Dr Olga Shimoni is Senior Lecturer at the University of Technology Sydney (UTS) and NHMRC-ARC Dementia Research Fellow. She is also co-chief investigator on the ARC Industrial Research Hub for Integrated Device for End-user Analysis at Low-levels (IDEAL Hub). She graduated with a BSc and MSc from Technion-Israeli Institute of Technology in chemical and materials engineering, respectively. She relocated to Australia to undertake her doctoral degree (PhD) at the University of Melbourne in Chemical and Biomolecular Engineering, graduating in 2012.
In 2014, she joined UTS as Chancellor’s Postdoctoral Research Fellow after a relatively short post-doctoral training in the School of Physics (Melbourne University) in the field of diamonds. While still being earlier career researcher (ECR), in addition to the above fellowships she received several grants and awards, including Ramaciotti Foundation Establishment grant (2015), UTS Science Dean’s Award for Research Excellence (2015), co-chief investigator on ARC LIEF grant (2016), Faculty of Science Staff Conference Travel Award (2014)and more. She is a member of the Australian Nanotechnology Network (ANN) and the American Chemical Society (ACS). She is a proactive member for gender equity for Women in STEMM and a spokeswoman for women in science at UTS.
Her research is multi-disciplinary in nature and involves chemistry, physics, nanotechnology and biology. Her research achievements include biomolecule attachment to nanocarrier of drug for targeted drug delivery, development of bio-imaging probes and nanoparticles, development of diagnostic tests for detection of celiac or cancer diseases. As a part of her NHMRC-ARC Dementia fellowship, she is working on novel multi-functional nanoparticles for investigation of causes and progression of Alzheimer’s disease. Furthermore, she is the founder of the Australian network of researchers working with nanoparticles for brain research (ANNxBBB).
Grants and Awards:
2014 - UTS Chancellor’s Postdoctoral Research Fellowship
2015 - Ramacciotti Foundation Establishment grant
2015 - UTS Faculty of Science Dean’s Award for Research Excellence
2016 - NHMRC-ARC Dementia Research Fellowship
2016 - ARC Industrial Research Hub for Integrated Device for End-user Analysis at Low-levels (IDEAL) (co-chief investigator).
2017 - ARC LIEF grant - UltraTEM: resolving the structure of matter in space, energy and time.
Dr Shimoni is a regular peer-reviewer in various scientific journals, such as Advanced Materials, Chemistry of Materials, ACS Applied Materials and Interfaces, Scientific Reports, and more.
Founding Member of the Australian Network for Nanoparticles Crossing the Blood-Brain Barrier
Member of the Australian Nanotechnology Network (ANN)
Member of the American Chemical Society (ACS)
Member of the Academic Women in Science (AWiS)
Member of Franklin Women - Women in Health & Medical Research
Can supervise: YES
For many years, nanoscale robots (nanobots) that can be injected into the patient’s body and accomplish multiple functions have been in a category of science fiction. With a vast nanotechnology development, these systems will become a reality in a near future. The goal of my research is to develop novel nanostructures that will have a superior ability to perform multiple functionalities, bringing the current technology closer towards a creation of nanobots. A number of related projects are currently available, and include (but not limited to):
- Development of hybrid nanostructures for bio-sensingand/or bio-imaging
- Biofunctionalization of fluorescent nanoparticles
- Trageted drug delivery
- Interaction of nanoparticles with biological samples
Kaur, A, Shimoni, O & Wallach, M 2018, 'Novel screening test for celiac disease using peptide functionalised gold nanoparticles.', World journal of gastroenterology, vol. 24, no. 47, pp. 5379-5390.View/Download from: Publisher's site
AIM:To develop a screening test for celiac disease based on the coating of gold nanoparticles with a peptide sequence derived from gliadin, the protein that triggers celiac disease. METHODS:20 nm gold nanoparticles were first coated with NeutrAvidin. A long chain Polyethylene glycol (PEG) linker containing Maleimide at the -end and Biotin group at the -end was used to ensure peptide coating to the gold nanoparticles. The maleimide group with the thiol (-SH) side chain reacted with the cysteine amino acid in the peptide sequence and the biotinylated and PEGylated peptide was added to the NeutrAvidin coated gold nanoparticles. The peptide coated gold nanoparticles were then converted into a serological assay. We used the peptide functionalised gold nanoparticle-based assay on thirty patient serum samples in a blinded assessment and compared our results with the previously run serological and pathological tests on these patients. RESULTS:A stable colloidal suspension of peptide coated gold nanoparticles was obtained without any aggregation. An absorbance peak shift as well as color change was caused by the aggregation of gold nanoparticles following the addition of anti-gliadin antibody to peptide coated nanoparticles at levels associated with celiac disease. The developed assay has been shown to detect anti-gliadin antibody not only in quantitatively spiked samples but also in a small-scale study on real non-hemolytic celiac disease patient's samples. CONCLUSION:The study demonstrates the potential of gold nanoparticle-peptide based approach to be adapted for developing a screening assay for celiac disease diagnosis. The assay could be a part of an exclusion based diagnostic strategy and prove particularly useful for testing high celiac disease risk populations.
