Vidanapathirana, Benjamin J. Pullen, Daniel W. Drumm, Lesley J. Ritter, Nisha Schwarz, Claudine S. Bonder, Peter J. Psaltis, Jeremy G. Thompson, Brant C. Gibson , Stephen J. Nicholls, and Andrew D. Abell.

Abstract: Biologically compatible fluorescent ion sensors, particularly those that are reversible, represent a key tool for answering a range of fundamental biological questions. We report a rationally designed probe with a 6′-fluoro spiropyran scaffold (5) for the reversible sensing of zinc (Zn2+) in cells. The 6′-fluoro substituent overcomes several limitations normally associated with spiropyran-based sensors to provide an improved signal-to-background ratio and faster photoswitching times in aqueous solution. In vitro studies were performed with 5 and the 6′-nitro analogues (6) in HEK 293 and endothelial cells. The new spiropyran (5) can detect exogenous Zn2+ inside both cell types and without affecting the proliferation of endothelial cells. Studies were also performed on dying HEK 293 cells, with results demonstrating the ability of the key compound to detect endogenous Zn2+ efflux from cells undergoing apoptosis. Biocompatibility and photoswitching of 5 were demonstrated within endothelial cells but not with 6, suggesting the future applicability of sensor 5 to study intracellular Zn2+ efflux in these systems.

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.

Sensors for calcium ion

15 June 2017:

Researchers from CNBP (lead author Dr Sabrina Heng pictured), have just had a paper published, reporting on three new spiropyran-based reversible sensors for calcium ion.

Journal: Sensors and Actuators B: Chemical.

Publication title: Photoswitchable calcium sensor: ‘On’–‘Off’ sensing in cells or with microstructured optical fibers.

Authors: Sabrina Heng, Adrian M. Mak, Roman Kostecki, Xiaozhou Zhang, Jinxin Peia, Daniel B. Stubing, Heike Ebendorff-Heidepriema, Andrew D. Abell.

Abstract: Calcium is a ubiquitous intracellular signaling ion that plays a critical role in the modulation of fundamental cellular processes. A detailed study of these processes requires selective and reversible sensing of Ca2+ and an ability to quantify and monitor concentration changes in a biological setting. Three new, rationally designed, synthesized and photoswitchable spiropyran-based reversible sensors for Ca2+ are reported. Sensor 1a is highly selective for Ca2+ with an improved profile relative to the other two analogues, 1b and 1c. Formation of the merocyanine–Ca2+ complex is proportional to an increase in Ca2+ released from HEK293 cells on stimulation with ionomycin. The photophysical processes surrounding the binding of Ca2+ to compound 1a were further explored using computational methods based on density functional theory (DFT). The ability of sensor 1a to bind Ca2+ and photoswitch reversibly was also characterized using silica suspended-core microstructured optical fiber (SCF). These SCF experiments (with 100 nM Ca2+) represent a first step toward developing photoswitchable, minimally invasive and highly sensitive Ca2+ sensing platforms for use in a biological setting.

The paper is accessible online.

CNBP participates in LEA outreach event

7 June 2017:

With a focus on STEM learning and the need for innovative outreach approaches, Learning Environments Australia (SA chapter) have coordinated a forum at the University of Adelaide, 7 June 2017, which saw significant support from the CNBP.

Prof Mark Hutchinson (CNBP Director), Tony Crawshaw (CNBP Communications and Outreach Coordinator) and Dr Sabrina Heng (CNBP Researcher, pictured) all participated in the LEA forum, providing talks and answering questions as to the Centre’s successful approach to engaging with schools and students and inspiring the next generation of young scientist.

Joanne Rogers, Head of Science, Concordia College who has been closely involved with CNBP outreach activity, talked about the real life changes experienced by her students, resulting from engagement with CNBP scientists. Students she said, had picked up additional science subjects on the back of CNBP school and laboratory visits.

Other University of Adelaide presenters at the event included Kiri Hagenus, Director, Children’s University; Dr Claudia Szabo, Associate Dean, Faculty of ECMS – MOOC in digital literacy for teachers; and Science’s Prof Bob Hill, who discussed successful Faculty outreach initiatives.

Centre researchers at Biosensor Symposium

guozhen_liu30 November 2016:

CNBP Research Fellows, Associate Professor Guozhen Liu (pictured), Dr Lindsay Parker and Dr Sabrina Heng have undertaken talks at the School of Biomedical Sciences at the University of Melbourne as part of a Biosensor Symposium, Wednesday 30th November, 2016.

Talks were as follows:

Guozhen Liu – Biophotonic Tools for Cytokine Sensing: From an on-cell surface ELISA to a spatial ELISA device.

Lindsay Parker – Biosensors and glycoproteins: linking nanoscience to neuroscience.

Sabrina Heng – Reversible Sensing with a Flip of the Switch.

The symposium shone a  spotlight on multidisciplinary research into developing, applying and using biosensors for biomedical sciences.

Outreach session at St. Ignatius College

Michelle-Zhang_1_sq23 August 2016

CNBP researchers from the University of Adelaide, Michelle Zhang and Sabrina Heng, have undertaken a school outreach session at St. Ignatius College, Adelaide, August 23, 2016.

The scientists spoke to two groups of children in an early-learning program about the science of light and the use of light in medicine. Several hands-on activities were also then run for the children to demonstrate that science can be fun as well as educational.

