Diamond coating Carbon Fibre
Carbon fibre is now wearing some flashy new jewellery, thanks to a team of Victorian scientists.
They’ve coated carbon fibre with diamond, enhancing the material’s usability in medical and sensor applications where the composite material offers huge potential advantages.
Microelectrodes are important in bioelectronic medicine for the treatment of a variety of debilitating conditions. They can often eliminate the need for drugs and, in the process, spare patients unwanted side effects. Treatable conditions include epilepsy, autoimmune and Parkinson’s disease and migraines.
Unfortunately, the materials currently used for fabrication of microelectrodes, such as noble metals or silicon, have a much higher density than human tissue, which is thought to produce scarring and reduce their long-term efficiency.
A team of researchers from CSIRO Manufacturing, Deakin University, Melbourne University and the Melbourne Centre for Nanofabrication (MCN), hope to solve this problem by combining two exceptional materials, carbon fibre and diamond that, used together, may possess the desired properties.
Carbon fibre has been exciting medical circles due to its small diameter (<10μm) and ability to act as a light-weight, conductive filament; but in practice it typically has to be insulated in bulky glass capillaries in order to be useful. To try and solve this, the team began attempting to coat the fibres with microcrystalline diamond to form a thin, insulating and biocompatible sheath.
The difficulty is that growing diamond requires harsh conditions that can easily damage the carbon fibres. Through careful tuning of the diamond seeding – an early stage process in which nanodiamond “seeds” are ultrasonically embedded in the fibre surface – and deposition conditions, the team has managed to achieve uniform diamond coatings that leave the carbon fibre intact.
“The project relied heavily on the diamond coating facilities and expertise of Dr Lachlan Hyde and Dr Alastair Stacey at MCN,” said Dr Kallista Sears, a CSIRO researcher and project leader. “I’ve been impressed by MCN staff, who have become an integral part of this project.” Both Kallista and Dr Julius Orwa, a Deakin University researcher on the project, received training on MCN’s diamond coating suite.
After coating, cross sections of the composite fibres were examined using MCN’s focused ion beam system in order to show that the carbon filaments were still intact.
"This has been an extremely rewarding project and these new micro-electrodes have real potential to improve neuroscience research and people’s lives with debilitating neurological conditions,” Kallista said. “One of the best aspects of this project has been to work with such a stimulating group of interdisciplinary scientists and leaders in their fields.”
The next step is to further optimise the process and benchmark the diamond- coated carbon fibres for their performance as microelectrodes. “This will require further involvement with ANFF-Vic staff and use of their world-class diamond coating facilities,” Julius added.
Exploring gold nanowires and nanorods
Professor Wenlong Cheng from Monash University has been exploring unique properties of gold nanomaterials for over 16 years. Two recent projects, conducted at ANFF-Vic’s Melbourne Centre for Nanofabrication (MCN), involved gold nanorods and gold nanowires.
Stretchable, conductive materials are driving the capabilities of tomorrow’s soft and wearable technologies.
Wearables may hold the key to accurate and comfortable health monitoring and movement detection. There’s also the potential for a range of intuitive human/machine interfaces to be created that could ultimately enable implantable biomedical devices.
Wenlong and a team of researchers from Monash University have been making a range of flexible sensors by coating elastic materials with interwoven networks of conductive ultra-thin gold nanowires (UGNWs). According to Wenlong, the UGNWs are the world’s thinnest gold nanowires at only 2nm wide — a DNA double helix, by comparison, is just over 2nm in width.
The elastic substrates that the UGNWs are grafted onto are flexible and biologically safe, making them ideal candidates for wearable electronics.
Researchers worked at MCN to create wearable pressure sensors, skin-attachable strain sensors, flexible transparent electrodes and stretchable supercapacitors.
To create a sensor, UGNWs are grown via a solvent-based chemical process that yields a host of hair- like ultra-thin fibres. Once in a liquid suspension, the wires are “painted” onto the elastic material, forming
an interwoven mesh of electrically conductive fibres once the paint dries. When the UGNW-coated elastic
is stretched, the device’s electrical resistance changes too, providing
a real-time and reversible electrical representation of the sensor’s state.
