Discovered in the Andean cloud forests of northern Peru, a new species in the blazing star family (Loasaceae) has reinforced the vital role of citizen science in plant research.
An international research team collected, identified and documented the rare plant after seeing photographs uploaded by Peruvian naturalist, Carlos Pérez Peña, on the citizen science platform iNaturalist. Assigning the species the name Nasa katjae, they published the discovery in the open-access journal PhytoKeys.
Nasa katjae has striking scarlet-red flowers adapted for hummingbird pollination and is endemic to a single forest near Colasay in the Cajamarca region of Peru, not far from a populated area. Due to its extremely narrow range, it is likely particularly vulnerable to the threat of habitat loss.
The discovery highlights the importance of protecting the remaining pristine habitats in the Amotape-Huancabamba Zone, a biodiversity hotspot home to many rare and isolated species. The team behind the study emphasise that, without immediate conservation efforts, these ecologically fragile regions could be lost to agricultural expansion and climate change before they are fully understood.
Lead author Dr Tilo Henning of the Leibniz Centre for Agricultural Landscape Research remarked on the significance of the find: “If we have overlooked this striking plant, think about what we have missed in more unobtrusive organismal groups such as mosses, fungi and insects.”
“Discovering such a conspicuous flowering plant in a forest directly adjacent to a larger human settlement signifies that we have not even begun to fully map the biodiversity of some regions. We urgently need more taxonomists and funding to meaningfully tackle this.”
While some areas in northern Peru have recently received formal protection, the forest fragment in which Nasa katjae is found remains unprotected. The authors of the study urge decision makers to take action to safeguard these habitats before it is too late.
The discovery of Nasa katjae displays the power of digital tools and citizen science in biodiversity research. Platforms like iNaturalist prove invaluable in detecting and documenting rare species, complementing traditional fieldwork and accelerating new discoveries.
Original source
Henning T, Allen JP, Montesinos-Tubée D, Rodríguez-Rodríguez EF, Peña JLM, Acuña-Castillo R (2025) No end to endemism – contributions to the difficult Nasa Weigend Series Alatae (Loasaceae). A new species from Peru and the rehabilitation of “ Loasa” calycina Benth. PhytoKeys 252: 163-186. https://doi.org/10.3897/phytokeys.252.141635
Based on this press release by the California Academy of Sciences.
Researchers have discovered the first new genus and species of plant in a U.S. national park for nearly 50 years.
Described in the OA journal PhytoKeys, the new-to-science woolly devil (Ovicula biradiata) is a member of the sunflower family, despite looking quite different to its sunburst-shaped relatives.
The small, fuzzy flower grows in the harsh, rocky soils of the Chihuahuan Desert and only appears after rainfall. (Photo courtesy of Big Bend National Park)
The national park is located within the Chihuahuan Desert, the largest and most biologically diverse warm desert in North America, and is a highly studied floristic region.
“While many assume that the plants and animals within our country’s national parks have probably been documented by now, scientists still make surprising new discoveries in these iconic protected landscapes,” says corresponding author and Academy researcher Isaac Lichter Marck, PhD.
From an elevation of less than 1,800 feet along the Rio Grande to nearly 8,000 feet in Chisos Mountains, Big Bend includes massive canyons, vast desert expanses, forest mountains, and an ever-changing river. (Photo courtesy of Big Bend National Park)
Park volunteer Deb Manley was first to observe the plant in March of 2024 by who uploaded the unknown species to the community science app iNaturalist, where an international community of botanists assembled to identify the mysterious flower.
Known to botanists as a “belly plant,” or a small, discreet plant that can only be properly observed by lying on the ground, this distinctive wild flower with furry white foliage and maroon ray florets is an ephemeral species that only blooms after rain. It thrives in harsh rocky habitats with scant rainfall and grows alongside a variety of drought-tolerant shrubs, such as ocotillo, hedgehog cactus, and creosote.
Researchers have only observed the plant in three narrow locations across the northernmost corner of the park, and it is possible that populations of the species are already diminishing.
