TITANIUM DIOXIDE

Visible light (VL, 400-700 nm) and long wavelength UVA1 (VL + UVA1, 370-700 nm) have been reported to cause erythema in light skin phototypes, Fitzpatrick skin types I-III (FST I-III), and to exacerbate pigmentary dermatologic conditions (e.g., melasma, hyperpigmentation, post-inflammatory hyperpigmentation) in individuals with dark skin phototypes (FST IV-VI). Until recently, limited options existed for photoprotection against VL + UVA1, including tinted formulations containing iron oxides (Fe 2 O 3 ) or pigmentary titanium dioxide (TiO 2 ), as well as antioxidant-enriched sunscreen systems. Zinc oxide (ZnO) and TiO 2 are often utilized in the development of mineral-based (inorganic) sunscreens as the active ingredients to protect against broad spectrum Ultraviolet (UV) radiation via their absorption properties. However, some of these products often leave a white cast, particularly on dark skin, making these products unfavorable, altering skin tone appearance leading to concerns for sunscreen compliance. Tinted sunscreens (Fe 2 O 3 ) are designed to enhance cosmetic elegance and improve compliance across diverse skin tones. This study aims to evaluate the photoprotection properties of a novel Zn-based inorganic tinted sunscreen enriched with five antioxidants (5 AOX) against VL + UVA1 induced biologic effects (hyperpigmentation and erythema). Twelve healthy adult subjects with FST IV-VI were enrolled and the effectiveness of the new Zn/Fe 2 O 3 /5 AOX sunscreen, compared to several commercially available tinted and non-tinted mineral sunscreens, was evaluated. The erythema and pigmentation assessments were performed by diffused reflectance spectroscopy (DRS), polarized photography, and investigator global scoring immediately, 24 h, and 7 days after irradiation (320 J/cm 2 ). DRS results demonstrated that the novel Zn/Fe 2 O 3 /5 AOX effectively reduced immediate erythema and pigmentation as well as delayed pigmentation when compared with formulas containing ZnO only (p < 0.05). Not all inorganic/Fe 2 O 3 formulas significantly reduced erythema and pigmentation induced by VL + UVA1 when compared with the ZnO only formula. These results highlight the enhanced effects of 5 AOX-enriched tinted mineral sunscreen to be photoprotective against VL + UVA1, with a blendable tint designed for use on skin of all colors aimed at improving patient compliance and overall sunscreen use.

Titanium dioxide (TiO 2 ) is a cornerstone UV-filtering material, yet its intrinsic photocatalytic activity continues to raise concerns regarding safety and photostability in cosmetic applications. Here, we introduce a quantum-dot (QD) surface passivation approach that transforms photoactive rutile TiO 2 into a safe-by-design (SbD) nanomaterial without compromising its UV-protection efficiency. Ultrathin Al(OH) 3 QDs (<5 nm) are selectively nucleated on TiO 2 surfaces via a scalable aqueous synthesis, forming discontinuous passivation domains that suppress surface photoactivity through localised charge trapping and recombination control. Comprehensive spectroscopy and microscopy analyses reveal preserved crystal integrity and a >90% reduction in photocatalytic activity. The resulting nanocomposites demonstrate preserved biocompatibility, reduced phototoxicity, and superior transparency when integrated into prototype sunscreen formulations. This study establishes a generalizable framework for nanoscale photocatalytic suppression via selective quantum-dot passivation, advancing ceramic-based nanomaterials for safe, sustainable UV protection and beyond.

