Sunscreen Research Articles

Construction of photo-responsive lignin as a broad-spectrum sunscreen agent

Lignin has potential to serve as promising sunscreen agents as it has good ultraviolet (UV) absorption and antioxidant properties. However, the weak absorption capacity of lignin in the long-wave UV region (UVA, 320–400 nm) limits its further development. In this work, a spiropyran-modified lignin (DLSP) with photo-responsive property was prepared by in-situ construction of spiropyran (SP) structure in the demethylated lignin (DL). Due to the presence of SP moiety, the absorption of DLSP in the UVA region was significantly improved. Under UV irradiation, its absorption peak was redshifted as unconjugated SP form isomerized to conjugated merocyanine (MC) form, and the UVA/UVB ratio increased from 0.62 to 0.74. The free-radical scavenging ability of lignin could protect SP from photodegradation, which provided DLSP excellent fatigue resistance. DLSP were blended into creams to investigate its sunscreen performance. Results indicated that DLSP exhibited radiation-enhanced sunscreen performance, the sun protection factor (SPF) of cream containing 10 wt% of DLSP improved from 20 to 67 after 8 h of UV irradiation. Moreover, DLSP showed low skin penetration and good biocompatibility. These results provide a useful guideline for the rational design of sunscreens with special functionalities.

New formulation technology to boost sun protection.

As every skin type worldwide is concerned by photoprotection, with consumers preferring cosmetic elegant and efficient sunscreen products, we aim at developing the most performant and desirable sun care products. We selected an interesting polymer, abbreviated AAHCP and designed scanning electron cryomicroscopy (cryoSEM), small angle and wide angle X-ray scattering and confocal laser scanning microscopy studies to understand its behaviour in solution and in simplex sun care formulations. This allowed us to develop innovative sunscreen formulation technology that was demonstrated by in vitro and in vivo photoprotection methods. Comprehensive photoprotection evaluations were made on the fully developed sun protection product. We observed the polymer oil structuring properties as well as its ability to form small and stable droplets in simplex emulsions. In vitro and in vivo sun protection factor (SPF) measurements demonstrated the sun protection boosting efficacy of AAHCP polymer in several emulsions or as a stand-alone emulsifier. This formulation technology also allowed to filtering system concentration optimization. Use-test performed on a fully developed AAHCP-based sunscreen validated its optimal performances as well as its ideal cosmetic features, with non-sticky, non-greasy perception and invisible skin result. For the first time, thanks to a new specific polymer creating a new type of emulsion, we succeed in reconciliate in a single sun care product maximal SPF efficacy, resistance to numerous stresses and optimal sensoriality.

Status quo on identified transformation products of organic ultraviolet filters and their persistence.

Organic micropollutants of concern - including organic UV filters (UVF) - are getting increasing attention. Personal care products such as sun screens or cosmetic articles often contain large quantities of UVF. These substances enter the environment either directly (during outdoor activities) or indirectly (via sewages from households). Therefore, the removal or degradation of UVF by natural or technical treatment processes is important to understand. UVF are often incompletely removed and transformed to side products of incomplete mineralization by abiotic and biotic processes. An extensive overview on transformation products (TPs) is essential to systematically identify knowledge gaps and to derive research needs. Whilst there are many reviews on the UVF themselves, the number of reviews which focus on their TPs is limited. Consequently, this review gives an overview on the latest findings regarding TPs of UVF. In this publication, known TPs of UVF, which were formed during abiotic and biotic processes, are reviewed. Target substances were defined and a literature database was reviewed for studies on TPs of the target substances. The first list of studies was shortened stepwise, thus generating a final list of studies which contained only the relevant studies. Since biodegradation is one of the most important pathways for removal of organic compounds from the environment, this review presents an overview on known TPs of organic UVF and their biodegradability, which determines their environmental fate. In this way, all identified TPs of UVF were listed and checked for information on their biodegradability. 2,731 records of studies were assessed. 42 studies, which assessed 46 processes that lead to the formation of identified TPs, were included in this review. 177 different TPs resulting from eleven different UVF were identified. Little to no data on the biodegradability was found for TPs. This indicates a severe lack of data on the biodegradability of TPs of organic UVF substances. Since most TPs lack information on biodegradability, further research should provide information on both - identity and biodegradability - of formed TPs to be able to assess their hazardousness for the environment.

