The Influence of Titanium Dioxide Particle Size on the Photo-Protective Properties of Pharmaceutical Preparations and Their Effectiveness Assessment Using Hyperspectral Imaging Methods
by
, , and
Anna Stolecka-Warzecha
*
,
Elżbieta Mickoś
,
Daria Śniecińska
,
Dominika Malewicz-Skrabania
,
Adam Wilczyński
and
Sławomir Wilczyński
Department of Basic Biomedical Science, Faculty of Pharmaceutical Sciences in Sosnowiec, Medical University of Silesia in Katowice, Jednosci 8B, 41-208 Sosnowiec, Poland
*
Author to whom correspondence should be addressed.
Cosmetics 2025, 12(6), 242; https://doi.org/10.3390/cosmetics12060242
Submission received: 29 August 2025
/
Revised: 21 October 2025
/
Accepted: 30 October 2025
/
Published: 3 November 2025
(This article belongs to the Special Issue Sunscreen Advances and Photoprotection Strategies in Cosmetics)
Abstract
Background: Titanium dioxide (TiO2) is widely used as a physical filter in sunscreen formulations due to its ability to reflect and scatter radiation. The effectiveness of TiO2-based preparations depends on particle size, influencing photoprotective properties across various wavelength ranges. The aim of this study was to assess the effect of TiO2 particle size on the photoprotective properties of pharmaceutical preparations using hyperspectral imaging (HIS). Methods: This study analyses directional reflectance of skin covered with preparations containing TiO2 particles < 5 µm and <100 nm across the spectral range 400–1002 nm. Results: Preparations with TiO2 < 5 µm showed higher reflectance in both the 400–633 nm and 900–1002 nm ranges, while no significant protective enhancement was observed in the 636–897 nm range. Conclusions: Larger TiO2 particles provided more significant photoprotection across a broader wavelength spectrum, highlighting the importance of particle size selection in modern sunscreen formulations. This experimental in vitro study evaluated the photoprotective properties of pharmaceutical preparations containing titanium dioxide particles of different sizes. The measurements were performed using hyperspectral imaging in the 400–1000 nm range, covering ultraviolet and visible light.
1. Introduction
Ultraviolet (UV) radiation is an important environmental factor that exerts both positive and negative biological effects. While UVB plays a beneficial role in vitamin D synthesis, excessive exposure to solar radiation increases the risk of premature skin aging, the development of precancerous conditions, and skin cancers such as basal cell carcinoma, squamous cell carcinoma, and malignant melanoma [1,2,3,4]. Therefore, the use of effective photoprotection methods constitutes a key element of disease prevention and health protection.
One of the most important methods of protection against the harmful effects of UV radiation is the use of preparations containing sunscreen filters. Currently, sunscreens are either classified as chemical (organic) or physical (inorganic) filters [5]. The latter group includes TiO2, which has been used for several decades as an ingredient in photoprotective cosmetics. Its effectiveness is primarily due to its mechanism of reflecting and scattering UV radiation, which limits its penetration into deeper layers of the skin [6,7]. In sunscreen formulations, TiO2 is most commonly used in the form of rutile or anatase, as micro- or nanoparticles. The particle size, crystalline form, and formulation of the preparation significantly affect its photoprotective properties, safety, and tolerability [7,8,9]. Due to the potential of certain forms of TiO2 to induce photocatalytic reactions, these formulations are often enriched with additional antioxidants to reduce the risk of adverse effects. Titanium dioxide (TiO2) plays a significant role in modern sunscreen formulations as an inorganic physical filter. Its mechanism of action is based primarily on the reflection, scattering, and partial absorption of ultraviolet radiation, effectively limiting the penetration of harmful radiation into the deeper layers of the skin [6,7]. TiO2 provides effective protection against UVB radiation and, to some extent, UVA radiation, which makes it suitable for use in broad-spectrum photoprotection systems. In cosmetic formulations, TiO2 is mainly present in two crystalline forms: rutile and anatase. Rutile is considered the safer form due to its lower photocatalytic activity compared to anatase. Modern cosmetic formulations often use TiO2 in micronized or nanoparticulate form, allowing for a high level of UV protection while maintaining desirable aesthetic properties, such as the absence of a whitening effect on the skin [7,8,9]. The use of TiO2 nanoparticles initially raised concerns about potential penetration into deeper layers of the skin and possible cytotoxicity. However, numerous studies have shown that under conditions of proper use, cosmetics containing TiO2 nanoparticles do not penetrate intact stratum corneum to any significant extent, and the risk of adverse effects is minimal [8,9]. Additionally, to enhance safety, TiO2 nanoparticles are often coated with other substances (e.g., silica, alumina), which reduce their ability to generate reactive oxygen species under UV radiation [10].