Wenlong exploits these changing properties to detect and monitor movement with an incredibly high degree of precision. His devices offer touch sensitivity and can pick up the tiny forces associated with artery wrist pulses.
“They are able to resolve pressing, stretching, bending, and torsion
forces as well as acoustic vibrations,” Wenlong said. The team’s devices are cheap to manufacture and attachable to almost any surface, allowing accurate measuring of skin or muscle deformation anytime, anywhere.
In the health sector, for example, increased sensitivity of these devices could reveal previously undetected heart defects or be used to monitor detailed hand movements in robotic infrastructure such as advanced prosthetics.
At present, the vast majority of cancer treatments work by attacking cancer cells but often affect healthy tissue in the process. The approach, whilst effective, produces a large number of side effects including irreparable and extensive tissue damage, hair loss and nausea, among others.
There has therefore been a great deal of effort devoted to improving the selectivity of cancer therapies in order to minimise collateral damage. Increasingly, the idea is to hunt with a sniper rifle, rather than a shotgun.
Wenlong and his colleagues have gone a step further and developed what is effectively a guided missile that exclusively binds to target tumours before heating defective tissue to the point of destruction. Advancing a treatment called photothermal therapy, the method uses gold nanorods (GNRs) – shorter, wider versions of gold nanowires – which rapidly heat up to 45°C when irradiated by near-infrared (NIR) light.
To specifically target the cancerous cells, the GNRs are coated with DNA-specific aptamers that Wenlong selected to identify DNA unique to
the tumour cells. Aptamers are single strands of DNA that bind selectively
to a complementary piece of genetic material. The theory is that once the aptamer binds to the target tumour cell, the GNR is heated with the NIR light and the cell is destroyed.
Wenlong and his team collaborated with a team led by Professor David Jans, NMHRC Senior Principal Research Fellow at Monash University to test the GNR-aptamer “missile” on breast ductal carcinoma cells residing in healthy tissue.
Wenlong’s team was able to observe the selectiveness and efficacy of this process using the MCN’s hyperspectral imaging capabilities. The initial results indicate that once the GNRs had been heated by NIR light, 96 per cent of tumour cells had been successfully targeted and 71 per cent of them were destroyed, with less than one per cent of healthy tissue affected.
Fighting resistance to antibiotics
Reconstructed 3D models of single, untreated bacteria (left) and treated with 2 mg/L polymyxin B (right).
Three bacterial cells reconstructed using FIB-SEM tomography.
As resistance to antibiotics becomes increasingly common, it is more important than ever to understand the mechanism by which antibiotics work on bacterial cells, and to develop new antibiotics which can be used against ‘super bugs.’
In order to understand the process by which potential combinations of antibiotics kill multi-drug resistant bacterial cells, a joint force from Monash Engineering (Mr. Boyin Liu and Dr. Jing Fu) and Monash Pharmaceutical Sciences (Professor Jian Li and Dr. Tony Velkov) together with the MCN, the Australian Synchrotron and the University of Queensland have been working on novel imaging approaches to assess the cellular responses of bacterial cells to the treatment of antibiotics, including the last-resort polymyxins.
The team has used the Focused Ion Beam (FIB) tool at MCN to mill away 25nm slices of a cell of resistant bacterial isolate (Klebsiella Pneumoniae) recently discovered in Queensland. After the removal of each slice, high-resolution scanning electron microscope images were taken and then reconstructed into a 3D model of a whole bacterial cell to reveal the effect of the antibiotic in different cellular regions.
The 3D models of both treated and untreated cells were reconstructed and compared. Their finding confirmed the invasion of polymyxin B on the cell envelope and the subsequent depletion of cytoplasmic materials. The results provided clear evidence for using rational antibiotic combinations to combat bacterial ‘superbugs.’
In the ongoing research, FIB is also being used to slice the bacterial cell to expose the interior surface, after which Atomic Force Microscopy (AFM) is employed to probe the intracellular changes and measure their mechanical properties. The investigators are also employing a single-molecule AFM tip functionalisation technique, Synchrotron imaging and secondary ion mass spectrometry to identify the chemical signatures due to antibiotic treatment. Their research is funded by the Australian NHMRC and the US National Institutes of Health (NIH).
You can read more about this project in In situ probing the interior of single bacterial cells at nanometer scale, published in IOP Science in September this year.
