Ferrofluids are nanomaterials consisting of magnetic nanoparticles that are dispersed in a carrier fluid. Their physical properties, and hence their field of application are determined by intertwined compositional, structural, and magnetic characteristics, including interparticle magnetic interactions. Magnetic nanoparticles were prepared by thermal decomposition of iron(III) chloride hexahydrate (FeCl₃·6H₂O) in 2-pyrrolidone, and were then dispersed in two different fluids, water and polyethylene glycol 400 (PEG). A number of experimental techniques (especially, transmission electron microscopy, Mössbauer spectroscopy and superconducting quantum interference device (SQUID) magnetometry) were employed to study both the as-prepared nanoparticles and the ferrofluids. We show that, with the adopted synthesis parameters of temperature and FeCl₃ relative concentration, nanoparticles are obtained that mainly consist of maghemite and present a high degree of structural disorder and strong spin canting, resulting in a low saturation magnetization (~45 emu/g). A remarkable feature is that the nanoparticles, ultimately due to the presence of 2-pyrrolidone at their surface, are arranged in nanoflower-shape structures, which are substantially stable in water and tend to disaggregate in PEG. The different arrangement of the nanoparticles in the two fluids implies a different strength of dipolar magnetic interactions, as revealed by the analysis of their magnetothermal behavior. The comparison between the magnetic heating capacities of the two ferrofluids demonstrates the possibility of tailoring the performances of the produced nanoparticles by exploiting the interplay with the carrier fluid.

As public attention on sustainability is increasing, the use of polysaccharides as rheological modifiers in skin-care products is becoming the first choice. Polysaccharide associations can be used to increase the spreading properties of products and to optimize their sensorial profile. Since the choice of natural raw materials for cosmetics is wide, instrumental methodologies are useful for formulators to easily characterize the materials and to create mixtures with specific applicative properties. In this work, we performed rheological and texture analyses on samples formulated with binary and ternary associations of polysaccharides to investigate their structural and mechanical features as a function of the concentration ratios. The rheological measurements were conducted under continuous and oscillatory flow conditions using a rotational rheometer. An immersion/de-immersion test conducted with a texture analyzer allowed us to measure some textural parameters. Sclerotium gum and iota-carrageenan imparted high viscosity, elasticity, and firmness in the system; carob gum and pectin influenced the viscoelastic properties and determined high adhesiveness and cohesiveness. The results indicated that these natural polymers combined in appropriate ratios can provide a wide range of different textures and that the use of these two complementary techniques represents a valid pre-screening tool for the formulation of green products.

Hyaluronic acid (HA), an excellent biomaterial with unique bio properties, is currently one of the most interesting polymers for many biomedical and cosmetic applications. However, several of its potential benefits are limited as it is rapidly degraded by hyaluronidase enzymes. To improve the half-life and consequently increase performance, native HA has been modified through cross-linking reactions with a natural and biocompatible amino acid, Ornithine, to overcome the potential toxicity commonly associated with traditional linkers. 2-chloro-dimethoxy-1,3,5-triazine/4-methylmorpholine (CDMT/NMM) was used as an activating agent. The new product (HA–Orn) was extensively characterized to confirm the chemical modification, and rheological analysis showed a gel-like profile. In vitro degradation experiments showed an improved resistance profile against enzymatic digestions. Furthermore, in vitro cytotoxicity studies were performed on lung cell lines (Calu-3 and H441), which showed no cytotoxicity.

Tamarind seed polysaccharide (TSP) is a xyloglucan of vegetable origin, recently proposed for the cosmetic and pharmaceutical market as a “green” alternative to hyaluronic acid. In this study, TSP water dispersions, at different concentrations, were characterized by means of rheological measurements, both in continuous and oscillatory flow conditions. The results were compared with those of hyaluronic acid of two different molecular weights. The results pointed out the close rheological behaviors between TSP and hyaluronic acid with comparable molecular weight. Afterwards, the structural features of binary and ternary polysaccharide associations prepared with TSP, hyaluronic acid (very high MW) and dehydropolysaccharide gum, a modified xanthan gum, with high stabilizing properties, were investigated. The rheological properties were significantly affected by the polysaccharide ratios in the mixture, suggesting that the combination of TSP with other polymers can lead to a modulation of the texture and functional properties of cosmetics.

Quality, safety, and efficacy concerns added to instability, poor absorption, and the dispersion of actives are common problems while formulating plant-based cosmetics. Furthermore, a correct balance between the stability of the emulsion, the sensory profile, and the high efficacy has to be considered to formulate an effective product. In this paper, we demonstrate that rheology is a methodological tool that can be used while designing a new product. In particular, we developed an O/W emulsion which is easy to spread on irritated skin, and that can soothe the redness and discomfort caused by the exposure to both physical and chemical irritating agents. The green active mixture consists of three natural raw materials: Bosexil^®, Zanthalene^®, and Xilogel^®. Each ingredient has a well-demonstrated efficacy in terms of soothing, anti-itching, and moisturizing properties respectively. Starting from the selection of a new green emulsifying system, through the analysis of the rheological properties, we obtained a stable and easy-to-apply o/w emulsion. The efficacy of the optimized product was assessed in vitro on intact and injured skin using the SkinEthic™ Reconstituted Human Epidermis (RHE) as a biological model.

Seborrheic dermatitis (SD) is a chronic inflammatory skin disease that primarily affects sebaceous-rich areas such as the scalp, face, and upper trunk. While the precise etiology remains multifactorial, the role of the skin microbiome, particularly the proliferation of Malassezia species, and alterations in the skin barrier function are critical in its pathogenesis. Disruption of the skin barrier, characterized by increased transepidermal water loss (TEWL) and reduced production of epidermal lipids, creates a favorable environment for microbial overgrowth and inflammation. Recent insights highlight the interplay between the impaired barrier function, immune responses, and the skin microbiome in perpetuating the disease. Additionally, novel dermocosmetic approaches are emerging that target these underlying mechanisms, offering promising therapeutic avenues. This review provides a comprehensive overview of the involvement of skin microbiome and barrier dysfunction in seborrheic dermatitis and discusses the potential of advanced dermocosmetic treatments aimed at restoring skin homeostasis and preventing disease recurrence.