Search Results (709)

Nicotinamide (NAM), the amide form of vitamin B3, has gained increasing attention in dermatology due to its potential role in both skin aging and non-melanoma skin cancer (NMSC) prevention. This review summarizes the biological rationale and current clinical evidence supporting the use of NAM and other NAD⁺ precursors in photoaging and cutaneous carcinogenesis. Chronic ultraviolet exposure induces DNA damage, oxidative stress, inflammation, immune dysregulation, and extracellular matrix remodeling, linking photoaged skin to increased susceptibility to actinic keratoses (AKs), squamous cell carcinoma (SCCs), and basal cell carcinoma (BCCs). Through the NAD⁺ salvage pathway, NAM contributes to the maintenance of intracellular NAD⁺ pools, thereby influencing energy metabolism, DNA repair, mitochondrial function, redox homeostasis, and the activity of NAD⁺-dependent enzymes. Preclinical studies indicate that NAM enhances DNA repair, reduces oxidative stress and inflammatory signaling, supports autophagy and mitophagy, and improves epidermal barrier function and extracellular matrix integrity. Clinically, the strongest evidence for anti-aging effects concerns topical NAM, which consistently improves wrinkles, texture irregularities, pigmentation, and barrier function. Oral NAM has demonstrated chemopreventive activity in high-risk patients with previous NMSC, particularly by reducing the incidence of new SCCs and AKs during active treatment. However, despite a strong mechanistic rationale, current evidence remains heterogeneous, and additional long-term, skin-focused clinical trials are needed to better define efficacy, safety, optimal dosing strategies, and patient selection. Full article

In the surface protection of stone and brick cultural heritage, a primary challenge is that traditional polymeric coatings are prone to photooxidative degradation under ultraviolet (UV) irradiation, and the resulting aged fragments readily block the substrate micropores, leading to a loss of “breathability”. To address the performance conflict among waterproofing, breathability, and weather resistance, this study prepared few-layer Ti₃C₂T_X MXene using a minimally intensive layer delamination (MILD) method. The poor compatibility between MXene and the fluorosilicone (FPS) resin matrix was effectively resolved through covalent modification with a silane coupling agent (KH-550). Results demonstrate that at an ultralow loading (0.5 wt%), the functionalized f-MXene is uniformly dispersed within the resin. This structure not only spontaneously constructs a hierarchical rough architecture on the surface that imparts high hydrophobicity (water contact angle of 131.6°), but its internal “labyrinth effect” also effectively blocks corrosive media. Simultaneously, the intrinsic water vapor transmission rate of the substrate is effectively maintained (with a reduction of less than 3%), and no visually perceptible color difference is generated (∆E = 1.2). Mechanically, f-MXene relies on interfacial interactions to act as a “nano-skeleton” for stress transfer, thereby increasing the uniaxial compressive strength of fragile limestone by 32.4%. Optical and spectroscopic characterizations further elucidate its anti-aging mechanism: f-MXene not only provides broadband UV shielding but also exhibits highly efficient radical scavenging activity during long-term UV aging. After 400 h of aging, the concentrations of hydroxyl and superoxide anion radicals within the system are significantly reduced, blocking the photooxidative chain reaction from the source. This work develops a composite protective material system for stone cultural heritage that simultaneously integrates high moisture permeability, minimal visual intervention, and long-term antioxidant performance. Full article