Wu, Y, Li, S, Liu, J, Liu, X, Ruan, W, Lu, J, Liu, Y, Lawson, T, Shimoni, O, Lovejoy, DB, Walker, AK, Cong, Y & Shi, B 2018, 'Stilbenes from Veratrum maackii Regel Protect against Ethanol-Induced DNA Damage in Mouse Cerebellum and Cerebral Cortex.', ACS chemical neuroscience, vol. 9, no. 7, pp. 1616-1624.View/Download from: Publisher's site
Ethanol is a principle ingredient of alcoholic beverages with potential neurotoxicity and genotoxicity, and the ethanol-associated oxidative DNA damage in the central nervous system is well documented. Natural source compounds may offer new options to protect the brain against ethanol-induced genotoxicity. Veratrum maackii Regel is a toxic rangeland plant linked to teratogenicity which is also used in traditional Chinese medicine as "Lilu" and is reported to contain a family of compounds called stilbenes that can have positive biological activity. In this study, nine stilbenes were isolated from the aerial parts of V. maackii Regel, and their structures were identified as cis-mulberroside A (1), resveratrol-4,3'- O--d-diglucopyranoside (2), mulberroside A (3), gentifolin K (4), resveratrol-3,5- O--d-diglucopyranoside (5), oxyresveratrol- 4'- O--d-glucopyranoside (6), oxyresveratrol-3- O--d-glucopyranoside (7), oxyresveratrol (8), and resveratrol (9) using ESI-MS and NMR techniques. The total concentration of extracted compounds 2-9 was 2.04 mg/g, suggesting that V. maackii Regel is a novel viable source of these compounds. In an in vivo comet assay, compounds 1-9 were observed to decrease DNA damage in mouse cerebellum and cerebral cortex caused by acute ethanol administration. Histological observation also revealed decreased brain injury in mice administered with compounds 1-9 after acute ethanol administration. The protective effects of compound 6 were associated with increasing T-SOD and GSH-PX activities and a decrease in NO and MDA concentrations. These findings suggest that these compounds are potent inhibitors of ethanol-induced brain injury possibly via the inhibition of oxidative stress and may be valuable leads for future therapeutic development.
Duong, HTT, Chen, Y, Tawfik, SA, Wen, S, Parviz, M, Shimoni, O & Ab, DJ 2018, 'Systematic investigation of functional ligands for colloidal stable upconversion nanoparticles†', RSC Advances, vol. 8, no. 9, pp. 4842-4849.View/Download from: Publisher's site
© The Royal Society of Chemistry 2018. Despite intense efforts on surface functionalization to generate hydrophilic upconversion nanoparticles (UCNPs), long-term colloidal stability in physiological buffers remains a major concern. Here we quantitatively investigate the competitive adsorption of phosphate, carboxylic acid and sulphonic acid onto the surface of UCNPs and study their binding strength to identify the best conjugation strategy. To achieve this, we designed and synthesized three di-block copolymers composed of poly(ethylene glycol) methyl ether acrylate and a polymer block bearing phosphate, carboxylic or sulphonic acid anchoring groups prepared by an advanced polymerization technique, Reversible Addition Fragmentation Chain Transfer (RAFT). Analytical tools provide the evidence that phosphate ligands completely replaced all the oleic acid capping molecules on the surface of the UCNPs compared with incomplete ligand exchange by carboxylic and sulphonic acid groups. Meanwhile, simulated quantitative adsorption energy measurements confirmed that among the three functional groups, the calculated adsorption strength for phosphate anchoring ligands is higher which is in good agreement with experimental results regarding the best colloidal stability, especially in phosphate buffer solution. This finding suggests that polymers with multiple anchoring negatively charged phosphate moieties provide excellent colloidal stability for lanthanide ion-doped luminescent nanoparticles for various potential applications.
Chen, Y, Duong, HTT, Wen, S, Mi, C, Zhou, Y, Shimoni, O, Valenzuela, SM & Jin, D 2018, 'Exonuclease III-Assisted Upconversion Resonance Energy Transfer in a Wash-Free Suspension DNA Assay.', Analytical Chemistry, vol. 90, no. 1, pp. 663-668.View/Download from: UTS OPUS or Publisher's site
Sensitivity is the key in optical detection of low-abundant analytes, such as circulating RNA or DNA. The enzyme Exonuclease III (Exo III) is a useful tool in this regard; its ability to recycle target DNA molecules results in markedly improved detection sensitivity. Lower limits of detection may be further achieved if the detection background of autofluorescence can be removed. Here we report an ultrasensitive and specific method to quantify trace amounts of DNA analytes in a wash-free suspension assay. In the presence of target DNA, the Exo III recycles the target DNA by selectively digesting the dye-tagged sequence-matched probe DNA strand only, so that the amount of free dye removed from the probe DNA is proportional to the number of target DNAs. Remaining intact probe DNAs are then bound onto upconversion nanoparticles (energy donor), which allows for upconversion luminescence resonance energy transfer (LRET) that can be used to quantify the difference between the free dye and tagged dye (energy acceptor). This scheme simply avoids both autofluorescence under infrared excitation and many tedious washing steps, as the free dye molecules are physically located away from the nanoparticle surface, and as such they remain "dark" in suspension. Compared to alternative approaches requiring enzyme-assisted amplification on the nanoparticle surface, introduction of probe DNAs onto nanoparticles only after DNA hybridization and signal amplification steps effectively avoids steric hindrance. Via this approach, we have achieved a detection limit of 15 pM in LRET assays of human immunodeficiency viral DNA.
