Monthly Archives: December 2019
An emerging technology involving tiny particles that absorb light and turn it into localized heat sources shows great promise in several fields, including medicine. For example, photothermal therapy, a new type of cancer treatment, involves aiming infrared laser light onto nanoparticles near the treatment site. Localized heating in these systems must be carefully controlled since living tissue is delicate. Serious burns and tissue damage can result if unwanted heating occurs in the wrong place. The ability to monitor temperature increases is crucial in developing this technology. Several approaches have been tried, but all of them have drawbacks of various kinds, including the need to insert probes or inject additional materials.
In this week’s issue of APL Photonics,, scientists report the development of a new method to measure temperatures in these systems using a form of light known as terahertz radiation. The study involved suspensions of gold nanorods of various sizes in water in small cuvettes, which were illuminated by a laser focused on a small spot within the cuvette. The tiny gold rods absorbed the laser light and converted it to heat that spread through the water by convection.
“We are able to map out the temperature distribution by scanning the cuvette with terahertz radiation, producing a thermal image,” co-author Junliang Dong said.
The study also looked at the way the temperature varied over time. “Using a mathematical model, we are able to calculate the efficiency by which the gold nanorod suspensions converted infrared light to heat,” said co-author Holger Breitenborn.
The smallest gold particles, which had a diameter of 10 nanometers, converted laser light to heat with the highest efficiency, approximately 90%. This value is similar to previous reports for these gold particles, indicating the measurements using terahertz radiation were accurate. Although the smaller gold rods had the highest light-to-heat conversion efficiency, the largest rods — those with a diameter of 50 nanometers — displayed the largest molar heating rate. This quantity has been recently introduced to help evaluate the use of nanoparticles in biomedical settings.
“By combining measurements of temperature transients in time and thermal images in space at terahertz frequencies, we have developed a noncontact and noninvasive technique for characterizing these nanoparticles,” co-author Roberto Morandotti said. This work offers an appealing alternative to invasive methods and holds promise for biomedical applications.
Russia’s first regiment of Avangard hypersonic missiles has been put into service, the defence ministry says. The location was not given, although officials had earlier indicated they would be deployed in the Urals. President Vladimir Putin has said the nuclear-capable missiles can travel more than 20 times the speed of sound and put Russia ahead of other nations. They have a “glide system” that affords great manoeuvrability and could make them impossible to defend against.
Defence Minister Sergei Shoigu confirmed the “Avangard hypersonic glide vehicle entered service at 10:00 Moscow time on 27 December“, calling it a “landmark“. Mr Putin said on Tuesday the Avangard system could penetrate current and future missile defence systems, adding: “Not a single country possesses hypersonic weapons, let alone continental-range hypersonic weapons.”
The West and other nations were “playing catch-up with us“, he said. Mr Putin unveiled the Avangard and other weapons systems in his annual state-of-the-nation address in March 2018, likening it to a “meteorite” and a “fireball“. In December 2018, the weapon hit a practice target 6,000km (3,700 miles) away in a test launch at Dombarovskiy missile base in the southern Ural Mountains.
“The Avangard is invulnerable to intercept by any existing and prospective missile defence means of the potential adversary,” Mr Putin said after the test.
Mounted on top of an intercontinental ballistic missile, the Avangard can carry a nuclear weapon of up to two megatons. Russia’s defence ministry has released video of the Avangard system, but weapons experts have expressed scepticism about its effectiveness.
In a statement, the Pentagon said it would “not characterise the Russian claims” about the Avangard‘s capabilities. The US has its own hypersonic missile programme, as does China, which in 2014 said it had conducted a test flight of such as weapon.
A Japanese firm is poised to carry out what it hailed as the world’s first experiment to test for cancer using urine samples, which would greatly facilitate screening for the deadly disease. Engineering and IT conglomerate Hitachi developed the basic technology to detect breast or colon cancer from urine samples two years ago. It will now begin testing the method using some 250 urine samples, to see if samples at room temperature are suitable for analysis, Hitachi spokesman Chiharu Odaira told AFP.
“If this method is put to practical use, it will be a lot easier for people to get a cancer test, as there will be no need to go to a medical organisation for a blood test,” he said. It is also intended to be used to detect paediatric cancers.
