Nanotechnology in cosmetics

Impact of Food Additives on Gut Homeostasis

In physiological conditions, the gut is heavily infiltrated with various subsets of inflammatory cells, whose activity is tightly controlled by counter-regulatory mechanisms. Defects in such mechanisms can favour the development of chronic intestinal disorders, such as Crohn’s disease (CD) and ulcerative colitis (UC), the principal forms of inflammatory bowel diseases (IBD) in humans, as well as systemic disorders. Over the last years, the frequency of intestinal and systemic immune-inflammatory disorders has increased in previously low incidence areas, likely due to the Westernization of lifestyles, including dietary habits. The Western diet is characterized by high consumption of proteins, saturated fats and sweets, as well as by a broad use of food additives (e.g., emulsifiers, bulking agents), which are used to preserve and enhance food quality. Accumulating evidence suggests that food additives can perturb gut homeostasis, thereby contributing to promote tissue-damaging inflammatory responses. For instance, mice given the emulsifiers carboxymethylcellulose and polysorbate 80 develop dysbiosis with overgrowth of mucus-degrading bacteria. Such an effect triggers colitis in animals deficient in either interleukin-10, a cytokine exerting anti-inflammatory and regulatory functions, or Toll-like receptor 5, a receptor recognizing the bacterial flagellin. Similarly, the polysaccharide maltodextrin induces endoplasmic reticulum stress in intestinal goblet cells, thereby impairing mucus release and increasing host susceptibility to colitis. In this review, we report and discuss the current knowledge about the impact of food additives on gut homeostasis and their potential contribution to the development of inflammatory disorders.

A reliable approach for assessing size-dependent effects of silica nanoparticles on cellular internalization behavior and cytotoxic mechanisms

Background

The size of nanoparticles is considered to influence their toxicity, as smaller-sized nanoparticles should more easily penetrate the cell and exert toxic effects. However, conflicting results and unstandardized methodology have resulted in controversy of these size-dependent effects. Here, we introduce a unique approach to study such size-dependent effects of nanoparticles and present evidence that reliably supports this general assumption along with elucidation of the underlying cytotoxic mechanism.

Methods

We prepared and physically characterized size-controlled (20-50 nm) monodispersed silica nanoparticles (SNPs) in aqueous suspensions. Then, a variety of biochemical assessments are used for evaluating the cytotoxic mechanisms.

Results

SNP treatment in three cell lines decreased cell viability and migration ability, while ROS production increased in dose- and size-dependent manners, with SNPs <30 nm showing the greatest effects. 30- and 40-nm SNPs were observed similar to these biological activities of 20- and 50-nm, respectively. Under the conventionally used serum-free conditions, both 20-nm and 50-nm SNPs at the IC₅₀ values (75.2 and 175.2 μg/mL) induced apoptosis and necrosis in HepG2 cells, whereas necrosis was more rapid with the smaller SNPs. Inhibiting endocytosis impeded the internalization of the 50-nm but not the 20-nm SNPs. However, agglomeration following serum exposure increased the size of the 20-nm SNPs to approximately 50 nm, preventing their internalization and cell membrane damage without necrosis. Thus, 20-nm and 50-nm SNPs show different modes of cellular uptake, with smaller SNPs capable of trafficking into the cells in an endocytosis-independent manner. This approach of using non-overlapping size classes of SNPs under the same dose, along with serum-induced agglomeration analysis clarifies this long-standing question about the safety of small SNPs.

Conclusion

Our results highlight the need to revise safety guidelines to account for this demonstrated size-dependent cytotoxicity under serum-free conditions, which may be similar to the microenvironment after tissue penetration.

Physiopathology and current treatments of androgenetic alopecia: Going beyond androgens and anti-androgens

Androgenetic alopecia (AGA) is the most diagnosed hair loss dysfunction. Its physiopathology comprises a genetic predisposition affording an exacerbated response of the hair follicles cells to androgens aggravated by scalp inflammation and extrinsic factors. This paper presents a review of the mechanisms and extrinsic factors involved in the AGA physiopathology as well as its conventional and emerging treatments. The research focused on reports regarding AGA physiopathology and treatments published between January 2001 and July 2019 in medical and related journals. The most used medical treatments for AGA-minoxidil and finasteride-present non satisfactory results in some cases. Currently, the low-level laser therapy is recognized as a safe and effective treatment for AGA. Some minimally invasive techniques-mesotherapy, microneedling, carboxytherapy, and platelet-rich plasma-are also used to stimulate hair growth. Pharmaceutical substances with mechanisms differing from the anti-androgen activity are under current investigation and many of them have botanical origins; however, formulations with higher performance are required, and the hair follicles ability of being a drug and nanoparticle reservoir has been researched. The association of different strategies, that is, substances with synergic mechanisms and the use of advantageous technologies associated with lifestyle changes could improve the treatment outcomes.