Sun, Y, Zhang, W, Wang, B, Xu, X, Chou, J, Shimoni, O, Ung, AT & Jin, D 2018, 'A supramolecular self-assembly strategy for upconversion nanoparticle bioconjugation.', Chemical communications (Cambridge, England), vol. 54, no. 31, pp. 3851-3854.View/Download from: UTS OPUS or Publisher's site
An efficient surface modification for upconversion nanoparticles (UCNPs) is reported via supramolecular host-guest self-assembly. Cucurbituril (CB) can provide a hydrophilic surface and cavities for most biomolecules. High biological efficiency, activity and versatility of the approach enable UCNPs to be significantly applied in bio-imaging, early disease detection, and bio-sensing.
Wang, F, Wen, S, He, H, Wang, B, Zhou, Z, Shimoni, O & Jin, D 2018, 'Microscopic inspection and tracking of single upconversion nanoparticles in living cells', Light: Science and Applications, vol. 7, no. 4.View/Download from: UTS OPUS or Publisher's site
© 2018 The Author(s). Nanoparticles have become new tools for cell biology imaging, sub-cellular sensing, super-resolution imaging, and drug delivery. Long-term 3D tracking of nanoparticles and their intracellular motions have advanced the understanding of endocytosis and exocytosis as well as of active transport processes. The sophisticated operation of correlative optical-electron microscopy and scientific-grade cameras is often used to study intercellular processes. Nonetheless, most of these studies are still limited by the insufficient sensitivity for separating a single nanoparticle from a cluster of nanoparticles or their aggregates8. Here we report that our eyes can track a single fluorescent nanoparticle that emits over 4000 photons per 100 milliseconds under a simple microscope setup. By tracking a single nanoparticle with high temporal, spectral and spatial resolution, we show the measurement of the local viscosity of the intracellular environment. Moreover, beyond the colour domain and 3D position, we introduce excitation power density as the fifth dimension for our eyes to simultaneously discriminate multiple sets of single nanoparticles.
Bray, K, Cheung, L, Hossain, KR, Aharonovich, I, Valenzuela, SM & Shimoni, O 2018, 'Versatile multicolor nanodiamond probes for intracellular imaging and targeted labeling', Journal of Materials Chemistry B, vol. 6, no. 19, pp. 3078-3084.View/Download from: UTS OPUS or Publisher's site
© 2018 The Royal Society of Chemistry. We report on the sizable production of fluorescent nanodiamonds (FNDs) containing a near infrared (NIR) color center-namely the silicon vacancy (SiV) defect, and their first demonstration inside cells for bio-imaging. We further demonstrate a concept of multi-color bio-imaging using FNDs to investigate intercellular processes using two types of FNDs. Due to their specific spectral properties, SiV FNDs can be distinguished from common nitrogen-vacancy (NV) FNDs and show a distinct initial spreading throughout the cell interior. The reported results are the first demonstration of multi-color labeling with FNDs that are especially interesting for in vivo bio-imaging due to their stable fluorescence.
Abu Saleh, D, Shimoni, O & Sosnik, A 2017, 'Novel core-corona hybrid nanomaterials based on the conjugation of amphiphilic polymeric diblocks to the surface of multifunctional nanodiamond anchors', Materials Today Chemistry, vol. 3, pp. 15-26.View/Download from: UTS OPUS or Publisher's site
© 2017 Elsevier Ltd The poor aqueous solubility and the physicochemical instability of many marketed drugs and new chemical entities is one of the most challenging issues in pharmaceutical research and development. Polymeric micelles (PMs) are produced by the self-assembly of polymeric amphiphiles and they represent one of the most extensively investigated nanotechnology platforms for encapsulation, delivery and targeting of hydrophobic drugs. However, a main challenge is preventing their disassembly under extreme dilution in the body fluids, which leads to uncontrolled release of the encapsulated cargo. In this work, we developed an amphiphilic nanomaterial that resembles the core-corona architecture of a PM with superior stability in the body fluids. Specifically, we utilized carboxylated nanodiamonds (cNDs) as particulate anchors to covalently link amphiphilic diblock copolymers consisting of poly(epsilon-caprolactone) (PCL) and poly(ethylene glycol) monomethyl ether (PEG) as hydrophobic and hydrophilic components, respectively. We confirmed a successful core-corona nanostructure using various characterization techniques. In addition, TEM revealed the presence of a thin polymeric layer. Then, the cell compatibility was evaluated in Caco2 cell monolayers, an in vitro model of the intestinal epithelium. Finally, the encapsulation of the hydrophobic anti-helmintic drug nitazoxanide was studied. Cargoes as high as 17.5% w/w were achieved and the sustained release of the cargo according to the Korsmeyer-Peppas model demonstrated in vitro. Overall, preliminary results highlight the potential of this novel approach to extend the applicability of PMs in drug delivery.