“That will be especially beneficial in testing for small children” who are often afraid of needles,” added Odaira. Research published earlier this year demonstrated that a new blood test has shown promise towards detecting eight different kinds of tumours before they spread elsewhere in the body.
Usual diagnostic methods for breast cancer consist of a mammogram followed by a biopsy if a risk is detected. For colon cancer, screening is generally conducted via a stool test and a colonoscopy for patients at high risk. The Hitachi technology centres around detecting waste materials inside urine samples that act as a “biomarker“—a naturally occurring substance by which a particular disease can be identified, the company said in a statement.
The procedure aims to improve the early detection of cancer, saving lives and reducing the medical and social cost to the country, Odaira explained.
The experiment is now completed in cooperation with Nagoya University in central Japan. “We aim to put the technology in use in the 2020s, although this depends on various things such as getting approval from the authorities,” Odaira said.
Doctors have been treating the symptoms of most diseases, and not the source, for centuries. They have cut out tumors, unclogged arteries, injected insulin and soothed fevers—and have been unable to touch the biological code within cells that tells them to grow malignantly, pass along abnormal nerve signals, take in too much or too little energy, and swell with inflammation. The code is the DNA molecule in each cell that tells it what to do and when, and it triggers dreaded diseases when it goes wrong. The molecule, and its messengers, had remained tucked away, beyond the reach of almost all drugs, unfixable when broken. But as this special report explains, that is no longer the case.
Things began to change after the DNA sequence for the entire human genome was laid out early in this century, and within the past several years the ability to synthesize and custom-design shorter sequences has shown scientists that the best substance for reaching DNA is, well, DNA. Fabricating new genes to replace badly working versions, or to “silence” them, has produced 14 approved DNA-related drugs. And the latest research indicates that such therapies can be even more effective if scientists depart from the basic linear strands and instead make DNA spheres, which have enhanced abilities to enter cells. DNA analysis has also yielded new targets, showing that although newborn babies in the U.S. are typically screened for between 30 and 60 genetic conditions right now, it is possible to and nearly 1,000 genes linked to childhood diseases that could be new treatment points.
But that same science has also created troubling issues: some of the gene tests for infants can raise false alarms, for instance, and not every child with a disease-associated gene ends up getting that disease. Research has also revealed unfair bias in DNA targets. Most of the data about those sequences comes from studies of white people and has missed gene variants that cause disease in nonwhites—inequality in research that will produce inequality in health if it isn’t fixed. Geneticists are starting projects designed to improve this diversity level. DNA in medicine has great power, and that power should be used for the many, not the few.
If any swine is fit to be an organ donor for people, then the dozens of pigs snuffling around Qihan Bio’s facility in Hangzhou, China, may be the best candidates so far. The Chinese company and its U.S. collaborators reported today that they have used the genome editor CRISPR to create the most extensively genetically engineered pigs to date—animals whose tissues, the researchers say, finally combine all the features necessary for a safe and successful transplant into humans.
“This is the first prototype,” says Luhan Yang, a geneticist at Qihan Bio. In a preprint published today on bioRxiv, Qihan researchers and collaborators, including Cambridge, Massachusetts–based eGenesis—which Yang co-founded with Harvard University geneticist George Church—described the new generation of animals and various tests on their cells; the researchers have already begun to transplant the pigs’ organs into nonhuman primates, a key step toward human trials.
Qihan and eGenesis aren’t alone in their quest. Several academic and commercial research groups are racing to make up a shortage of life-saving human organs with the comparably sized hearts, kidneys, and livers of pigs. For these cross-species transplants, also known as xenotransplants, the pig’s genome must be re-engineered so that its organs will get along with the new host body. Pigs produce species-specific molecules that set off the human immune system, prompting rejection. Their tissue can also cause abnormal clotting and bleeding when it interacts with human blood. And the pig genome is littered with DNA sequences from viruses that infected the animals long ago and slipped genes into their chromosomes. These sequences, known as porcine endogenous retroviruses (PERVs), have been shown to produce potentially infectious viral particles, though their risk to humans is unclear.
