8 February 2019:
In a new publication, a responsive Ruthenium-based luminescence sensor was employed as a molecular probe for detecting nitric oxide (NO). The research suggests potential clinical utility for the measurement of soluble NO in the circulation system and possibly tissue. Lead authors of this paper are CNBP’s Dr Achini Vidanapathirana and Benjamin Pullen (both based at SAHMRI).
Journal: Scientific Reports.
Publication title: A Novel Ruthenium-based Molecular Sensor to Detect Endothelial Nitric Oxide.
Authors: Achini K. Vidanapathirana, Benjamin J. Pullen, Run Zhang, MyNgan Duong, Jarrad M.Goyne, Xiaozhou Zhang, Claudine S. Bonder, Andrew D.Abell, Christina A. Bursill, Stephen J. Nicholls & Peter J. Psaltis.
Abstract: Nitric oxide (NO) is a key regulator of endothelial cell and vascular function. The direct measurement of NO is challenging due to its short half-life, and as such surrogate measurements are typically used to approximate its relative concentrations. Here we demonstrate that ruthenium-based [Ru(bpy)2(dabpy)]2+ is a potent sensor for NO in its irreversible, NO-bound active form, [Ru(bpy)2(T-bpy)]2+. Using spectrophotometry we established the sensor’s ability to detect and measure soluble NO in a concentration-dependent manner in cell-free media. Endothelial cells cultured with acetylcholine or hydrogen peroxide to induce endogenous NO production showed modest increases of 7.3 ± 7.1% and 36.3 ± 25.0% respectively in fluorescence signal from baseline state, while addition of exogenous NO increased their fluorescence by 5.2-fold. The changes in fluorescence signal were proportionate and comparable against conventional NO assays. Rabbit blood samples immediately exposed to [Ru(bpy)2(dabpy)]2+ displayed 8-fold higher mean fluorescence, relative to blood without sensor. Approximately 14% of the observed signal was NO/NO adduct-specific. Optimal readings were obtained when sensor was added to freshly collected blood, remaining stable during subsequent freeze-thaw cycles. Clinical studies are now required to test the utility of [Ru(bpy)2(dabpy)]2+ as a sensor to detect changes in NO from human blood samples in cardiovascular health and disease.
1 February 2019:
In a break-through in the field of nano membrane related research, CNBP alumni scientist Dr Peipei Jia and colleagues report on the development of large-area freestanding gold nanomembranes with nanohole arrays fabricated using a replication-releasing procedure. More information available below!
Journal: Materials Horizons.
Publication title: Large-area Freestanding Gold Nanomembranes with Nanoholes.
Authors: Peipei Jia, Kamil Zuber, Qiuquan Guo, Brant C. Gibson, Jun Yang and Heike Ebendorff-Heidepriem.
Abstract: Thin metal films with nanohole arrays have opened up new opportunities in applications ranging from plasmonics to optoelectronics. However, their dependence on substrates limits not only their performance but also other application possibilities. A key challenge to overcome this limitation is to make these nanostructured films substrate-free. Here we report large-area freestanding gold nanomembranes with nanohole arrays fabricated using a replication-releasing procedure. The structures maintain spatial uniformity and pristine quality after release across the entire membrane up to 75 cm2 in area and as thin as 50 nm. The freestanding nanomembranes show significantly enhanced optical transmission and effective field extension compared to the same nanomembranes on substrates. A plasmonic coupling resonance with a 2.7 nm linewidth achieves a record figure-of-merit of 240 for refractive index sensing. The gold nanomembranes can be geometrically converted to 3D microstructures by ion-irradiation-based kirigami technique. The transformed micro-objects can be precisely controlled via geometry design and strategic cutting. Furthermore, we find the presence of nanoholes can significantly change the in-plane modulus of the gold nanomembranes. Finally, the freestanding gold nanomembranes can be transferred to non-planar substrates, enabling their future integration with advanced optical and electronic systems for emerging applications.
28 January 2019:
Hundreds of individual tiny fluorescent diamond particles have been imaged and characterized by CNBP researchers, reported in the journal ‘Particle & Particle Systems Characterization’.
Fluorescent nanodiamonds (FNDs) are vital to many emerging nanotechnological applications, from bioimaging and sensing to quantum nanophotonics.
The study identifies opportunities to improve the properties of single fluorescent nanodiamonds, to develop a better understanding of their underlying physical mechanisms and to advance current nanofabrication technologies.
Lead author on the paper is CNBP Associate Investigator Dr Philipp Reineck at RMIT University.
Journal: Particle & Particle Systems Characterization.
Publication title: Not All Fluorescent Nanodiamonds Are Created Equal: A Comparative Study.