Methods for assessing the effectiveness of UV-protective preparations and factors influencing their efficacy: The effectiveness of sunscreen preparations is assessed through both in vivo and in vitro studies, in accordance with standards developed by international organizations (including ISO, COLIPA, and FDA). The primary parameter determining a product’s ability to protect against UVB is the sun protection factor (SPF), which expresses the ratio of the minimal erythema dose (MED) after applying the sunscreen to the MED without the sunscreen [9]. For UVA protection, indicators such as PPD (persistent pigment darkening), IPD (immediate pigment darkening), and UVA-PF are used to evaluate the ability of the preparation to limit UVA-induced pigmentation [11,12]. In vivo methods involve applying the preparation to the skin of volunteers and exposing it to controlled doses of radiation, while in vitro studies use special plates or films and spectrophotometric analysis of radiation transmission through the product layer [10,11,12]. Currently, in vitro methods are growing in importance, as they allow for fast and reproducible assessment of photoprotective properties without involving study participants. The effectiveness of sun protection is not only affected by the active ingredients implemented, but also by technological factors (e.g., homogeneity of TiO2 dispersion in the cosmetic base, stability of the formulation) and the method of applying the product. The amount of product applied, the accuracy of skin surface coverage and the frequency of reapplication are key determinants of achieving the claimed level of protection [12].
The aim of this study was to analyse the use of the photoprotective properties of titanium dioxide (TiO2) in sunscreen preparations and to evaluate the impact of particle size on the effectiveness of protection against ultraviolet radiation. This study compared the reflectance properties of preparations containing TiO2 particles of different sizes and reviewed available methods for assessing the effectiveness of photoprotective preparations, with particular emphasis on hyperspectral imaging techniques.
2. Materials and Methods
This study was conducted with 20 volunteers (11 women and 9 men) aged 21 to 65 years. The participants were students and employees of the Medical University of Silesia in Katowice who provided informed consent to participate. Preparations containing titanium dioxide (IV) particles of different sizes and a reference cream were applied to the forearm skin of each volunteer in accordance with FDA guidelines for the amount of product applied (2 mg/cm2). Two types of ointments were prepared for this study using Mediderm Cream (a commercially available product) as the base (INCI: Aqua, Petrolatum, Cetearyl Alcohol, Paraffinum Liquidum (Mineral Oil), Cetomacrogol 1000, Phenoxyethanol). The first preparation contained titanium dioxide with particle size < 5 μm, and the second contained titanium dioxide with particle size < 100 nm. The concentration of the active substance in both ointments was 20%. The ointments were prepared in accordance with pharmaceutical procedures described in the Polish Pharmacopoeia XII. Formulations were included if they contained titanium dioxide as the main UV filter; products containing organic filters or colored pigments were excluded.
Each preparation was applied to a designated area of the forearm using plastic spatulas. Application was performed on a precisely defined area, ensuring standardization of the amount applied. After application, the participants were positioned under uniform lighting conditions provided by two halogen lamps with a flat spectral characteristic in the 400–1000 nm range. To analyse the photoprotective properties, a SPECIM IQ hyperspectral camera (Spectral Imaging Ltd., Oulu, Finland) was used, allowing for data acquisition in the wavelength range of 400–1000 nm with a spectral resolution of 7 nm and a spatial resolution of 512 × 512 pixels. Image data were recorded from a distance of approximately 30 cm from the tested surface. A reflectance standard was placed next to the forearm to enable calibration and determination of the absolute reflectance of the tested preparations. Imaging was performed under controlled lighting conditions. The recorded data were saved in *.dat format, converted to *.mat format, and analysed using Matlab® R25b. Minimum, maximum, and mean absorption values were determined in the designated regions of interest (ROI), and reflectance characteristics were determined across the entire working range of the camera. The data obtained from the hyperspectral image analysis were imported into Excel and subjected to statistical analysis using Statistica 13.3 (Statsoft). The normality of data distribution was assessed with the Shapiro–Wilk test. Due to the lack of normal distribution, the Friedman ANOVA test was applied. A result was considered statistically significant at p < 0.05.
3. Results
3.1. Analysis of the Full Wavelength Range
In the full wavelength range, statistically significant differences in reflectance were observed depending on the composition of the preparation applied to the skin (p < 0.001). Post hoc tests showed that skin reflectance differed significantly from the reflectance of skin with cream containing titanium dioxide with a particle size < 5 µm (p < 0.05) and titanium dioxide with a particle size < 100 nm (p < 0.05), whereas no significant difference was found compared to skin with cream without titanium dioxide (Figure 1, Table 1). Additionally, statistically significant differences were demonstrated between the reflectance of skin with cream containing titanium dioxide < 5 µm (p < 0.05) and skin with cream without titanium dioxide (p < 0.05), as well as between the reflectance of skin with cream containing titanium dioxide < 100 nm and skin with cream without titanium dioxide (p < 0.05). The median (Md), first quartile (Q1), and third quartile (Q3) reflectance values were as follows: for skin Md 0.683; Q1 0.446; Q3 0.727; for skin with cream containing titanium dioxide < 5 µm Md 0.699; Q1 0.569; Q3 0.718; for skin with cream containing titanium dioxide < 100 nm Md 0.685; Q1 0.545; Q3 0.724; and for skin with cream without titanium dioxide Md 0.684; Q1 0.478; Q3 0.723.