INDIVIDUAL ARTICLE: NECOM 3: A Practical Algorithm for the Management of Radiation Therapy-Related Acute Radiation Dermatitis.

In the Nordic European countries in 2020, cancer diagnoses accounted for 175,925 patients. About 50% of cancer patients receive radiation therapy (RT), which may lead to radiation dermatitis (RD). Notably, patients with breast, head, neck, and anal cancers may be prone to developing RD. However, few algorithms exist for the prevention and treatment of RD. The Nordic European Cutaneous Oncodermatology Management (NECOM) project aims to improve cancer patient outcomes by offering tools to prevent and treat cancer therapy-related cutaneous adverse events (cAEs). The first 2 NECOM papers presented various cAEs and skincare regimens involving hygiene, moisturization, sun protection, and camouflage products for preventing and managing cAEs. The NECOM 3 practical algorithm for preventing and managing acute RD (ARD) is intended to promote healthy skin and reduce RT-related ARD, improving cancer patient outcomes.  Results: The NECOM advisors discussed the results of a systematic literature review and obtained consensus on the evidence and opinion-based practical algorithm for ARD to support all stakeholders in the Nordic European healthcare setting. The algorithm starts with skin-preserving therapy, followed by skin condition assessment and patient-specific interventions based on the grade of RD present.  Conclusion: ARD may lead to symptoms of pruritus and pain, decreased QoL and morbidity, and treatment interruptions. Patient education on the prevention of RD and treatment recommendations given in the NECOM 3 algorithm may help prevent and manage RD and improve the overall care of patients receiving RT. J Drugs Dermatol. 2023;22:11(Suppl 2):s3-s10.

Potential of Herbal Extracts as Sunscreens and Antihyperpigmentation Treatment

Background: Skin pigmentation is one of the most serious problems in the adult population of all races. The underlying factors of skin pigmentation are excessive exposure to UV radiation, oxidative stress, and other provocative causes that cause melasma, black spots, and post-inflammatory hyperpigmentation. Hence, treating hyperpigmentation disorders is challenging. Objective: Skin pigmentation occurs as a process of melanin biosynthesis triggered by UV exposure. Tyrosinase, an enzyme that catalyzes the rate-confining step in melanogenesis, if inhibited, can cause skin hypopigmentation. This has evoked an interest in reviewing plant extracts/ phytoconstituents, which can serve the purpose of sun protection and treat hyperpigmentation, ensuring skin glow for a better quality of life. Methods: A literature search on Medline, PubMed, Embase, and Scopus databases was done using various keywords like hyperpigmentation, melasma, skin-lightening agents, and sunscreen. Results: Sun protection products for canopy with photo-aging and skin pigmentation are recommended. Tyrosinase inhibitors are first-line topical medicines available as single or combined topical formulations. Hydroquinone, retinoids, corticosteroids, and kojic acid are clinically proven as exceptionally powerful. However, the adverse effects reported with these small molecules largely impact skin appearance, dermatitis, and exogenous ochronosis. Currently, there is a rising trend towards comfortable, fascinating, and well-endured skin depigmenting agents from natural products that might be utilized by a wide populace. Conclusion: This present study aimed at exploring plant and fruit extracts together with their active ingredients as potential multitargeted anti-hyperpigmentation agents with sunscreen properties, tyrosinase inhibition, and skin whitening effects.