Authors: Philipp Reineck; Leevan Fremiot Trindade, Jan Havlik, Jan Stursa, Ashleigh Heffernan, Aaron Elbourne, Antony Orth, Marco Capelli, Petr Cigler, David A. Simpson, Brant C. Gibson.
Abstract: Fluorescent nanodiamonds (FNDs) are vital to many emerging nanotechnological applications, from bioimaging and sensing to quantum nanophotonics. Yet, understanding and engineering the properties of fluorescent defects in nanodiamonds remain challenging. The most comprehensive study to date is presented, of the optical and physical properties of five different nanodiamond samples, in which fluorescent nitrogen‐vacancy (NV) centers are created using different fabrication techniques. The FNDs’ fluorescence spectra, lifetime, and spin relaxation time (T1) are investigated via single‐particle confocal fluorescence microscopy and in ensemble measurements in solution (T1 excepted). Particle sizes and shapes are determined using scanning electron microscopy and correlated with the optical results. Statistical tests are used to explore correlations between the properties of individual particles and also analyze average results to directly compare different fabrication techniques. Spectral unmixing is used to quantify the relative NV charge‐state (NV− and NV0) contributions to the overall fluorescence. A strong variation is found and quantified in the properties of individual particles within all analyzed samples and significant differences between the different particle types. This study is an important contribution toward understanding the properties of NV centers in nanodiamonds. It motivates new approaches to the improved engineering of NV‐containing nanodiamonds for future applications.
25 January 2019:
CNBP Associate Investigator Dr Stephen C. Warren-Smith is lead author on a new publication that has demonstrated multi-wavelength third-harmonic generation from an exposed-core microstructured optical fibre.
Journal: Optics Letters.
Publication title: Tunable multi-wavelength third-harmonic generation using exposed-core microstructured optical fiber.
Authors: Stephen C. Warren-Smith, Kay Schaarschmidt, Mario Chemnitz, Erik P. Schartner, Henrik Schneidewind, Heike Ebendorff-Heidepriem, and Markus A. Schmidt.
Abstract: We demonstrate that exposed-core microstructured optical fibers offer multiple degrees of freedom for tailoring third-harmonic generation through the core diameter, input polarization, and nanofilm deposition. Varying these parameters allows control of the phase-matching position between an infrared pump wavelength and the generated visible wavelengths. In this Letter, we show how increasing the core diameter over previous experiments (2.57 μm compared to 1.85 μm) allows the generation of multiple wavelengths, which can be further controlled by rotating the input pump polarization and the deposition of dielectric nanofilms. This can lead to highly tailorable light sources for applications such as spectroscopy or nonlinear microscopy.
16 January 2019:
A new aptamer sensor has been developed for the sensitive detection of AFM1 toxin in milk products. Lead author of the paper published in the journal ‘Nanomaterials’ is CNBP PhD candidate Fuyuan Zhang (pictured).
Publication title: Turn-On Fluorescence Aptasensor on Magnetic Nanobeads for Aflatoxin M1 Detection Based on an Exonuclease III-Assisted Signal Amplification Strategy.
Authors: Fuyuan Zhang, Linyang Liu, Shengnan Ni, Jiankang Deng, Guo-Jun Liu, Ryan Middleton, David W. Inglis, Shuo Wang and Guozhen Liu.
Abstract: In order to satisfy the need for sensitive detection of Aflatoxin M1 (AFM1), we constructed a simple and signal-on fluorescence aptasensor based on an autocatalytic Exonuclease III (Exo III)-assisted signal amplification strategy. In this sensor, the DNA hybridization on magnetic nanobeads could be triggered by the target AFM1, resulting in the release of a single-stranded DNA to induce an Exo III-assisted signal amplification, in which numerous G-quadruplex structures would be produced and then associated with the fluorescent dye to generate significantly amplified fluorescence signals resulting in the increased sensitivity. Under the optimized conditions, this aptasensor was able to detect AFM1 with a practical detection limit of 9.73 ng kg−1 in milk samples. Furthermore, the prepared sensor was successfully used for detection of AFM1 in the commercially available milk samples with the recovery percentages ranging from 80.13% to 108.67%. Also, the sensor performance was evaluated by the commercial immunoassay kit with satisfactory results.
14 January 2019:
A new paper by CNBP researchers and colleagues (including CNBP Associate Investigator Guozhen Liu, UNSW Sydney) reviews cutting-edge biosensing applications of CRISPR.
Journal: Trends in Biotechnology.
Publication title: CRISPR/Cas Systems towards Next-Generation Biosensing.
Authors: Yi Li, Shiyuan Li, Jin Wang and Guozhen Liu.