Cancer treatment to be delivered to lungs
Surface acoustic waves propagate along the surface of the nanofabricated Respire® device, leading to the atomisation of drug solutions into a fine mist suitable for inhalation.
A schematic of the SAW nebulisation mechanism which propagates along the substrate and leaks energy into the liquid film to nebulise the meniscus. Collection of the aerosolised DNA or antibodies is accomplished by placing the device within a conical tube.
In treating diseases such as lung cancer, tuberculosis, cystic fybrosis and asthma, a large range of intravenous drugs are directed at the lungs but inefficiently delivered. This has led to significant research into devices that can deliver drugs to the lungs effectively and efficiently. A device under investigation for the generation and delivery of aerosolised drugs is the Respire® system.
At present, many large drugs directed at the lung, including antibodies, are injected intravenously because of the lack of effective inhalation devices. The Respire® inhalation system would enable a portable way of delivering large macromolecular drugs straight to the lungs where they are needed, creating a high local concentration of active drug in the lung to improve patient outcomes.
MCN Technology Fellow, Christina Cortez Jugo from Monash University and colleagues from RMIT University are investigating the formation of inhalable droplets of clinically significant drugs including monoclonal antibodies for cancer therapy and asthma. Promising results show that these fragile drugs remain stable and active after atomisation, paving the way for further testing of their efficacy in treating disease.
The device, developed by Professors James Friend and Leslie Yeo, was fabricated at MCN using standard photolithography techniques. The technology is based on surface acoustic wave (SAW) atomisation. When power is supplied to the miniature device, waves akin to nano-earthquakes travel along the device causing the destabilisation and atomisation of liquid droplets in its path. A fine mist suitable for inhalation is formed.
The group atomised a solution of monoclonal antibodies targeted against the epidermal growth factor receptor, which is over-expressed in lung cancer. The stability, immunoactivity and function of the atomised antibodies were characterised using gel electrophoresis, confocal microscopy and flow cytometry. The results indicate that the Respire® system provides a feasible means of delivering active antibodies as a fine inhalable mist to the lung. Collaboration with Dr. Manuel Ferreira at the Queensland Institute for Medical Research is in place to test the device for the biodistribution and efficacy of the atomised antibodies.
In collaboration with Dr. Manuel Ferreira, the group will be undertaking biodistribution and efficacy studies of inhaled antibody formulations in mice. In addition to monoclonal antibodies, the Respire® system is also being investigated for the inhalable delivery of nanomedicinal formulations and nucleic acid drugs, including small interfering RNA or siRNA for gene silencing applications. Access to the capabilities and expertise at MCN will continue to be important to facilitate the ongoing and future work in this project.
You can read more about this project in Enabling practical surface acoustic wave nebuliser drug delivery via amplitude modulation, published in Lab on a Chip.
A pain-free solution to vaccines
A NanopatchTM placed on a finger to demonstrate its size and application
Vaccinations, though vital in preventing the spread of disease in the modern world, have several major drawbacks which limit their effectiveness and uptake in developing countries.
Professor Mark Kendall from the Australian Institute of Bioengineering and Nanotechnology, has spent the last ten years developing the NanopatchTM - a needle free solution to many of the problems facing vaccine use. A tiny square of microneedles coated in vaccine, the Nanopatch is simply placed on the skin and the vaccine dispersed into the immune system just below the skin.
Vaxxas Pty. Ltd., which was established to develop the NanopatchTM, engaged with MCN to increase the outputs of their trial patches. By providing Vaxxas with access to state-of-the-art development equipment and expertise, MCN has accelerated and improved the production of the NanopatchTM.
The NanopatchTM is manufactured using mono-crystalline silicon wafers which are subjected to deep-reactive ion etching (DRIE), the same proccess that is commonly used to fabricate components of smart phones and other microtechnology devices.
MCN has helped to fine tune the NanopatchTM production process so that the layers deposited on these wafers achieves better uniformity, increasing the output from each wafer. Furthermore, MCN has allowed Vaxxas to move from four inch wafers to six inch wafers, once again increasing the yield. MCN also hosts two DRIE systems which enables them to double their final outputs by processing wafers in parallel.