Kaur, A, Shimoni, O & Wallach, M 2017, 'Celiac disease: from etiological factors to evolving diagnostic approaches.', Journal of gastroenterology, vol. 52, no. 9, pp. 1001-1012.View/Download from: UTS OPUS or Publisher's site
Celiac disease has advanced from a medical rarity to a highly prevalent disorder. Patients with the disease show varying degrees of chronic inflammation within the small intestine due to an aberrant immune response to the digestion of gliadin found in wheat. As a result, cytokines and antibodies are produced in celiac patients that can be used as specific biomarkers for developing diagnostic tests. This review paper describes celiac disease in terms of its etiological cause, pathological effects, current diagnostic tests based on mucosal biopsy, and the genetic basis for the disease. In addition, it discusses the use of gliadin-induced cytokines, antibodies and autoantibodies as a diagnostic tool for celiac disease. Despite good initial results in terms of sensitivity and specificity, when these immunological tests were used on a large scale, even in combination with genetic testing, the results showed lower predictive value. This review addresses that issue and ends with an outlook on future work required to develop diagnostic tests with greater accuracy in predicting celiac disease in the general public, thus avoiding the need for endoscopy and mucosal biopsy.
Shimoni, O, Bray, K, Cheung, L, Aharanovich, I & Valenzuela, S 2017, 'Versatile Multicolor Nanodiamond Probes for Intracellular Imaging and Targeted Labeling'.View/Download from: UTS OPUS or Publisher's site
Diamond nanoparticles that host bright luminescent centers are attracting attention for applications in bio-labeling and bio-sensing. Beyond their unsurpassed photostability, diamond can host multiple color centers, from the blue to the near infra-red spectral range. While nanodiamonds hosting nitrogen vacancy defects have been widely employed as bio-imaging probes, production and fabrication of nanodiamonds with other color centers is a challenge. In this work, a large scale production of fluorescent nanodiamonds (FNDs) containing a near infrared (NIR) color center - namely the silicon vacancy (SiV) defect, is reported. More importantly, a concept of application of different color centers for multi-color bio-imaging to investigate intercellular processes is demonstrated. Furthermore, two types of FNDs within cells can be easily resolved by their specific spectral properties, where data shows that SiV FNDs initially dispersed throughout the cell interior while NV FNDs localized in a close proximity to nucleus. The reported results are the first demonstration of multi-color labeling with FNDs that can pave the way for the wide-ranging use of FNDs in applications, including bio-sensing, bio-imaging and drug delivery applications.
Hong, J, Aramesh, M, Shimoni, O, Seo, DH, Yick, S, Greig, A, Charles, C, Prawer, S & Murphy, AB 2016, 'Plasma Catalytic Synthesis of Ammonia Using Functionalized-Carbon Coatings in an Atmospheric-Pressure Non-equilibrium Discharge', Plasma Chemistry and Plasma Processing, vol. 36, no. 4, pp. 917-940.View/Download from: UTS OPUS or Publisher's site
© 2016, Springer Science+Business Media New York. We investigate the synthesis of ammonia in a non-equilibrium atmospheric-pressure plasma using functionalized-nanodiamond and diamond-like-carbon coatings on -Al2O3 spheres as catalysts. Oxygenated nanodiamonds were found to increase the production yield of ammonia, while hydrogenated nanodiamonds decreased the yield. Neither type of nanodiamond affected the plasma properties significantly. Using diffuse-reflectance FT-IR and XPS, the role of different functional groups on the catalyst surface was investigated. Evidence is presented that the carbonyl group is associated with an efficient surface adsorption and desorption of hydrogen in ammonia synthesis on the surface of the nanodiamonds, and an increased production of ammonia. Conformal diamond-like-carbon coatings, deposited by plasma-enhanced chemical vapour deposition, led to a plasma with a higher electron density, and increased the production of ammonia.
Shimoni, O, Shi, B, Adlard, PA & Bush, AI 2016, 'Delivery of Fluorescent Nanoparticles to the Brain.', Journal of molecular neuroscience : MN, vol. 60, no. 3, pp. 405-409.View/Download from: UTS OPUS or Publisher's site
Nanotechnology applications in neuroscience promises to deliver significant scientific and technological breakthroughs, providing answers to unresolved questions regarding the processes occurring in the brain. In this perspective, we provide a short background on two distinct fluorescent nanoparticles and summarize several studies focussed on achieving delivery of these into the brain and their interaction with brain tissue. Furthermore, we discuss challenges and opportunities for further development of nanoparticle-based therapies for targeting delivery of drugs across the blood-brain barrier.
Kianinia, M, Shimoni, O, Bendavid, A, Schell, AW, Randolph, SJ, Toth, M, Aharonovich, I & Lobo, CJ 2016, 'Robust, directed assembly of fluorescent nanodiamonds.', Nanoscale, vol. 8, no. 42, pp. 18032-18037.View/Download from: UTS OPUS or Publisher's site
Arrays of fluorescent nanoparticles are highly sought after for applications in sensing, nanophotonics and quantum communications. Here we present a simple and robust method of assembling fluorescent nanodiamonds into macroscopic arrays. Remarkably, the yield of this directed assembly process is greater than 90% and the assembled patterns withstand ultra-sonication for more than three hours. The assembly process is based on covalent bonding of carboxyl to amine functional carbon seeds and is applicable to any material, and to non-planar surfaces. Our results pave the way to directed assembly of sensors and nanophotonics devices.