It is well established that a complete package of photoprotection includes staying in the shade, wearing photoprotective clothing, hat, and sunglasses, and on otherwise exposed sites, applying sunscreen. Recent advances have modified photoprotection through new active ingredients, innovative formulations, complementary oral strategies, and personalized approaches. This review aims to summarize the latest new developments in photoprotection. A narrative review of the literature was conducted from January 2010 to October 2025 using terms related to photoprotection, sunscreen innovation, visible light, oral photoprotection, microbiome interaction, climate change, and personalized approaches. Articles in English and Spanish were selected based on scientific relevance. Advances in photoprotection include the development of new topical filters targeting UVA1 and visible light, as well as the incorporation of iron oxides and, in some formulations, pigmentary titanium dioxide in tinted sunscreens to enhance protection against visible light. In addition, the use of antioxidants and DNA repair enzymes has been explored to mitigate oxidative stress and address field cancerization. Natural and eco-friendly bioactive ingredients derived from botanical and marine sources show growing potential as photoprotective agents. Additional considerations such as the role of skin microbiome, and personalized photoprotection strategies tailored to skin phototype, lifestyle, diseases, and high-exposure conditions further refine preventive practice. Photoprotection is evolving into a multidimensional approach that integrates advanced topical formulations, oral agents, and individualized recommendations. This paradigm offers improved prevention of photoaging, pigmentary disorders, and photocarcinogenesis while promoting safer and more sustainable photoprotection practices.

Wound healing is a complex, dynamic and multistep biological process involving haemostasis, inflammation, proliferation and remodelling, which can be severely compromised in chronic, infected, or non-healing wounds. Conventional wound care strategies often suffer from limitations such as poor drug stability, inadequate tissue penetration, frequent dressing changes and a lack of spatiotemporal control over therapeutic release. In recent years, nanotechnology-based drug delivery systems have emerged as promising platforms to overcome these challenges by enabling targeted, controlled and multifunctional therapeutic interventions. This comprehensive review highlights emerging trends in nanotechnology-driven approaches for wound healing, with a focus on their design and therapeutic potential across different stages of wound repair. The review systematically discusses major nanotechnological platforms, including electrospun nanofibers, advanced hydrogel systems, nanocomposites, polymeric micelles and a wide range of inorganic nanoparticles such as silver, gold, copper, silica and titanium dioxide nanoparticles. Additionally, advanced materials such as graphene and scaffold-based systems, including scaffold-integrated nanoparticles and hydrogel-based scaffolds, are critically examined for their roles in promoting angiogenesis, antimicrobial activity, cell migration and tissue regeneration. Ultimately, this review provides valuable insights into future perspectives and research directions, highlighting the need for multifunctional nanoplatforms to advance next-generation wound healing therapies.

Titanium dioxide nanoparticles (TiO 2 NPs) are widely used as inorganic UV filters, yet their photocatalytic activity and resulting phototoxicity raise serious safety issues. Here, we report a Pickering double emulsion templating strategy for constructing chitosan-based porous microspheres encapsulating TiO 2 NPs (TiO 2 @CS-PMs), with controllable microstructures and mass loading of TiO 2 NPs. The oil-in-water-in-oil double emulsion template confines TiO 2 NPs within a cross-linked porous polymer skeleton. Structural confinement, combined with the antioxidant capacity of chitosan (CS), greatly reduces UV-induced reactive oxygen species generation of TiO 2 NPs. In vitro assays reveal that TiO 2 @CS-PMs have good biocompatibility and significantly lower phototoxicity to HaCaT cells than naked TiO 2 NPs. The porous architecture promotes optical confinement, and the encapsulation causes interfacial interactions between TiO 2 NPs and the CS matrix, resulting in broadened and enhanced UV attenuation. Sunscreen incorporating TiO 2 @CS-PMs exhibits higher sun protection factors and cellular photoprotection at lower TiO 2 NPs doses, while the CS matrix provides antibacterial activity. This work reveals Pickering double emulsion templating porous microstructure as a versatile platform for managing particle photochemistry, providing insights into the development of safer and multifunctional UV filters.

Recent studies reveal that inorganic nanoparticles (NPs) can alter allergic skin reactions in a contact hypersensitivity (CHS) mouse model. Specifically, negatively charged silica (SiO 2 ) NPs suppressed the response whereas manganese doped titanium dioxide (mTiO 2 ) exacerbated it. Mast cells are critically important in transducing the CHS response. In this study we investigated the effect of SiO 2 and mTiO 2 NPs on bone marrow derived mast cell (BMMC) activation markers, degranulation and cytokine release. Sensitized BMMC were exposed to NPs alone or NPs plus antigen. Cytokines (IL-6, IL-13, TNF-α) and degranulation (β-hexosaminidase) studies were performed. Flow cytometry was used to follow cell surface activation markers including FcεRI, CD63 (LAMP-3), and CD107a (LAMP-1). Transmission Electron Microscopy (TEM) studies were preformed to assess NP endocytosis. Results found that mTiO 2 NPs were cytotoxic to BMMC in a dose- and time-dependent manner. SiO 2 NPs showed minimal cytotoxicity up to 100 µg/ml. In the absence of antigen the NPs had limited effect on sensitized BMMC degranulation or cytokine release. However, in the presence of antigen, 30 min co-culture studies (NP plus antigen) showed that SiO 2 NPs protect against degranulation, and they suppressed the expression of cell surface activation markers whereas mTiO 2 NPs exacerbated these.