Big Bend National Park staff members Carolyn Whiting, Deb Manley, and Patty Manning discovered the plant while hiking through the northernmost reaches of the park. (Photo courtesy of Big Bend National Park)
“Plants that thrive in deserts are often quite unique, having evolved specific mechanisms to withstand the extreme drought-and-deluge conditions of these arid landscapes—from water-storing structures to rapid life cycles triggered by rain,” says Lichter Marck.
“But as climate change pushes deserts to become hotter and drier, highly specialized plants like the woolly devil face extinction.”
The plant’s woolly appearance and striking red petals inspired the name Ovicula biradiata. Ovicula, meaning “tiny sheep,” refers to the thick, white hairs that cover the plant’s leaves and honors a more iconic endangered species in Big Bend: the bighorn sheep (Ovis canadensis). Biradiata, or “bi-radial,” refers to the two ray florets in each of the plant’s flowers. Researchers working with the plant affectionately dubbed the fuzzy flower the “woolly devil,” which has become its suggested common name.
Park botanist Carolyn Whiting observes the unknown species in March 2024. (Photo courtesy of Big Bend National Park)
“Now that the species has been identified and named, there is a tremendous amount we have yet to learn about it,” says Big Bend National Park botanist Carolyn Whiting.
“I’m excited to discover whether there are other populations in the park, the details of its life cycle, what pollinates it, and whether we’ll observe it this spring, given the current drought.”
Researchers are now investigating the woolly devil’s potential medicinal properties.
“Under the microscope, we noticed specific glands that are known to possess compounds with anti-cancer and anti-inflammatory properties in other plants within the sunflower family,” says Academy co-author Keily Peralta.
“While further research is needed to determine these properties, this discovery underscores the potential knowledge we stand to gain from preserving plant diversity in fragile desert ecosystems.”
Original source
Manley DL, Lichter Marck IH, Peralta K, Castro Castro A, Wogan KA, Whiting CV, Powell AM (2025) Ovicula biradiata, a new genus of Compositae from Big Bend National Park in Trans-Pecos Texas. PhytoKeys 252: 141-162. https://doi.org/10.3897/phytokeys.252.137624
Regarding recent changes to the journal, Editor-in-Chief Marc Stadler said: “The journal has a new editorial board, including many experienced as well as young, excellent scientists from around the world. Together, they cover a broad spectrum of mycological subdisciplines. They have already helped with processing of the new manuscripts, part of which were transferred from the previous publisher.
“We hope that the revenue that the IMA gains from the APC can substantially contribute to a sustainable income of the association. This will hopefully allow us to support mycologists in low-to middle income countries, initiatives to implement fungal conservation and other important tasks that need to be tackled by the mycological community in the future.”
See the full list of newly published articles below:
More than 99.9% of global species diversity is found within soils, according to a new review paper published in ZooKeys.
Comparing different studies on soil biota, author Robert J. Blakemore challenges previous estimates, which suggested a much lower proportion of life in soils. “Most life is found in Soil and most is microbial, affected by the current mass extinction event having profound effects influencing all evolution on Earth,” he says.
From the review paper: “Micro monde” progressions with microbial proportions greatly increased from Blakemore after Larsen et al.
“Soil filters and stores freshwater stocks (being subject to Earth tides!) and, as well as ~ 99% of human food, it provides most building materials plus many of our essential medicines/antibiotics. Thus, an important metric must be the scope and snapshot status of living or dormant Soil biota.”
One of the most recent estimates suggests that the soil realm is home to approximately 2.1 x 1024 taxa, which is thought to be more than 99.9% of global species biodiversity, mainly comprised of bacteria and other microbes.
The more you look, the more you find (lhs, pin-head after SCIENCE 2002; rhs, Bacteria on a pin tip courtesy Dr Kateryna Kon of Kharkiv National Medical University).
“Soil also supplies >99.7% of calorific food (just 0.3% from ocean plus 0.3% from aquaculture mostly fed with farmed stockfeed); with just about 6% total global protein from all fish; soil filters and stores most freshwater and is thus responsible for hydrological-recycle rainfall on land,” Blakemore says.