Ascorbic acid plays an important role in the human body due to its antioxidant and anti-inflammatory properties, as well as its involvement in collagen synthesis, enzymatic regulation, and the biosynthesis of corticosteroids and selected neurotransmitters. Owing to these diverse functions, it is used both in the prevention and supportive treatment of several disorders and as a mild, non-toxic reducing agent in the synthesis of gold nanoparticles (AuNPs). In the present study, a method for synthesizing gold nanoparticles was developed using second-generation poly(amidoamine) dendrimers (PAMAM G2) with an ethylenediamine core as stabilizing agents and ascorbic acid as the reducing agent. The synthesis was performed using two techniques: sonication and microwave irradiation. A comparative analysis was conducted for colloidal systems obtained at various molar ratios of PAMAM G2 dendrimers to chloroauric acid (ranging from 1:1 to 1:5). The presence of gold nanoparticles was confirmed using ultraviolet–visible spectroscopy (UV–Vis). Nanoparticle diameters and zeta potentials were determined by dynamic light scattering (DLS). The sizes of the metallic cores were estimated using scanning transmission electron microscopy (STEM). Furthermore, the morphology and topography of entire complexes deposited on silicon substrates were visualized using atomic force microscopy (AFM). For cytotoxicity studies on human breast adenocarcinoma and human osteosarcoma cell lines, the most stable colloids—those obtained at a PAMAM G2:HAuCl₄ molar ratio of 1:3—were selected. Results indicate that the synthesized nanoparticles exhibit slightly higher cytotoxicity compared with AuNPs/PAMAM G2 complexes reduced with sodium citrate, as evidenced by lower EC₅₀ values (the concentration responsible for reducing cell viability to 50%). It should be emphasized, however, that AuNPs/PAMAM G2 reduced with ascorbic acid are significantly smaller, with diameters of approximately 10 nm, whereas citrate-reduced nanoparticles exhibit diameters of around 20 nm. These results indicate that nanoparticle size, rather than the chemical nature of the reducing agent, is a dominant factor governing the cytotoxic response of AuNPs/PAMAM G2 complexes. Full article

Geroprotective molecules are currently being actively investigated for the prevention of skin aging. An overview of geroprotectors in dermatology encompasses agents such as antioxidants, ultraviolet (UV) photoprotective agents, chemical peels, and carbon dioxide (CO₂) lasers, each with inherent limitations, including poor tolerability in individuals with sensitive skin. Regarding biostimulators, high-molecular-weight peptides (exceeding 500 kDa) exhibit limited cutaneous bioavailability, underscoring the need for low-molecular-weight geroprotective compounds. One such candidate is dehydroepiandrosterone DHEA, a neurosteroid with anti-aging and anti-stress properties, which also serves as a precursor to sex steroids. Although topical hormone replacement therapy with estrogens and androgens is being utilized, it remains confined to formal hormone replacement regimens and is associated with a significant adverse effect profile. The aim of this review was to analyze the key molecular mechanisms underlying the effects of DHEA on the skin, with particular emphasis on its metabolism and sex- and age-dependent mechanisms of action. Additionally, this review seeks to elucidate the factors contributing to the absence of approved topical DHEA formulations and to outline the potential of DHEA as an anti-aging agent in dermatological applications. DHEA has demonstrated significant skin-improving effects in several studies; its investigation has been predominantly confined to postmenopausal women. Furthermore, the outcome measures employed in these studies lacked specificity. DHEA is not permitted for use in cosmetic products within the European Union due to its hormonal activity. Its use is only allowed as an extemporaneous formulation under the established regulatory frameworks of individual countries. The indications for its use and the appropriate dosage for men and women must be clearly defined based on the results of future clinical studies. Promising research directions include the pharmacogenetic characterization of steroidogenic enzymes and sex hormone receptors, as well as the evaluation of DHEA in both sexes, specifically in premenopausal women and in men presenting with late-onset hypogonadism. Additionally, the biological effects of the primary metabolites of DHEA, androstenedione, and 5-androstenediol, on the cutaneous function remain unexplored, including their potential anti-aging activity mediated through retinoid receptor activation. Full article