Bray, K, Sandstrom, R, Elbadawi, C, Fischer, M, Schreck, M, Shimoni, O, Lobo, C, Toth, M & Aharonovich, I 2016, 'Localization of Narrowband Single Photon Emitters in Nanodiamonds.', ACS applied materials & interfaces, vol. 8, no. 11, pp. 7590-7594.View/Download from: UTS OPUS or Publisher's site
Diamond nanocrystals that host room temperature narrowband single photon emitters are highly sought after for applications in nanophotonics and bioimaging. However, current understanding of the origin of these emitters is extremely limited. In this work, we demonstrate that the narrowband emitters are point defects localized at extended morphological defects in individual nanodiamonds. In particular, we show that nanocrystals with defects such as twin boundaries and secondary nucleation sites exhibit narrowband emission that is absent from pristine individual nanocrystals grown under the same conditions. Critically, we prove that the narrowband emission lines vanish when extended defects are removed deterministically using highly localized electron beam induced etching. Our results enhance the current understanding of single photon emitters in diamond and are directly relevant to fabrication of novel quantum optics devices and sensors.
Aramesh, M, Shimoni, O, Fox, K, Karle, TJ, Lohrmann, A, Ostrikov, K, Prawer, S & Cervenka, J 2015, 'Ultra-high-density 3D DNA arrays within nanoporous biocompatible membranes for single-molecule-level detection and purification of circulating nucleic acids.', Nanoscale, vol. 7, no. 14, pp. 5998-6006.View/Download from: UTS OPUS or Publisher's site
Extracellular nucleic acids freely circulating in blood and other physiologic fluids are important biomarkers for non-invasive diagnostics and early detection of cancer and other diseases, yet difficult to detect because they exist in very low concentrations and large volumes. Here we demonstrate a new broad-range sensor platform for ultrasensitive and selective detection of circulating DNA down to the single-molecule level. The biosensor is based on a chemically functionalized nanoporous diamond-like carbon (DLC) coated alumina membrane. The few nanometer-thick, yet perfect and continuous DLC-coating confers the chemical stability and biocompatibility of the sensor, allowing its direct application in biological conditions. The selective detection is based on complementary hybridization of a fluorescently-tagged circulating cancer oncomarker (a 21-mer nucleic acid) with covalently immobilized DNA on the surface of the membrane. The captured DNAs are detected in the nanoporous structure of the sensor using confocal scanning laser microscopy. The flow-through membrane sensor demonstrates broad-range sensitivity, spanning from 10(15) molecules per cm(2) down to single molecules, which is several orders of magnitude improvement compared to the flat DNA microarrays. Our study suggests that these flow-through type nanoporous sensors represent a new powerful platform for large volume sampling and ultrasensitive detection of different chemical biomarkers.
Aramesh, M, Shimoni, O, Ostrikov, K, Prawer, S & Cervenka, J 2015, 'Surface charge effects in protein adsorption on nanodiamonds.', Nanoscale, vol. 7, no. 13, pp. 5726-5736.View/Download from: UTS OPUS or Publisher's site
Understanding the interaction of proteins with charged diamond nanoparticles is of fundamental importance for diverse biomedical applications. Here we present a thorough study of protein binding, adsorption kinetics and structure on strongly positively (hydrogen-terminated) and negatively (oxygen-terminated) charged nanodiamond particles using a quartz crystal microbalance by dissipation and infrared spectroscopy. By using two model proteins (bovine serum albumin and lysozyme) of different properties (charge, molecular weight and rigidity), the main driving mechanism responsible for the protein binding to the charged nanoparticles was identified. Electrostatic interactions were found to dominate the protein adsorption dynamics, attachment and conformation. We developed a simple electrostatic model that can qualitatively explain the observed adsorption behaviour based on charge-induced pH modifications near the charged nanoparticle surfaces. Under neutral conditions, the local pH around the positively and negatively charged nanodiamonds becomes very high (11-12) and low (1-3) respectively, which has a profound impact on the protein charge, hydration and affinity to the nanodiamonds. Small proteins (lysozyme) were found to form multilayers with significant conformational changes to screen the surface charge, while larger proteins (albumin) formed monolayers with minor conformational changes. The findings of this study provide a step forward toward understanding and eventually predicting nanoparticle interactions with biofluids.
Dontschuk, N, Stacey, A, Tadich, A, Rietwyk, KJ, Schenk, A, Edmonds, MT, Shimoni, O, Pakes, CI, Prawer, S & Cervenka, J 2015, 'A graphene field-effect transistor as a molecule-specific probe of DNA nucleobases.', Nature communications, vol. 6, p. 6563.View/Download from: UTS OPUS or Publisher's site
Fast and reliable DNA sequencing is a long-standing target in biomedical research. Recent advances in graphene-based electrical sensors have demonstrated their unprecedented sensitivity to adsorbed molecules, which holds great promise for label-free DNA sequencing technology. To date, the proposed sequencing approaches rely on the ability of graphene electric devices to probe molecular-specific interactions with a graphene surface. Here we experimentally demonstrate the use of graphene field-effect transistors (GFETs) as probes of the presence of a layer of individual DNA nucleobases adsorbed on the graphene surface. We show that GFETs are able to measure distinct coverage-dependent conductance signatures upon adsorption of the four different DNA nucleobases; a result that can be attributed to the formation of an interface dipole field. Comparison between experimental GFET results and synchrotron-based material analysis allowed prediction of the ultimate device sensitivity, and assessment of the feasibility of single nucleobase sensing with graphene.
