Category Archives: beauty and cosmetics

Oxygen-deficient nanotitania (titanium dioxide nanoparticles) for whiter teeth without the damage

A September 8, 2021 news item on phys.org announces research that could make the process of whitening teeth safer,

Most people would like to flash a smile of pearly whites, but over time teeth can become stained by foods, beverages and some medications. Unfortunately, the high levels of hydrogen peroxide in dentists’ bleaching treatments can damage enamel and cause tooth sensitivity and gum irritation. Now, researchers reporting in ACS Applied Materials & Interfaces have developed a gel that, when exposed to near infrared (NIR) light, safely whitens teeth without the burn.

Caption: A new bleaching gel whitened tooth samples by six shades, using a low level of hydrogen peroxide (12%). Credit: Adapted from ACS Applied Materials & Interfaces 2021, DOI: 10.1021/acsami.1c06774

A September 8, 2021Amercian Chemical Society (ACS) news release (also on EurekAlert), which originated the news item, provides more detail,

The growing demand for selfie-ready smiles has made tooth whitening one of the most popular dental procedures. Treatments at a dentist’s office are effective, but they use high-concentration hydrogen peroxide (30–40%). Home bleaching products contain less peroxide (6–12%), but they usually require weeks of treatment and don’t work as well. When a bleaching gel is applied to teeth, hydrogen peroxide and peroxide-derived reactive oxygen species (mainly the hydroxyl radical) degrade pigments in stains. The hydroxyl radical is much better at doing this than hydrogen peroxide itself, so researchers have tried to improve the bleaching capacity of low-concentration hydrogen peroxide by boosting the generation of powerful hydroxyl radicals. Because previous approaches have had limitations, Xingyu Hu, Li Xie, Weidong Tian and colleagues wanted to develop a safe, effective whitening gel containing a catalyst that, when exposed to NIR light, would convert low levels of hydrogen peroxide into abundant hydroxyl radicals.

The researchers made oxygen-deficient titania nanoparticles that catalyzed hydroxyl radical production from hydrogen peroxide. Exposing the nanoparticles to NIR light increased their catalytic activity, allowing them to completely bleach tooth samples stained with orange dye, tea or red dye within 2 hours. Then, the researchers made a gel containing the nanoparticles, a carbomer gel and 12% hydrogen peroxide. They applied it to naturally stained tooth samples and treated them with NIR light for an hour. The gel bleached teeth just as well as a popular tooth whitening gel containing 40% hydrogen peroxide, with less damage to enamel. The nanoparticle system is highly promising for tooth bleaching and could also be extended to other biomedical applications, such as developing antibacterial materials, the researchers say.

The authors acknowledge funding from the National Natural Science Foundation of China, the National Key R&D Program of China and the Key Technologies R&D Program of Sichuan Province.

Here’s a link to and a citation for the paper,

Photothermal-Enhanced Fenton-like Catalytic Activity of Oxygen-Deficient Nanotitania for Efficient and Safe Tooth Whitening by Xingyu Hu, Li Xie, Zhaoyu Xu, Suru Liu, Xinzhi Tan, Ruojing Qian, Ruitao Zhang, Mingyan Jiang, Wenjia Xie, and Weidong Tian. ACS Appl. Mater. Interfaces 2021, 13, 30, 35315–35327 Publication Date: July 22, 2021 DOI: https://doi.org/10.1021/acsami.1c06774 Copyright © 2021 American Chemical Society

This paper is behind a paywall.

Cerium-containing nanoparticles in microneedle patches for hair regrowth (a treatment for baldness?)

It’s still being tested but according to an August 11, 2021 news item on ScienceDaily, this is a promising treatment for baldness,

Although some people say that baldness is the “new sexy,” for those losing their hair, it can be distressing. An array of over-the-counter remedies are available, but most of them don’t focus on the primary causes: oxidative stress and insufficient circulation. Now, researchers reporting in ACS Nano have designed a preliminary microneedle patch containing cerium nanoparticles to combat both problems, regrowing hair in a mouse model faster than a leading treatment.

An August 11, 2021 American Chemical Society (ACS) news release (also on EurekAlert) provides more detail (Note: Links have been removed),

The most common hair loss condition is called androgenic alopecia, also known as male- or female- pattern baldness. Hair loss is permanent for people with the condition because there aren’t enough blood vessels surrounding the follicles to deliver nutrients, cytokines and other essential molecules. In addition, an accumulation of reactive oxygen species in the scalp can trigger the untimely death of the cells that form and grow new hair. Previously, Fangyuan Li, Jianqing Gao and colleagues determined that cerium-containing nanoparticles can mimic enzymes that remove excess reactive oxygen species, which reduced oxidative stress in liver injuries, wounds and Alzheimer’s disease. However, these nanoparticles cannot cross the outermost layer of skin. So, the researchers wanted to design a minimally invasive way to deliver cerium-containing nanoparticles near hair roots deep under the skin to promote hair regrowth.

As a first step, the researchers coated cerium nanoparticles with a biodegradable polyethylene glycol-lipid compound. Then they made the dissolvable microneedle patch by pouring a mixture of hyaluronic acid — a substance that is naturally abundant in human skin — and cerium-containing nanoparticles into a mold. The team tested control patches and the cerium-containing ones on male mice with bald spots formed by a hair removal cream. Both applications stimulated the formation of new blood vessels around the mice’s hair follicles. However, those treated with the nanoparticle patch showed faster signs of hair undergoing a transition in the root, such as earlier skin pigmentation and higher levels of a compound found only at the onset of new hair development. These mice also had fewer oxidative stress compounds in their skin. Finally, the researchers found that the cerium-containing microneedle patches resulted in faster mouse hair regrowth with similar coverage, density and diameter compared with a leading topical treatment and could be applied less frequently. Microneedle patches that introduce cerium nanoparticles into the skin are a promising strategy to reverse balding for androgenetic alopecia patients, the researchers say.