“My other paper last year on Biomass shows Soil houses >99% of organic carbon and it is the loss of this vital resources that is the greatest contributor to atmospheric carbon increase, despite the ‘greening’ effect on land.”
However, this immense biodiversity is under threat. “Soil erosion is one of our greatest global issues of concern, and one of the most ignored. Droughts, floods, deserts, poisoning, capping and so on are affecting all soils and, due to this massive soil loss, plants are incapable of thriving. At the same time deforestation continues, mainly clearing for cattle pastures or soy fields to feed CAFO cows (or other stock),” the author says.
The loss of soil biodiversity has far-reaching consequences, leading to ecosystem degradation, reduced food production, and loss of potentially valuable resources, such as sources of medicines and antibiotics. Furthermore, soil loss inevitably results in silent species loss, mostly of microbes that are most dominant in soils, but also of more obvious soil macrobes, and specifically of earthworms, which are vital for soil health.
Around 7,000 ‘true’ earthworm species have been described, but estimates suggest the total number of earthworm species may be closer to 30,000-35,000 globally. “Due to their high endemicity and Soil’s heterogeneity, their unknowns are legion,” the author notes in his paper.
From the review paper: Global Soil Biodiversity Atlas (GBIF 2016) reporting ~ 667,000 soil biota or just about one third of known 2 million). Note that earthworms have 7,000 known and > 30,000 estimated species. Bacteria had 15,000 known species but estimated over one million (< 1.5% described). However, when microbes (excluding viruses) are properly considered and counted, as herein, soil unknowns are much higher (likely just < 0.0001% known at best). Vascular plants add ~ 400,000 species (cf. Anthony et al. 2023 with 466,000 angiosperm “Plantae”).
Earthworms enhance microbial activity, improve soil structure, and promote plant growth, which is why Blakemore suggests that “a simple solution to soil degradation is to attempt, in any way and at all times, to preserve and enhance earthworm populations.”
“Healthy soils are carbon-rich, hugely biodiverse and are a massive sponge for water – neither flooding nor drying during climatic extremes,” the author says, a reminder that healthy soils are not only vital for maintaining biodiversity, but also indispensable in supporting essential functions of planet and human survival.
“Due to the most pressing problem of topsoil erosion and irreversible extinction losses, a major shift should be realizing the overwhelming importance and fragility of our precious Soil,” Robert Blakemore writes in his paper.
Calling for a change in attitudes and funding to recognise the true scope of soil biodiversity, he encourages the formation of a dedicated Soil Ecology Institute that would catalogue, research and reverse the mass degradation of our planet’s most crucial, yet most neglected ecosystem – that of the Soil Realm.
Published in the open-access journal NeoBiota, the study focused on domestic air travel into Tasmania, Australia, an island state with an especially low pest presence due to its geographic isolation.
Researchers utilised an extensive database of more than 66,000 biosecurity risk interceptions from over 6 million passengers entering Tasmania from mainland Australia. With this, they applied advanced statistical modelling tools to assess how effective different interventions are at catching risky material at the border.
Their analysis found that air passengers pose a significant biosecurity risk, with pests potentially introduced via items like fruits, vegetables, and animal products carried in luggage.
To combat this risk, border interventions using biosecurity inspectors and detector dogs were found to be effective, both by encouraging voluntary declarations by passengers and detecting risk items that passengers failed to declare.
While biosecurity inspectors play a significant role, detector dogs are especially effective, detecting a higher rate of risky items and targeting undeclared materials that might otherwise go unnoticed. The presence of detector dogs substantially increased interception rates, including for items linked to the spread of the invasive fruit fly.
Lead author Dr Nicholas Moran said: “Dogs being great at sniffing things out might seem obvious, but measuring precisely how effective different interventions are, what they capture, and how, is incredibly valuable information for biosecurity operations.