Formulasi dan uji aktivitas sediaan lotion tabir surya ekstrak etanol 96% bekatul beras merah (Oryza nivara)

Brown Rice Bran (Oryza nivara) contains phenolic compounds, flavonoids, tannins, steroids, or terpenoids that can function as an antioxidant activity that can protect the skin from the adverse effects of UV rays of the sun. Extraction was carried out by maceration method using 96% ethanol as solvent. The viscous extract obtained was then subjected to phytochemical screening and SPF test and made into three different concentrations, 5%, 10%, and 15%, which would then be formulated into a sunscreen lotion dosage form. The resulting preparations evaluated the physical quality of lotion preparations in the form of organoleptic tests, homogeneity tests, pH tests, dispersibility tests, and SPF tests of preparations. The results of the SPF test extract with concentrations of 5%, 10%, and 15% showed that the protection produced was in the ultra-category with SPF values respectively 31.1, 40.1, and 45.1. The results of the physical evaluation of the preparation of sunscreen lotion with brown rice bran extract showed that the lotion produced was not homogeneous, and the results of the pH test and dispersion test still met the requirements. Testing the SPF value of lotion preparations showed that the protection produced by each formula was in the maximum to ultra-category with SPF values of 11.7, 14.1, and 16.4, respectively.

Effects of TiO2 ultraviolet filter and sunscreens on coastal dune plant performance and competitive interactions

Ultraviolet filters (UVFs) added to sunscreens (SS) are emerging contaminants in marine environments due to their adverse effects on organisms and ecosystems. UVFs have also been detected in beach-dune systems, but their influence on resident organisms has not been explored yet. Native plants are fundamental components of coastal dunes, and these ecologically/economically important systems are currently among the most threatened globally. Thus, understanding whether UVFs may act as threats to dune plants is crucial. This field study evaluated and compared the effects of titanium dioxide nanoparticles (nTiO2), one of the inorganic UVFs most commonly added to sunscreens, and those of a commercial sunscreen product containing it (SS-nTiO2) on the performance of adult dune plants of a native (Thinopyrum junceum) and a non-native invasive species (Carpobrotus sp. pl.) and their competitive interactions at environmentally realistic concentrations. The effects of nTiO2, SS-nTiO2 and of a sunscreen product containing just organic UVFs (SS-OF) on early life stages of T. junceum were also examined. Ti bulk content in sand and plants at the study site ranged from 970 to 1069 mg kg−1 and from 2 to 7.9 mg kg−1, respectively. Thinopyrum junceum adult plants periodically exposed during the summer season to seawater contaminated by SS-nTiO2 produced less biomass than un-exposed plants and nTiO2 exposed plants. nTiO2 and SS-nTiO2 reduced the capacity of T. junceum to control the spread of Carpobrotus. Both SS-nTiO2 and SS-OF reduced seedling emergence in T. junceum whereas nTiO2 did not. These results demonstrated that the periodical exposures of native dune plants to sunscreens could reduce their establishment success and growth and favor invasive plant spread potentially resulting in community structure changes. They also emphasize the need to assess the phytotoxicity not only of single UVFs but especially that of complete sunscreen products to design more eco-friendly formulations in the future.

The Analysis of Beneunder's Marketingstrategy Based on Consumer Psychology

As living standards improve and knowledge becomes more widespread, people are becoming more and more aware of sun protection and the discussion of sun protection products has now become a hot topic in life. In terms of annual data, the number of sunscreen-related company registrations in China increased year on year from 2015 to 2019, while Brand Beneunder stood out from the crowds as the number one popular Chinese sunscreen brand of the moment. Therefore, this paper will analyze the reasons for Beneunder's success by collecting its financial data and social media placement data, and conducting a swot analysis of Beneunder based on consumer psychology data to analyze marketing strategies. The analysis finds that the success of Beneunder is inextricably linked to differentiated marketing but in addition to maintaining this excellent marketing strategy, the quality of the product itself has to be strengthened because good products are the most important factor for the long-term survival of the brand. The significance of this paper is to analyze the marketing strategies of successful brands to provide implications for other companies so that they can organize their business activities in a planned manner and promote healthy and sustainable growth.