Aiming at the problems of high friction coefficient, severe wear, and unsatisfactory service life and operational reliability of brass under complex working conditions such as dry friction, wet friction, and oil-lubricated friction, H62 brass was taken as the research object to improve its friction and wear properties via surface micro-texture technology. This study systematically compares the tribological performance of three typical geometric micro-textures under three coupled working conditions for the first time. Circular, rectangular, and hexagonal micro-dimple textures were fabricated on the brass surface using ultraviolet laser micromachining. The control variable method was adopted to systematically investigate the effects of micro-texture parameters including shape, size, and area density on the friction and wear properties of brass under the three typical working conditions, combined with reciprocating friction and wear tests and ultra-depth-of-field microscope characterization. The results show that the hexagonal micro-dimple texture (200 μm in size, 10% in area density) exhibits the optimal friction-reducing and anti-wear performance. Compared with the smooth surface, the friction coefficient decreases from 0.51 to 0.43, and the wear rate of the GCr15 steel ball is reduced by 2.8% under dry friction; the friction coefficient decreases from 0.43 to 0.12 with an 11.8% reduction in wear rate under wet friction; and the friction coefficient decreases from 0.29 to 0.24 with an 8.3% reduction in wear rate under oil lubrication. Relative to dry friction, the wear rates are further reduced by 16.7% and 8.3% under wet friction and oil lubrication, respectively. Different from most existing studies that only focus on a single texture type or a single friction condition, this paper systematically reveals the coupling regulation mechanism between texture parameters and working conditions, clarifies the optimal micro-texture design strategy for multi-working conditions, verifies that hexagonal micro-textures can significantly improve the wear resistance of brass, and provides technical support for the surface optimization design of brass workpieces under complex working conditions. Full article

We present a pedagogical and self-contained account of the functional formulation of non-Abelian gauge theories, aimed at the construction of a process-independent effective charge for Yang–Mills theory. Starting from the path integral quantization of gauge fields, we review gauge fixing and the emergence of Faddeev–Popov ghosts, illustrating how gauge invariance is preserved at the quantum level through Becchi–Rouet–Stora–Tyutin (BRST) symmetry. We then develop the BRST and anti-BRST formalisms and show how their simultaneous implementation leads to powerful functional identities that severely constrain the ghost and gluon sectors. Background field gauges are introduced as a natural framework in which these symmetries manifest themselves through Abelian-like Ward identities, allowing for a transparent separation between quantum and background degrees of freedom. This structure makes it possible to define renormalization group-invariant combinations of Green functions that generalize the QED effective charge to the non-Abelian case. The resulting effective charge is shown to be unique, gauge-invariant, and process-independent, providing a unified description of the theory from the ultraviolet down to the infrared. The interplay between functional identities, Dyson–Schwinger equations, and lattice results is discussed in detail, highlighting how dynamical mass generation and infrared saturation naturally emerge within this framework. Full article

Ultraviolet radiation (UVR) exposure accelerates skin aging by disrupting cellular homeostasis and inducing epigenetic changes, such as promoter hypermethylation of key regulatory genes. However, the molecular mechanisms underlying UVR-driven epigenetic silencing remain poorly understood. By integrating high-throughput DNA methylation profiling with co-regulatory network analysis, we identified KIT as a hub gene in a photoaging-associated methylation module. Pathway enrichment further revealed coordinated hypermethylation of the canonical Wnt/β-catenin signaling pathway, establishing the Wnt/KIT axis as a critical epigenetic-signaling nexus in UVR-induced skin fibroblast aging. In immortalized human skin fibroblasts (HSFs), UVR suppressed Wnt signaling, leading to KIT promoter hypermethylation, transcriptional silencing, and premature photoaging. Gain-of-function studies revealed that reversing KIT hypermethylation either via Wnt pathway activation or KIT overexpression effectively mitigated photoaging-associated phenotypes. Crucially, we found that puerarin (PUE), a natural isoflavone, reversed UVR-induced epigenetic silencing by directly interacting with β-catenin, reactivating Wnt signaling, and restoring KIT expression. PUE treatment preserved cellular function in UVR-damaged fibroblasts. These findings establish the Wnt/β-catenin-KIT axis as a critical epigenetic driver of skin aging and highlight puerarin as a promising therapeutic candidate for targeted anti-aging intervention. Full article