Considering the full spectral range, it can be observed that the shape of the reflectance curve for the skin and for the skin with applied preparations is similar, with the lowest reflectance occurring between 400 and 633 nm, followed by an increase, and then a decrease again at higher wavelengths. However, a more detailed analysis showed that depending on the spectral range, either the reflectance of the skin with cream containing titanium dioxide < 5 µm or the reflectance of the untreated skin predominated in terms of value. Therefore, further analysis was conducted after dividing the spectral data into three ranges: I—400–633 nm, II—636–897 nm, and III—900–1002 nm.
3.2. Analysis of the 400–633 nm Wavelength Range
In the wavelength range of 400–633 nm, statistically significant differences in reflectance were observed depending on the type of preparation applied to the skin (p < 0.001). Post hoc tests showed that skin reflectance differed significantly from the reflectance of skin with cream containing titanium dioxide < 5 µm (p < 0.05), titanium dioxide < 100 nm (p < 0.05), and cream without titanium dioxide (p < 0.05) (Figure 2, Table 2). Additionally, statistically significant differences were found between the reflectance of skin with cream containing titanium dioxide < 5 µm (p < 0.05) and titanium dioxide < 100 nm (p < 0.05), as well as between skin with cream containing titanium dioxide < 5 µm and cream without titanium dioxide (p < 0.05). Differences were also observed between the reflectance of skin with cream containing titanium dioxide < 100 nm and cream without titanium dioxide (p < 0.05). The median (Md), first quartile (Q1), and third quartile (Q3) reflectance values were as follows: for skin Md 0.440; Q1 0.409; Q3 0.457; for skin with cream containing titanium dioxide < 5 µm Md 0.567; Q1 0.560; Q3 0.571; for skin with cream containing titanium dioxide < 100 nm Md 0.541; Q1 0.535; Q3 0.550; and for skin with cream without titanium dioxide Md 0.472; Q1 0.456; Q3 0.490.
In the wavelength range of 400–633 nm, it can be observed that the highest reflectance values correspond to skin with cream containing titanium dioxide particles < 5 µm. At the lowest wavelengths, its reflectance is approximately 0.450 [a.u.], then increases sharply and remains stable at above 0.550 [a.u.]. In contrast, skin with cream containing titanium dioxide particles < 100 nm initially reaches the highest reflectance values, which then decrease and remain below 0.550 [a.u.]. Both particle sizes show clearly higher reflectance values in the first wavelength range (400–633 nm) compared to skin with cream without titanium dioxide particles or untreated skin. Within the 400–633 nm wavelength range, the shapes of the mean reflectance curves for untreated skin, skin with cream without titanium dioxide, and skin with cream containing titanium dioxide < 100 nm are similar (Table 3).
3.3. Analysis of the 636–897 nm Wavelength Range
In the wavelength range of 636–897 nm, statistically significant differences in reflectance were observed depending on the presence of a specific preparation on the skin (p < 0.001). Post hoc tests showed that skin reflectance differed significantly from the reflectance of skin with cream containing titanium dioxide < 5 µm (p < 0.05), titanium dioxide < 100 nm (p < 0.05), and cream without titanium dioxide (Figure 3, Table 4). Additionally, statistically significant differences were found between the reflectance of skin with cream containing titanium dioxide < 5 µm and titanium dioxide < 100 nm (p < 0.05), as well as between skin with cream containing titanium dioxide < 5 µm and cream without titanium dioxide (p < 0.05). However, no statistically significant differences were observed between the reflectance of skin with cream without titanium dioxide and skin with cream containing titanium dioxide < 100 nm. The median (Md), first quartile (Q1), and third quartile (Q3) reflectance values were as follows: for skin Md 0.729; Q1 0.718; Q3 0.740; for skin with cream containing titanium dioxide < 5 µm Md 0.718; Q1 0.711; Q3 0.723; for skin with cream containing titanium dioxide < 100 nm Md 0.725; Q1 0.716; Q3 0.733; and for skin with cream without titanium dioxide Md 0.726; Q1 0.714; Q3 0.739.
In the wavelength range of 636–897 nm, two increases in reflectance measurements can be observed (Figure 3, Table 5). The first reflectance maximum was noted at a wavelength of approximately 734 nm, and the second at approximately 832 nm, for both untreated skin and skin with applied preparations. At the beginning of this range, the highest reflectance was observed for skin with cream containing titanium dioxide particles < 100 nm; however, in the later part of the graph, the reflectance of untreated skin began to predominate. The shapes of the mean reflectance curves for skin and skin with applied preparations showed similarities.