The trouble with encryption is that everyone needs it, and every threat actor wants to break it. Thankfully, current cryptographic techniques are still at least one step ahead of the cracking curve. That could, scientists say, all change in the not too distant future as quantum computers enter the encryption battlefield. But what if there were a method of enabling data to be sent using an “absolutely unbreakable” one-time communication technique? What if that technique could achieve perfect secrecy cryptography via correlated mixing of chaotic waves in an irreversible time-varying silicon chip?
A team of scientists claims that’s exactly what it has done, developing a prototype silicon chip that uses the laws of nature, including chaos theory. With no software or code to manipulate, traditional methods of cracking computer encryption are irrelevant, the scientists claim. What’s more, it is also claimed to overcome the threat of quantum computers and can do so using existing communication networks.
An international collaboration of researchers from the School of Physics and Astronomy at University of St Andrews, King Abdullah University of Science and Technology (KAUST) and the Center for Unconventional Processes of Sciences (CUP Sciences) has today published a paper to demonstrate perfect secrecy cryptography in classical optical channels.
“With the advent of more powerful and quantum computers, all current encryptions will be broken in a very short time,” Dr. Andrea Fratalocchi, Associate Professor of Electrical Engineering at KAUST and leader of the study, said, “exposing the privacy of our present and, more importantly, past communications.”
The prototype chip the scientists have developed uses the classical laws of physics, including chaos theory and the second law of thermodynamics, to achieve “perfect secrecy.” The cryptographic keys generated by the chip, which are used to unlock each message, are never stored and are not communicated with the message. It exploits correlated chaotic wavepackets, mixed in inexpensive and CMOS compatible silicon chips. All of which start life as digital human fingerprint images that are transformed into a “chaotic microresonator.” It is claimed that even facing an attacker with “unlimited” technological power, even if they could access the system and copy the chips, would be unable to break the encryption because it is protected by the second law of thermodynamics and the “exponential sensitivity of chaos.”
“This system is the practical solution the cybersecurity sector has been waiting for since the perfect secrecy theoretical proof in 1917 by Gilbert Vernam,” Dr. Al Cruz, founder of the Center for Unconventional Processes of Sciences (CUP Sciences) in California, and co-author of the study said.
China is about to start operation on its “artificial sun“—a nuclear fusion device that produces energy by replicating the reactions that take place at the center of the sun. If successful, the device could edge scientists closer to achieving the ultimate goal of nuclear fusion: near limitless, cheap clean energy.
The device, called HL-2M Tokamak, is part of the nation’s Experimental Advanced Superconducting Tokamak project, which has been running since 2006. In March, an official from the China National Nuclear Corporation announced it would complete building HL-2M by the end of the year.
The coil system was installed in June and since then, work on HL-2M has gone “smoothly,” the Xinhua News Agency reported in November.
Duan Xuru, head of the Southwestern Institute of Physics, which is part of the corporation, announced the device will become operational in 2020 at the 2019 China Fusion Energy Conference, the state news agency said. He told attendees how the new device will achieve temperatures of over 200 million degrees Celsius. That’s about 13 times hotter than the center of the sun. Previous devices developed for the artificial sun experiment reached 100 million degrees Celsius, a breakthrough that was announced in November last year.
Nuclear fusion is the reaction that powers the sun. It involves fusing two lighter atomic nuclei to form a heavier nucleus—a reaction that releases a huge amount of energy. On the sun, where core temperatures reach about 15 million degrees Celsius, hydrogen nuclei combine to form helium.
To recreate this on Earth, scientists must heat the fuel—types of hydrogen—to temperatures over 100 million degrees Celsius. At this point, the fuel becomes a plasma. This extremely hot plasma must be confined and one method scientists have been developing is a donut shaped device called a tokamak. This uses magnetic fields to try to stabilize the plasma so reactions can take place and energy be released. However, plasma is prone to producing bursts. If these touch the reactor wall it can damage the device.
Using human blood cells, Brazilian researchers have succeeded in obtaining hepatic organoids (“mini-livers”) that perform all of the liver’s typical functions, such as producing vital proteins, storing vitamins, and secreting bile, among many others. The innovation permits the production of hepatic tissue in the laboratory in only 90 days and may in the future become an alternative to organ transplantation.