Titanium Oxide Microspheres with Tunable Size and Phase Composition

Due to their unique physical and chemical properties, monodisperse titanium oxide microspheres can be used in dye-sensitized solar cells, as cosmetic pigments, and for other applications. However, the synthesis of microspheres with narrow size distribution, desired phase composition, and porosity is still a challenge. In this work, spherical titania particles with controllable size, crystallinity, and pore size were obtained by Ti(OⁿBu)₄ hydrolysis in ethanol. The influence of NaOH addition on the particles’ size and morphology was investigated for the first time. Particle diameter can be tailored from 300 nm to 1.5 μm by changing water and NaOH concentrations. Particle size was analyzed by the statistical processing of scanning electron microscopy (SEM) images and differential centrifugal sedimentation (DCS) measurements. Optical properties of the microspheres were studied by diffuse reflectance UV-Vis spectroscopy. Thermal and hydrothermal treatment allowed transforming amorphous phase in as-prepared particles into nanocrystalline anatase and/or rutile. Transmission electron microscopy (TEM) study of the lamellae, cut out from spherical particles using focused ion beam (FIB), revealed that as-synthesized microspheres are non-hollow, homogeneous, and crystallize throughout the whole volume of the particle. The spherical particles possess photoprotective properties; the highest sun protection factor (SPF) was observed for amorphous microspheres.

Legal and practical challenges in classifying nanomaterials according to regulatory definitions

The European Union (EU) has adopted nano-specific provisions for cosmetics, food and biocides, among others, which include binding definitions of the term "nanomaterial". Here we take an interdisciplinary approach to analyse the respective definitions from a legal and practical perspective. Our assessment reveals that the definitions contain several ill-defined terms such as "insoluble" or "characteristic properties" and/or are missing thresholds. Furthermore, the definitions pose major and so far unsolved analytical challenges that, in practice, make it nearly impossible to classify nanomaterials according to EU regulatory requirements. An important purpose of the regulations, the protection of human health and the environment, may remain unfulfilled and the development of innovative applications of nanomaterials may be facing a path full of (legal) uncertainties. Based on our findings, we provide five recommendations for a more coherent and practical approach towards the regulation of nanomaterials.

Recent advances in layered double hydroxides applied to photoprotection

Layered double hydroxides have received more attention from researchers due to their range of applications, ease of synthesis and low cost of production. With broader knowledge about solar radiation effects on the body, the use of sunscreens has become even more important. The ability of some nanostructures, such as layered double hydroxides, to act as matrices has made it possible to obtain improvements in photoprotective formulations, with solutions to problems caused by radiation and sunscreens. This review article brings together the most recent advances of these clays, the layered double hydroxides, applied to photoprotection.

Solid Lipid Nanoparticles Loading Idebenone Ester with Pyroglutamic Acid: In Vitro Antioxidant Activity and In Vivo Topical Efficacy

Idebenone (IDE), a strong antioxidant widely investigated for the treatment of neurodegenerative diseases and skin disorders, shows low oral and topical bioavailability due to its unfavorable physico-chemical properties. In this work, to improve IDE topical effectiveness, we explored a two-steps approach: (1) we synthesized an IDE ester (IDEPCA) with pyroglutamic acid, a molecule whose hydrating effects are well known; (2) we loaded IDEPCA into solid lipid nanocarriers (SLN). We evaluated in vitro antioxidant and anti-glycation activity and in vivo hydrating effects after topical application in human volunteers from gel vehicles of IDEPCA SLN in comparison to IDE SLN. All SLN showed good technological properties (mean particle size < 25 nm, polydispersity index < 0.300, good stability). The oxygen radical absorbance capacity assay showed that IDEPCA SLN and IDE SLN had similar antioxidant activity while IDEPCA SLN were more effective in the in vitro NO scavenging assay. Both IDEPCA and IDE SLN showed the same effectiveness in inhibiting the formation of advanced glycation end products. In vivo experiments pointed out a better hydrating effect of IDEPCA SLN in comparison to IDE SLN. These results suggest that the investigated approach could be a promising strategy to obtain topical formulations with increased hydrating effects.