3.4. Analysis of the 900–1002 nm Wavelength Range
In the wavelength range of 900–1002 nm, statistically significant differences in reflectance were observed depending on the presence of the preparation on the skin (p < 0.001). Post hoc tests showed that skin reflectance differed significantly from the reflectance of skin with cream containing titanium dioxide < 5 µm (p < 0.05). Furthermore, statistically significant differences were found between the reflectance of skin with cream containing titanium dioxide <100 nm and titanium dioxide < 5 µm (p < 0.05), as well as between skin with cream without titanium dioxide and skin with cream containing titanium dioxide < 100 nm (p < 0.05) and titanium dioxide < 5 µm (p < 0.05) (Figure 4, Table 6). However, no statistically significant differences were observed between the reflectance of untreated skin and skin with cream containing titanium dioxide < 100 nm, nor between untreated skin and skin with cream without titanium dioxide. The median (Md), first quartile (Q1), and third quartile (Q3) reflectance values were as follows: for skin Md 0.686; Q1 0.676; Q3 0.701; for skin with cream containing titanium dioxide < 5 µm Md 0.704; Q1 0.700; Q3 0.708; for skin with cream containing titanium dioxide < 100 nm Md 0.686; Q1 0.681; Q3 0.702; and for skin with cream without titanium dioxide Md 0.685; Q1 0.666; Q3 0.689.
The mean reflectance values of the skin change dynamically with wavelength within range III (900–1002 nm) (Figure 4, Table 7). It can be observed that in the wavelength range of 900–1002 nm, skin with cream containing titanium dioxide particles < 5 µm reaches significantly higher reflectance values. At its maximum, the reflectance reaches approximately 0.730 [a.u.]. In the upper end of the wavelength range, the reflectance of skin with cream containing titanium dioxide < 5 µm as well as titanium dioxide < 100 nm exceeds that of untreated skin and skin with cream without titanium dioxide. The shapes of the mean reflectance curves for skin and skin with applied preparations show similarities.
4. Discussion
Titanium dioxide (TiO2) is widely used as a physical protective filter against radiation, mainly due to its ability to reflect and scatter radiation. Its protective mechanism is based on optical properties that effectively block radiation from penetrating into deeper layers of the skin, thus protecting it from the harmful effects of such radiation. The main finding of this study is that smaller TiO2 particles demonstrated higher photoprotective uniformity under hyperspectral analysis. An important aspect is the particle size of TiO2, which influences its photoprotective effectiveness and was the main hypothesis of this study [13,14,15,16]. The hypothesis assumed that smaller TiO2 particles, especially in the form of nanoparticles, would provide higher effectiveness in UV protection due to their greater specific surface area, which enhances their ability to reflect and scatter radiation. At the same time, excessively small nanoparticles may penetrate the skin barrier, raising concerns about potential health effects. Therefore, optimizing the particle size of TiO2 is crucial to achieving maximum photoprotective efficacy while minimizing risk.
This study used hyperspectral imaging, which enables detailed analysis of the optical properties of pharmaceutical preparations across a broad wavelength range (400–1000 nm) [17,18]. The SPECIM IQ hyperspectral camera allowed for precise recording of reflectance changes in skin covered with preparations containing TiO2 particles of different diameters. This technique, combining elements of imaging and spectroscopy, is characterized by high precision and non-invasiveness, enabling comprehensive analysis of the optical spectra of the tested objects. Analysis of the obtained results showed that hyperspectral imaging is a modern tool that enables quantitative analysis of the photoprotective properties of pharmaceutical preparations containing TiO2 particles [15,17,18,19,20]. In the full wavelength range (400–1000 nm), statistically significant differences in reflectance were observed depending on the presence and type of preparation applied to the skin.
In the 400–633 nm wavelength range, preparations containing TiO2 particles < 5 µm showed the highest reflectance values. These findings suggest that larger TiO2 particles are more effective in reflecting and scattering UV radiation within this spectral range, thereby enhancing the photoprotective properties of the preparations [21,22,23,24]. Differences in reflectance across various wavelength ranges indicate that in the 636–897 nm range, the addition of TiO2 particles < 5 µm or <100 nm does not improve the photoprotective capacity of the tested preparations. In contrast, in the 900–1002 nm wavelength range, preparations containing TiO2 particles < 5 µm exhibited significantly higher reflectance values than those containing particles < 100 nm and preparations without TiO2. These results do not confirm the research hypothesis that smaller TiO2 particles exhibit better photoprotective properties. Preparations containing TiO2 particles < 5 µm significantly improved the protective capacity both in the lower and higher wavelength ranges. Numerous studies, including those by Ghamarpoor et al. [15], indicate that the smaller the TiO2 particles, the higher the photoprotective efficacy. Therefore, these results are inconsistent with those obtained in the present study, where the preparation with larger particle size exhibited superior photoprotective properties. However, it should be noted that the studies by Ghamarpoor et al. [15] focused on the protective effect of titanium dioxide against ultraviolet radiation. The present study addressed higher wavelength ranges.