“Fruit flies are a serious risk to Tasmania, and many parts of the world. So, this work is about knowing what biosecurity interventions to deploy, and where is best to deploy them to reduce the risk of outbreaks.”
The study is a part of the “Risk Analysis of Tasmanian Border Inspection Approaches and Procedures” project, conducted by CEBRA with Biosecurity Tasmania. The two-phase project investigated the invasive risk of five pest species that are common across Australia’s mainland but are not currently found in Tasmania.
Original study
Moran NP, Hanea AM, Robinson AP (2025) Border biosecurity interceptions for air passengers – assessing intervention methods and analytic tools. NeoBiota 97: 161-178. https://doi.org/10.3897/neobiota.97.141784
The Chinese muntjac(Muntiacus reevesi)is an invasive alien species for Europe with established populations across the western part of the continent. Photo by Mario Shimbov (Pensoft).
As one of the partners in charge of maximising the project’s impact, Pensoft will work on OneSTOP’s visual branding, communication, dissemination and exploitation, and the development of a data management plan for the project.
Invasive alien species (IAS) pose one of the most significant threats to global biodiversity, contributing to species extinctions, ecosystem degradation, and economic losses exceeding $400 billion annually.
To tackle this, the EU enforces Regulation (EU) 1143/2014 and the Biodiversity Strategy for 2030, aiming to prevent IAS introduction, enhance early detection, and manage their spread. Member States coordinate efforts with scientific support and citizen engagement to minimise their impact and protect Europe’s biodiversity. Addressing this urgent challenge, the EU Horizon project OneSTOP has officially launched as part of a coordinated European effort to combat biological invasions in terrestrial environments.
Comprehensive Approach to Tackling Invasive Alien Species
OneSTOP is one of two ambitious projects funded under the Horizon Europe programme, the other being GuardIAS, which focuses on marine and freshwater habitats. The two collaborative initiatives held their joint official kick-off meeting in January at the Joint Research Centre in Ispra, Italy. Together, these projects aim to develop innovative solutions for detecting, preventing, and managing invasive alien species across all ecosystem realms.
The ОneSTOP project consortium at the project’s kick-off meeting held on 20-24 January 2025 in Ispra, Italy.
The project is structured around four key objectives:
Improve species detection and response time by incorporating computer vision, environmental DNA (eDNA) analysis and citizen science initiatives.
Facilitate swift action against invasive species threats by openly sharing data in international standards for biodiversity data with stakeholders who need it.
Support policy-makers in making informed decisions about where and how to allocate resources for invasive species management by developing data-driven systems.
Ensure stakeholder collaboration and knowledge exchange by implementing Living Labs at the regional level and an international policy forum, thereby encouraging socio-political action.
OneSTOP aligns with the European Alien Species Information Network (EASIN) mission to protect EU biodiversity by improving IAS management through advanced biosecurity technologies and enhanced data integration. By fostering collaboration with the Joint Research Centre (JRC) and supporting Member States with innovative tools, the project strengthens the EU’s capacity to detect, respond to, and mitigate IAS threats in line with existing regulations.
Pensoft’s role in OneSTOP
As the leader of Work Package 1, Pensoft is responsible for shaping OneSTOP’s visual identity and developing a comprehensive strategy for communication, dissemination, and impact. This includes crafting a data and knowledge management plan to ensure the project’s findings are effectively shared and utilised. By fostering collaboration with key biosecurity networks, these efforts will strengthen OneSTOP’s long-term influence.
A key part of this work is to raise awareness about invasive alien species (IAS) and their pathways, ensuring that policymakers, researchers, and the public understand their impact and the importance of prevention. Pensoft will contribute to translating complex scientific findings into accessible content—including infographics, policy briefs, and interactive visualisations—to engage policymakers, researchers, and the public. These efforts will ensure that IAS knowledge is effectively shared, fostering collaboration and informed decision-making across sectors. Knowledge transfer materials will be shared through various channels, including OneSTOP’s five Living Labs across Europe, where stakeholders will be actively engaged in outreach and citizen science initiatives.