Ferritin, a natural cage-like protein, can be applied as a nanomaterial to encapsulate and deliver bioactive ingredients, while challenges remain when using ferritin to deliver multiple bioactive ingredients. In this study, a ferritin–zinc ion–alginate oligosaccharide (AOS) core–shell complex (FZA) and hydrophobic astaxanthin (AST) were applied as the water and oil phase to prepare oil-in-water emulsions simultaneously containing mineral element and hydrophobic AST. The ferritin works as a multicompartment carrier to encapsulate the Zn²⁺ ions and bind with the AOS. This emulsion exhibited smaller particle size and higher apparent viscosity, elastic modulus, and anti-delamination stability. After heat treatment, natural light irradiation, and ultraviolet irradiation, the retention rates of AST in FZA-stabilized emulsion were increased by 23.09%, 18.25%, and 19.24%, respectively, compared with AST dissolved in oil. The release rate of AST in FZA-stabilized emulsion was increased by 26.97% compared with that dissolved in oil in vitro digestion simulation, and release rate of Zn²⁺ ions in FZA-stabilized emulsion improved by 20.38% relative to the control. This study provides experimental evidence for the emulsion stabilized by the AOS and ferritin multi-interface, which achieves dual co-delivery and protection of mineral and hydrophobic molecules. Full article

To reveal the long-term anti-aging mechanisms of rubber–plastic elastomer-modified asphalt in complex service environments and overcome the inherent defects of single polymer modifiers—namely their susceptibility to degradation or phase separation—this study prepared styrene-butadiene-styrene (SBS), low Mooney rubber (LMMR), and low-density polyethylene (LDPE)-modified asphalts. Simultaneously, an LMMR-LDPE rubber–plastic thermoplastic elastomer (TPE) was fabricated utilizing twin-screw extrusion technology and subsequently used to prepare a composite-modified asphalt. Three aging protocols were simulated: short-term thermo-oxidative aging (RTFOT), long-term pressure aging (PAV), and ultraviolet light aging (UV). A multi-scale quantitative characterization was conducted using a dynamic shear rheometer, Fourier transform infrared spectroscopy, and atomic force microscopy to evaluate the rutting factor, carbonyl index, and surface microroughness of each system before and after aging. The experimental results indicate that the coupled effect of long-term stress and thermal oxidation causes the most severe damage to the colloidal structure of modified asphalt. Conventional SBS-modified asphalt, due to its abundance of unsaturated double bonds, exhibits a sharp increase in the carbonyl index and aging index of the rutting factor after aging, making it highly susceptible to oxidative chain scission. Although LDPE-modified asphalt possesses chemical inertness, it is prone to crystalline phase separation under aging conditions, resulting in a microroughness distortion rate of up to 86.36%. In contrast, the LMMR-LDPE composite system, leveraging the high chemical stability of the saturated aliphatic carbon chain and the flexibility-enhancing and crystallization-inhibiting effects of LMMR, effectively reduces active oxidation sites and improves interfacial compatibility. This composite system exhibits the lowest carbonyl increment and rheological attenuation under all aging conditions, while effectively inhibiting the free migration and agglomeration of macromolecular components. The LMMR-LDPE composite modification technology effectively overcomes the inherent drawbacks of single polymers, such as susceptibility to degradation or segregation, demonstrating excellent long-term macroscopic rheological stability and microscopic phase morphology anti-aging capability. The present findings provide laboratory-scale mechanistic support for the design of durable rubber–plastic-modified asphalt systems, while further pilot-scale, economic, and field validation is still required before practical engineering application can be fully assessed. Full article