Bray, K, Previdi, R, Gibson, BC, Shimoni, O & Aharonovich, I 2015, 'Enhanced photoluminescence from single nitrogen-vacancy defects in nanodiamonds coated with phenol-ionic complexes.', Nanoscale, vol. 7, no. 11, pp. 4869-4874.View/Download from: UTS OPUS or Publisher's site
Fluorescent nanodiamonds are attracting major attention in the field of bio-sensing and bio-labeling. In this work we demonstrate a robust approach to achieve an encapsulation of individual nanodiamonds with phenol-ionic complexes that enhance the photoluminescence from single nitrogen vacancy (NV) centers. We show that single NV centres in the coated nanodiamonds also exhibit shorter lifetimes, opening another channel for high resolution sensing. We propose that the nanodiamond encapsulation reduces the non-radiative decay pathways of the NV color centers. Our results provide a versatile and assessable way to enhance photoluminescence from nanodiamond defects that can be used in a variety of sensing and imaging applications.
Tran, TT, Fang, J, Zhang, H, Rath, P, Bray, K, Sandstrom, RG, Shimoni, O, Toth, M & Aharonovich, I 2015, 'Facile Self-Assembly of Quantum Plasmonic Circuit Components.', Advanced materials (Deerfield Beach, Fla.), vol. 27, no. 27, pp. 4048-4053.View/Download from: UTS OPUS or Publisher's site
A facile and cost-effective self-assembly route to engineering of vital quantum plasmonic circuit components is reported. By modifying the surface energy of silver nanowires, the position and density of attached nanodiamonds can be maneuvered leading to silver nanowire/nanodiamond(s) hybrid nanostructures. These structures exhibit strong plasmonic coupling effects and thus hold promise to serve as quantum plasmonic components.
Shimoni, O, Cervenka, J, Karle, T, Fox, K, Gibson, BC, Tomljenovic-Hanic, S, Greentree, AD & Prawer, S 2014, 'Development of a Templated Approach to Fabricate Diamond Patterns on Various Substrates', ACS Applied Materials and Interfaces, vol. 6, no. 11, pp. 8894-8902.View/Download from: UTS OPUS or Publisher's site
We demonstrate a robust templated approach to pattern thin films of chemical vapor deposited nanocrystalline diamond grown from monodispersed nanodiamond (mdND) seeds. The method works on a range of substrates, and we herein demonstrate the method using silicon, aluminum nitride (AlN), and sapphire substrates. Patterns are defined using photo- and e-beam lithography, which are seeded with mdND colloids and subsequently introduced into microwave assisted chemical vapor deposition reactor to grow patterned nanocrystalline diamond films. In this study, we investigate various factors that affect the selective seeding of different substrates to create high quality diamond thin films, including mdND surface termination, zeta potential, surface treatment, and plasma cleaning. Although the electrostatic interaction between mdND colloids and substrates is the main process driving adherence, we found that chemical reaction (esterification) or hydrogen bonding can potentially dominate the seeding process. Leveraging the knowledge on these different interactions, we optimize fabrication protocols to eliminate unwanted diamond nucleation outside the patterned areas. Furthermore, we have achieved the deposition of patterned diamond films and arrays over a range of feature sizes. This study contributes to a comprehensive understanding of the mdNDsubstrate interaction that will enable the fabrication of integrated nanocrystalline diamond thin films for microelectronics, sensors, and tissue culturing applications.
Tong, W, Fox, K, Ganesan, K, Turnley, AM, Shimoni, O, Tran, PA, Lohrmann, A, McFarlane, T, Ahnood, A, Garrett, DJ, Meffin, H, O'Brien-Simpson, NM, Reynolds, EC & Prawer, S 2014, 'Fabrication of planarised conductively patterned diamond for bio-applications.', Materials Science and Engineering: C, vol. 43, pp. 135-144.View/Download from: UTS OPUS or Publisher's site
The development of smooth, featureless surfaces for biomedical microelectronics is a challenging feat. Other than the traditional electronic materials like silicon, few microelectronic circuits can be produced with conductive features without compromising the surface topography and/or biocompatibility. Diamond is fast becoming a highly sought after biomaterial for electrical stimulation, however, its inherent surface roughness introduced by the growth process limits its applications in electronic circuitry. In this study, we introduce a fabrication method for developing conductive features in an insulating diamond substrate whilst maintaining a planar topography. Using a combination of microwave plasma enhanced chemical vapour deposition, inductively coupled plasma reactive ion etching, secondary diamond growth and silicon wet-etching, we have produced a patterned substrate in which the surface roughness at the interface between the conducting and insulating diamond is approximately 3 nm. We also show that the patterned smooth topography is capable of neuronal cell adhesion and growth whilst restricting bacterial adhesion.