Evidence for an accumulation of mineral oil saturated hydrocarbons (MOSH) in human tissues: a re-evaluation of biopsy and autopsy data

AbstractConsumers are exposed to mineral oil hydrocarbons (MOH) e.g. through foodstuffs and cosmetics. Upon ingestion, MOH follow the absorption pathway of dietary lipids. Analytical chemistry has revealed the presence of the main fraction, designated as mineral oil saturated hydrocarbons (MOSH), in mesenteric lymph nodes (MLNs), liver, spleen, and adipose tissue. Recent results from animal studies raised concerns about a long-term, possibly irreversible accumulation of some MOSH in humans. To address this issue, we performed a statistical re-analysis of published biopsy and autopsy data regarding the age-dependence of MOSH levels in human tissue. MOSH concentrations in MLNs and adipose tissue showed a 1.2–1.4-fold increase per decade, pointing to very long-term accumulation in both tissues. There was no evidence for age-dependent MOSH concentrations in liver and spleen. There was no sex difference in the MOSH concentrations in MLNs, suggesting a similar oral exposure for men and women. On average, women had a 2.2–2.5-fold higher MOSH concentration in the liver, spleen and adipose tissue compared to men. This finding may point to a sex difference in metabolism, in line with animal data. The use of certain cosmetics was a relevant predictor in addition to age. Women that used cosmetics like lipstick, hand cream, and sun cream had an average 2.1-fold higher MOSH concentration in abdominal subcutaneous fat than non-users.

Easy determination of benzophenone and its derivatives in sunscreen samples by direct-immersion solid-phase microextraction and gas chromatography–mass spectrometry

Benzophenones (BPs) absorb different sun radiation wavelengths, making them effective UVA and UVB filters, widely used in industry. In Europe, sunscreen products contain regulated amounts (6 % w/w) of benzophenone-3 (BP-3), usually combined with other filters like octocrylene. BPs are mutagens in UV radiation, and octocrylene may degrade into BPs, making their monitoring crucial. The present manuscript proposed a novel procedure based on liquid-liquid extraction followed by direct-immersion solid-phase microextraction (LLE-DI-SPME) to isolate and determine 10 BPs in sunscreen lotions with potential results. Parameters like extraction solvent, pH, adsorption, desorption time, stirring, sating effect, and presence of organic solvents were optimized and compared with different SPME fibers, being polyacrylate (PA) fiber the most effective. Detection and quantification were performed by gas chromatography–mass-spectrometry. Analytical parameters as limits of detection were 0.05–0.10 µg kg-1, while the linear range was 0.16 up to 2000 µg kg-1. In terms of recovery, the method ranged from 83 % to 103 %; the precision of the method was good in terms of relative standard deviation (RSD) from 3.2 % to 18.7 % and without a remarkable matrix effect (–15.06–8.45 %). Despite the complexity of the samples and the difficulty posed by the DI-SPME technique, the method proved robust. The proposed method successfully detected 10 BPs in 6 different sunscreen lotions. The total presence of BPs in sunscreens ranged from 165 to 931 mg kg-1, with BP-3 detected in all samples from 4.2 to 740 mg kg-1.

Enhanced photostability and biocompatibility of sunscreen formulation of 2-phenylbenzimidazole-5-sulfonic acid with methyl-beta-cyclodextrin