The authors acknowledge funding from the Ten-thousand Talents Program of Zhejiang Province, National Key R&D Program of China, National Natural Science Foundation of China, One Belt and One Road International Cooperation Project from the Key Research and Development Program of Zhejiang Province, Fundamental Research Funds for the Central Universities and Zhejiang Provincial Natural Science Foundation of China.

Here’s a link to and a citation for the paper,

Ceria Nanozyme-Integrated Microneedles Reshape the Perifollicular Microenvironment for Androgenetic Alopecia Treatment by Anran Yuan, Fan Xia, Qiong Bian, Haibin Wu, Yueting Gu, Tao Wang, Ruxuan Wang, Lingling Huang, Qiaoling Huang, Yuefeng Rao, Daishun Ling, Fangyuan Li, and Jianqing Gao. ACS Nano 2021, XXXX, XXX, XXX-XXX DOI: https://doi.org/10.1021/acsnano.1c05272 Publication Date:July 19, 2021 © 2021 American Chemical Society

This paper is behind a paywall.

Precision skincare

An inkjet printer for your skin—it’s an idea I’m not sure I’m ready for. Still, I’m not the target market for the product being described in Rachel Kim Raczka’s June 2, 2021 article for Fast Company (Note: Links have been removed),

… I’ve had broken capillaries, patchy spots, and enlarged pores most of my adult life. And after I turned 30, I developed a glorious strip of melasma (a “sun mustache”) across my upper lip. The delicate balance of maintaining my “good” texture—skin that looks like skin—while disguising my “bad” texture is a constant push and pull. Still, I continue to fall victim to “no makeup” makeup, the frustratingly contradictory trend that will never die. A white whale that $599 high-tech beauty printer Opte hopes to fill.

Weirdly enough, “printer” is a fair representation of what Opte is. The size and shape of an electric razor, Opte’s Precision Wand’s tiny computer claims to detect and camouflage hyperpigmentation with a series of gentle swipes. The product deposits extremely small blends of white, yellow, and red pigments to hide discoloration using a blue LED and a hypersensitive camera that scans 200 photos per second. Opte then relies on an algorithm to apply color—housed in replaceable serum cartridges, delivered through 120 thermal inkjet nozzles—only onto contrasting patches of melanin via what CEO Matt Petersen calls “the world’s smallest inkjet printer.” 

Opte is a 15-year, 500,000-R&D-hour project developed under P&G Ventures, officially launched in 2020. While targeting hyperpigmentation was an end goal, the broader mission looked at focusing on “precision skincare.” …

… You start by dropping the included 11-ingredient serum cartridge into the pod; the $129 cartridges and refills come in three shades that the company says cover 98% of skin tones and last 90 days. The handheld device very loudly refills itself and displays instructions on a tiny screen on its handle. …

… While I can’t rely on the Opte to hide a blemish or dark circles—I’ll still need concealer to achieve that level of coverage—I can’t quite describe the “glowiness” using this gadget generates. With more use, I’ve come to retrain my brain to expect Opte to work more like an eraser than a crayon; it’s skincare, not makeup. My skin looks healthier and brighter but still, without a doubt, like my skin. 

There’s more discussion of how this product works in Raczka’s June 2, 2021 article and you can find the Opte website here. I have no idea if they ship this product outside the US or what that might cost.

Sunscreens 2020 and the Environmental Working Group (EWG)

There must be some sweet satisfaction or perhaps it’s better described as relief for the Environmental Working Group (EWG) now that sunscreens with metallic (zinc oxide and/or titanium dioxide) nanoparticles are gaining wide acceptance. (More about the history and politics EWG and metallic nanoparticles at the end of this posting.)

This acceptance has happened alongside growing concerns about oxybenzone, a sunscreen ingredient that EWG has long warned against. Oxybenzone has been banned from use in Hawaii due to environmental concerns (see my July 6, 2018 posting; scroll down about 40% of the way for specifics about Hawaii). Also, it is one of the common sunscreen ingredients for which the US Food and Drug Administration (FDA) is completing a safety review.

Today, zinc oxide and titanium dioxide metallic nanoparticles are being called minerals, as in, “mineral-based” sunscreens. They are categorized as physical sunscreens as opposed to chemical sunscreens.

I believe the most recent sunscreen posting here was my 2018 update (uly 6, 2018 posting) so the topic is overdue for some attention here. From a May 21, 2020 EWG news release (received via email),

As states reopen and Americans leave their homes to venture outside, it’s important for them to remember to protect their skin from the sun’s harmful rays. Today the Environmental Working Group released its 14th annual Guide to Sunscreens.  

This year researchers rated the safety and efficacy of more than 1,300 SPF products – including sunscreens, moisturizers and lip balms – and found that only 25 percent offer adequate protection and do not contain worrisome ingredients such as oxybenzone, a potential hormone-disrupting chemical that is readily absorbed by the body.

Despite a delay in finalizing rules that would make all sunscreens on U.S. store shelves safer, the Food and Drug Administration, the agency that governs sunscreen safety, is completing tests that highlight concerns with common sunscreen ingredients. Last year, the agency published two studies showing that, with just a single application, six commonly used chemical active ingredients, including oxybenzone, are readily absorbed through the skin and could be detected in our bodies at levels that could cause harm.

“It’s quite concerning,” said Nneka Leiba, EWG’s vice president of Healthy Living science. “Those studies don’t prove whether the sunscreens are unsafe, but they do highlight problems with how these products are regulated.”

“EWG has been advocating for the FDA to review these chemical ingredients for 14 years,” Leiba said. “We slather these ingredients on our skin, but these chemicals haven’t been adequately tested. This is just one example of the backward nature of product regulation in the U.S.”

Oxybenzone remains a commonly used active ingredient, found in more than 40 percent of the non-mineral sunscreens in this year’s guide. Oxybenzone is allergenic and a potential endocrine disruptor, and has been detected in human breast milk, amniotic fluid, urine and blood.

According to EWG’s assessment, fewer than half of the products in this year’s guide contain active ingredients that the FDA has proposed are safe and effective.

“Based on the best current science and toxicology data, we continue to recommend sunscreens with the mineral active ingredients zinc dioxide and titanium dioxide, because they are the only two ingredients the FDA recognized as safe or effective in their proposed draft rules,” said Carla Burns, an EWG research and database analyst who manages the updates to the sunscreen guide.

