15 November 2018:
A new CNBP research publication (lead author Dr Roman Kostecki, University of Adelaide) describes how molecular interactions can be modulated by defining the local nano-environment to give a specific chemical outcome.
Journal: ACS Applied Materials and Interfaces.
Publication title: Control of Molecular Recognition via Modulation of the Nanoenvironment.
Authors: Roman Kostecki, Sabrina Heng, Adrian M. Mak, Heike Ebendorff-Heidepriem, Tanya M. Monro, and Andrew D. Abell.
Abstract: Many biological processes are driven by the interaction of a host with a guest molecule. We show such interactions can be modulated by carefully defining the local molecular environment to give a specific chemical outcome. Particularly, the selectivity of a host toward two different ions (Ca2+ and Al3+) is defined by it being in solution or the physisorbed state. In solution, the host displays greater selectivity toward Ca2+. When physisorbed, the selectivity profile of the host is reversed with enhanced binding of Al3+. This demonstrates a single host molecule can be tailored to selectively bind multiple guests by altering its nanoenvironment.
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.
13 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.
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.
19 April 2016:
CNBP was happy to host the next generation of young scientists at today’s ‘STEMSEL Photonics’ session at the University of Adelaide node.
STEMSEL clubs, standing for ‘Science, Technology, Engineering, Maths and Social Enterprise Learning’ are an arm of the STEMSEL Foundation which is a not for profit organisation that aims to teach every child how to use electronics.
Over twenty Year 3 to Year 9 students were in attendance at this session, with CNBP researchers Roman Kostecki (a physics focus) and Sabrina Heng (a chemistry focus) helping lead the discussion and activities.
Concepts such as photons, light interaction with matter, Fermat’s principle, emission, absorption, lasers, fibre optics and organic chemistry, were all described and demonstrated.
Both researchers enjoyed the afternoon, showing the kids that science, technology and photonics can be awesomely interesting, as well as really good fun!
4 March 2016:
Roman Kostecki, CNBP researcher, has given an invited talk at the ‘Annual World Congress of Smart Materials’ in Singapore, 4th March 2016 (WCSM-2016).
Talk title: Smart Microstructured Optical Fibers for Chemical and Biological Recognition.
Optical detection of chemical or biological species relies on the interaction between a target species and light. While conventional optical fibers are exceptionally good at carrying light, they have limitations towards sensing applications due to the small fiber tip interaction area. To overcome this problem, microstructured optical fibers (MOFs) provide extended interaction between the light and chemical or biological species, while maintaining the integrity of the device. Thin struts from the surrounding structure suspend the MOF core, the surface of which can be used as a scaffold to add functionality and provide specificity. Guided light that extends outside the core of a MOF provides opportunities for measurements of the composition and concentration of an analyte along the fiber length.
We will review the use of suspended- and exposed- core MOFs for optical sensing, with focus on the different modalities for their deployment in sensing applications using label-based fluorescence and label-free detection techniques. For label-based fluorescence sensing, we discuss the different chemical and physical mechanisms used for surface attachment of suitable marker and photo-switchable molecules, the fiber geometries, and the varied target species that can be detected. For label-free sensing we explore whispering gallery modes, surface plasmon resonance, Bragg grating-based sensing, and Raman spectroscopy using MOFs, highlighting the toolset of sensing mechanisms for MOF-based chemical and biological sensing.
Full details regarding the conference can be found online.
28 June 2015:
CNBP researcher Roman Kostecki presented his latest research paper at the 8th International Conference on Materials for Advanced Technologies (ICMAT2015). The conference, twinned with the 4th Photonics Global Conference took place in Singapore 28 June – 3 July 2015.
The paper, titled “Thin-film Polymer Functionalization of Optical Fiber Enabling Multiligand Chemosensing” was published with an author list consisting of Roman KOSTECKI, Sabrina HENG, Heike EBENDORFF-HEIDEPRIEM, Andrew ABELL, and Tanya MONRO.
Silica exposed-core microstructured optical fibers (EC-MOFs) are a platform for distributed, in situ, and/or remote sensors based on fluorescence. The portion of light guided outside of the glass core, often described as ‘evanescent field’, is affected by the refractive index and absorption characteristics of the surrounding medium. This light-matter overlap provides opportunities for fluorometric measurements of the composition and concentration of an analyte along the fiber length. Functionalizing the core with a chemosensor removes the need for chemosensor/analyte premixing. Detection of aluminum cations (Al) is of particular interest as a means to monitor corrosion, human health and the environment.
We demonstrate the first example of a photo-switchable chemosensor for Al detection using a modified photochromic spiropyran (SP-I), which is appended to an ionophore for cation binding. Photochemical switching of the spiropyran allows ion binding to be switched on and off, creating a multiple use chemosensor. The SP-I sensor binds Al or calcium cations as multi- or single-ligand complexes respectively, and was modified for surface attachment. Silane- or polyelectrolyte-based methodology allows subsequent attachment of the SP-I to a glass surface. Studies with the dual ion binding SP-I integrated with the EC-MOF sensing platform provide evidence that covalent attachment is ineffective, where multiligand binding chemosensors are needed. Functionalizing EC-MOFs with a thin-film (50 nm) polymer doped with SP-I demonstrates capacity to use both multi- and single-ligand binding chemosensors. This demonstrates that the integration of photo-switchable chemosensor, thin-film polymer, and silica optical fiber elements creates a sensor capable of multiligand chemosensing anywhere along the fiber’s length. The work demonstrates a new pathway to next generation reusable and continuous operation ion sensing platforms, and that the local molecular environment of a chemosensor affects its function which can be used to control how metal ions interact with chemosensors.
22 December 2014: New CNBP Researcher.
Welcome to Roman Kostecki who joined the Adelaide Node of the CNBP today. Roman will be working in the Illuminate theme.
3 July 2014: Publication in Optical Society of America
Novel polymer functionalization method for exposed-core optical fiber
Authors: by Roman Kostecki, Heike Ebendorff-Heidepriem, Shahraam Afshar, GrantMcAdam, Claire Davis, and Tanya M. Monro
Abstract: We report on a one step functionalization process for optical
fiber sensing applications in which a thin film (∼50 nm) polymer doped
with sensor molecules is applied to a silica exposed-core fiber. The method
removes the need for surface attachment of functional groups, while
integrating the polymer, silica and sensor molecule elements to create a
distributed sensor capable of detecting an analyte of interest anywhere
along the fiber’s length. We also show that the thin film coating serves a
protective function, reducing deterioration in the transmission properties of
the silica exposed-core fiber, but increasing loss.