According to Mie theory, which describes light scattering by particles with sizes comparable to the wavelength of light, particles in the micrometre range are more effective at scattering higher-wavelength radiation than nanoparticles. Mie theory, named after the German physicist Gustav Mie, provides a general solution to Maxwell’s equations for spherical particles, as opposed to simpler theories that apply only to particles small relative to the wavelength. Mie theory provides a comprehensive description of the interaction of light with particles that may be larger or smaller than the wavelength of light. According to the assumptions of Mie theory, for particles much smaller than the wavelength (on the nanometre scale), Rayleigh scattering dominates. This is isotropic scattering, where the intensity of scattered light is proportional to the fourth power of frequency (inversely proportional to the fourth power of wavelength). In contrast, for particles of sizes comparable to or larger than the wavelength, Mie solutions apply. In this case, scattering becomes more complex, and the intensity and angle of scattering depend on the size, shape, and refractive index of the particles. The size parameter α is defined as α = 2πr/λ, where r is the particle radius and λ is the wavelength of light. Mie theory thus covers both cases where α is small (Rayleigh) and where α is large (Mie). Consequently, radiation at higher wavelengths (visible light and near-infrared) may be more effectively reflected by larger TiO2 particle sizes [25,26,27,28].
Although this study provides promising results, several limitations should be considered when interpreting these findings. First, this study was conducted with a limited number of participants, which may affect the generalizability of the results. Second, the experiments were performed under controlled laboratory conditions, which may differ from real-world conditions in which consumers use protective preparations. Standardization of the application method and control of the amount applied could minimize this effect [29,30,31,32]. Additionally, standardized SPF and UVA-PF measurements according to international guidelines were not performed for the experimental formulations, which limits direct comparison with commercial sunscreen products. Future studies should combine hyperspectral imaging with traditional SPF and UVA-PF testing for comprehensive photoprotection assessment.
In conclusion, this study demonstrated that larger TiO2 particles, with a diameter < 5 µm, exhibit better photoprotective properties compared to smaller particles < 100 nm. Hyperspectral imaging proved to be an effective tool for the quantitative analysis of the photoprotective properties of TiO2-containing preparations [33,34]. The results indicate the need for further research, particularly regarding the long-term effectiveness and safety of preparations containing TiO2 nanoparticles. The data obtained may contribute to a better understanding of the mechanisms of TiO2 photoprotection and to the optimization of sunscreen formulations, ensuring more effective protection against harmful radiation across a broader wavelength range than just ultraviolet radiation.
5. Conclusions
The analysis of directional reflectance results obtained using hyperspectral imaging demonstrated that this technique is a modern and precise tool for the quantitative assessment of the photoprotective properties of pharmaceutical preparations containing titanium dioxide. This study confirms a significant impact from both the presence and particle size of TiO2 on skin reflectance across a broad spectral range. In the 400–633 nm range, preparations containing TiO2 particles, both <5 µm and <100 nm, significantly increased reflectance, with higher values observed for larger particles. In the 636–897 nm range, the addition of TiO2 did not significantly affect the photoprotective capacity of the preparations. In contrast, in the 900–1002 nm range, preparations containing TiO2 particles < 5 µm showed clearly higher reflectance values than those containing TiO2 < 100 nm and those without titanium dioxide. The selection of TiO2 particle size in sunscreen formulations should be tailored to the expected protection range against UV and near-infrared radiation, as larger particles may offer more effective protection across a broad wavelength spectrum, which is important in designing modern photoprotective preparations.
Author Contributions
Conceptualization, A.S.-W., E.M. and A.W.; methodology, A.S.-W., E.M. and A.W.; software, A.W. and S.W.; validation, A.S.-W., D.M.-S. and S.W.; formal analysis, A.S.-W., E.M. and S.W.; investigation, A.S.-W., E.M., D.Ś. and D.M.-S.; resources, A.S.-W. and S.W.; data curation, A.S.-W., E.M., D.Ś. and D.M.-S.; writing—original draft preparation, A.S.-W. and D.Ś.; writing—review and editing, A.S.-W. and D.Ś.; visualization, A.W.; supervision, S.W.; project administration, A.S.-W.; funding acquisition, S.W. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by Medical University of Silesia, Grant Numbers: BNW-1-010/N/3/F; BNW-1-103/N/4/F.
Institutional Review Board Statement
This study was conducted in accordance with the Declaration of Helsinki, and approved by the Bioethics Committee of the Medical University of Silesia (PCN/CBN/0022/KB1/27/III/16/17/21).
Informed Consent Statement
Informed consent was obtained from all subjects involved in this study.
Data Availability Statement
Data is contained within the article.