Pensoft will play a vital role in strengthening public awareness, fostering engagement, and promoting effective strategies for monitoring and managing IAS.
International Consortium
The project brings together twenty international partners from fifteen countries operating in various sectors, ultimately contributing with diverse expertise:
For more information visit the OneSTOP project website, and make sure to follow the project’s progress via our social media channels on BlueSky and LinkedIn.
Picture in your mind the discovery of a new species.
What do you see? Researchers cutting through dense, untouched rainforests? Perhaps a submarine plunging into a deep-sea trench, illuminating a new world?
Well, it’s not always quite so dramatic. In fact, researchers in China discovered Branchiostegus sanae when they were scrolling through online seafood markets and noticed some deepwater tilefish with unique cheek patterns.
Branchiostegus sanae. Credit: Huang et al.
These red-and-white facial markings reminded the research team of the Studio Ghibli character San from Princess Mononoke, whom they chose to honour in their naming of the species.
Published in the open-access journal ZooKeys, Branchiostegus sanae is a deepwater tilefish belonging to the family Branchiostegidae. Researchers confirmed its new-species status using genetic analysis, and chose “sanae” as the specific epithet (that’s the part that differentiates species within a genus), in a nod to Hayao Miyazaki’s animated creation.
Branchiostegus sanae at a seafood market. Credit: Jiangyuan Chen.
“Finding a new species in this group is a rare and fortunate event, especially one as distinctive as Branchiostegus sanae.
“In Princess Mononoke, San is a young woman raised by wolves after being abandoned by her human parents. She sees herself as a part of the forest and fights to protect it. The film delves into the complex relationship between humans and nature, promoting a message of harmonious coexistence between the two: something we hope to echo through this naming.”
Lead author, Haochen Huang.
The Chinese fishermen who sell the new-to-science species call it the“鬼马头鱼” (ghost horsehead fish), and this also contributed to the species name because, fittingly, “Mononoke” (もののけ) refers to supernatural spirits in Japanese folklore.
As their name suggests, deepwater tilefish are found at great depths, with some species found 600 m below the surface. They are important food fish, commonly found in seafood markets in East and Southeast Asia.
Branchiostegus sanae is far from the only new species discovered at a seafood market. Indeed, a new giant isopod was recently dicovered in the same way – and also recieved a pop-culture inspired name. Check it out below!
So far only 31 species are described in the family Branchiostegidae, and 19 species in the genus Branchiostegus. From 1990 to 2024, only three new species of Branchiostegus have been described.
Other species of the genus Branchiostegus found in Chinese waters. Credit: Huang et al.
The study, led by researchers from the South China Sea Institute of Oceanology, Chinese Academy of Science, Zhejiang University and Ocean University of China, involved a combination of morphological analysis and genetic sequencing. Specimens were deposited in prestigious marine biological collections in China to facilitate future research.
Original study
Huang H, Chen J, Ke Z, Zhang C (2025) Branchiostegus sanae, a new species of deepwater tilefish (Eupercaria, Branchiostegidae) from the South China Sea. ZooKeys 1227: 129–142. https://doi.org/10.3897/zookeys.1227.130512
Large-scale ground-mounted solar parks are relatively new phenomena. Over time, ideas have been put forward about how they can accommodate biodiversity, and some parks are indeed becoming more multifunctional, for example by providing habitats for plants, invertebrates and birds. From a background of studying idyllic ecosystems in dynamic change, Dr. Markus Zaplata, research technician at Anhalt University of Applied Sciences, Germany, has come to appreciate the biology of solar parks, and has found evidence that they can support a wide range of biodiversity.
Biodiversity in solar parks is a given (here two Mantis religiosa nymphs) and, with the possible exception of self-seeded woody plants, is desirable. Photo by Dr Markus Zaplata
His research, published in the open-access journal One Ecosystem, proves the previously overlooked fact that vegetation succession also takes place in solar parks, and that certain intrinsic technical structures can even help self-seeded woody plants live there. Vegetation succession refers to the directional development from easily spreading but low-competitive species such as herbs and grasses towards highly competitive species such as woody plants. Mowing alone is not enough to deal with woody plants, he argues. “The fact is that subsurface woody structures continue to grow after mowing, and may at some point massively interfere with the solar installations”, he says.