The study was conducted at the Human Genome and Stem Cell Research Center (HUG-CELL). Hosted by the University of São Paulo (USP), HUG-CELL is one of the Research, Innovation and Dissemination Centers (RIDCs) funded by FAPESP.
This study combined bioengineering techniques, such as cell reprogramming and the cultivation of pluripotent stem cells, with 3D bioprinting. Thanks to this strategy, the tissue produced by the bioprinter maintained hepatic functions for longer than reported by other groups in previous studies.
“More stages have yet to be achieved until we obtain a complete organ, but we’re on the right track to highly promising results. In the very near future, instead of waiting for an organ transplant, it may be possible to take cells from the patient and reprogram them to make a new liver in the laboratory. Another important advantage is zero probability of rejection, given that the cells come from the patient,” said Mayana Zatz, director of HUG-CELL and last author of the article published in Biofabrication.
The innovative part of the study resided in how the cells were included in the bioink used to produce tissue in the 3D printer. “Instead of printing individualized cells, we developed a method of grouping them before printing. These ‘clumps’ of cells, or spheroids, are what constitute the tissue and maintain its functionality much longer,” said Ernesto Goulart, a postdoctoral fellow in USP’s Institute of Biosciences and first author of the article. The researchers thereby avoided a problem faced by most human tissue bioprinting techniques, namely, the gradual loss of contact among cells and hence loss of tissue functionality.
Spheroid formation in this study already occurred in the differentiation process, when pluripotent cells were transformed into hepatic tissue cells (hepatocytes, vascular cells, and mesenchymal cells). “We started the differentiation process with the cells already grouped together. They were cultured in agitation, and groups formed spontaneously,” Goulart told Agência FAPESP.
According to the researchers, the complete process from collection of the patient’s blood to functional tissue production takes approximately 90 days and can be divided into three stages: differentiation, printing, and maturation.
In this study, researchers developed mini-livers using blood cells from three volunteers as raw material and compared markers relating to functionality, such as the maintenance of cell contact and protein production and release. “Our spheroids worked much better than those obtained from single-cell dispersion. As expected, during maturation, the markers of hepatic function were not reduced,” Goulart said. Although the study was limited to producing miniature livers, the technique can be used in the future to produce complete organs suitable for transplantation, according to Goulart. “We did it on a small scale, but with investment and interest, it can easily be scaled up,” he said.
The article can be retrieved from iopscience.iop.org/.
Researchers at McMaster (Canada) have solved a vexing problem by engineering surface coatings that can repel everything, such as bacteria, viruses and living cells, but can be modified to permit beneficial exceptions. The discovery holds significant promise for medical and other applications, making it possible for implants such as vascular grafts, replacement heart valves and artificial joints to bond to the body without risk of infection or blood clotting. The new nanotechnology has the potential to greatly reduce false positives and negatives in medical tests by eliminating interference from non-target elements in blood and urine.
The research adds significant utility to completely repellent surfaces that have existed since 2011. Those surface coatings are useful for waterproofing phones and windshields, and repelling bacteria from food-preparation areas, for example, but have offered limited utility in medical applications where specific beneficial binding is required
“It was a huge achievement to have completely repellent surfaces, but to maximize the benefits of such surfaces, we needed to create a selective door that would allow beneficial elements to bond with those surfaces,” explains Tohid Didar of McMaster’s Department of Mechanical Engineering and School of Biomedical Engineering, the senior author of a paper that appears today in the journal ACS Nano.
In the case of a synthetic heart valve, for example, a repellent coating can prevent blood cells from sticking and forming clots, making it much safer.
“A coating that repels blood cells could potentially eliminate the need for medicines such as warfarin that are used after implants to cut the risk of clots,” says co-author , a McMaster PhD student in Biomedical Engineering. Still, she explains, a completely repellent coating also prevents the body from integrating the new valve into the tissue of the heart itself.
By designing the surface to permit adhesion only with heart tissue cells, the researchers are making it possible for the body to integrate the new valve naturally, avoiding the complications of rejection. The same would be true for other implants, such as artificial joints and stents used to open blood vessels.
“If you want a device to perform better and not be rejected by the body, this is what you need to do,” says co-author Maryam Badv, also a McMaster PhD student in Biomedical Engineering. “It is a huge problem in medicine.”