Ultraviolet (UV) radiation is a main environmental factor responsible for skin damage, leading to oxidative stress, inflammation, and impairment of the skin barrier function. Furthermore, many components in sunscreen may accumulate in aquatic systems, causing environmental pollution. Therefore, the identification of novel natural bioactives that counteract these effects and can be useful as effective adjuvants in sunscreen formulations is of particular interest. Morin (1), a natural flavonoid, represents an attractive scaffold for modifications to enhance its biological activity. Herein, we aimed to investigate the effects of combining the flavonoid 1 and its derivative, morin semicarbazone (2), with the carotenoid fucoxanthin (FX) on UVB-exposed HaCaT keratinocytes. All compounds exhibited higher radical scavenging activity compared to Trolox. In this cell model, the phenolic–carotenoid combinations provided greater photoprotection than individual compounds, significantly enhancing cell viability and reducing necrosis, FX-2 emerged as the most potent combination, as evidenced by a marked reduction in reactive oxygen species (ROS) and malondialdehyde (MDA) levels, likely mediated through the activation of the nuclear factor erythroid 2-related factor 2/Heme oxygenase-1 (Nrf2/HO-1) signaling pathway. Furthermore, the tested treatments exerted enhanced anti-inflammatory effects by significantly reducing interleukin-6 (IL-6), cyclooxygenase 2 (COX-2), and matrix metalloproteinase-9 (MMP-9) mediators, with FX-2 being the most active combination. In conclusion, our findings highlight the protective effects of the combinations of these phenolics with the carotenoid FX against UVB radiation and support their potential application as natural active ingredients in sunscreen formulations. Full article

The long-term exposure of asphalt pavement to ultraviolet radiation causes significant performance degradation and reduces its service life. To enhance the UV resistance of asphalt, nanocomposite modifiers have been incorporated through mechanical blending. However, their effectiveness has been largely limited by poor component uniformity. To address this issue, UV-resistant antioxidant nano-TiO₂ was employed to modify the UV-shielding of layered porous carbon (PC), resulting in the synthesis of nano-TiO₂ intercalated PC (TiO₂/PC). The PC nanosheet was modified by TiO₂ nanoparticles via in situ growth, significantly improving the dispersion homogeneity of TiO₂. Comprehensive characterization (SEM/EDS/FT-IR/XPS) confirmed the successful synthesis of TiO₂/PC with well-defined interfacial bonding. Compared to control samples (PC, TiO₂, and TiO₂ + PC), the asphalt modified by TiO₂/PC-2 composite demonstrated superior UV aging resistance, lower physical aging indices and reduced rheological aging parameters. Moreover, TiO₂/PC modifier prominently suppressed the formation of oxidative groups (C=O/S=O), improved the colloidal stability, and delayed the sol–gel transition of the modified asphalt. The synergistic UV shielding mechanism was attributed to the enhanced UV absorption of TiO₂, multi-reflection and scattering within the PC matrix, and the radical scavenging capabilities of both components. These results provide new design insights for developing anti-UV aging modifiers for asphalt pavements. Full article

Wood coatings play a critical role in protecting wood substrates from environmental degradation, particularly ultraviolet (UV)-induced photodegradation. This review comprehensively examines the mechanisms of wood coating photodegradation, the factors influencing their durability, and current anti-aging strategies. Photodegradation arises from polymer chain scission, chemical structure reorganization, and photo-oxidation of lignin and cellulose, leading to coating chalking, cracking, gloss loss, and color changes, ultimately compromising wood mechanical properties and service life. Key anti-aging strategies include UV absorbers, which convert harmful UV radiation into heat; hindered amine light stabilizers (HALSs) that capture free radicals and quench excited-state molecules; barrier and shielding materials that form dense physical or nanostructured networks to block UV penetration and enhance mechanical and water resistance; and antioxidants that neutralize free radicals or decompose peroxides at the molecular level. Each approach can be employed individually or synergistically to enhance coating durability. Challenges remain in achieving long-term outdoor stability, balancing transparency and UV shielding, optimizing nanoparticle dispersion, and maintaining the activity of natural antioxidants. Future research should focus on multifunctional composite coatings integrating bio-based materials and nanotechnology, smart responsive systems, adaptive protection mechanisms, and standardized long-term evaluation protocols. These advancements will facilitate the development of high-performance, sustainable wood coatings and promote the value-added utilization of wood resources. Full article