Most people select sunscreen products based on their SPF, or sunburn protection factor, and mistakenly assume that bigger numbers offer better protection. According to the FDA, higher SPF values have not been shown to provide additional clinical benefit and may give users a false sense of protection. This may lead to overexposure to UVA rays that increase the risk of long-term skin damage and cancer. The FDA has proposed limiting SPF claims to 60+.

EWG continues to hone our recommendations by strengthening the criteria for assessing sunscreens, which are based on the latest findings in the scientific literature and commissioned tests of sunscreen product efficacy. This year EWG made changes to our methodology in order to strengthen our requirement that products provide the highest level of UVA protection.

“Our understanding of the dangers associated with UVA exposure is increasing, and they are of great concern,” said Burns. “Sunburn during early life, especially childhood, is very dangerous and a risk factor for all skin cancers, but especially melanoma. Babies and young children are especially vulnerable to sun damage. Just a few blistering sunburns early in life can double a person’s risk of developing melanoma later in life.”

EWG researchers found 180 sunscreens that meet our criteria for safety and efficacy and would likely meet the proposed FDA standards. Even the biggest brands now provide mineral options for consumers.  

Even for Americans continuing to follow stay-at-home orders, wearing an SPF product may still be important. If you’re sitting by a window, UVA and UVB rays can penetrate the glass.  

It is important to remember that sunscreen is only one part of a sun safety routine. People should also protect their skin by covering up with clothing, hats and sunglasses. And sunscreen must be reapplied at least every two hours to stay effective.

EWG’s Guide to Sunscreens helps consumers find products that get high ratings for providing adequate broad-spectrum protection and that are made with ingredients that pose fewer health concerns.

The new guide also includes lists of:

Here are more quick tips for choosing better sunscreens:

  • Check your products in EWG’s sunscreen database and avoid those with harmful ingredients.
  • Avoid products with oxybenzone. This chemical penetrates the skin, gets into the bloodstream and can affect normal hormone activities.
  • Steer clear of products with SPF higher than 50+. High SPF values do not necessarily provide increased UVA protection and may fool you into thinking you are safe from sun damage.
  • Avoid sprays. These popular products pose inhalation concerns, and they may not provide a thick and uniform coating on the skin.
  • Stay away from retinyl palmitate. Government studies link the use of retinyl palmitate, a form of vitamin A, to the formation of skin tumors and lesions when it is applied to sun-exposed skin.
  • Avoid intense sun exposure during the peak hours of 10 a.m. to 4 p.m.

Shoppers on the go can download EWG’s Healthy Living app to get ratings and safety information on sunscreens and other personal care products. Also be sure to check out EWG’s sunscreen label decoder.

One caveat, these EWG-recommended products might not be found in Canadian stores or your favourite product may not have been reviewed for inclusion, as a product to be sought out or avoided, in their database. For example, I use a sunscreen that isn’t listed in the database, although at least a few other of the company’s sunscreen products are. On the plus side, my sunscreen doesn’t include oxybenzone or retinyl palmitate as ingredients.

To sum up the situation with sunscreens containing metallic nanoparticles (minerals), they are considered to be relatively safe but should new research emerge that designation could change. In effect, all we can do is our best with the information at hand.

History and politics of metallic nanoparticles in sunscreens

In 2009 it was a bit of a shock when the EWG released a report recommending the use of sunscreens with metallic nanoparticles in the list of ingredients. From my July 9, 2009 posting,

The EWG (Environmental Working Group) is, according to Maynard [as of 20202: Dr. Andrew Maynard is a scientist and author, Associate Director of Faculty in the ASU {Arizona State University} School for the Future of Innovation in Society, also the director of the ASU Risk Innovation Lab, and leader of the Risk Innovation Nexus], not usually friendly to industry and they had this to say about their own predisposition prior to reviewing the data (from EWG),

When we began our sunscreen investigation at the Environmental Working Group, our researchers thought we would ultimately recommend against micronized and nano-sized zinc oxide and titanium dioxide sunscreens. After all, no one has taken a more expansive and critical look than EWG at the use of nanoparticles in cosmetics and sunscreens, including the lack of definitive safety data and consumer information on these common new ingredients, and few substances more dramatically highlight gaps in our system of public health protections than the raw materials used in the burgeoning field of nanotechnology. But many months and nearly 400 peer-reviewed studies later, we find ourselves drawing a different conclusion, and recommending some sunscreens that may contain nano-sized ingredients.

My understanding is that after this report, the EWG was somewhat ostracized by collegial organizations. Friends of the Earth (FoE) and the ETC Group both of which issued reports that were published after the EWG report and were highly critical of ‘nano sunscreens’.

The ETC Group did not continue its anti nanosunscreen campaign for long (I saw only one report) but FoE (in particular the Australian arm of the organization) more than made up for that withdrawal and to sad effect. My February 9, 2012 post title was this: Unintended consequences: Australians not using sunscreens to avoid nanoparticles?

An Australian government survey found that 13% of Australians were not using any sunscreen due to fears about nanoparticles. In a country with the highest incidence of skin cancer in the world and, which spent untold millions over decades getting people to cover up in the sun, it was devastating news.

FoE immediately withdrew all their anti nanosunscreen materials in Australia from circulation while firing broadsides at the government. The organization’s focus on sunscreens with metallic nanoparticles has diminished since 2012.

Research

I have difficulty trusting materials from FoE and you can see why here in this July 26, 2011 posting (Misunderstanding the data or a failure to research? Georgia Straight article about nanoparticles). In it, I analyze Alex Roslin’s profoundly problematic article about metallic nanoparticles and other engineered nanoparticles. All of Roslin’s article was based on research and materials produced by FoE which misrepresented some of the research. Roslin would have realized that if he had bothered to do any research for himself.

EWG impressed me mightily with their refusal to set aside or dismiss the research disputing their initial assumption that metallic nanoparticles in sunscreens were hazardous. (BTW, there is one instance where metallic nanoparticles in sunscreens are of concern. My October 13, 2013 posting about anatase and rutile forms of titanium dioxide at the nanoscale features research on that issue.)

