30 april 2018
Terahertz radiation could produce safe and effective medical images
Researchers from the University of Strathclyde and Capital Normal University in Beijing have developed a new form of terahertz (THz) radiation, which could enable medical images to be produced more safely than conventional X-rays.
In the article ‘High-energy coherent terahertz radiation emitted by wide-angle electron beams from a laser-wakefield accelerator’, published in the New Journal of Physics, the team explains how the radiation’s ability to carry ultra-high bandwidth communications enables it to detect molecules.
“This is an unprecedented efficiency at these THz energies,” said director of the Scottish Centre for the Application Plasma-based Accelerators, which initiated the project, Professor Dino Jaroszynski. “The increasing availability of intense THz sources will lead to completely new avenues in science and technology.”
THz radiation is far-infrared electromagnetic radiation with a frequency between 0.1 THz and 10 THz. The vibrational and rotational properties of the radiation enable it to identify hazardous substances, such as drugs.
Many biological macromolecules, such as DNA and proteins, experience movement at THz frequencies, and so would be most accurately documented using THz radiation. The radiation can also be used to observe semiconductors and nanostructures, and so is an important tool for developing new electro-mechanical devices, which could include medical implants.
THz can be generated in a number of ways, including driving photocurrents in semiconductor antennas, but its maximum power is restricted due to the potential for damage of optical materials. If plasma is used, however, this restriction is limited as it is already broken. Jaroszynski’s team was able to use the high-charge and low-energy electron bunches to efficiently transfer laser energy to an intense pulse of THz radiation.
“Since the charge of wide-angle beams increases linearly with laser intensity and plasma density, the energy of THz radiation will scale to milijoule-levels, which would make an intense source of THz radiation with peak powers in excess of GW, which is comparable with that of a far-infrared free-electron laser,” said Dr Enrico Brunetti of Strathclyde’s department of physics.
30 april 2018
Butterfly wings inspire eye implant for monitoring glaucoma
Engineers at the California Institute of Technology (Caltech) have developed a synthetic analogue coating for eye implants that makes them more effective and longer-lasting. The implant, which aims to improve the monitoring of intra-eye pressure in glaucoma patients, was coated by nanopillars that enable readings to be taken more easily from a handheld device.
These nanopillars were inspired by the structural properties of a longtail glasswing butterfly. Research by Caltech postdoctoral researcher Radwanul Hasan Siddique found that see-through sections of the wings are coated in tiny pillars, each about 100 nanometres in diameter and spaced about 150 nanometres apart.
Their size, and the way the pillars redirect the light, allows light to pass through regardless of the angle at which it hits the wings, making it clearer than if they were made of plain glass.
That redirection property, known as angle-independent antireflection, was applied to the eye implant previously developed by Caltech’s Hyuck Choo. Choo’s implant measures an increase in pressure inside the eye, which the leading theory suggests is the cause of glaucoma.
“Right now, eye pressure is typically measured just a couple times a year in a doctor’s office. Glaucoma patients need a way to measure their eye pressure easily and regularly,” said Choo, assistant professor of electrical engineering in the Division of Engineering and Applied Science.
The drum-shaped implant, measuring the width of a few strands of hair, is inserted into an eye and flexes its surface when pressure increases. That depth can then be measured by a handheld reader.
However, to get an accurate reading the handheld reader has to be held almost perfectly perpendicular to the surface of the implant. Choo applied the angle-insensitive property of the butterflies’ nanopillars to ensure that light would always pass perpendicularly through the implant and provide an accurate reading regardless of the reader’s position.
The research team created pillars approximately the same size and shape of those on a butterflies’ wings, made from silicon nitride. After experimenting with various configurations of size and placement of the pillars, the team was able to reduce the error in the implants’ readings threefold.
“The nanostructures unlock the potential of this implant, making it practical for glaucoma patients to test their own eye pressure every day,” said Choo.
The long-lasting, non-toxic and anti-biofouling properties of the pillars’ surfaces also make it difficult for cells to latch onto the implant and reduce their effectiveness. This longevity is possible because of the nanopillars’ hydrophilic properties, which cause the implant to become encased in a coating of water and therefore difficult for cells to gain a foothold.
“Cells attach to an implant by binding with proteins that are adhered to the implant’s surface. The water, however, prevents those proteins from establishing a strong connection on this surface,” said Caltech graduate Vinayak Narasimhan, who worked with Choo on the implant.
Early tests suggest that the nanopillar-equipped implant reduces such biofouling ten times more when compared to previous designs. The team plans to explore what other medical implants could benefit from their new nanostructures, which can be mass-produced inexpensively.
The research was published in Nature Nanotechnology.
30 april 2018
Broad Institute’s SHERLOCK to detect virus in blood
US-based researchers from Broad Institute have developed a technique that can be used to update the CRISPR-based SHERLOCK diagnostic platform to rapidly identify viruses directly in bodily fluids such as blood and saliva.
This HUDSON technique is intended to eliminate the need for a lab environment and trained personnel to extract nucleic acids from samples. It is intended to be useful during outbreaks and pandemics in regions lacking access to laboratories and medical staff.
