Directive 2010/63/EU laid down restrictions on animal testing for the testing of cosmetics and their ingredients throughout the EU. Therefore, there is an intense search for alternatives to test the absorption and toxicity of nanoparticles from cosmetics such as sun creams. A team of researchers from Graz University of Technology (TU Graz) and the Vellore Institute of Technology (VIT) in India is working on the development of skin imitations that mimic the native three-layer tissue structure and biomechanics of human skin. Such imitations can be produced using 3D printing and consist of hydrogel formulations that are printed together with living cells.

Hydrogels in which skin cells survive and grow

“The hydrogels for our skin imitation from the 3D printer have to fulfil a number of requirements,” says Karin Stana Kleinschek from the Institute of Chemistry and Technology of Biobased Systems. “The hydrogels must be able to interact with living skin cells. These cells not only have to survive, but also have to be able to grow and multiply.” The starting point for stable and 3D-printable structures are hydrogel formulations developed at TU Graz. Hydrogels are characterised by their high-water content, which creates ideal conditions for the integration and growth of cells. However, the high-water content also requires methods for mechanical and chemical stabilisation of the 3D prints.

TU Graz is working intensively on cross-linking methods for stabilisation. Ideally, following nature’s example, the cross-linking takes place under very mild conditions and without the use of cytotoxic chemicals. After successful stabilisation, the cooperation partners in India test the resistance and toxicity of the 3D prints in cell culture. Only when skin cells in the hydrogel survive in cell culture for two to three weeks and develop skin tissue can we speak of a skin imitation. This skin imitation can then be used for further cell tests on cosmetics.

Successful tests

The first tests of 3D-printed hydrogels in cell culture were very successful. The cross-linked materials are non-cytotoxic and mechanically stable. “In the next step, the 3D-printed models (skin imitations) will be used to test nanoparticles,” says Karin Stana Kleinschek. “This is a success for the complementary research at TU Graz and VIT. Our many years of expertise in the field of material research for tissue imitations and VIT’s expertise in molecular and cell biology have complemented each other perfectly. We are now working together to further optimise the hydrogel formulations and validate their usefulness as a substitute for animal experiments.”

In a recent study published in the journal Proceedings of the Royal Society B, an international team of researchers tested a new hypothesis for why some Lepidoptera have very specific diets, feeding on only a few types of plants, while others are far less picky.

The new idea, called the Salient Aroma Hypothesis, suggests that the smells plants release play a crucial role in determining how specialized a butterfly or moth’s diet becomes. The researchers found that greater availability of plant aromas during the day provides more chemical information for day-active insects to use to locate and specialize on particular host plants, while the decrease in plant aromas at nighttime means night-active Lepidoptera have to take what they can get and have a more varied diet.

“This idea provides a new perspective on why some butterflies and moths are picky eaters while others are not,” said Po-An Lin, an assistant professor at the National Taiwan University who launched the research while earning his doctoral degree from Penn State and continued the work as a postdoc in Taiwan. “It also highlights the critical role of plant volatiles, or scents, in shaping insect-plant interactions and evolutionary adaptations.”

To determine whether plant scent may have driven adaptation, the researchers looked at the insects’ primary organs for smelling — the antennae — and compared the antennal size of 582 specimens from 94 species of butterflies and moths.

The Penn State team collaborated with a team at Harvard that found that female Lepidoptera that are active during the day tend to have larger antennae relative to their body size than those active at night.

This might suggest that having better “smelling” equipment is more beneficial when there are more smells to detect, explained Gary Felton, the Ralph O. Mumma Professor of Entomology at Penn State, co-author on the paper and Lin’s research adviser. Similarly, specialist female Lepidoptera — those that feed from only a few types of plants — often have larger antennae than generalist females, possibly because they need to be very good at detecting the specific aromas of their host plants.

“The relationship between antennal size and host plant breadth was very strong,” Felton said. “Larger antennal sizes have been associated with a greater number of sensilla, the sensory structures involved in the sense of smell, thereby increasing the surface area for sensory receptors. The enhanced capacity may be a key adaptation for how certain Lepidoptera have evolved to feed on a limited and specific range of plants.”

The findings suggest a potential link between the availability of plant aromas during the day and an evolutionary investment in olfactory structures in the insects, particularly in females that engage in host plant selection by laying their eggs on the plant, Lin explained.

“This finding demonstrates how the availability of chemical signals influences the evolution of sensory organs in insects,” he said. “It provides a fascinating example of how plants, through their chemical emissions, have played a direct role in shaping the evolution of the insects that rely on them.”