EWG’s Wikipedia entry

Whoever and however many are maintaining this page, they don’t like EWG at all,

The accuracy of EWG reports and statements have been criticized, as has its funding by the organic food industry[2][3][4][5] Its warnings have been labeled “alarmist”, “scaremongering” and “misleading”.[6][7][8] Despite the questionable status of its work, EWG has been influential.[9]

This is the third paragraph in the Introduction. At its very best, the information is neutral, otherwise, it’s much like that third paragraph.

Even John D. Rockeller’s entry is more flattering and he was known as the ‘most hated man in America’ as this show description on the Public Broadcasting Service (PBS) website makes clear,

American Experience

The Rockefellers Chapter One

Clip: Season 13 Episode 1 | 9m 37s

John D. Rockefeller was the world’s first billionaire and the most hated man in America. Watch the epic story of the man who monopolized oil.

Fun in the sun

Have fun in the sun this summer. There’s EWG’s sunscreen database, the tips listed in the news release, and EWG also has a webpage where they describe their methodology for how they assess sunscreens. It gets a little technical (for me anyway) but it should answer any further safety questions you might have after reading this post.

It may require a bit of ingenuity given the concerns over COVID-19 but I’m constantly amazed at the inventiveness with which so many people have met this pandemic. (This June 15, 2020 Canadian Broadcasting Corporation article by Sheena Goodyear features a family that created a machine that won the 2020 Rube Goldberg Bar of Soap Video challenge. The article includes an embedded video of the winning machine in action.)

Replacing human tissue with nanostructured rubber-like material?

The scientists started out with an idea for creating a bone-like material)and ended up with something completely different. A March 16, 2020 news item on ScienceDaily announces news about a new material that could be used to replace human tissue,

Researchers from Chalmers University of Technology, Sweden, have created a new, rubber-like material with a unique set of properties, which could act as a replacement for human tissue in medical procedures. The material has the potential to make a big difference to many people’s lives. The research was recently published in the highly regarded scientific journal ACS Nano.

In the development of medical technology products, there is a great demand for new naturalistic materials suitable for integration with the body. Introducing materials into the body comes with many risks, such as serious infections, among other things. Many of the substances used today, such as Botox, are very toxic. There is a need for new, more adaptable materials.

In the new study, the Chalmers researchers developed a material consisting solely of components that have already been shown to work well in the body.

A March 17, 2020 Chalmers University of Technology press release (also on EurekAlert but published on March 16, 2020), which originated the news item, describes the scientists’ surprising discovery and how they shifted their focus,

The foundation of the material is the same as plexiglass, a material which is common in medical technology applications. Through redesigning its makeup, and through a process called nanostructuring, they gave the newly patented material a unique combination of properties. The researchers’ initial intention was to produce a hard bone-like material, but they were met with surprising results.

“We were really surprised that the material turned to be very soft, flexible and extremely elastic. It would not work as a bone replacement material, we concluded. But the new and unexpected properties made our discovery just as exciting,” says Anand Kumar Rajasekharan, PhD in Materials Science and one of the researchers behind the study.

The results showed that the new rubber-like material may be appropriate for many applications which require an uncommon combination of properties – high elasticity, easy processability, and suitability for medical uses.

“The first application we are looking at now is urinary catheters. The material can be constructed in such a way that prevents bacteria from growing on the surface, meaning it is very well suited for medical uses,” says Martin Andersson, research leader for the study and Professor of Chemistry at Chalmers.

The structure of the new nano-rubber material allows its surface to be treated so that it becomes antibacterial, in a natural, non-toxic way. This is achieved by sticking antimicrobial peptides – small proteins which are part of our innate immune system – onto its surface. This can help reduce the need for antibiotics, an important contribution to the fight against growing antibiotic resistance.

Because the new material can be injected and inserted via keyhole surgery, it can also help reduce the need for drastic surgery and operations to rebuild parts of the body. The material can be injected via a standard cannula as a viscous fluid, so that it forms its own elastic structures within the body. Or, the material can also be 3D printed into specific structures as required.

“There are many diseases where the cartilage breaks down and friction results between bones, causing great pain for the affected person. This material could potentially act as a replacement in those cases,” Martin Andersson continues.

A further advantage of the material is that it contains three-dimensionally ordered nanopores. This means it can be loaded with medicine, for various therapeutic purposes such as improving healing and reducing inflammation. This allows for localised treatment, avoiding, for example, having to treat the entire body with drugs, something that could help reduce problems associated with side effects. Since it is non-toxic, it also works well as a filler – the researchers see plastic surgery therefore as another very interesting potential area of application for the new material.

“I am now working full time with our newly founded company, Amferia, to get the research out to industry. I have been pleased to see a lot of real interest in our material. It’s promising in terms of achieving our goal, which is to provide real societal benefit,” Anand concludes.

The path of the research to societal benefit and commercialisation, through start-up company Amferia and Chalmers Ventures

In order for the discovery of the new material to be useful and commercialised, the researchers patented their innovation before the study was published. The patent is owned by start-up company Amferia, which was founded by Martin Andersson and Anand Kumar Rajasekharan, two of the researchers behind the study, as well as researcher Saba Atefyekta who recently completed a PhD in Materials Science at Chalmers. Anand is now CEO of Amferia and will drive the application of the new material and development of the company.

Amferia has previously been noted for an antibacterial wound patch developed by the same team. Amferia now has the innovation of both the new nano-rubber and the antibacterial wound patch. The development of the company and the innovations’ path to making profit are now being carried out in collaboration with Chalmers Ventures, a subsidiary of Chalmers University of Technology.

Here’s a link to and a citation for the paper,

Tough Ordered Mesoporous Elastomeric Biomaterials Formed at Ambient Conditions by Anand K. Rajasekharan, Christoffer Gyllensten, Edvin Blomstrand, Marianne Liebi, Martin Andersson. ACS Nano 2020, 14, 1, 241-254 DOI: https://doi.org/10.1021/acsnano.9b01924 Publication Date:December 17, 2019 Copyright © 2019 American Chemical Society

This paper is behind a paywall.