Conflicts of Interest
The authors declare no conflicts of interest.
References
- Salminen, A.; Kaarniranta, K.; Kauppinen, A. Photoaging: UV radiation-induced inflammation and immunosuppression accelerate the aging process in the skin. Inflamm. Res. 2022, 71, 817–831. [Google Scholar] [CrossRef]
- Kamińska, M.; Hartman-Petrycka, M.; Bożek, M.; Krusiec-Świdergoł, B.; Nędza, M.; Wilczyński, S. Assessment of knowledge and selected attitudes among Silesians about effects of ultraviolet radiation on health. Przegl. Epidemiol. 2018, 72, 525–536. [Google Scholar] [CrossRef] [PubMed]
- Yu, Z.W.; Zheng, M.; Fan, H.Y.; Liang, X.H.; Tang, Y.L. Ultraviolet (UV) radiation: A double-edged sword in cancer development and therapy. Mol. Biomed. 2024, 5, 49. [Google Scholar] [CrossRef] [PubMed]
- Tran, V.; Duarte Romero, B.L.; Andersen, H.; Clarke, M.; Collins, L.G.; Dawson, T.; Hartel, G.; Lefevre, J.G.; Lucas, R.M.; McLeod, D.S.A.; et al. The effect of daily sunscreen application on vitamin D: Findings from the open-label, randomised, controlled Sun-D Trial. Br. J. Dermatol. 2025, ljaf310. [Google Scholar] [CrossRef]
- Abdel Azim, S.; Bainvoll, L.; Vecerek, N.; DeLeo, V.A.; Adler, B.L. Sunscreens part 1: Mechanisms and efficacy. J. Am. Acad. Dermatol. 2025, 92, 677–686. [Google Scholar] [CrossRef]
- Schneider, S.L.; Lim, H.W. A review of inorganic UV filters zinc oxide and titanium dioxide. Photodermatol. Photoimmunol. Photomed. 2019, 35, 442–446. [Google Scholar] [CrossRef]
- Serpone, N. Sunscreens and their usefulness: Have we made any progress in the last two decades? Photochem. Photobiol. Sci. 2021, 20, 189–244. [Google Scholar] [CrossRef]
- Bens, G. Sunscreens. Adv. Exp. Med. Biol. 2014, 810, 429–463. [Google Scholar] [CrossRef]
- Buchalska, M.; Kras, G.; Oszajca, M.; Łasocha, W.; Macyk, W. Singlet oxygen generation in the presence of titanium dioxide materials used as sunscreens in suntan lotions. J. Photochem. Photobiol. A Chem. 2010, 213, 158–163. [Google Scholar] [CrossRef]
- He, H.; Li, A.; Li, S.; Tang, J.; Li, L.; Xiong, L. Natural components in sunscreens: Topical formulations with sun protection factor (SPF). Biomed. Pharmacother. 2021, 134, 111161. [Google Scholar] [CrossRef]
- Ferrero, L.; Pissavini, M.; Marguerie, S.; Zastrow, L. Sunscreen in vitro spectroscopy: Application to UVA protection assessment and correlation with in vivo persistent pigment darkening. Int. J. Cosmet. Sci. 2002, 24, 63–70. [Google Scholar] [CrossRef] [PubMed]
- European Commission. Regulation (EU) 2022/63 of 14 January 2022 amending Annexes II and III to Regulation (EU) No 1333/2008 of the European Parliament and of the Council as regards titanium dioxide (E 171) as a food additive. Off. J. Eur. Union 2022, L11, 1–3. [Google Scholar]
- Smijs, T.G.; Pavel, S. Titanium dioxide and zinc oxide nanoparticles in sunscreens: Focus on their safety and effectiveness. Nanotechnol. Sci. Appl. 2011, 4, 95–112. [Google Scholar] [CrossRef] [PubMed]
- Slomberg, D.L.; Catalano, R.; Bartolomei, V.; Labille, J. Release and fate of nanoparticulate TiO2 UV filters from sunscreen: Effects of particle coating and formulation type. Environ Pollut. 2021, 271, 116263. [Google Scholar] [CrossRef]
- Ghamarpoor, R.; Fallah, A.; Jamshidi, M. Investigating the use of titanium dioxide (TiO2) nanoparticles on the amount of protection against UV irradiation. Sci. Rep. 2023, 13, 9793. [Google Scholar] [CrossRef]
- Lu, G.; Fei, B. Medical hyperspectral imaging: A review. J. Biomed. Opt. 2014, 19, 010901. [Google Scholar] [CrossRef]
- Newman, M.D.; Stotland, M.; Ellis, J.I. The safety of nanosized particles in titanium dioxide- and zinc oxide-based sun-screens. J Am Acad Dermatol. 2009, 61, 685–692. [Google Scholar] [CrossRef]
- Zvyagin, A.V.; Zhao, X.; Gierden, A.; Sanchez, W.; Ross, J.A.; Roberts, M.S. Imaging of zinc oxide nanoparticle penetration in human skin in vitro and in vivo. J. Biomed. Opt. 2008, 13, 064031–064038. [Google Scholar] [CrossRef]