Lin and colleagues at Penn State used a combination of approaches to investigate the link between plant aromas and Lepidoptera diets. They first conducted a meta-analysis of existing scientific literature to confirm that plants generally release more diverse and abundant volatile organic compounds, or aromas, during the day versus the night. Then they studied the Lepidoptera family tree to analyze the relationship between the insects’ activity patterns — day or night active — and their preferred host plants, using statistical models that account for evolutionary relationships.

“Our analyses showed a significant correlation between being active during the day or night and the diversity of host plant species that Lepidoptera consume,” said Naomi Pierce, professor of biology at Harvard University and co-author on the paper.

The researchers found that day-active Lepidoptera, like monarch butterflies, have more opportunities and more specialized organs to detect plant aromas and, as such, have evolved to be picky eaters. On the other hand, night-active species, like the Polyphemus Moth, encounter fewer and less diverse plant aromas. With less clear chemical information available, it might be harder for them to be so selective, potentially leading them to have more generalized diets, feeding on a wider range of plants.

“Insect herbivores, such as butterflies and moths, must find the right plants to feed on and, in the case of females, to lay their eggs,” Lin said. “This is a crucial decision because caterpillars depend entirely on the selected plant for survival. Unlike humans, who eat a wide variety of foods to stay healthy, many insect herbivores specialize in feeding on only a few plant species. The Salient Aroma Hypothesis helps explain why some insects are highly specialized while others are more flexible in their diet.”

The other authors on the paper are Wei-Ping Chan and Even Dankowicz of Harvard University; Liming Cai of the University of Texas Austin; Yun Hsiao of National Taiwan University; and Kadeem Gilbert of Michigan State University.

The U.S. National Science Foundation, Taiwan’s National Science and Technology Council and the Yushan Fellowship Program from the Ministry of Education of Taiwan funded this work.

The aptamers — short single-strand snippets of DNA that can target molecules like larger antibodies do — not only deliver cancer-fighting drugs, but also are themselves toxic to the cancer stem cells, the researchers said.

Led by Xing Wang, a U. of I. professor of bioengineering and of chemistry, the researchers documented their findings in the journal Advanced Functional Materials.

“This work demonstrates a way to get to the root of leukemia,” Wang said. “Targeted cancer treatments often have problems with toxicity or efficacy. Our aptamers seek out these stem cells specifically and kill them effectively.”

Leukemia and other cancers of the blood are more difficult to target than cancers that produce localized tumors because the cancerous cells circulate throughout the body and can’t be surgically removed, said postdoctoral researcher Abhisek Dwivedy, first author of the paper. Leukemia has a high rate of relapse due to its evasive stem cells. Though they make up a tiny fraction of cancerous cells, leukemia stem cells have the ability to evade chemotherapy by retreating to the bone marrow, since they share markers and properties, Dwivedy said. The cancerous cells can lurk, sometimes for years, and later proliferate and migrate.

“It’s important in leukemia, lymphoma or other blood cancers that we actually target and eliminate these stem cells, because as long as any are remaining, they can cause relapse and secondary cancers,” Dwivedy said.

The researchers began by finding DNA aptamers that seek out markers found on the surface of acute myeloid leukemia stem cells. They wanted to target not just the cancer, but the stem cells specifically.

“A big thing we showed in this study is that having two targets is better than one in terms of selectivity,” Wang said. “There are known antibody-drug conjugates for blood cancers that target one marker, but that marker is also found on a lot of healthy cells. So there is a lot of toxicity associated with antibody conjugates. But we used two targets: a combination often found in leukemia cancer cells and leukemia stem cells. The two together give a very specific target.”

The researchers then paired their aptamers with the leukemia-fighting drug daunorubicin. The drug-laden aptamers carry the drug to their target, then release the drug once inside the cell so the drug can act.

“This is especially important for drugs like daunorubicin, because the drug on its own cannot cross the cell membrane easily. But aptamers can carry it in,” Dwivedy said.

The researchers tested the drug-delivering aptamers in leukemia cell cultures as well as in live mice with leukemia.

After 72 hours, the aptamer alone had reduced the cancer cells in culture by 40 percent, demonstrating the aptamer’s toxicity to the cancer, the researchers report. When the aptamers carried the leukemia-fighting drug, the cells were wiped out with a dose 500 times smaller than the standard dosage of the drug. In mice with leukemia, delivering the drug via aptamer yielded the same efficacy at a dose 10 times smaller than the clinical standard, showing that the one-two punch of the aptamer and drug is more effective than either alone.