With 18 years of experience in studying vegetation succession, Dr. Zaplata has supported a research project on biodiversity in solar parks since 2021.
“I do the mowing myself, so I experience the very things I write about in this paper”, he says.
Mowing can also be expensive and labour-intensive, he adds, suggesting that other construction methods and grazing could provide a more sustainable alternative.
Including insights from succession research can make global solar energy landscapes more sustainable, he argues. “The universal and unstoppable ecological process of succession is here linked to a management recommendation that can bring society closer again, on the new or neutral territory of new energy landscapes. In fact, new and old professions are connected, for example solar park manager and livestock farmer.”
Above-ground parts of a willow tree (Salix sp.) that have resisted a recent mowing campaign. Photo by Dr Markus Zaplata
“Finally, and very importantly, my article points out that experts with in-depth predictive knowledge of dynamic vegetation processes must be consulted in the future on everything that has to do with the technical transformation of landscape units, including solar parks,” he says in conclusion.
Original source
Zaplata M (2025) Management and sustainability of ground-mounted solar parks requires consideration of vegetation succession as an omnipresent process. One Ecosystem 10: e141583. https://doi.org/10.3897/oneeco.10.e141583
For centuries, all kinds of species have been transported by humans around the globe, allowing them to cross the boundaries of their native range and settle in new ecosystems. Over the past decades the numbers of these introduced species and the impacts they cause have been continuously increasing. Biological invasions nowadays represent one of the biggest threats to biodiversity worldwide.
Humans are and have always been an essential part of biological invasions and in order to fully understand the issue and how to tackle it, we need to understand and include the human dimensions in our research.
My research on European flounder in Iceland began in 2017 when I was writing my Master’s thesis. The flounder is a flatfish species that had been officially documented in the country since 1999 but not much was known on its impacts. In my thesis I looked at the flounder through ecological lenses, trying to identify how the presence of the flounder affects other species. Living in a small community in the Westfjords of Iceland during this time, I got to meet many local people who shared their personal stories, experiences and knowledge with me in every-day conversations. I truly enjoyed these conversations and learning about the species I study from different perspectives beyond the academic settings. These exchanges sparked my interest in exploring the human dimensions of biological invasions and, looking back, have really shaped my academic path going forward.
Theresa Henke holding a flounder.
In our recently published NeoBiota study “Have you seen this fish? – Important contribution of stakeholder observations in documenting the distribution and spread of an alien fish species in Iceland” we wanted to explore how the knowledge and experience of recreational anglers in Iceland can help us understand how far the flounder has spread in Iceland. The flounder in Iceland had only received little scientific interest before and the available information was limited and scattered between different institutions and scientists. Recreational anglers, on the other hand, who chase after native salmon, trout, and char in the Icelandic rivers and lakes, often encounter the flounder.
A net full of flounder.
In 2019, we asked anglers in Iceland to take part in an online survey, where we asked them different questions about the flounder, including where in Iceland they have seen or caught it. We then compared locations named by anglers to the locations that were available from different databases of the Marine and Freshwater Research Institute of Iceland. The locations we received included data collected during scientific surveys and research projects done by the institute as well as observations that were reported to the institute by the public (mostly recreational anglers and commercial fishermen).
Our goal was to evaluate whether observations made by stakeholders, in this case the recreational angling community in Iceland, could be a good source of additional information for monitoring of an alien fish species. Collecting information on the distribution and spread of an alien species is a very important step in addressing biological invasions but is often underdeveloped because not enough resources (i.e. money, time, scientists…) are made available.
Theresa Henke holding a 43-cm flounder in Eyjafjörður.