Get better protection from a sunscreen with a ‘flamenco dancing’ molecule?

Caption: illustrative image for the University of Warwick research on ‘Flamenco dancing’ molecule could lead to better-protecting sunscreen created by Dr. Michael Horbury. Credit:: created by Dr Michael Horbury

There are high hopes (more about why later) for a plant-based ‘flamenco dancing molecule’ and its inclusion in sunscreens as described in an October 18, 2019 University of Warwick press release (also on EurekAlert),

A molecule that protects plants from overexposure to harmful sunlight thanks to its flamenco-style twist could form the basis for a new longer-lasting sunscreen, chemists at the University of Warwick have found, in collaboration with colleagues in France and Spain. Research on the green molecule by the scientists has revealed that it absorbs ultraviolet light and then disperses it in a ‘flamenco-style’ dance, making it ideal for use as a UV filter in sunscreens.

The team of scientists report today, Friday 18th October 2019, in the journal Nature Communications that, as well as being plant-inspired, this molecule is also among a small number of suitable substances that are effective in absorbing light in the Ultraviolet A (UVA) region of wavelengths. It opens up the possibility of developing a naturally-derived and eco-friendly sunscreen that protects against the full range of harmful wavelengths of light from the sun.

The UV filters in a sunscreen are the ingredients that predominantly provide the protection from the sun’s rays. In addition to UV filters, sunscreens will typically also include:

Emollients, used for moisturising and lubricating the skin
Thickening agents
Emulsifiers to bind all the ingredients
Water
Other components that improve aesthetics, water resistance, etc.

The researchers tested a molecule called diethyl sinapate, a close mimic to a molecule that is commonly found in the leaves of plants, which is responsible for protecting them from overexposure to UV light while they absorb visible light for photosynthesis.

They first exposed the molecule to a number of different solvents to determine whether that had any impact on its (principally) light absorbing behaviour. They then deposited a sample of the molecule on an industry standard human skin mimic (VITRO-CORNEUM®) where it was irradiated with different wavelengths of UV light. They used the state-of-the-art laser facilities within the Warwick Centre for Ultrafast Spectroscopy to take images of the molecule at extremely high speeds, to observe what happens to the light’s energy when it’s absorbed in the molecule in the very early stages (millionths of millionths of a second). Other techniques were also used to establish longer term (many hours) properties of diethyl sinapate, such as endocrine disruption activity and antioxidant potential.

Professor Vasilios Stavros from the University of Warwick, Department of Chemistry, who was part of the research team, explains: “A really good sunscreen absorbs light and converts it to harmless heat. A bad sunscreen is one that absorbs light and then, for example, breaks down potentially inducing other chemistry that you don’t want. Diethyl sinapate generates lots of heat, and that’s really crucial.”

When irradiated the molecule absorbs light and goes into an excited state but that energy then has to be disposed of somehow. The team of researchers observed that it does a kind of molecular ‘dance’ a mere 10 picoseconds (ten millionths of a millionth of a second) long: a twist in a similar fashion to the filigranas and floreos hand movements of flamenco dancers. That causes it to come back to its original ground state and convert that energy into vibrational energy, or heat.

It is this ‘flamenco dance’ that gives the molecule its long-lasting qualities. When the scientists bombarded the molecule with UVA light they found that it degraded only 3% over two hours, compared to the industry requirement of 30%.

Dr Michael Horbury, who was a Postgraduate Research Fellow at The University Warwick when he undertook this research (and now at the University of Leeds) adds: “We have shown that by studying the molecular dance on such a short time-scale, the information that you gain can have tremendous repercussions on how you design future sunscreens.
Emily Holt, a PhD student in the Department of Chemistry at the University of Warwick who was part of the research team, said: “The next step would be to test it on human skin, then to mix it with other ingredients that you find in a sunscreen to see how those affect its characteristics.”

Professor Florent Allais and Dr Louis Mouterde, URD Agro-Biotechnologies Industrielles at AgroParisTech (Pomacle, France) commented: “What we have developed together is a molecule based upon a UV photoprotective molecule found in the surface of leaves on a plant and refunctionalised it using greener synthetic procedures. Indeed, this molecule has excellent long-term properties while exhibiting low endocrine disruption and valuable antioxidant properties.”

Professor Laurent Blasco, Global Technical Manager (Skin Essentials) at Lubrizol and Honorary Professor at the University of Warwick commented: “In sunscreen formulations at the moment there is a lack of broad-spectrum protection from a single UV filter. Our collaboration has gone some way towards developing a next generation broad-spectrum UV filter inspired by nature. Our collaboration has also highlighted the importance of academia and industry working together towards a common goal.”

Professor Vasilios Stavros added, “Amidst escalating concerns about their impact on human toxicity (e.g. endocrine disruption) and ecotoxicity (e.g. coral bleaching), developing new UV filters is essential. We have demonstrated that a highly attractive avenue is ‘nature-inspired’ UV filters, which provide a front-line defence against skin cancer and premature skin aging.”

Here’s a link to and a citation for the paper,

Towards symmetry driven and nature inspired UV filter design by Michael D. Horbury, Emily L. Holt, Louis M. M. Mouterde, Patrick Balaguer, Juan Cebrián, Laurent Blasco, Florent Allais & Vasilios G. Stavros. Nature Communications volume 10, Article number: 4748 (2019) DOI: https://doi.org/10.1038/s41467-019-12719-z

This paper is open access.

Why the high hopes?

Briefly (the long story stretches over 10 years), the most recommended sunscreens today (2020) are ‘mineral-based’. This is painfully amusing because civil society groups (activists) such as Friends of the Earth (in particular the Australia chapter under Georgia Miller’s leadership) and Canada’s own ETC Group had campaigned against these same sunscreen when they were billed as being based on metal oxide nanoparticles such zinc oxide and/or titanium oxide. The ETC Group under Pat Roy Mooney’s leadership didn’t press the campaign after an initial push. As for Australia and Friend of the Earth, their anti-metallic oxide nanoparticle sunscreen campaign didn’t work out well as I noted in a February 9, 2012 posting and with a follow-up in an October 31, 2012 posting.