HUDSON involves a rapid chemical and heat treatment of patient samples to inactivate some enzymes that degrade the genetic targets. When tested on saliva and blood serum, the combination of HUDSON and SHERLOCK demonstrated direct identification of Dengue virus. It also detected Zika virus particles in blood and urine samples.
Harvard graduate student and lead researcher Catherine Freije said: “With this new assay, a patient can give a single blood or urine sample, it can be analysed in just a few reactions to determine which virus it contains, and then that patient can get started on the right treatment.”
Researchers added a feature for SHERLOCK to differentiate related viral species and to identify clinically relevant mutations, including small variations in Zika virus that has been found in microcephaly.
Broad Institute member Pardis Sabeti said: “Rapid and sensitive tools are critical for diagnosing, surveilling and characterising an infection. We’ve taken the SHERLOCK technology and optimised it in the context of these very applied biological scenarios.”
The team is planning to test SHERLOCK in Nigeria, which recently suffered an unusual surge in Lassa fever. As this disease requires early intervention, an accurate and fast diagnosis is considered critical. Furthermore, they are developing a framework to enable easy access to the SHERLOCK platform during outbreaks.
30 April 2018
Ultrasound can enable non-invasive biopsy for brain tumours
US researchers have developed a technique that uses non-invasive focused ultrasound and microbubbles to detect brain tumour biomarkers in blood samples. The team from Washington University in St Louis (WUSTL) will offer the new approach as an alternative to existing invasive surgical biopsy. Focused ultrasound employs ultrasonic energy to target deep body tissues without incisions or radiation.
After focusing the ultrasound on the tumour, researchers inject microbubbles that travel through the bloodstream and pop after reaching the target, leading to tiny ruptures in the blood-brain barrier (BBB). This technique enables biomarkers from a brain tumour to pass through the BBB into the blood.
WUSTL School of Medicine radiation oncology assistant professor Hong Chen said: “Once the blood-brain barrier is open, physicians can deliver drugs to the brain tumour.
“Physicians can also collect the blood and detect the expression level of biomarkers in the patient. It enables them to perform molecular characterisations of the brain tumour from a blood draw and guide the choice of treatment for individual patients.”
The test is designed to look for a tumour-specific biomarker called messenger RNA (mRNA) in the blood, allowing diagnosis and then treatment of cancer. It is expected that the technique will allow personalised medicine, as well as long-term monitoring of brain cancer treatment response.
Chen added: “Meanwhile, variations within tumours pose a significant challenge to cancer biomarker research.
“Focused ultrasound can precisely target different locations of the tumour, thereby causing biomarkers to be released in a spatially localised manner and allow us to better understand the spatial variations of the tumour and develop better treatment.”
Researchers are also working towards integrating their technique with advanced genomic sequencing and bioinformatics for improved optimisation.
27 april 2018
Algorithm creates reliable sensory feedback for prosthetic arm users
Researchers at the University of Illinois have developed a control algorithm that regulates current so that prosthetic arm users can feel a steady sensation of touch, even if electrodes begin to peel off or sweat builds up.
University of Illinois MD/PhD student and lead author of a paper describing the sensory control module Aadeel Akhtar said: “We’re giving sensation back to someone who’s lost their hand. The idea is that we no longer want the prosthetic hand to feel like a tool, we want it to feel like an extension of the body.
“Commercial prosthetics don’t have good sensory feedback. This is a step toward getting reliable sensory feedback to users of prosthetics.”
Akhtar is also the founder and CEO of PSYONIC, a start-up company that specialises in developing low-cost bionic arms.
The nerve-stimulating prosthetic arm has sensors on the fingertips that can measure how much pressure the arm exerts so that a corresponding electrical signal can be felt on the skin. A light fingertip touch generates a light sensation whereas a hard push would have a stronger signal.
However, nerve stimulating prosthetics have been known to give users unreliable feedback due to ordinary wear causing electrodes to peel off which can lead to a build-up of electrical current on the remaining attached areas. This current build-up can give cause painful electric shocks. In addition, sweat can disrupt the connection between electrodes and skin, causing the user to feel less or no feedback.
The researchers aimed to provide a solution to these issues by creating a prosthetic with a reliable sensory experience. They created a controller that monitors the feedback the patient is experiencing and can automatically adjust the current level so that the user feels steady feedback, even when sweating or when the electrodes are 75% peeled off.
The controller was tested on two patient volunteers who performed tasks as the electrodes were progressively peeled back. It was found that the control module reduced the electrical current so that the patients reported steady feedback without shocks. The patients also performed a series of everyday tasks that could cause loss of sensation due to sweat such as climbing stairs, hammering a nail into a board and running on an elliptical machine.
Akhtar said: “What we found is that when we didn’t use our controller, the users couldn’t feel the sensation any more by the end of the activity. However, when we had the control algorithm on, after the activity they said they could still feel the sensation just fine.”
He added: “Although we don’t know yet the exact breakdown of costs, our goal is to have it be completely covered by insurance at no out-of-pocket costs to users.”