- Aggarwal, S.L.P.; Papay, F.A. Applications of multispectral and hyperspectral imaging in dermatology. Exp. Dermatol. 2022, 31, 1128–1135. [Google Scholar] [CrossRef]
- Zherebtsov, E.; Dremin, V.; Popov, A.; Doronin, A.; Kurakina, D.; Kirillin, M.; Meglinski, I.; Bykov, A. Hyperspectral imaging of human skin aided by artificial neural networks. Biomed. Opt. Express 2019, 10, 3545–3559. [Google Scholar] [CrossRef]
- Stolecka-Warzecha, A.; Wilczyński, S.; Pawlus, A.; Lebiedowska, A.; Chmielewski, Ł.; Niezgoda, Z. The Use of Hemispheric Directional Reflectance Method to Verify the Usefulness of Filters Protecting the Skin Against Infrared Radiation. Clin. Cosmet. Investig. Dermatol. 2023, 16, 2663–2675. [Google Scholar] [CrossRef]
- Cole, C.; Shyr, T.; Ou-Yang, H. Metal oxide sunscreens protect skin by absorption, not by reflection or scattering. Photodermatol. Photoimmunol. Photomed. 2016, 32, 5–10. [Google Scholar] [CrossRef]
- Egerton, T.A.; Tooley, I.R. UV absorption and scattering properties of inorganic-based sunscreens. Int. J. Cosmet. Sci. 2012, 34, 117–122. [Google Scholar] [CrossRef]
- Vujovic, M.; Kostic, E. Titanium Dioxide and Zinc Oxide Nanoparticles in Sunscreens: A Review of Toxicological Data. J. Cosmet. Sci. 70, 223–234. [PubMed]
- Popov, A.P.; Lademann, J.; Priezzhev, A.V.; Myllylä, R. Effect of size of TiO2 nanoparticles embedded into stratum corneum on ultraviolet-A and ultraviolet-B sun-blocking properties of the skin. J. Biomed. Opt. 2005, 10, 064037. [Google Scholar] [CrossRef]
- Wokovich, A.; Tyner, K.; Doub, W.; Sadrieh, N.; Buhse, L.F. Particle size determination of sunscreens formulated with various forms of titanium dioxide. Drug Dev. Ind. Pharm. 2009, 35, 1180–1189. [Google Scholar] [CrossRef] [PubMed]
- Lécureux, M.; Enoch, S.; Deumié, C.; Tayeb, G. Electromagnetic sunscreen model: Implementation and comparison between several methods: Step-film model, differential method, Mie scattering, and scattering by a set of parallel cylinders. Appl. Opt. 2014, 53, 6537–6545. [Google Scholar] [CrossRef] [PubMed]
- Wulf, H.C. Solbeskyttelse med solcreme [Sun protection with sunscreens]. Ugeskr. Laeger 2025, 187, V05250383. [Google Scholar] [CrossRef]
- Ziglar, J.; Mohammad, T.F.; Gilaberte, Y.; Lim, H.W. Sunscreens: Updates on Sunscreen Filters and Formulations. Photodermatol. Photoimmunol. Photomed. 2025, 41, e70026. [Google Scholar] [CrossRef]
- Schalka, S.; dos Reis, V.M.; Cucé, L.C. The influence of the amount of sunscreen applied and its sun protection factor (SPF): Evaluation of two sunscreens including the same ingredients at different concentrations. Photodermatol. Photoimmunol. Photomed. 2009, 25, 175–180. [Google Scholar] [CrossRef]
- Kim, S.M.; Oh, B.H.; Lee, Y.W.; Choe, Y.B.; Ahn, K.J. The relation between the amount of sunscreen applied and the sun protection factor in Asian skin. J. Am. Acad. Dermatol. 2010, 62, 218–222. [Google Scholar] [CrossRef] [PubMed]
- Goodman, G.; Yip, L.; McDonald, C.; Lin, F.; Liu, W.; Sullivan, J. Recommendations on Periprocedural Skincare for Energy-Based Dermatologic Procedures. Aesthet. Surg. J. Open Forum 2025, 7, ojaf039. [Google Scholar] [CrossRef]
- Le Digabel, J.; Questel, E.; Lauze, C.; Carballido, F.; Josse, G. In vivo evaluation of sunscreen application by multispectral imaging: A new tool for educating sunscreen users. Skin Res. Technol. 2023, 29, e13320. [Google Scholar] [CrossRef] [PubMed]
- Le Digabel, J.; Filiol, J.; Lauze, C.; Redoulès, D.; Josse, G. In vivo method for evaluating sunscreen protection against high-energy visible light. J. Eur. Acad. Dermatol. Venereol. 2023, 37, 6–11. [Google Scholar] [CrossRef] [PubMed]
Figure 1.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured across the full spectral range 400–1002 nm for each of the selected wavelengths. Arrows indicate the wavelength at which the preparation with the highest reflectance value changes.