Ensuring the photostability of sunscreen lotions is crucial for their effectiveness and safety when exposed to sunlight. Photostability refers to the ability of a substance to remain stable and undergo minimal chemical degradation or photochemical reactions upon exposure to ultraviolet (UV) radiation, especially from sunlight. In this study, we focused on 2-phenylbenzimidazole-5-sulfonic acid (PBS), one of the leading sunscreen agents, and aimed to form inclusion complexes (IC) with methyl-β-cyclodextrin (MCD). Through phase solubility measurements, we determined the stoichiometry of the IC to be 1:1, with a binding constant of 155.4 M−1. Proton Nuclear Magnetic Resonance (1H NMR) and ROESY analysis provided evidence that the benzimidazole part of PBS is successfully included in the cavity of MCD. Quantum mechanical calculations using the B3LYP/6-31G(D, P) method in the Gaussian 16 package further supported the formation of the IC by providing energy data. Notably, the photostability of the IC is maintained for up to four hours of UV exposure, showing no significant structural changes in PBS. Moreover, we conducted biocompatibility tests, and the results are encouraging for the superior activity, and suggest the potential of the IC for promoting its cosmetic application as a UVB sunscreen.

Efficient ultraviolet blocking film on the lignin-rich lignocellulosic nanofibril from bamboo

The ultraviolet (UV) blocking performance of current bio-based devices is always limited by delignification and exploited chemical treatment. Lignocellulosic nanofibril (LCNF) is a promising green alternative that could efficiently impede UV radiation. Herein, we proposed a robust LCNF film that achieved 99.8 ± 0.19 % UVB blocking, 96.1 ± 0.23 % UVA blocking, and was highly transparent without complex chemical modification. Compared to conventional lignin composites, this LCNF method involves 29.5 ± 2.31 % lignin content directly extracted from bamboo as a broad-spectrum sun blocker. This bamboo-based LCNF film revealed an excellent tensile strength of 94.9 ± 3.6 MPa and outstanding stability, adapting to the natural environment's variability. The residual hemicellulose could also embed the link between lignin and cellulose, confirming high lignin content in the network. The connection between lignin and hemicelluloses in the cellulose network was explored and described for the fibrillation of lignocellulosic nanofibrils. This research highlights the promising development of LCNFs for UV protection and bio-based solar absorption materials.

Isoamyl (E)-3-(3,4-Dimethoxyphenyl)acrylate

Isoamyl (E)-3-(3,4-dimethoxyphenyl)acrylate (1) was obtained from the 2-methyl-6-nitrobenzoic anhydride (MNBA)/4-dimethylaminopyridine (DMAP)-catalyzed reaction at room temperature for 190 min in dichloromethane with a yield of 95%. The structure of isoamyl (E)-3-(3,4-dimethoxyphenyl)acrylate (1) was elucidated using NMR, FTIR, and high-resolution mass spectrometry. In vitro sun protection factor evaluation exhibited a value of 37.10 ± 0.03 which indicates that isoamyl (E)-3-(3,4-dimethoxyphenyl)acrylate (1) is a sunscreen agent with high protection.

Vitamin D Levels in Children During Winter and the Relationship Between Sunscreen and Sun Protection Behaviors.

Sunlight is the major source of vitamin D, thus, the use of sunscreens could result in vitamin D insufficiency or deficiency. Our study aimed to assess serum vitamin D levels in healthy children aged 0-18 years in the winter season and determine the association between sunscreen use and sun protection behaviors on vitamin D status. The demographic data, clothing style, skin type, history of sunburn, history of visiting seaside towns in summer, sun protection behaviors including sunscreen use, wearing sunglasses and hats, and further detailed information about sunscreen use were recorded. Vitamin D status was assessed by measuring blood levels of total 25(OH)D during winter. Three hundred seventy-six children (172 boys and 204 girls) with a mean age of 128.38±56.39 months were enrolled. The mean serum level of 25(OH)D was 15.32±8.64 ng/mL. The mean values of vitamin D were associated with age, sex, traditional clothing style, having a sunburn history, and sunscreen use (P < 0.05). Adolescents and girls had vitamin D deficiency and inadequacy more than younger children and boys (P < 0.05). Sunscreen use in the adequacy group was lower than in the inadequacy and deficiency groups (P = 0.001). There was no significant difference between vitamin D status according to the sunscreen details (sun protection factor, product source, season, and body areas) (P > 0.05). Sunscreen use appears to reduce vitamin D levels measured in winter. Children, especially girls and adolescents, should be exposed to sufficient sunlight to maintain normal serum vitamin D levels. Vitamin D supplementation should be given to children, especially during winter.