Sandstrom, RG, Shimoni, O, Martin, AA & Aharonovich, I 2014, 'Study of narrowband single photon emitters in polycrystalline diamond films', APPLIED PHYSICS LETTERS, vol. 105, no. 18.View/Download from: UTS OPUS or Publisher's site
Cervenka, J, Lau, DW, Dontschuk, N, Shimoni, O, Silvestri, L, Ladouceur, F, Duvall, SG & Prawer, S 2013, 'Nucleation and Chemical Vapor Deposition Growth of Polycrystalline Diamond on Aluminium Nitride: The Role of Surface Termination and Polarity', Crystal Growth and Design, vol. 13, no. 8, pp. 3490-3497.View/Download from: UTS OPUS or Publisher's site
We have investigated the growth and atomic interface structures of diamond on aluminum nitride (AlN). The two-step chemical vapor deposition technique is used to control diamond nucleation density, crystal size, and AlN surface orientation and polarity. Highly uniform diamond layers with a nucleation density in the range of 1051011 cm2 and a grain size of 0.15 µm are fabricated. Crystallographically abrupt interfaces between polycrystalline diamond and single-crystal AlN(0001) layers have been observed via high-resolution transmission electron microscopy and electron energy-loss spectroscopy. A majority of the diamond crystals have been found to have the diamond(111)/AlN(0001) interface relationship. Atomistic models of the bonding mechanism at the heterointerface are used to elucidate experimental observations and the role of hydrogen plasma on the growth of diamond on AlN. Nonpolar and semipolar AlN surfaces have been found to have higher resistance to process plasma and led to better crystallinity of the diamond/AlN heterointerfaces. These results underline the potential of nonpolar and semipolar AlN surfaces for the growth of high-crystal quality diamond/AlN heterointerfaces.
Hosta-Rigau, L, Shimoni, O, Stadler, BM & Caruso, F 2013, 'Advanced Subcompartmentalized Microreactors: Polymer Hydrogel Carriers Encapsulating Polymer Hydrogel Capsules and Liposomes', Small, vol. 9, no. 21, pp. 3573-3583.View/Download from: UTS OPUS or Publisher's site
The design of compartmentalized carriers for advanced drug delivery systems or artificial cells and organelles is of interest for biomedical applications. Herein, a polymer carrier microreactor that contains two different classes of subcompartments, multilayered polymer capsules and liposomes, is presented. 50 nm-diameter liposomes and 300 nm-diameter polymer capsules are encapsulated into a larger polymer carrier capsule, demonstrating control over the spatial positioning of the subcompartments, which are either `membrane-associated or 'free-floating in the aqueous interior. Selective and spatially dependent degradation of the 300 nm-diameter subcompartments (without destroying the structural integrity of the enzyme-loaded liposomes) is also shown, by performing an encapsulated enzymatic reaction using the liposomal subcompartments. These findings cover several important aspects toward the development of engineered compartmentalized carrier vessels for the creation of artificial cell mimics or advanced therapeutic delivery systems.
Particle shape is emerging as a key design parameter for tailoring the interactions between particles and cells. Herein, we report the preparation of rod-shaped layer-by-layer (LbL)-assembled polymer hydrogel capsules with tunable aspect ratios (ARs). By templating spherical and rodlike silica particles, disulfide-stabilized poly(methacrylic acid) hydrogel capsules (PMA HCs) with different ARs (from 1 to 4) are generated. The influence of capsule AR on cellular internalization and intracellular fate was quantitatively investigated by flow cytometry, imaging flow cytometry, and fluorescence deconvolution microscopy. These experiments reveal that the cellular internalization kinetics of PMA HCs are dependent on the AR, with spherical capsules being internalized more rapidly and to a greater extent compared with rod-shaped capsules. In contrast, the capsules with different ARs are colocalized with the lysosomal marker LAMP1, suggesting that the lysosomal compartmentalization is independent of shape for these soft polymer capsules.
Shimoni, O, Postma, A, Yan, Y, Scott, AM, Heath, JK, Nice, EC, Zelikin, AN & Caruso, F 2012, 'Macromolecule Functionalization of Disulfide-Bonded Polymer Hydrogel Capsules and Cancer Cell Targeting', ACS Nano, vol. 6, no. 2, pp. 1463-1472.View/Download from: UTS OPUS or Publisher's site
We present a generic and versatile method for functionalization of disulfide-stabilized PMA hydrogel capsules (HCs) with macromolecules, including a number of specific antibodies to cancer cells. Functionalization was achieved by reversible additionfragmentation chain transfer (RAFT) polymerization of poly(N-vinyl pyrrolidone) (PVPON), which introduced biorelevant heterotelechelic end groups (thiol and amine) to the polymer chain. The PVPON with heterotelechelic end groups was conjugated to the outermost layer of PMA HCs through the thiol groups and reacted with biotin via the amine groups to generate PMA/PVPONbiotin HCs. On the basis of the high specific interaction and high affinity between biotin and avidin, and its derivates, such as NeutrAvidin (NAv), we functionalized the PMA HCs with biotinylated antibodies. We demonstrate significantly enhanced cellular binding and internalization of the antibody (Ab)-functionalized capsules compared with control human immunoglobulin (IgG)-functionalized capsules, suggesting these capsules can specifically interact with cells through antibody/antigen recognition. We anticipate that the versatility of the functionalization approach reported in this study will assist in targeted therapeutic delivery applications.