Comano thermal water (CTW) is a hypotonic, bicarbonate–calcium–magnesium mineral water traditionally used to manage chronic inflammatory and relapsing skin diseases. This review summarises and discusses the available clinical, experimental, and translational evidence on CTW, with a particular focus on dermatological indications. The physicochemical properties of CTW, along with the presence of a stable, non-pathogenic microbial community, are examined in relation to their potential biological activity. Clinical studies indicate that CTW-based balneotherapy, alone or in combination with narrowband Ultraviolet B (UVB) phototherapy, is associated with improvements in disease severity, symptom burden, and quality of life in patients with psoriasis and atopic dermatitis, and has a favourable safety and tolerability profile. Experimental data further suggest that CTW may exert anti-inflammatory and immunomodulatory effects, modulate keratinocyte function, support skin barrier restoration, and influence the cutaneous microenvironment, including microbiome-related pathways. The review also outlines emerging evidence for CTW in skin regeneration and in upper airway inflammatory conditions treated via inhalation-based approaches. Overall, this review suggests that CTW may serve as a biologically active therapeutic resource, warranting further investigation as a complementary approach within integrative management strategies for inflammatory and barrier-related conditions. Full article

Background/Objectives: Propolis is well recognized for its antioxidant, anti-inflammatory, and wound-healing properties, supporting its cutaneous application in phytopharmaceuticals for the management of ultraviolet B (UVB)-induced skin damage. However, the application of propolis is limited by its intense coloration, stickiness, and poor user convenience. In situ film-forming systems (FFS) represent a novel dosage form designed to overcome these challenges, although efficacy data for using FFS remains limited. Consequently, this study aimed to develop a propolis-based FFS and evaluate its efficacy in mitigating UVB-irradiated HaCaT keratinocytes. Methods: Apis mellifera propolis was macerated and analyzed for total phenolic content (TPC) and total flavonoid content (TFC), radical scavenging activity (DPPH assay), and nitric oxide scavenging capability. Bioactive compounds were identified using high-performance liquid chromatography analysis (HPLC). The propolis extract was formulated into FFS and investigated on UVB-damaged HaCaT keratinocytes. An MTT viability assay, propidium iodide flow cytometry for cell cycle analysis, and a scratch wound healing assay were used to evaluate the therapeutic effects of the FFS. Results: The 72 h macerated propolis extract contained high levels of TPC, TFC, and targeted phytochemicals. The propolis extract exhibited free radical scavenging and nitric oxide inhibitory activities. Seven formulations exhibited suitable performance, with formulation F7 (FFS-F7) demonstrating superior drying time and dose-dependent free radical scavenging. Notably, FFS-F7 (≥12.5 µg/mL) significantly enhanced HaCaT proliferation, mitigated UVB-induced cell cycle arrest, reduced cellular damage, and accelerated wound closure. Conclusions: This study successfully developed an FFS that not only overcomes these physical drawbacks but also preserves the biological activity of the extract. The significant protective and restorative effects against UVB-induced HaCaT damage demonstrate the therapeutic potential of Thai Apis mellifera propolis and establish the FFS as a versatile base with the potential for delivering other bioactive compounds. Full article

Astragalin (AST), a natural flavonoid found in various plants, possesses antioxidant and anti-inflammatory properties. However, its protective efficacy against ultraviolet B (UVB)-induced cutaneous damage remains unclear. This study investigated the photoprotective effects of AST against UVB-induced photodamage using HaCaT keratinocytes and Kunming mice. In vitro, AST mitigated UVB-induced cytotoxicity and apoptosis in HaCaT cells. In vivo, topical application of AST attenuated UVB-induced erythema, epidermal hyperplasia, and collagen degradation in mouse skin. Additionally, AST reduced reactive oxygen species accumulation and enhanced antioxidant enzyme activity via activation of the Keap1/Nrf2 pathway. Furthermore, AST suppressed the expression of proinflammatory cytokines by inhibiting the TLR4/NF-κB signaling pathway. These findings demonstrate the photoprotective properties of AST and support its potential as a natural therapeutic agent for preventing UVB-induced skin damage. Full article