The only civil society group to give approval (very reluctantly) was the Environmental Working Group (EWG) as I noted in a July 9, 2009 posting. They had concerns about the fact that these ingredients are metallic but after a thorough of then available research, EWG gave the sunscreens a passing grade and noted, in their report, that they had more concerns about the use of oxybenzone in sunscreens. That latter concern has since been flagged by others (e.g., the state of Hawai’i) as noted in my July 6, 2018 posting.

So, rebranding metallic oxides as minerals has allowed the various civil society groups to support the very same sunscreens many of them were advocating against.

In the meantime, scientists continue work on developing plant-based sunscreens as an improvement to the ‘mineral-based’ sunscreens used now.

Needle-free tattoos, smart and otherwise

Before getting to the research news from the University of Twente (Netherlands), there’s this related event which took place on April 18, 2019 (from the Future Under Our Skin webpage (on the University of Twente website) Note: I have made some formatting changes,

Why this event?

Our skin can give information about our health, mood and surroundings. Medical and recreational tattoos have decorated humans for centuries. But we can inject other materials besides ink, such as sensing devices, nano- or bio-responsive materials. With the increased percentage of tattooed population in recent years new health challenges have emerged; but is also a unique possibility to “read from our own skin”, beyond an artistic design. 
 
We have invited scientists, innovators, entrepreneurs, dermatologists, cosmetic permanent make-up technicians, tattoo artists, philosophers, and other experts. They will share with us their vision of the current and future role our skin has for improving the quality of life.

Open Event

This event is open to students, citizens in general as well as societal and governmental organisations around the different uses of our skin. The presence of scientists, medical doctors, tattoo artists and industry representatives is guaranteed. Then, we will all explore together the potential for co-creation with healthy citizens, patients, entreprises and other stakeholders.


If you want to hear from experts and share your own ideas, feel free to come to this Open Event!
 
It is possible to take the dish of the day (‘goed gevulde noedels met kippendij en satésaus en kroepoek’) in restaurant The Gallery (same building as DesignLab) at own costs (€7,85). Of course it is also possible to eat à la carte in Grand Café 

Wanneer: : 18 april 2019
Tijd: :17:30 – 20:00
Organisator: University of Twente
Locatie: Design Lab University of Twente
Hengelosestraat 500
7521 AN Enschede

Just days before, the University of Twente announced this research in an April 16, 2019 news item on Naowerk (Note: A link has been removed),

A tattoo that is warning you for too many hours of sunlight exposure, or is alerting you for taking your medication? Next to their cosmetic role, tattoos could get new functionality using intelligent ink. That would require more precise and less invasive injection technique.

Researchers of the University of Twente now develop a micro-jet injection technology that doesn’t use needles at all. Instead, an ultrafast liquid jet with the thickness of a human hair penetrates the skin. It isn’t painful and there is less waste.

In their new publication in the American Journal of Physics (“High speed imaging of solid needle and liquid micro-jet injections”), the scientists compare both the needle and the fluid jet approach.

Here’s an image provided by the researchers which illustrates the technique they have developed,

Working principle of needle-free injection: laser heating the fluid.The growing bubble pushes out the fluid (medicine or ink) at very high speed. Courtesy: University of Twente

An April 15, 2019 University of Twente press release, which originated the news item, provides more detail about tattoos and the research leading to ‘need-free’ tattoos,

Ötzi the Iceman already had, over 5000 years ago, dozens of simple tattoos on his body, apparently for pain relief. Since the classic ‘anchor’ tattoo that sailors had on their arms, tattoos have become more and more common. About 44 million Europeans wear one or more of them. Despite its wider acceptance in society, the underlying technique didn’t change and still has health risks. One or more moving needles put ink underneath the skin surface. This is painful and can damage the skin. Apart from that, needles have to be disposed of in a responsible way, and quite some ink is wasted. The alternative that David Fernández Rivas and his colleagues are developing, doesn’t use any needles. In their new paper, they compare this new approach with classic needle technology, on an artificial skin material and using high speed images. Remarkably, according to Fernández Rivas, the classic needle technology has never been subject of research in such a thorough way, using high speed images.

Fast fluid jet

The new technique employs a laser for rapidly heating a fluid that is inside a microchannel on a glass chip. Heated above the boiling point, a vapour bubble forms and grows, pushing the liquid out at speeds up to 100 meter per second (360 km/h). The jet, about the diameter of a human hair, is capable of going through human skin. “You don’t feel much of it, no more than a mosquito bite”, say Fernandez Rivas.

The researchers did their experiments with a number of commercially available inks. Compared to a tattoo machine, the micro-jet consumes a small amount of energy. What’s more important, it minimizes skin damage and the injection efficiency is much higher, there is no loss of fluids. And there is no risk of contaminated needles. The current microjet is a single one, while tattooing is often done using multiple needles with different types or colours of ink. Also, the volume that can be ‘delivered’ by the microjet has to be increased. These are next steps in developing the needle-free technology.

Skin treatment

In today’s medical world, tattoo-resembling techniques are used for treatment of skin, masking scars, or treating hair diseases. These are other areas in which the new technique can be used, as well as in vaccination. A challenging idea is using tattoos for cosmetic purposes and as health sensors at the same time. What if ink is light-sensitive or responds to certain substances that are present in the skin or in sweat?

On this new approach, scientists, students, entrepreneurs and tattoo artists join a special event ‘The future under our skin’, organized by David Fernandez Rivas.

Research has been done in the Mesoscale Chemical Systems group, part of UT’s MESA+ Institute.

Here’s a link to an d a citation for the paper,

High speed imaging of solid needle and liquid micro-jet injections by Loreto Oyarte Gálveza, Maria Brió Pérez, and David Fernández Rivas. Journal of Applied Physics 125, 144504 (2019); Volume 125, Issue 14 DOI: 10.1063/1.5074176 https://doi.org/10.1063/1.5074176 Free Published Online: 09 April 2019

This paper appears to be open access.