“This was exciting to us, because in cancer research, what we see in vitro is not always what we see in the body. Yet we saw excellent survivability and tumor reduction in the mice treated with our aptamer-drug conjugates, at one-tenth of the therapeutic dose, and no off-target effects,” Wang said.

The researchers said they hope to expand their suite of drug-delivering aptamers by identifying key marker combinations for other cancers, as well as coupling the aptamers with other drugs.

“Every cancer cell has a signature in its surface biomarkers. If we can find markers that are present uniquely in cancer cells, we can target other cancer types as well. Also, in my experience, it’s much easier to pair a drug with the DNA molecules than proteins, so that opens possibilities for delivering more drugs this way,” Dwivedy said.

These teleconnections between the tropical Pacific and far-flung areas are reported in a Cornell University-led computer-model study published in Nature Geoscience.

While other computer models have projected similar precipitation increases generated by a warming Southern Ocean, major uncertainties and a wide range of predictions exist between models.

The new study serves to reduce those uncertainties, which could improve predictions of global mean temperatures and regional precipitation.

“We needed to find the cause of those uncertainties,” said Hanjun Kim, the study’s co-corresponding author and a postdoctoral associate working with co-authors Flavio Lehner and Angeline Pendergrass, both assistant professors of atmospheric sciences at Cornell. Sarah Kang, professor in the Max Planck Institute for Meteorology in Hamburg, Germany, is the paper’s other corresponding author.

“I found that low-altitude cloud feedbacks over the Southern Hemisphere can be one cause of those uncertainties in remote Northern Hemisphere regional precipitation,” Kim said. “If we try to reduce the uncertainty of Southern Hemisphere cloud feedbacks, then we can also improve the prediction of global mean temperatures.”

The Southern Ocean has a higher capacity for absorbing heat than other bodies of water due to a strong upwelling of deep cold water, but eventually the water will warm and gradually release heat. When this happens, that heat is distributed, creating teleconnections, which are predicted to increase precipitation in East Asia during summers and in the Western U.S. during winters. Such teleconnections are very similar to how El Niño affects weather patterns.

The model predicted that due to the ocean’s slow release of heat, the new precipitation patterns could persist for up to 150 years, regardless of efforts to reduce greenhouse gases.

“We can occasionally see these processes today, which allows us to study them,” Lehner said, “but we expect in the future for these processes to switch from being an occasional occurrence to being a more permanent state of the system.”

Kim found that low-lying clouds over the Southern Ocean act as a key regulator affecting sea-surface temperatures. Accounting for these cloud feedbacks in climate models help explain the uncertainties and variations from one model to another, according to the study.

There are few observational facilities in Antarctica to provide data on cloud feedbacks in the Southern Ocean, so increasing those would in turn improve predictions, Kim said.

HIV-diagnostic technology traditionally relied on the detection of HIV-specific antibodies that form several weeks after infection. This has limited their use in early detection, complicating patient care and HIV prevention efforts. Newer tests that detect both HIV antibodies and the p24 antigen (an earlier marker of HIV infection) are now the gold standard for diagnosis, but require clinical labs to run results, contributing to longer processing times, higher costs and the need for multiple patient visits.

The technology described in a study published today (April 2) in the journal Biosensors and Bioelectronics uses a nanomechanical platform and tiny cantilevers to detect multiple HIV antigens at high sensitivity in a matter of minutes. These silicon cantilevers are cheap and easy to mass produce and can be readily equipped with a digital readout. Built into a solar-powered device, this technology could be taken to hard-to-reach parts of the world where early detection remains a challenge to deliver fast interventions to vulnerable populations without waiting for a lab.

“We hope this technology will lead to the development of new point-of-care diagnostics for HIV to improve patient health and help bring an end to this epidemic,” said Northwestern virologist and co-author of the study, Judd F. Hultquist.

After proving its efficacy in testing for both the SARS-CoV-2 virus that causes COVID-19, and now HIV, the team is confident that the biosensor will continue to prove effective when testing for additional diseases. A potential next target, they say, could be measles, another infection in desperate need of point-of-care interventions as cases rise across multiple U.S. states.

The team was led by co-corresponding authors Vinayak Dravid, a materials engineer, Hultquist, a virologist, and co-author Gajendra Shekhawat, a micro- and nanofabrication expert in the Dravid Lab.