The researchers are working on miniaturising the electrical feedback component so that it fits inside a prosthetic arm rather than attaching to the outside. They also plan to do more extensive patient testing with a larger group of participants who would be able to take the prosthetic arms back home to test daily living activities.
27 april 2018
Breath and urine test helps diagnose breast cancer early
Israeli researchers have combined commercially existing, inexpensive breath and urines tests to accurately detect biomarkers of breast cancer in early stages.
The team from Ben-Gurion University of the Negev and Soroka University Medical Center used two different electronic nose (e-nose) gas sensors to analyse breath and gas-chromatography mass spectrometry (GC-MS) for quantification of substances in urine.
While the e-nose demonstrated an average of 95% accuracy in detecting unique breath patterns in breast cancer patients, a revamped GC-MS had 85% average accuracy for statistical analyses of urine samples.
Ben-Gurion University Biomedical Engineering department professor Yehuda Zeiri said: “Breast cancer survival is strongly tied to the sensitivity of tumour detection; accurate methods for detecting smaller, earlier tumours remain a priority.
“Our new approach utilising urine and exhaled breath samples, analysed with inexpensive, commercially available processes, is non-invasive, accessible and may be easily implemented in a variety of settings.”
Current approaches for the diagnosis of breast cancer are said to have significant drawbacks such as more radiation exposure with dual-energy digital mammography, and invasive biopsies.
Even though mammography screenings were found to significantly decrease breast cancer related mortality rates, they are limited due to an incapability to identify small tumours in dense breast tissue.
Zeiri added: “We’ve now shown that inexpensive, commercial electronic noses are sufficient for classifying cancer patients at early stages. With further study, it may also be possible to analyse exhaled breath and urine samples to identify other cancer types, as well.”
26 April 2018
World’s smallest optical implant controls brain patterns
Researchers at the Nara Institute of Science and Technology (NAIST) have developed a tiny implantable device that can be used to control brain patterns.
The implant, which is the same size as the width of a coin, works by converting infrared light into blue light to control neural activity. It is both the smallest and the lightest wireless optical biodevice to ever be reported.
Light can activate certain proteins in the brain to change brain patterns. Scientists have previously implanted optical devices in mouse models to control behaviour with nothing more than light of specific wavelengths as a stimulus. However, the devices used in these previous experiments are often bulky and can cause discomfort and distress.
NAIST associate professor Takashi Tokuda has been investigating ways to tackle this problem by miniaturising implantable optical devices. He describes his creation as ‘the world’s smallest wireless optical neural stimulator’.
Miniaturising implantable devices has been hindered by a dependency on electromagnetics. Both voltage and current decrease with a reduction in size. However, the voltage of a device dependent on photovoltaics is not affected by size.
Tokuda and his research team built used this property to create their device, which uses a complementary metal-oxide semiconductor that controls photovoltaic power.
He said: “We integrated two sets of photovoltaic cells onto semiconductor chips. Ten cells were integrated for powering, and seven cells for biasing.”
The device contains an InGaN LED chip, which causes it to emit blue light. However, it can be activated with infrared light, which is used in many light therapies because it penetrates deep into the body, unlike blue light which remains at the surface. The infrared feature means that the device can be implant several centimetres into the body. The researchers acknowledge that the device will need to be modified before it reaches full potential.
Tokuda said: “The device can be applied only for pulse stimulations and requires a charge time for each stimulation. Most optogenetics use multiple pulses. We need to improve the power receiving and conversion efficiency.”
26 April 2018
3D-printed dentures release medicine to prevent infections
Researchers from the University of Buffalo have used 3D printing to construct dentures that are filled with microscopic capsules that release antifungal medication Amphotericin B.
In the study ‘Functionalised prosthetic interfaces using 3D printing: Generating infection-neutralising prosthesis in dentistry’, published in the journal Materials Today Communications, the scientists describe how they repurposed poly(methyl methacrylate), a commonly-used dental polymer, for 3D printing. The polymer contains polycaprolactone microspheres that release Amphotericin B.
“The major impact of this innovative 3D printing system is its potential impact on saving cost and time,” said assistant professor in the university’s department of oral biology and senior author of the study Praveen Arany.
“The antifungal application could prove invaluable among those highly susceptible to infection, such as the elderly, hospitalised or disabled patients.”
The team printed the dentures with acrylamide, a chemical compound that resembles a white crystalline solid and decomposes in the presence of acids. The dentures were then bent over a flexural strength testing machine to measure their breaking point; while the 3D printed dentures were recorded as having a flexural strength 35% lower than that of conventional dentures, they did not break.
The scientists then tested the ability of the dentures to release Amphotericin B. The teeth were tested with one, five and ten layers of the medication, to see if more could be held within the teeth without impeding its ability to be released. The researchers found that sets of teeth with five and ten layers were impermeable, preventing the medicine from being released, but that Amphotericin B was easily released by dentures with a single porous layer.
The technique could enable dentists to produce dentures faster than using conventional manufacturing, and the team intends to further refine the technology by strengthening the dentures with glass fibres and carbon nanotubes. The technology could also potentially be used for other clinical therapies, such as splints and casts.