Real-time tracking of UV (ultraviolet light) exposure for all skin types (light to dark)

It’s nice to find this research after my August 21, 2018 posting where I highlighted (scroll down to ‘Final comments’) the issues around databases and skin cancer data which is usually derived from fair-skinned people while people with darker hues tend not to be included. This is partly due to the fact that fair-skinned people have a higher risk and also partly due to myths about how more melanin in your skin somehow protects you from skin cancer.

This October 4, 2018 news item on ScienceDaily announces research into a way to track UV exposure for all skin types,

Researchers from the University of Granada [Spain] and RMIT University in Melbourne [Australia] have developed personalised and low-cost wearable ultraviolet (UV) sensors that warn users when their exposure to the sun has become dangerous.

The paper-based sensor, which can be worn as a wristband, features happy and sad emoticon faces — drawn in an invisible UV-sensitive ink — that successively light up as you reach 25%, 50%, 75% and finally 100% of your daily recommended UV exposure.

The research team have also created six versions of the colour-changing wristbands, each of which is personalised for a specific skin tone  [emphasis mine]– an important characteristic given that darker people need more sun exposure to produce vitamin D, which is essential for healthy bones, teeth and muscles.

An October 2, 2018 University of Granada press release (also on EurekAlert) delves further,

Four of the wristbands, each of which indicates a different stage of exposure to UV radiation (25%, 50%, 75% and 100%)

The emoticon faces on the wristband successively “light up” as exposure to UV radiation increases

Skin cancer, one of the most common types of cancer throughout the world, is primarily caused by overexposure to ultraviolet radiation (UVR). In Spain, over 74,000 people are diagnosed with non-melanoma skin cancer every year, while a further 4,000 are diagnosed with melanoma skin cancer. In regions such as Australia, where the ozone layer has been substantially depleted, it is estimated that approximately 2 in 3 people will be diagnosed with skin cancer by the time they reach the age of 70.

“UVB and UVC radiation is retained by the ozone layer. This sensor is especially important in the current context, given that the hole in the ozone layer is exposing us to such dangerous radiation”, explains José Manuel Domínguez Vera, a researcher at the University of Granada’s Department of Inorganic Chemistry and the main author of the paper.

Domínguez Vera also highlights that other sensors currently available on the market only measure overall UV radiation, without distinguishing between UVA, UVB and UVC, each of which has a significantly different impact on human health.  In contrast, the new paper-based sensor can differentiate between UVA, UVB and UVC radiation. Prolonged exposure to UVA radiation is associated with skin ageing and wrinkling, while excessive exposure to UVB causes sunburn and increases the likelihood of skin cancer and eye damage.

Drawbacks of the traditional UV index

Ultraviolet radiation is determined by aspects such as location, time of day, pollution levels, astronomical factors, weather conditions such as clouds, and can be heightened by reflective surfaces like bodies of water, sand and snow. But UV rays are not visible to the human eye (even if it is cloudy UV radiation can be high) and until now the only way of monitoring UV intensity has been to use the UV index, which is standardly given in weather reports and indicates 5 degrees of radiation;  low, moderate, high, very high or extreme.

Despite its usefulness, the UV index is a relatively limited tool. For instance, it does not clearly indicate what time of the day or for how long you should be outside to get your essential vitamin D dose, or when to cover up to avoid sunburn and a heightened risk of skin cancer.

Moreover, the UV index is normally based on calculations for fair skin, making it unsuitable for ethnically diverse populations.  While individuals with fairer skin are more susceptible to UV damage, those with darker skin require much longer periods in the sun in order to absorb healthy amounts of vitamin D. In this regard, the UV index is not an accurate tool for gauging and monitoring an individual’s recommended daily exposure.

UV-sensitive ink

The research team set out to tackle the drawbacks of the traditional UV index by developing an inexpensive, disposable and personalised sensor that allows the wearer to track their UV exposure in real-time. The sensor paper they created features a special ink, containing phosphomolybdic acid (PMA), which turns from colourless to blue when exposed to UV radiation. They can use the initially-invisible ink to draw faces—or any other design—on paper and other surfaces. Depending on the type and intensity of the UV radiation to which the ink is exposed, the paper begins to turn blue; the greater the exposure to UV radiation, the faster the paper turns blue.

Additionally, by tweaking the ink composition and the sensor design, the team were able to make the ink change colour faster or slower, allowing them to produce different sensors that are tailored to the six different types of skin colour. [emphasis mine]

Applications beyond health

This low-cost, paper-based sensor technology will not only help people of all colours to strike an optimum balance between absorbing enough vitamin D and avoiding sun damage — it also has significant applications for the agricultural and industrial sectors. UV rays affect the growth of crops and the shelf life of a range of consumer products. As the UV sensors can detect even the slightest doses of UV radiation, as well as the most extreme, this new technology could have vast potential for industries and companies seeking to evaluate the prolonged impact of UV exposure on products that are cultivated or kept outdoors.

The research project is the result of fruitful collaborations between two members of the UGR BIONanoMet (FQM368) research group; Ana González and José Manuel Domínguez-Vera, and the research group led by Dr. Vipul Bansal at RMIT University in Melbourne (Australia).

Here’s a link to and a citation for the paper,

Skin color-specific and spectrally-selective naked-eye dosimetry of UVA, B and C radiations by Wenyue Zou, Ana González, Deshetti Jampaiah, Rajesh Ramanathan, Mohammad Taha, Sumeet Walia, Sharath Sriram, Madhu Bhaskaran, José M. Dominguez-Vera, & Vipul Bansal. Nature Communicationsvolume 9, Article number: 3743 (2018) DOI: https://doi.org/10.1038/s41467-018-06273-3 Published 25 September 2018

This paper is open access.

Cosmetics breakthrough for Ulsan National Institute of Science and Technology (UNIST)?

Cosmetics would not have been my first thought on reading the title for the paper (“Rates of cavity filling by liquids”) produced  by scientists from Ulsan National Institute of Science and Technology (UNIST).