Nanoparticles in Daily Life: Applications, Toxicity and Regulations

At nanoscale, man-made materials may show unique properties that differ from bulk and dissolved counterparts. The unique properties of engineered nanomaterials not only impart critical advantages but also confer toxicity because of their unwanted interactions with different biological compartments and cellular processes. In this review, we discuss various entry routes of nanomaterials in the human body, their applications in daily life, and the mechanisms underlying their toxicity. We further explore the passage of nanomaterials into air, water, and soil ecosystems, resulting in diverse environmental impacts. Briefly, we probe the available strategies for risk assessment and risk management to assist in reducing the occupational risks of potentially hazardous engineered nanomaterials including the control banding (CB) approach. Moreover, we substantiate the need for uniform guidelines for systematic analysis of nanomaterial toxicity, in silico toxicological investigations, and obligation to ensure the safe disposal of nanowaste to reduce or eliminate untoward environmental and health impacts. At the end, we scrutinize global regulatory trends, hurdles, and efforts to develop better regulatory sciences in the field of nanomedicines.

Comparative toxicity of silver nanoparticles and silver ions to Escherichia coli

With the increase in silver (Ag)-based products in our lives, it is essential to test the potential toxicity of silver nanoparticles (AgNPs) and silver ions (Ag ions) on living organisms under various conditions. Here, we investigated the toxicity of AgNPs with Ag ions to Escherichia coli K-12 strain under various conditions. We observed that both AgNPs and Ag ions display antibacterial activities, and that Ag ions had higher toxicity to E. coli K-12 strain than AgNPs under the same concentrations. To understand the toxicity of AgNPs at a cellular level, reactive oxygen species (ROS) enzymes were detected for use as antioxidant enzymatic biomarkers. We have also studied the toxicity of AgNPs and Ag ions under various coexistence conditions including: fixed total concentration, with a varied the ratio of AgNPs to Ag ions; fixed the AgNPs concentration and then increased the Ag ions concentration; fixed Ag ions concentration and then increasing the AgNPs concentration. Exposure to AgNPs and Ag ions clearly had synergistic toxicity; however, decreased toxicity (for a fixed AgNPs concentration of 5mg/L, after increasing the Ag ions concentration) to E. coli K-12 strain. AgNPs and Ag ions in the presence of L-cysteine accelerated the bacterial cell growth rate, thereby reducing the bioavailability of Ag ions released from AgNPs under the single and coexistence conditions. Further works are needed to consider this potential for AgNPs and Ag ions toxicity across a range of environmental conditions.

ENVIRONMENTAL SIGNIFICANCE STATEMENT

As silver nanoparticles (AgNPs)-based products are being broadly used in commercial industries, an ecotoxicological understanding of the AgNPs being released into the environment should be further considered. Here, we investigate the comparative toxicity of AgNPs and silver ions (Ag ions) to Escherichia coli K-12 strain, a representative ecotoxicological bioreporter. This study showed that toxicities of AgNPs and Ag ions to E. coli K-12 strain display different relationships when existing individually or when coexisting, and in the presence of L-cysteine materials. These findings suggest that the toxicology research of nanomaterials should consider conditions when NPs coexist with and without their bioavailable ions.

Dual-responsive biocompatible microgels as high loaded cargo: understanding of encapsulation/release driving forces by NMR NOESY

The suitability of biocompatible microgels as a new cosmetic carrier has been demonstrated through their ability of encapsulation/release of cosmetic active molecules.

Rosemary Essential Oil-Loaded Lipid Nanoparticles: In Vivo Topical Activity from Gel Vehicles

Although rosemary essential oil (EO) shows many biological activities, its topical benefits have not been clearly demonstrated. In this work, we assessed the effects on skin hydration and elasticity of rosemary EO after topical application via gel vehicles in human volunteers. To improve its topical efficacy, rosemary EO was loaded into lipid nanoparticles (NLCs) consisting of cetyl palmitate as a solid lipid, and non-ionic surfactants. Such NLCs were prepared using different ratios of EO/solid lipid and those containing EO 3% w/w and cetyl pamitate 7% w/w were selected for in vivo studies, showing the best technological properties (small particle size, low polydispersity index and good stability). Gels containing free EO or EO-loaded NLCs were applied on the hand skin surface of ten healthy volunteers twice a day for one week. Skin hydration and elasticity changes were recorded using the instrument Soft Plus. Gels containing EO-loaded NLCs showed a significant increase in skin hydration in comparison with gels containing free EO. Skin elasticity increased, as well, although to a lesser extent. The results of this study point out the usefulness of rosemary EO-loaded NLCs for the treatment of cutaneous alterations involving loss of skin hydration and elasticity.

Is the European regulatory framework sufficient to assure the safety of citizens using health products containing nanomaterials?

The growing application of nanomaterials in healthcare products (i.e., cosmetics, medical devices, and medicinal products) has encouraged the upgrade of the regulatory framework within the European Community to better control their use and manage the risk of negative effects on human health and environment. Unfortunately, despite the efforts of European Authorities, the current legislation is still stratified and several criticisms remain because of the lack of well-established scientific knowledge on nanomaterials. Although the regulatory framework for cosmetic products is almost complete, the efficacy and/or safety assessment of nanomaterials in medicinal products and medical devices is still based on case-by-case evaluation because of the complexity of such systems.