This included:

  • the use of UV-sensitive beads for making into a bracelet that was then worn for several outdoor activities
  • sunscreen applied to the beads to teach how sunscreen protects against sun-burn
  • the use of spectroscopes that can diffract room-light into a series of colourful bands at differing wavelengths (the students were asked to draw what they saw)
  • a simple kit that converted youtube videos to holograms
  • and CNBP colouring-in sheets that demonstrate life at the nanoscale

Positive feedback from the teachers at St. Ignatius College and also the parents of the children that attended the session was received over the course of a very fulfilling day!

Photochromic molecules explored in MOF environment

Daniel Stubing High Res Edit 005510 August 2016:

Researchers from the CNBP have published a paper representing the first major study of the stability and compatibility of the major classes of photochromic compounds within the microstructured optical fibre (MOF) environment.

In developing light-responsive surfaces, investigators face several challenges, not only in achieving high photostationary states and fully reversible switching, but also in fluorescence properties and fatigue resistance upon continuous exposure to high intensity light. However, information on the latter two are often lacking as studies on photochromic compounds are often focused on photoswitching, or absorbance and colour changes. To address this gap in literature, the fluorescence and photostability of four major types of photochromic molecules (azobenzene, spiropyran, indolyfulgide and diarylalkene) when dissolved in DMSO, or acetonitrile, or adsorbed to a MOF silica surface were investigated.

Journal: Sensors and Actuators B: Chemical.

Publication title: A Comparative Study of the Fluorescence and Photostability of Common Photoswitches in Microstructured Optical Fibre.

Authors: Daniel B. Stubing (pictured top left), Sabrina Heng, Tanya M. Monro and Andrew D. Abell.

Abstract: The fluorescence spectra and photostability under 532 nm laser excitation of four different common photoswitches (an azobenzene, spiropyran, indolylfulgide, and a diarylperfluorocyclopentene) were investigated in a silica microstructured optical fibre. An example of each photoswitch was examined in solution and physically adsorbed to the silica fibre surface. This comparison was made to define fluorescence behaviour in these two states and to determine which photoswitch has the best performance in this light intense microenvironment. The azobenzene and the spiropyran switches demonstrated the strongest fluorescence response and the least degradation of the fluorescence signal.

The paper is available online.

Sensing Zn2+ ions in biological samples

sabrina213 May 2016:

CNBP researchers have created nanoscale biosensors that are capable of sensing Zn2+ ions in biological samples. Such sensors have potential application in disease diagnosis and study, as well as in environmental sensing. The study was published in the journal ACS Applied Materials and Interfaces, May 13th, 2016.

Publication title: Microstructured Optical Fiber-based Biosensors: Reversible and Nanoliter-Scale Measurement of Zinc Ions.

Authors: Sabrina Heng (pictured), Christopher A. McDevitt, Roman Kostecki, Jacqueline R. Morey, Bart A. Eijkelkamp, Heike Ebendorff-Heidepriem, Tanya M. Monro, and Andrew D. Abell.

Abstract:
Sensing platforms that allow rapid and efficient detection of metal ions would have applications in disease diagnosis and study, as well as environmental sensing. Here, we report the first microstructured optical fiber-based biosensor for the reversible and nanoliter-scale measurement of metal ions. Specifically, a photoswitchable spiropyran Zn2+ sensor is incorporated within the microenvironment of a liposome attached to microstructured optical fibers (exposed-core and suspended-core microstructured optical fibers). Both fiber-based platforms retains high selectivity of ion binding associated with a small molecule sensor, while also allowing nanoliter volume sampling and on/off switching. We have demonstrated that multiple measurements can be made on a single sample without the need to change the sensor. The ability of the new sensing platform to sense Zn2+ in pleural lavage and nasopharynx of mice was compared to that of established ion sensing methodologies such as inductively coupled plasma mass spectrometry (ICP-MS) and a commercially available fluorophore (Fluozin-3), where the optical-fiber-based sensor provides a significant advantage in that it allows the use of nanoliter (nL) sampling when compared to ICP-MS (mL) and FluoZin-3 (μL). This work paves the way to a generic approach for developing surface-based ion sensors using a range of sensor molecules, which can be attached to a surface without the need for its chemical modification and presents an opportunity for the development of new and highly specific ion sensors for real time sensing applications.

The paper is available online.

CNBP at SIRT 2016

Erik Shartner Low Res Edit 00791 May 2016:

CNBP researchers Dr Hannah Brown, Dr Sabrina Heng and Dr Erik Schartner (pictured) presented invited talks to a range of researchers and clinicians at the ‘Scientists in Reproductive Technology (SIRT)’ conference in Adelaide on the 1st of May, 2016.

Explored in their talks were differing ways in which upcoming Centre research might find use within the embryology labs of the future – this tying into the meeting theme “From basic research to clinical practice: How to revolutionise IVF practice.”

Talk titles from the CNBP researchers were as follows:

  • Hannah: Haemoglobin: Exciting and unexpected roles in fertility.
  • Sabrina: Developing light-driven regenerable chemical tools for biological applications.
  • Erik: Developing optical fibre probes for biosensing.

Further information on Scientists in Reproductive Technology (SIRT), a sub-group representing the scientific membership of The Fertility Society of Australia, can be found online.