Mussel-inspired anti-permeation hybrid sunscreen with reinforced UV-blocking and safety performance

Sun protection has gradually become an indispensable living habit of human beings, and sunscreens are needed under various circumstances. Considering the disadvantages and abuse of traditional sunscreen additives which are proved to have some potential threats to human body and natural environment, it is an urgent need to develop new sunscreens with both safety and high efficiency for the evolution of the industry. Therefore, as a complement to the shortcomings, polydopamine (PDA) was hybridized with zinc oxide (ZnO) by a simple sol-gel method. The obtained novel sunscreen agent had high ultraviolet (UV) resistance efficiency, as the SPF (∼77.2) and PA (PA+++) value at only 10 wt% addition could meet the daily sunscreen requirements. Besides, the permeation of ZnO and Zn2+ could be almost completely avoided through the epidermis layer of skin, due to the increase of mussel-inspired adhesive force. Furthermore, the free radical scavenging rate could reach 88.1% at low concentration, and it was proved to have no cytotoxicity. Overall, the ZnO-PDA has a good application prospect in high-efficiency and safe sunscreen, and it can be an impetus for the development of novel cosmetics.

Molecular Modelling Based on TD-DFT Applied to UV Spectra of Coumarin Derivatives

The optimization of geometry and electronic transition of seven coumarin derivatives for sunscreen activity have been conducted using Orca. DFT methods is applied to find optimum geometry and parameter data is measured like bond length and bond angle. TD-DFT is conducted to get electronic transition to get ultraviolet (UV) spectra. The result shows that the coumarin derivative transition type is n to π* and π to π*. All coumarin exhibits the properties of UV-B protection, however, two out of seven show properties as a UV-A protection. The energy difference HOMO-LUMO shows that coumarin with isopropyl substituent has the smallest energy gap, around 0.1559, whereas coumarin with fluorine atom substituent has the biggest energy gap.

Multi-omics approach to understand the impact of sun exposure on an in vitro skin ecosystem and evaluate a new broad-spectrum sunscreen.

A reconstructed human epidermal model (RHE) colonized with human microbiota and sebum was developed to reproduce the complexity of the skin ecosystem in vitro. The RHE model was exposed to simulated solar radiation (SSR) with or without SPF50+ sunscreen (with UVB, UVA, long-UVA, and visible light protection). Structural identification of discriminant metabolites was acquired by nuclear magnetic resonance and metabolomic fingerprints were identified using reverse phase-ultra high-performance liquid chromatography-high resolution mass spectrometry, followed by pathway enrichment analysis. Over 50 metabolites were significantly altered by SSR (p < 0.05, log2 values), showing high skin oxidative stress (glutathione and purine pathways, urea cycle) and altered skin microbiota (branched-chain amino acid cycle and tryptophan pathway). 16S and internal transcribed spacer rRNA sequencing showed the relative abundance of various bacteria and fungi altered by SSR. This study identified highly accurate metabolomic fingerprints and metagenomic modifications of sun-exposed skin to help elucidate the interactions between the skin and its microbiota. Application of SPF50+ sunscreen protected the skin ecosystem model from the deleterious effects of SSR and preserved the physiological interactions within the skin ecosystem. These innovative technologies could thus be used to evaluate the effectiveness of sunscreen.