Shimoni, O, Price, AD, Chong, S, Stadler, BM, Zelikin, AN & Caruso, F 2010, 'Subcompartmentalized Polymer Hydrogel Capsules with Selectively Degradable Carrier and Subunits', Small, vol. 6, no. 14, pp. 1558-1564.View/Download from: UTS OPUS or Publisher's site
Subcompartmentalized hydrogel capsules (SHCs) with selectively degradable carriers and subunits are designed for potential applications in drug delivery and microencapsulated biocatalysis. Thiolated poly(methacrylic acid) and poly(N-vinyl pyrrolidone) are used to assemble 3-µm-diameter carrier capsules and 300-nm-diameter subunits, independently stabilized by a diverse range of covalent linkages. This paper presents examples of SHCs with tens of subcompartments and their successful drug loading, as well as selective degradation of the SHC carrier and/or subunits in response to multiple chemical stimuli.
Shimoni, O & Silverstein, MS 2007, 'Porous Poly(2-hydroxyethyl methacrylate) Hydrogels Synthesized within High Internal Phase Emulsions', Soft Matter, vol. 2, pp. 1525-1529.View/Download from: Publisher's site
Hydrogels, such as those based on poly(2-hydroxyethyl methacrylate) (PHEMA), are hydrophilic three dimensional network structures that undergo extensive swelling in water. PolyHIPEs are highly porous, crosslinked polymers typically synthesized within high internal phase emulsions (HIPEs). This research describes materials with enhanced water absorption that combine hydrogel water absorption with capillary action by synthesizing PHEMA-based polyHIPEs within oil-in-water HIPEs. The variation in the N,N-methylenebisacrylamide (MBAM) crosslinking comonomer content yields a narrow synthesis window in which water-swollen micro-gel particles phase separate, agglomerate, and form a heterogeneous polyHIPE wall structure with nanoscale porosity. Surprisingly, a hydrogel polyHIPE with a relatively high MBAM content also had the highest surface area and the highest water absorption. Ultimately, it is the influence of the MBAM content on the polymer hydrophilicity and on the porous structure that determines its effects on the properties.
Elbadawi, C, Tran, TT, Shimoni, O, Totonjian, D, Lobo, CJ, Grosso, G, Moon, H, Englund, DR, Ford, MJ, Aharonovich, I & Toth, M 2016, 'Ultra-bright emission from hexagonal boron nitride defects as a new platform for bio-imaging and bio-labelling', Proceedings of SPIE - The International Society for Optical Engineering.View/Download from: UTS OPUS or Publisher's site
© 2016 SPIE. Bio-imaging requires robust ultra-bright probes without causing any toxicity to the cellular environment, maintain their stability and are chemically inert. In this work we present hexagonal boron nitride (hBN) nanoflakes which exhibit narrowband ultra-bright single photon emitters1. The emitters are optically stable at room temperature and under ambient environment. hBN has also been noted to be noncytotoxic and seen significant advances in functionalization with biomolecules2,3. We further demonstrate two methods of engineering this new range of extremely robust multicolour emitters across the visible and near infrared spectral ranges for large scale sensing and biolabeling applications.
Hong, J, Shimoni, O, Seo, DH, Aramesh, M, Prawer, S & Murphy, AB 2015, 'Plasma catalytic synthesis of ammonia using functionalized-nanodiamond coatings in an atmospheric-pressure non-equilibrium discharge', 22nd International Symposium on Plasma Chemistry, Antwerp, Belgium.
Shimoni, O, Aramesh, M, Ostrikov, K, Prawer, S & Cervenka, J 2015, 'Study of protein corona formation on nanodiamonds'.
Silverstein, MS, Gitli, T & Kulygin, O 2008, 'POLY 190-Continuous and bicontinuous porous hydrogel systems through emulsion templating', ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY.
Silverstein, MS, Gitli, T & Shimoni, O 2008, 'CONTINUOUS AND BICONTINUOUS POROUS HYDROGEL SYSTEMS THROUGH EMULSION TEMPLATING', Polymer Preprints, The 236th ACS National Meeting, ACS Publications, Philadelphia, PA, USA, pp. 1041-1041.
Hydrogel systems synthesized within high internal phase emulsions (HIPE) could be of interest for drug delivery and tissue engineering applications. Continuous porous hydrogels based on poly(2-hydroxyethyl methacrylate) (PHEMA) were synthesized within the continuous phase of HIPE. The combination of polyHIPE capillary action and stronger hydrogen bonding through copolymerization with N,N-methylenebisacrylamide (MBAM) produced a significant enhancement in water absorption. The polyHIPE with a 75/25 HEMA/MBAM molar ratio had a relatively high surface area, a relatively high tan d peak temperature, a relatively low modulus, and absorbed 800% of its weight in water. Bicontinuous systems consisting of polyacrylamide-based hydrogels in the internal phase and hydrophobic polymers in the external phase were also synthesized within HIPE. Although the external phase remained unchanged, the modulus of the bicontinuous polyHIPE decreased with increasing acrylamide content in the internal phase, indicating that the polymerization reactions were not mutually exclusive.