Eliminating the pain of traditional injections is just one small advantage of the NanopatchTM. As the vaccine is dry coated onto the patch, the need for refrigeration is eliminated. This vastly increases its stability and reduces cost barriers for transporting vaccines to where they are needed most in third world countries. The NanopatchTM has the capacity to transform the world’s disease landscape, and to stamp out illnesses in third world countries that have long been preventable in the developed world.
NB: The material for this case study has been provided by Vaxxas Pty. Ltd. Although care has been taken to ensure the accuracy and completeness of the information that is provided, the MCN assumes no responsibility in relation to the interpretation or use of this information.
More information can be found at www.vaxxas.com.au
Nano-engineered intelligent delivery systems
Data points plotted using data generated from Malvern Nanosizer ZS. (a) Hydrodynamic size distribution of PNIPAM and AuNP/PNIPAM as a result of Temperature Elevation and (b) Heat induced swelling of 12nm AuNP conjugated with PNIPAM.
One method proposed to fight multi-drug resistant bacteria is that of an intelligent delivery system which targets drugs at specific cells, minimising unwanted side effects from drug treatments. Researchers from Monash University, including MCN Technology Fellows Associate Professor Wenlong Cheng and Dr. Christina Cortez-Jugo are working on a project to develop a rational design of multi-materials composite particles for targeted, light-controllable drug delivery.
The team are looking to simulate an intelligent delivery system, whereby gold nanoparticles are incorporated with poly N-isopropylacrylamide (PNIPAM) to formulate an intelligent delivery vehicle to combat multidrug resistance.
Preliminary work suggests that gold nanoparticles could be successfully incorporated into PNIPAM particles using a rotating mixer without destroying the stimuli-responsive properties of PNIPAM. To observe this, the hydrodynamic diameters and zeta potentials of Au-PNIPAM nanoparticles were characterised under various temperatures using the Malven Nanosizer ZS at MCN. The results suggest that at a lower critical solution temperature, PNIPAM was not altered with the incorporation of gold nanoparticles which range in size from 3.5nm to 45nm. The size of the nanoparticles was confirmed via the use of the Field Emission Gun Scanning Electron Microscope.
All instruments and equipment used to formulate and characterise the Au-PNIPAM particles were located at MCN. The facilities provided by MCN in the Biochemistry and PC2 Laboratories allowed characterisations to be carried out to a greater depth and verification of the results achieved via imaging of the formulated particles. Further studies using the intelligent delivery vehicle for delivery of vaccine and drugs are forecast using MCN’s microarray system.
Safer surgeries with microbots
a) Photo of the micro-motor prototype showing the helically cut stainless steel ball as a rotor and the PZT element. b) Magnets were used to increase the friction coupling preload
The future is here - microrobots are making minimally invasive vascular surgery safer and more efficient.
Researchers at MCN have developed a 240μm-diameter ultrasonic micromotor capable of navigating through arteries deep inside the human body. The technology, developed by Professor James Friend of RMIT University, is designed to assist surgeons whilst performing minimally invasive vascular surgery (MIVS).
The ultrasonic micromotor comprises a 50μm-diameter stainless steel ball rotor mounted on a laser machined precision tube, prepared at the ANFF OptoFab node. The stainless steel ball is held in place using a magnetic payload generated from a permanent magnet, allowing it to make contact with the inner diameter of the tube. According to Professor Friend, the micro-sized motor generates rotational motion from a combination of orthogonal and longitudinal vibration modes. The drive’s input signals are provided via two 50μm diameter wires. The micromotor assembly is designed to be affixed to standard catheter tips, providing smooth navigation through vascular pathways.
This technology has several advantages over existing MIVS techniques that traditionally have a failure rate of up to 40%. The first major advantage is that the catheter guide wire is actively navigated using a motor, rather than being forcibly pushed through arterial passages. This is likely to result in a reduction in injury to vascular membranes. Further, complex cerebral events (such as an aneurism) have a time-sensitive treatment window. This technology allows medical specialists to locate and treat the cerebral event up to 20% faster than conventional MIVS procedures.
In addition, Professor Friend notes that modelling shows that up to 85% of 350μm cerebral arteries can be accessed easily with this novel micromotor because its tip size is less than 250μm. Combined with an additional 4 cm of reach, this technology provides opportunities for treatment well outside the scope previously available.