Roles of temperature and flow velocity on the mobility of nano-sized titanium dioxide in natural waters

While environmental fate and transport of nano-sized TiO2 (nTiO2) attracts intensive attention, how physical characters of natural waters, such as water type, temperature, and flowing velocity, impact the mobility of nTiO2 remain unclear now. In this work, ultrapure water, lake water, and sea water were chosen to investigate the aggregation and sedimentation behaviors of nTiO2 under a series of environmental conditions with varying feeding concentration, water temperature, and flow velocity. In general, the results demonstrated poorer stability of nTiO2 in sea water than other water types. After a 7-hour test (initial nTiO2=100mg/L), the nTiO2 hydrodynamic sizes, sedimentation rates, and zeta potentials differed significantly in ultrapure water (545nm, 24%, -30mV), lake water (1374nm, 56%, -16mV) and sea water (2152nm, 87%, -3mV). Meanwhile, the study exhibited significant influences of initial nTiO2 concentration (10-100mg/L) on the behaviors of nTiO2 in sea water and lake water but negligible impact on ultrapure water. Ambient temperature also directly affected the aggregation and sedimentation rates of nTiO2, both hydrodynamic diameters and sedimentation of nTiO2 increased markedly with the rising ambient temperatures (10-60°C). In contrast, increasing water flow velocity (0-0.32m/s) lowered the hydrodynamic diameters and sedimentation rates of nTiO2, although the influence of flowing velocity on the aggregation of nTiO2 was partially reversible.

Current application of phytocompound-based nanocosmeceuticals for beauty and skin therapy

Phytocompounds have been used in cosmeceuticals for decades and have shown potential for beauty applications, including sunscreen, moisturizing and antiaging, and skin-based therapy. The major concerns in the usage of phyto-based cosmeceuticals are lower penetration and high compound instability of various cosmetic products for sustained and enhanced compound delivery to the beauty-based skin therapy. To overcome these disadvantages, nanosized delivery technologies are currently in use for sustained and enhanced delivery of phyto-derived bioactive compounds in cosmeceutical sectors and products. Nanosizing of phytocompounds enhances the aseptic feel in various cosmeceutical products with sustained delivery and enhanced skin protecting activities. Solid lipid nanoparticles, transfersomes, ethosomes, nanostructured lipid carriers, fullerenes, and carbon nanotubes are some of the emerging nanotechnologies currently in use for their enhanced delivery of phytocompounds in skin care. Aloe vera, curcumin, resveratrol, quercetin, vitamins C and E, genistein, and green tea catechins were successfully nanosized using various delivery technologies and incorporated in various gels, lotions, and creams for skin, lip, and hair care for their sustained effects. However, certain delivery agents such as carbon nanotubes need to be studied for their roles in toxicity. This review broadly focuses on the usage of phytocompounds in various cosmeceutical products, nanodelivery technologies used in the delivery of phytocompounds to various cosmeceuticals, and various nanosized phytocompounds used in the development of novel nanocosmeceuticals to enhance skin-based therapy.

Oral subchronic exposure to silver nanoparticles in rats

Because of their extremely small size, silver nanoparticles (AgNPs) show unique physical and chemical properties, with specific biological effects, which make them particularly attractive for being used in a number of consumer applications. However, these properties also influence the potential toxicity of AgNPs. In this study, we assessed the potential toxic effects of an in vivo oral sub-chronic exposure to polyvinyl pyrrolidone coated AgNPs (PVP-AgNPs) in adult male rats. We also assessed if oral PVP-AgNPs exposure could alter the levels of various metals (Fe, Mg, Zn and Cu) in tissues. Rats were orally given 0, 50, 100 and 200 mg/kg/day of PVP-AgNPs. Silver (Ag) accumulation in tissues, Ag excretion, biochemical and hematological parameters, metal levels, as well as histopathological changes and subcellular distribution following PVP-AgNPs exposure, were also investigated. After 90 days of treatment, AgNPs were found within hepatic and ileum cells. The major tissue concentration of Ag was found in ileum of treated animals. However, all tissues of PVP-AgNPs-exposed animals showed increased levels of Ag in comparison with those of rats in the control group. No harmful effects in liver and kidney, as well as in biochemical markers were noted at any treatment dose. In addition, no hematological or histopathological changes were found in treated animals. However, significant differences in Cu and Zn levels were found in thymus and brain of PVP-AgNPs-treated rats.