We have shown that neither source offers a perfect solution to the monitoring of the flounder in Iceland. But we show that each of the sources has their own advantages and disadvantages and by combining them, we are able to get a much clearer picture of where in Iceland the flounder currently occurs and how fast it spread in the early years. Information that was shared by stakeholders, whether it was in our study or to the databases of the Marine and Freshwater Research Institute, played a big role in better understanding the flounder in Iceland.
The interactions with the recreational angling community in Iceland during my PhD have taught me a lot about the flounder in Iceland but even more about my own approach to science. I think as scientists, we should more often take a step outside of our academic bubble and take a look at the issue we are studying from the perspectives of the public and other stakeholders. In the case of biological invasions, we can learn a lot from those who are directly confronted by an invasive species, regardless of whether they have a scientific degree or not.
Research article:
Henke T, Bárðarson H, Thorlacius M, Ólafsdóttir GA (2025) Have you seen this fish? Important contribution of stakeholder observations in documenting the distribution and spread of an alien fish species in Iceland. NeoBiota 97: 67-90. https://doi.org/10.3897/neobiota.97.132365
A trustful concentration range was established in which the active agent was effective against the cancer cells but remained non-toxic to the normal cells.
Melanoma is a fast-progressing skin cancer characterized by a high mortality rate after metastasis. Local chemotherapy could be considered a therapeutic approach only in stage 0 of progression (in situ melanoma) and in the postoperative phase after surgical removal of suspected skin lesions. For this purpose, drugs such as Imiquimod, 5-Fluorouracil, Dacarbazine, and Doxorubicin have been tested and shown positive effects. Recently, metal nanoparticles as separate therapeutic units or drug carriers have also fallen into the research focus.
Silver nanoparticles (AgNPs), in particular, are widely recognized as multifunctional tools in nanomedicine, drug delivery, and theranostics. They exert wide-spectrum antimicrobial and anti-tumor properties but their pharmacological effects are in a tight bond with the so-called “surface functionality”. For example, negatively charged and spherical particles are proven less toxic than positively charged particles, especially irregularly shaped (e.g., rods, wires, etc.). Still, because of this, the former are less potent anti-cancer agents.
Contemporary pharmaceutical development relies very much on eco-friendly technologies (often referred to as “green” technologies) that avoid the use of toxic solvents and reagents. This research has implemented one such method based on Camellia sinensis (green tea leaves) as a natural reducer of silver ions. To achieve enhanced antimicrobial and anti-tumor activity, the thus obtained AgNPs were further conjugated to chlorhexidine (Cx+) — a broad-spectrum antimicrobial agent and a cationic surfactant. Indeed, the AgNP-Cx+ complexes have shown highly increased antimicrobial properties, about 18-fold stronger anti-melanoma activity, and 3 times better tumor selectivity compared to the non-functionalized AgNPs.
Anti-tumor activity of silver nanoparticles (AgNPs) and chlorhexidine-silver nanoparticles conjugates (AgNP-Cx+) against melanoma. Legend: ζ-zeta potential – characterizes the charge of the silver nanoparticles; dH hydrodynamic diameter – the size that the particles acquire in an aqueous dispersion; HaCaT – normal cells, human keratinocytes; SH-4 – tumor cells, human melanoma; IC50 – the concentration that inhibits cell proliferation at 50%; SD – standard deviation of the values based on six repetitions of the experiment; ppm – part per million; Selectivity Index – an index that is calculated as the quotient of IC50 on normal cells and IC50 on tumor cells; the greater its value, the more selective the agent against the cancer cells; p-value – statistical indicator; the lower the value the greater the statistical significance between the results obtained with the different samples; a borderline for significance is normally set at p<0.05; n/a – not applicable.
The most valuable outcome of this new study, published in the journal Pharmacia, was the establishment of an adhesive patch prototype as a topical dosage form for the AgNP-Cx+ complex. The used polymers, Hydroxypropyl methylcellulose and Eudragit® RS, demonstrated a lack of negative interference with the antiproliferative action of the active agent but also ensured twice as high activity and even better selectivity against the tumor cells.