A September 17, 2018 news item on Nanowerk announces the research,

A research team, affiliated with Ulsan National Institute of Science and Technology (UNIST) has examined the rates of liquid penetration on rough or patterned surfaces, especially those with pores or cavities. Their findings provide important insights into the development of everyday products, including cosmetics, paints, as well as industrial applications, like enhanced oil recovery.

This study has been jointly led by Professor Dong Woog Lee and his research team in the School of Energy and Chemical Engineering at UNIST and a research team in the University of California, Santa Barbara. Published online in the July 19th issue of the Proceedings of the National Academy of Sciences (“Rates of cavity filling by liquids”), the study identifies five variables that control the cavity-filling (wetting transition) rates, required for liquids to penetrate into the cavities.

A July 26, 2018 UNIST press release (also on EurekAlert but published on September 17, 2018), which originated the news item, delves further into the work,

In the study, Professor Lee fabricated silicon wafers with cylindrical cavities of different geometries. After immersing them in bulk water, they observed the details of, and the rates associated with, water penetration into the cavities from the bulk, using bright-field and confocal fluorescence microscopy. Cylindrical cavities are like skin pores with narrow entrance and specious interior. The cavity filling generally progresses when bulk water is spread above a hydrophilic, reentrant cavity. As described in “Wetting Transition from the Cassie–Baxter State to Wenzel State”, the liquid droplet that sits on top of the textured surface with trapped air underneath will be completely absorbed by the rough surface cavities.

Their findings revealed that the cavity-filling rates are affected by the following variables: (i) the intrinsic contact angle, (ii) the concentration of dissolved air in the bulk water phase, (iii) the liquid volatility that determines the rate of capillary condensation inside the cavities, (iv) the types of surfactants, and (v) the cavity geometry.

“Our results can used in the manufacture of special-purpose cosmetic products,” says Professor Lee. “For instance, pore minimizing face primers and facial cleansers that remove sebum need to reduce the amount of dissolved air, so that they can penetrate into the pores quickly.”

On the other hand, beauty products, like sunscreens should be designed to protect the skin from harmful sun, while preventing pores clogging. Because, clogged pores hinder the skin’s function of breathing or exchange of carbon dioxide and then cause further irritation, pimples, and blemished areas on your skin. In this case, it is better to reduce volatility and increase the amount of dissolved air in the cosmetic products, as opposed to facial cleansers.

“This knowledge of how cavities under bulk water are filled and what variables control the rate of filling can provide insights into the engineering of temporarily or permanently superhydrophobic surfaces, and the designing and manufacturing of various products that are applied to rough, textured, or patterned surfaces,” says Professor Lee. “Many of the fundamental insights gained can also be applied to other liquids (e.g., oils), contact angles, and cavities or pores of different dimensions or geometries.”

This study has been supported by the National Research Foundation of Korea (NRF) grant, funded by the Ministry of Science and ICT.

Here’s a link to and a citation for the paper,

Rates of cavity filling by liquids by Dongjin Seo, Alex M. Schrader, Szu-Ying Chen, Yair Kaufman, Thomas R. Cristiani, Steven H. Page, Peter H. Koenig, Yonas Gizaw, Dong Woog Lee, and Jacob N. Israelachvili. PNAS August 7, 2018 115 (32) 8070-8075 https://doi.org/10.1073/pnas.1804437115 Published ahead of print July 19, 2018

This paper is behind a paywall.

Brighten and whiten your teeth (more safely) with nanoparticles?

This is for anyone who’s ever suspected that the all the tooth brightening and whitening might not be such a good idea after all. A July 18, 2018 news item on Nanowerk announces work on what scientists hope will be a safer way to whiten teeth (Note: A link has been removed),

In the age of Instagram and Snapchat, everyone wants to have perfect pearly whites. To get a brighter smile, consumers can opt for over the counter teeth-whitening treatments or a trip to the dentist to have their teeth bleached professionally. But both types of treatments can harm teeth.

According to an article published in ACS Biomaterials Science & Engineering (“Blue-Light -Activated Nano-TiO2@PDA for Highly Effective and Nondestructive Tooth Whitening”), researchers have now developed a new, less destructive method.

A July 18, 2018 American Chemical Society (ACS) news release (also on EurekAlert), which originated the news item expands on the theme,

Teeth can become discolored on their outer surfaces when people consume colored foods and drinks, such as coffee, tea or red wine. As a result, many people turn to non-invasive whitening treatments that bleach the teeth. Currently, the most common bleaching agent is hydrogen peroxide, which steals electrons from the pigment molecules that cause teeth discoloration, and this process can be sped up by exposing teeth to blue light. But high concentrations of hydrogen peroxide can break down a tooth’s enamel, causing sensitivity or cell death. So, Xiaolei Wang, Lan Liao and colleagues wanted to see if a different blue-light-activated compound could be a safer, but still effective, alternative.

The team modified titanium dioxide nanoparticles with polydopamine (nano-TiO2@PDA) so that they could be activated with blue light. In a proof-of-concept experiment, the nano-TiO2@PDA particles were evenly coated on the surface of a tooth and irradiated with blue light. After four hours of treatment, the whitening level was similar to that obtained with hydrogen-peroxide-based agents. The group notes that no significant enamel damage was found on the surface of the tooth, and the treatment was significantly less cytotoxic than hydrogen peroxide. In addition, the nano-TiO2@PDA therapy showed antibacterial activity against certain bacteria.

Here’s a link to and a citation for the paper,

Blue-Light -Activated Nano-TiO2@PDA for Highly Effective and Nondestructive Tooth Whitening by Feng Zhang, Chongxue Wu, Ziyu Zhou, Jiaolong Wang, Weiwei Bao, Lina Dong, Zihao Zhang, Jing Ye, Lan Liao, and Xiaolei Wang. ACS Biomater. Sci. Eng., Article ASAP DOI: 10.1021/acsbiomaterials.8b00548 Publication Date (Web): June 19, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.

Of course, there’s always the question of what happens as we pour more and more engineered titanium dioxide nanoparticles into our bodies and ultimately into the environment.