“When we first developed the microcantilever technology 20 years ago, I realized that this technology is so generally applicable,” Dravid said. “It is a very powerful tool that depends on three basic things: sensitivity, antigen-antibody affinity and specificity. This is where HIV comes in, because HIV is so pernicious that it mutates so there is no unique antibody. We had to figure out how to overcome that challenge.”

Beginning with pure samples of the p24 antigen, the team applied layers of antibodies onto each “finger” of the gold-coated microcantilever to measure how strongly p24 bonded to the surface, which would cause the cantilever to bend a measurable and quantifiable amount.

After this proof-of-concept, the team introduced human blood samples, which are much more complex than purified samples. The sensor continued to bend only in samples where p24 was present, demonstrating high specificity.

Finally, the scientists added two antibodies to different “fingers” of the microcantilever to more broadly cover all HIV subtypes. Even in very low concentrations, the test accurately responded when antigens specific to HIV were introduced.

“To account for HIV’s genetic diversity, we functionalized the test for HIV using broadly cross-reactive antibodies (ANT-152 and C65690M),” Shekhawat said. “This allowed accurate detection across diverse HIV-1 subtypes, ensuring reliability in global settings.”

To streamline diagnostics and enable immediate medical care, the team envisions developing a point-of-care test simultaneously detecting HIV, hepatitis B and hepatitis C antigens, acknowledging the higher prevalence of hepatitis co-infections in people living with HIV that can lead to severe liver complications if left untreated.

Dravid is the Abraham Harris Professor of Materials Science and Engineering at the McCormick School of Engineering and a faculty affiliate of the Paula M. Trienens Institute for Sustainability and Energy. He is also the founding director of the Northwestern University Atomic and Nanoscale Characterization (NUANCE) Center as well as the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource, and also serves as the associate director for global programs at the International Institute of Nanotechnology.

Hultquist is an assistant professor of medicine at Northwestern University Feinberg School of Medicine and serves as the associate director for the Center for Pathogen Genomics and Microbial Evolution in the Havey Institute for Global Health. He specializes in translational research of infectious diseases and host-pathogen interactions.

Shekhawat is a research professor of materials science and engineering at McCormick, researching semiconductor microfabrication, integration of sensors with synthetic biology and biomaterials and nanoscale characterization.

The research was supported by an award from the National Institutes of Health-funded Third Coast Center for AIDS Research (P30AI117943), as well as through NIH funding for the HIV Accessory & Regulatory Complexes Center (U54 AI170792) and NIH funding for HIV research (R01AI176599, R01AI167778, R01AI150455, R01AI165236, R01AI150998, R21 AI174864, and R56AI174877).

Vinayak Dravid, Gajendra Shekhawat, Judd Hultquist and Northwestern have financial interests (equities, royalties) in the reported research.

A dissection in the artery wall is most often caused by trauma due to motor vehicle accidents but can also occur with smaller injuries. Heavy lifting has also been shown to cause dissection in some people.

“Cervical artery dissection is an important cause of stroke, especially in people under 50, so it is crucial to detect it right away,” said Shadi Yaghi, MD, of Brown University in Providence, Rhode Island. “Strokes that are not fatal can lead to long-term disability, poor mental health and reduced quality of life. Our research found a dramatic increase in the number of hospitalizations for cervical artery dissection with rates rising steadily year over year.”

For the study, researchers reviewed 15 years of U.S. health data to identify 125,102 people hospitalized for cervical artery dissection. Participants had an average age of 51, and just over half had a stroke at the same time as dissection. Of all participants, 65% were white, 10% were Black, 8% were Hispanic, 3% were Asian or Pacific Islander, and 14% were of other racial groups.

Researchers compared the number of hospitalizations to U.S. Census data to determine the annual rate of cervical artery dissections. They then calculated the average annual percentage change in those rates.

Researchers found the number of dissections increased from 11 cases per one million people in 2005 to 46 cases per one million people in 2019, with an average annual increase of 10%. Results were similar for both female and male participants.

The average annual increase for Hispanic participants was 16%, for Black participants it was 13%, Asian participants, 12% and white participants, 8%.

Researchers also found a greater average annual increase among people 65 and older at 12% compared to 8% for people under 65.

“Possible reasons for this nearly five-fold increase over 15 years include greater awareness of cervical artery dissection by health care professionals, better access to imaging to help identify it and an overall increase in this condition for which a cause has yet to be determined,” said Yaghi. “Given the rising incidence of cervical artery dissection, our study underscores the importance of finding prevention strategies as well as new treatments to reduce the risk of stroke.”

A limitation of the study was that the hospital admission data does not include undiagnosed or untreated cases, so the number of cases may be even higher.