Natural Antioxidant-Loaded Nanoemulsions for Sun Protection Enhancement

The aim of this study was to formulate nanodispersions to encapsulate antioxidants extracted from olive mill wastewater (OMW) and phycocyanin extracted from Spirulina maxima to act as enhancers for the skin’s protection against UV radiation. For this purpose, two water-in-oil nanoemulsions were prepared using a low-energy homogenization method. Both systems were based on isopropyl myristate as the continuous phase, while water or a mixture of glycerol and water was used as the dispersed phase. Then, antioxidants extracted from OMW and phycocyanin from Spirulina maxima were encapsulated in the water core of the nanoemulsions. The empty and antioxidant-loaded systems were then structurally studied using dynamic light scattering for the detection of their droplet size and stability over time. Electron paramagnetic resonance (EPR) spectroscopy using adequate probes was applied for the characterization of the surfactants’ monolayer in the presence and absence of antioxidants. It was found that the mean droplet diameter of the emulsions was 200 nm. The nanoemulsions remained stable for over 2 months. The encapsulated antioxidants were assessed for their scavenging activity of a model stable radical by applying EPR spectroscopy. It was found that the loaded systems exhibited an increased antioxidant capacity compared with the empty ones. Finally, the most stable system was added to commercial sunscreen lotions and the overall sun protection factor (SPF) was assessed. The sunscreen lotions that contained the nanoemulsions loaded with OMW extracts or phycocyanin showed an increase in their SPF value.

Facile Synthesis and Biophysical Characterization of Novel Zinc Oxide/Fe3O4 Hybrid Nanocomposite as a Potentially Active Agent in Sunscreens

Zinc oxide nanoparticles (ZnO NPs) are attractive sunscreens for UV protection, but they still face some challenges due to their white color and skin whitening, and the extent of UV blocking is still limited to UV-B. Therefore, the present work aimed to develop novel sunscreen agents based on ZnO/Fe3O4 hybrid nanocomposites. ZnO/Fe3O4 hybrid nanocomposites were prepared using a facile one-step combustion method and characterized by XRD, FTIR, FESEM, and UV–Vis diffuse reflectance techniques. The in vitro sun protection factor (SPF) and antioxidant activity of the prepared samples were carried out by spectrophotometric methods. The biocompatibility potential was tested on the normal (Human lung fibroblast: WI38) and cancerous (Hepatocellular carcinoma: HEPG-2) cell lines and the antibacterial activity was tested against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Bare ZnO NPs and ZnO/Fe3O4 hybrid nanocomposites had pure structures with average particle sizes on a scale below 100 nm. The samples had antibacterial and antioxidant activity as well as the potential for biocompatibility and anticancer activity (cell viability was 80% for all nanocomposites up to 6.25 μg/mL indicating non-toxicity). The nanocomposite presented good UV absorption and SPF values (SPF = 12.2–14) not too far from those of bare ZnO (SPF = 15.4) and achieved extended protection over the UV and visible range. ZnO/Fe3O4 hybrid nanocomposites are colored compounds that can match a desired tanned skin tone and have biophysical properties that make them a promising future as a cosmetic UV protectant.

Structural and Photoprotective Characteristics of Zn-Ti, Zn-Al, and Mg-Al Layered Double Hydroxides—A Comparative Study

Organic UV filters have been known to generate harmful by-products and undergo photoreactive degradation, which ultimately poses a great threat to consumers using sunscreen products. Inorganic UV filters such as TiO2 and ZnO, although considered safer options, are not without threat considering their photocatalytic nature and ability to generate reactive oxygen species. A study was conducted to identify the influence of different metal ions on the photochemical properties of layered double hydroxides (LDH), Zinc-Titanium LDH (Zn-Ti LDH), Zinc-Aluminium LDH (Zn-Al LDH), and Magnesium- Aluminium LDH (Mg-Al LDH) and their prospects in photoprotection. The photocatalytic properties of the LDH were analyzed and compared to TiO2 and ZnO. The intermediate band gaps of Zn-Ti (3.72 eV) and Zn-Al LDH (3.3 eV) proved favorable and safer for the use of these LDH in cosmetic formulations as they offer lower photo-reactivity when compared to cosmetic grade ZnO and TiO2. The in vitro SPF values obtained for formulations containing 2 wt% Zn-Ti and 2 wt% Zn-Al LDH showed promise, with both samples claiming “broad spectrum” protection and valid claims of UVA protection.