Category Archives: publication

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Soft-glass imaging microstructured optical fiber

10 December 2018:

A proof-of-concept fabrication of a soft-glass imaging microstructured optical fiber has been demonstrated by CNBP scientists in a new research paper published in the journal Optics Express. Lead author of the paper is Dr Stephen C. Warren-Smith, CNBP Associate Investigator at the University of Adelaide who notes that it is envisaged that the glass-based optical fibers will find potential use in applications such as in-vivo white-light and spectroscopic imaging.

Journal: Optics Express.

Publication title: Soft-glass imaging microstructured optical fibers.

Authors: Stephen C. Warren-Smith, Alastair Dowler, and Heike Ebendorff-Heidepriem.

Abstract: We demonstrate the fabrication of multi-core (imaging) microstructured optical fiber via soft-glass preform extrusion through a 3D printed titanium die. The combination of extrusion through 3D printed dies and structured element (capillary) stacking allows for unprecedented control of the optical fiber geometry. We have exploited this to demonstrate a 100 pixel rectangular array imaging microstructured fiber. Due to the high refractive index of the glass used (n = 1.62), such a fiber can theoretically have a pixel pitch as small as 1.8 µm. This opens opportunities for ultra-small, high-resolution imaging fibers fabricated from diverse glass types.

Modulation of the nano-environment

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.

Optical fiber based immunosensor detects cytokines

13 November 2018:

An immunosensor created on an optical fiber surface has been developed by CNBP researchers that has successfully detected cytokine proteins in a rat’s spinal cord. The result indicates that such fiber sensors can be used as an effective and sensitive tool for localised detection of cytokines in vivo, in a range of research and clinical applications. Lead author on the published research paper was CNBP’s Kaixin Zhang.

Journal: Sensors and Actuators B: Chemical.

Publication title: An optical fiber based immunosensor for localized detection of IL-1 in rat spinal cord.

Authors: Kaixin Zhang, Azim Arman, Ayad G. Anwer, Mark R. Hutchinson, Ewa M. Goldys.

Abstract: Sensitive and localized measurements of cytokines is important in biomedicine as cytokines are produced locally where needed to induce an immune reaction. Here, we present a novel immunosensor deposited on the optical fiber surface. The sensor is capable of localized detection of interleukin-1beta (IL-1β) in the rat spinal cord. In this immunosensor, a stable immunocapture surface was formed via a biotin-streptavidin coupling strategy and fluorescent carboxylated supermagnetic iron oxide (SPIO)-IL-1β detection antibody conjugates were used for signal amplification. Under the optimal condition, the proposed immunosensor can be used for the estimation of IL-1β in vitro in the range from 3.13 pg.mL-1 to 400 pg.mL-1 with a detection limit of 1.12 pg.mL-1. Furthermore, the performance of the fiber sensor was firstly assessed by ex-vivo monitoring the secretions of the rat macrophages stimulated by lipopolysaccharide (LPS), and the results demonstrated significant correlations with a commercial ELISA kit. Furthermore, the fiber sensor was successfully utilized to carry out a localized measurement of IL-1β in a spinal cord of an anesthetized rat. The result indicates that such fiber sensors can be used as an effective and sensitive tool for localised detection of IL-1β in vivo, in a range of research and clinical applications.

A spiropyran-based nanocarrier

10 November 2018:

CNBP researchers have published a new science paper reporting on a new zinc responsive delivery system with real-time intracellular sensing capabilities. Lead author of the publication is Dr Sabrina Heng (pictured).

Journal: Chemistry.

Publication title: Spiropyran‐based Nanocarrier: A New Zn2+‐Responsive Delivery System with Real Time Intracellular Sensing Capabilities.

Authors: Sabrina Heng, Xiaozhou Zhang, Jinxin Pei, Alaknanda Adwal, Philipp Reineck, Brant Gibson, Mark Hutchinson, Andrew Abell.

Abstract: A new spiropyran‐based stimuli‐responsive delivery system is presented that encapsulates and then releases an extraneous compound in response to elevated levels of Zn2+, a critical factor in cell apoptosis. A C12‐alkyl substituent on the spiropyran promotes self‐assembly into a micelle‐like nanocarrier in aqueous media, with nanoprecipitation and encapsulation of added payload. Zn2+ binding occurs to an appended bis(2‐pyridylmethyl)amine group at biologically relevant micromolar concentration. This leads to switching of the spiropyran (SP) isomer to the strongly fluorescent ring opened merocyanine‐Zn2+ (MC‐Zn2+) complex, with associated expansion of the nanocarriers to release the encapsulated payload. Payload release is demonstrated in solution and in HEK293 cells by encapsulation of a blue fluorophore, 7‐hydroxycoumarin, and monitoring its release using fluorescence spectroscopy and microscopy. Furthermore, we demonstrate the use of the nanocarriers to deliver a caspase inhibitor, Azure B, into apoptotic cells in response to an elevated Zn2+ concentration. This then inhibits intracellular caspase activity, as evidenced by confocal microscopy and in real‐time by time‐lapsed microscopy. Finally, the nanocarriers are shown to release an encapsulated proteasome inhibitor (5) in Zn2+‐treated breast carcinoma cell line models. This then inhibits intracellular proteasome and induces cytotoxicity to the carcinoma cells.