Bacterial infections can delay wound healing and represent serious medical problems both in the hospital and community settings, especially skin wound infections caused by Staphylococcus aureus . In this work, a gelatin hydrogel modified with photo-cross-linkable methacrylamide groups at 10% concentration (GelMA10%), enriched with titanium dioxide nanoparticles (TiO 2 NPs), and loaded with Neomycin sulphate was developed with the aim to realize a tissue for wound care with improved mechanical and antimicrobial properties. TiO 2 nanocomposite GelMA films with two concentrations of TiO 2 NPs were characterized to assess physicochemical, structural and mechanical properties by scanning electron microscopy equipped with an energy-dispersive X-ray spectrometer (SEM/EDX), micro-computed tomography (micro-CT) and X-ray photoelectron spectroscopy (XPS). TiO 2 nanocomposite GelMA films showed a more compact structure, reduced pore sizes and a higher compressive modulus at the increasing concentration of TiO 2 NPs. They were able to absorb and retain water for a prolonged time; however, no significant differences in the swelling degree at the increasing concentration of TiO 2 NPs were observed. In vitro drug release and antibacterial activity against Staphylococcus aureus of TiO 2 nanocomposite GelMA film enriched with higher concentrations of TiO 2 NPs, identified as a suitable candidate for wound healing, were investigated. Both GelMA10% and TiO 2 nanocomposite GelMA films loaded with drug exhibited a strong antibacterial action, whereas GelMA10% containing only TiO 2 NPs did not show any antimicrobial properties.

Consumer interest in "natural" cosmetics has expanded to photoprotective products. Plant-derived ingredients, including oils and extracts, are frequently marketed as natural alternatives to conventional UV filters, often with claims of high photoprotective efficacy. However, their actual ability to provide broad-spectrum, clinically relevant photoprotection remains largely unverified, raising concerns about potential inadequate UV protection. In this study, eleven plant oils and nine cosmetic products marketed as "natural" (declared sun protection factor (SPF) 25-50) were tested. Test products were applied in standardized amounts on polymethyl methacrylate (PMMA) plates. Absorbance spectra were measured using an SPF Analyzer, then in vitro photoprotective parameters were calculated. Plant oils, including raspberry seed, carrot seed, coconut, shea butter, and others, exhibited negligible in vitro SPF and in vitro UVA PF values, with the exception of tamanu oil (in vitro SPF 21.5, in vitro UVA PF 3.3). However, its in vitro SPF decreased to 5.2 after photostability testing. Among cosmetic products, those containing primarily inorganic UV filters (titanium dioxide, zinc oxide) displayed variable efficacy, with most providing insufficient protection despite marketing claims, while one formulation containing titanium dioxide achieved high in vitro SPF (64.2) but low in vitro UVA PF (9.8). In overall, plant oils do not provide adequate photoprotection and cannot replace conventional UV filters. Consumers relying on such products may be unknowingly exposed to harmful UV radiation, potentially compromising dermatological interventions, including hyperpigmentation therapies. Effective photoprotection requires formulations containing multiple complementary UV filters, and highlights the need for standardized in vitro testing to ensure accurate product labelling and reliable consumer protection.