Abstract: Beyond its remarkable genome editing ability, the CRISPR/Cas9 effector has also been utilized in biosensing applications. The recent discovery of the collateral RNA cleavage activity of the Cas13a effector has sparked even greater interest in developing novel biosensing technologies for nucleic acid detection and promised significant advances in CRISPR diagnostics. Now, along with the discovery of Cas12 collateral cleavage activities on single stranded DNA (ssDNA), several CRISPR/Cas systems have been established for detecting various targets, including bacteria, viruses, cancer mutations, and
others. Based on key Cas effectors, we provide a detailed classification of CRISPR/Cas biosensing systems and propose their future utility. As the field continues to mature, CRISPR/Cas systems have the potential to become promising candidates for next-generation diagnostic biosensing platforms.
19 December 2018:
Researchers from CNBP and the Institute for Photonics and Advanced Sensing, together with Sir Charles Gairdner Hospital and University of Western Australia collaborators, have demonstrated the potential of an ‘imaging needle’ for reducing the risk of dangerous brain bleeds in patients undergoing brain biopsy. In the journal Science Advances, the researchers describe how a tiny imaging needle can detect blood vessels with a very high degree of accuracy (91.2% sensitivity and 97.7% specificity). Pictured is corresponding author of the paper CNBP Investigator Prof Robert McLaughlin, University of Adelaide.
Journal: Science Advances.
Publication title: Intraoperative detection of blood vessels with an imaging needle during neurosurgery in humans.
Authors: Hari Ramakonar, Bryden C. Quirk, Rodney W. Kirk, Jiawen Li, Angela Jacques, Christopher R. P. Lind and Robert A. McLaughlin.
Abstract: Intracranial hemorrhage can be a devastating complication associated with needle biopsies of the brain. Hemorrhage can occur to vessels located adjacent to the biopsy needle as tissue is aspirated into the needle and removed. No intraoperative technology exists to reliably identify blood vessels that are at risk of damage. To address this problem, we developed an “imaging needle” that can visualize nearby blood vessels in real time. The imaging needle contains a miniaturized optical coherence tomography probe that allows differentiation of blood flow and tissue. In 11 patients, we were able to intraoperatively detect blood vessels (diameter, >500 μm) with a sensitivity of 91.2% and a specificity of 97.7%. This is the first reported use of an optical coherence tomography needle probe in human brain in vivo. These results suggest that imaging needles may serve as a valuable tool in a range of neurosurgical needle interventions.
17 December 2018:
A review paper by CNBP researchers (lead author Sameera Iqbal pictured) reports on the examination of cellular glycan surfaces in the central nervous system and links to disorders and disease such as Alzheimer’s disease, multiple sclerosis and more.
Journal: Biochemical Society Transactions.
Publication title: Understanding cellular glycan surfaces in the central nervous system.
Authors: Sameera Iqbal, Mina Ghanimi Fard, Arun Everest-Dass, Nicolle H. Packer, Lindsay M. Parker.
Abstract: Glycosylation, the enzymatic process by which glycans are attached to proteins and lipids, is the most abundant and functionally important type of post-translational modification associated with brain development, neurodegenerative disorders, psychopathologies and brain cancers. Glycan structures are diverse and complex; however, they have been detected and targeted in the central nervous system (CNS) by various immunohistochemical detection methods using glycan-binding proteins such as anti-glycan antibodies or lectins and/or characterized with analytical techniques such as chromatography and mass spectrometry. The glycan structures on glycoproteins and glycolipids expressed in neural stem cells play key roles in neural development, biological processes and CNS maintenance, such as cell adhesion, signal transduction, molecular trafficking and differentiation. This brief review will highlight some of the important findings on differential glycan expression across stages of CNS cell differentiation and in pathological disorders and diseases such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, multiple sclerosis, amyotrophic lateral sclerosis, schizophrenia and brain cancer.
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.
24 November 2018:
An improved method to convert nitrogen to nitrogen-vacancy (NV) color centers in diamond has been reported by CNBP researchers in a paper published in the journal Carbon. Lead author of the paper was CNBP student Marco Capelli (pictured).
Publication title: Increased nitrogen-vacancy centre creation yield in diamond through electron beam irradiation at high temperature.
Authors: M. Capelli, A.H. Heffernan, T. Ohshima, H. Abe, J. Jeske, A. Hope, A.D. Greentree, P. Reineck, B.C. Gibson.
Abstract: The nitrogen-vacancy (NV) centre is a fluorescent defect in diamond that is of critical importance for applications from ensemble sensing to biolabelling. Hence, understanding and optimising the creation of NV centres in diamond is vital for technological progress in these areas. We demonstrate that simultaneous
electron irradiation and annealing of a high-pressure high-temperature diamond sample increases the NV centre creation efficiency from substitutional nitrogen defects by up to 117 % with respect to a sample where the processes are carried out consecutively, but using the same process parameters. This increase in fluorescence is supported by visible and infrared absorption spectroscopy experiments. Our results pave the way for a more efficient creation of NV centres in diamond as well as higher overall NV densities in the future.