A simulated video can be viewed here.
Automated systems for cell transfection
(a) Image of RTCM created using the Nanoprint MicroArray System located at MCN. (b) Close-up of Array Spots. Protein vectors are tagged with GFP and appear green. HeLa Cell Nuclei are labelled with DAPI and appear blue. DNA is cy3 labelled and appears red.
Research areas that involve time consuming and repetitive processes may benefit by adopting new experimentation methods, which involve efficient screening. Incorporating nanosystems into these experiments can also provide useful insight into the interaction of nanomaterials within the biological environment, gene expression, targeted cell delivery and encapsulation.
Michael Nastasie, a researcher from Monash University is working in collaboration with MCN’s Varsha Lal to design a novel process capable of conducting a series of simultaneous nano-experiments within an automated array system. This will allow them to observe the transfection of numerous known DNA constructs into specific mammalian cell populations.
Transfection is the process of deliberately introducing nucleic acids into cells. Using the MCN’s MicroArray system, the team can perform transfection experiments simultaneously using the high throughput capabilities of the microarray system. According to Michael, “the microarray system available at the MCN will be crucial in the ability to simultaneously test numerous different transfection solutions, on a large variety of surfaces, under controlled humidified conditions, with minimal user interaction.” Since an array can contain tens of thousands of probes, the automation and concurrent nature accomplished by this MicroArray system drastically improves the efficiency of experimentation and accuracy of results and gives researchers the power to test large quantities of cells in concurrent experiments.
Liquitab, not a hard pill to swallow
The liquitab will potentially assist millions in taking their daily medications.
The days of taking costly liquid antibiotics will soon be over for people suffering dysphagia - discomfort when swallowing pills. Liquitab Systems Ltd. has engaged with MCN to develop a unique technology, capable of grinding pills into a palatable liquid
Utilising facilities at MCN, Liquitab have developed a unique technology capable of crushing and grinding commercially pressed-pill medications into a palatable liquid. The technology harnesses high frequency ultrasonic vibrations to grind pressed-pill medicines and is aimed at assisting those who have difficulty swallowing conventional tablets.
The Liquitab tablet-crushing technology involves the deformation of a metal ring embedded with a removable non-reactive cup. The pressed pill is placed into the cup and ground using the resonant frequency omitted by a transducer. The result is a powdered medication that can be mixed with water to assist with administration.
Professor James Friend applied his expertise and knowledge of ultrasonics to enhance performance of the device. According to Professor Friend, “Tweaking and refining the design of the connecting arm, and adjusting the resonant frequency omitted by the transducer,” produced a far more efficient delivery of ultrasonic vibration. Upon completion of the simulation, design and testing phases, the transition time from solid to tablet powder was reduced from 6 minutes to approximately 1 minute.
This collaboration was facilitated by Grey Innovation and further highlights how the STIUP program can facilitate innovation between industry and academia.
Nanoscale study of biological cells
SEM image of a single cell showing the FIB milled areas. The top row shows 1x1 μm2 areas milled at 5 kV, and the bottom row shows 1x1 μm2 areas milled at 30 kV.
Focused Ion Beam Scanning Electron Microscopes (FIB-SEM) are able to mill away at layers of a material in a very small, very uniform way. This is enabling the study of biological cells on a nanoscale as researchers at MCN and Monash University are utilising the FIB-SEM as well as protein nanoprobes to study protein assemblies and their place within cells. This project aims to find the optimum FIB milling conditions to mill away a very small, uniform thickness (10nm - 50nm) of a single biological cell. The ability to selectively remove such a thin, uniform layer from a single cell, coupled with protein nanoprobes, will be able to describe protein assemblies and their associated locations inside a cell, providing valuable information for drug delivery and targeted therapies.
As an initial stage, the team are characterising the FIB milling rate of a single biological cell at different beam conditions. Initial experimental results indicate that the FIB milling rate at 30kV is approximately 2μm3/nC, while the milling rate at 5kV is approximately 0.6 μm3/nC, indicating that it may be more suitable to use the FIB at 5kV for delicate milling of cells.
Further experiments are currently underway to validate initial findings and to characterise the cell morphology before and after FIB milling to determine the damage caused by the FIB milling process.