Psoriasis is a chronic inflammatory skin disorder marked by epidermal hyperplasia and hyperkeratosis, with lesions presenting highly irregular geometric patterns and a discrete distribution. Traditional phototherapy, lacking spatial selectivity, often causes radiation damage to surrounding healthy tissue, thereby limiting treatment dosage and frequency. In this study, we developed three-dimensional (3D)-printed lesion-conformal light-guiding patches, precisely customized based on lesion characteristics, marking a significant advancement from traditional point light sources to high-performance uniform surface light sources. The system integrates titanium dioxide nanoparticles (TiO 2 NPs) within a polydimethylsiloxane (PDMS) matrix to form scattering centers. Through a lateral coupling design, it redirects photons, generating a highly uniform surface-emitting light field. This approach overcomes the intensity attenuation inherent to point sources, enabling the simultaneous irradiation of multiple plaques while sparing surrounding healthy tissue with precision. In an imiquimod (IMQ)-induced mouse model, this system significantly mitigated damage to normal skin while effectively repairing psoriatic lesions. Histopathological (HE) analysis revealed a dramatic increase in epidermal thickness in the model group, which was five times greater than that of the control group. In contrast, the patterned group exhibited notable improvements in the pathological features of the lesions, with epidermal thickness returning to levels comparable to those of healthy controls. Immunohistochemical analysis showed that in the patterned group the expression of the keratinocyte proliferation marker K16 and the inflammatory cytokine IL-17 was substantially reduced, demonstrating superior efficacy over conventional point-source irradiation. Additionally, this closed-loop system demonstrated promising therapeutic potential for refractory plaques in preliminary clinical cases, providing new insights for the development of next-generation personalized and precision dermatology treatment devices.

The oscillatory motion of titanium dioxide (TiO 2 ) nanoparticles in water-based fluid for heat and mass transfer performance over vertical plate has been investigated. The novelty of this work evaluates the steady and periodical behavior of heat and mass transfer using TiO 2 -water nanofluid, magnetic field and mixed convection. The artificial neural network on dissipative Maxwell TiO 2 -water nanofluid is applied to predict the accuracy and convergence of velocity profile under defined boundary conditions. The oscillatory flow pattern is applied to develop the fluctuating layers in heating frequency and mass transmission. This model converts the mathematical equations into steady, real and imaginary forms using stokes and primitive transformations. Several authors solved the fluid models by converting into ordinary-differential form but this model presents direct unsteady partial differential equations. Implicit finite-difference approach is used to convert the mathematical model into algebraic system in the presence of Gaussian elimination simulation. It is noticed that the rate of velocity amplitude increases as radiation, Maxwell index, and heat dissipation increase. The lowest training mean square error (1.77 × 10⁻ 10 ), close validation, testing errors, small gradient (9.82 × 10⁻ 8 ) at fewer epochs (636) are observed for magnetic number Mf = 3.0. The steady behavior of heat and mass rate increases as Schmidt number and thermal radiation are enhanced. The amplitude of oscillatory heat and mass transfer intensifies as magnetic number and Richardson number are increased. The increasing skin friction rate is observed at each value of Maxwell parameter and Eckert number.

Hybrid nanofluids have attracted significant attention due to their enhanced thermal performance in engineering applications. This study numerically investigates the effects of magnetohydrodynamics (MHD), Joule heating, thermal radiation, heat source, and nanoparticle volume fractions on the flow and heat transfer characteristics of a copper-titanium dioxide/sodium alginate (Cu-TiO₂/SA) hybrid nanofluid over a Darcy-Forchheimer porous shrinking sheet using the non-Newtonian Reiner-Philippoff model. The governing partial differential equations were transformed into ordinary differential equations via similarity transformations and solved using the MATLAB bvp4c solver. Dual solutions were obtained for the shrinking case, and stability analysis confirmed that the first solution is physically stable. The results indicate that increasing nanoparticle concentration enhances fluid viscosity and skin friction while slightly reducing the heat transfer rate due to the dominance of conductive heat transport. The Cu-TiO₂/SA hybrid nanofluid enhances heat transfer by 34.2%, outperforming TiO₂ (4.5%) and Cu (29.1%) nanofluids. Thermal radiation and suction effect further improve heat transfer, whereas higher Eckert number and heat source parameters reduce thermal performance. Meanwhile, the effects of a magnetic field have been shown to reduce the fluid velocity. These findings highlight the importance of controlling physical parameters to optimize heat transfer in non-Newtonian hybrid nanofluid systems.