Strong microwave photon-magnon coupling in multiresonant dielectric antennas

9 October 2018:

A new perspectives paper by CNBP researcher Dr Ivan Maksymov, RMIT University discusses dielectric resonant systems and demonstrates their ability to operate as multiresonant antennas for light, microwaves, magnons, sound, vibrations and heat.

Journal: Journal of Applied Physics.

Publication title: Perspective: Strong microwave photon-magnon coupling in multiresonant dielectric antennas.

Author: Ivan S. Maksymov.

Abstract: Achieving quantum-level control over electromagnetic waves, magnetisation dynamics, vibrations, and heat is invaluable for many practical applications and possible by exploiting the strong radiation-matter coupling. Most of the modern strong microwave photon-magnon coupling developments rely on the integration of metal-based microwave resonators with a magnetic material. However, it has recently been realised that all-dielectric resonators made of or containing magneto-insulating materials can operate as a standalone strongly coupled system characterised by low dissipation losses and strong local microwave field enhancement. Here, after a brief overview of recent developments in the field, I discuss examples of such dielectric resonant systems and demonstrate their ability to operate as multiresonant antennas for light, microwaves, magnons, sound, vibrations, and heat. This multiphysics behavior opens up novel opportunities for the realisation of multiresonant coupling such as, for example, photon-magnon-phonon coupling. I also propose several novel systems in which strong photon-magnon coupling in dielectric antennas and similar structures is expected to extend the capability of existing devices or may provide an entirely new functionality. Examples of such systems include novel magnetofluidic devices, high-power microwave power generators, and hybrid devices exploiting the unique properties of electrical solitons.

Nanoporous anodic alumina photonic crystals

4 October 2018:

A new review paper by CNBP student Cheryl Suwen Law (University of Adelaide) & other CNBP coauthors provides a comprehensive and up-to-date collation of fundamental and applied developments of nanoporous anodic alumina photonic crystals as optical platforms for chemo- and biosensing applications.

Journal: Nanomaterials.

Publication title: Nanoporous Anodic Alumina Photonic Crystals for Optical Chemo- and Biosensing: Fundamentals, Advances, and Perspectives.

Authors: Cheryl Suwen Law, Siew Yee Lim, Andrew D. Abell, Nicolas H. Voelcker and Abel Santos.

Abstract: Optical sensors are a class of devices that enable the identification and/or quantification of analyte molecules across multiple fields and disciplines such as environmental protection, medical diagnosis, security, food technology, biotechnology, and animal welfare. Nanoporous photonic crystal (PC) structures provide excellent platforms to develop such systems for a plethora of applications since these engineered materials enable precise and versatile control of light–matter interactions at the nanoscale. Nanoporous PCs provide both high sensitivity to monitor in real-time molecular binding events and a nanoporous matrix for selective immobilization of molecules of interest over increased surface areas. Nanoporous anodic alumina (NAA), a nanomaterial long envisaged as a PC, is an outstanding platform material to develop optical sensing systems in combination with multiple photonic technologies. Nanoporous anodic alumina photonic crystals (NAA-PCs) provide a versatile nanoporous structure that can be engineered in a multidimensional fashion to create unique PC sensing platforms such as Fabry–Pérot interferometers, distributed Bragg reflectors, gradient-index filters, optical microcavities, and others. The effective medium of NAA-PCs undergoes changes upon interactions with analyte molecules. These changes modify the NAA-PCs’ spectral fingerprints, which can be readily quantified to develop different sensing systems. This review introduces the fundamental development of NAA-PCs, compiling the most significant advances in the use of these optical materials for chemo- and biosensing applications, with a final prospective outlook about this exciting and dynamic field.

3D printing of OCT probes

4 October 2018:

A new paper published in Scientific Reports demonstrates the feasibility of 3D printing of optical coherence tomography (OCT) fibre-optic probes. Lead author on the publication is CNBP’s Dr Jiawen Li (pictured).

Journal: Scientific Reports.

Publication title: Two-photon polymerisation 3D printed freeform micro-optics for optical coherence tomography fibre probes.

Authors: Jiawen Li, Peter Fejes, Dirk Lorenser, Bryden C. Quirk, Peter B. Noble, Rodney W. Kirk, Antony Orth, Fiona M. Wood, Brant C. Gibson, David D. Sampson & Robert A. McLaughlin.

Abstract: Miniaturised optical coherence tomography (OCT) fibre-optic probes have enabled high-resolution cross-sectional imaging deep within the body. However, existing OCT fibre-optic probe fabrication methods cannot generate miniaturised freeform optics, which limits our ability to fabricate probes with both complex optical function and dimensions comparable to the optical fibre diameter. Recently, major advances in two-photon direct laser writing have enabled 3D printing of arbitrary three-dimensional micro/nanostructures with a surface roughness acceptable for optical applications. Here, we demonstrate the feasibility of 3D printing of OCT probes. We evaluate the capability of this method based on a series of characterisation experiments. We report fabrication of a micro-optic containing an off-axis paraboloidal total internal reflecting surface, its integration as part of a common-path OCT probe, and demonstrate proof-of-principle imaging of biological samples.

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.

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.