Figure 1.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured across the full spectral range 400–1002 nm for each of the selected wavelengths. Arrows indicate the wavelength at which the preparation with the highest reflectance value changes.
Figure 2.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured in the spectral range 400–633 nm for each of the selected wavelengths.
Figure 2.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured in the spectral range 400–633 nm for each of the selected wavelengths.
Figure 3.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured in the spectral range 636–897 nm for each of the selected wavelengths.
Figure 3.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured in the spectral range 636–897 nm for each of the selected wavelengths.
Figure 4.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured in the spectral range 900–1002 nm for each of the selected wavelengths.
Figure 4.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured in the spectral range 900–1002 nm for each of the selected wavelengths.
Table 1.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured across the full spectral range 400–1002 nm.
Table 1.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured across the full spectral range 400–1002 nm.
| Md | Q1 | Q3 | Min | Max | Mean | SD | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| Skin | 0.683 | 0.446 | 0.727 | 0.325 | 0.758 | 0.609 | 0.141 | |||
| T < 5 μm | 0.699 | 0.569 | 0.718 | 0.456 | 0.739 | 0.656 | 0.073 | Skin vs. T < 5 μm * | ||
| T < 100 nm | 0.685 | 0.545 | 0.724 | 0.497 | 0.742 | 0.648 | 0.084 | Skin vs. T < 100 nm * | T < 5 μm vs. T < 100 nm ns | |
| Cream | 0.684 | 0.478 | 0.723 | 0.384 | 0.754 | 0.621 | 0.121 | Skin vs. Cream ns | T < 5 μm vs. Cream * | T < 100 nm vs. Cream * |
* p < 0.05, ns—Not Significant.
Table 2.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured across the full spectral range 400–633 nm.
Table 2.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured across the full spectral range 400–633 nm.
| Md | Q1 | Q3 | Min | Max | Mean | SD | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| Skin | 0.440 | 0.409 | 0.457 | 0.325 | 0.651 | 0.445 | 0.074 | |||
| T < 5 | 0.567 | 0.560 | 0.571 | 0.456 | 0.664 | 0.570 | 0.034 | Skin vs. T < 5 μm * | ||
| T < 100 | 0.541 | 0.535 | 0.550 | 0.497 | 0.663 | 0.550 | 0.036 | Skin vs. T < 100 nm * | T < 5 μm vs. T < 100 nm * | |
| Cream | 0.472 | 0.456 | 0.490 | 0.384 | 0.658 | 0.480 | 0.062 | Skin vs. Cream * | T < 5 μm vs. Cream * | T < 100 nm vs. Cream * |
* p < 0.05.
Table 3.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured in the spectral range 400–633 nm for each of the selected wavelengths. The greatest intensity of green colour indicates the highest reflectance value.
Table 3.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured in the spectral range 400–633 nm for each of the selected wavelengths. The greatest intensity of green colour indicates the highest reflectance value.
| λ [nm] | Skin | T < 5 | T < 100 | Skin | λ [nm] | Skin | T < 5 | T < 100 | Cream |
|---|---|---|---|---|---|---|---|---|---|
| 400 | 0.435 | 0.456 | 0.546 | 0.481 | 518 | 0.461 | 0.571 | 0.551 | 0.493 |
| 403 | 0.407 | 0.466 | 0.543 | 0.458 | 521 | 0.461 | 0.570 | 0.552 | 0.493 |
| 406 | 0.396 | 0.494 | 0.544 | 0.446 | 524 | 0.460 | 0.570 | 0.552 | 0.492 |
| 409 | 0.386 | 0.526 | 0.546 | 0.437 | 527 | 0.459 | 0.569 | 0.551 | 0.490 |
| 413 | 0.375 | 0.547 | 0.541 | 0.427 | 530 | 0.456 | 0.568 | 0.550 | 0.487 |
| 416 | 0.364 | 0.559 | 0.535 | 0.417 | 534 | 0.453 | 0.567 | 0.549 | 0.483 |
| 419 | 0.355 | 0.565 | 0.528 | 0.409 | 537 | 0.449 | 0.565 | 0.548 | 0.478 |
| 422 | 0.346 | 0.565 | 0.522 | 0.402 | 540 | 0.445 | 0.564 | 0.545 | 0.474 |
| 425 | 0.339 | 0.562 | 0.516 | 0.395 | 543 | 0.441 | 0.562 | 0.543 | 0.470 |
| 428 | 0.334 | 0.557 | 0.511 | 0.389 | 546 | 0.437 | 0.561 | 0.539 | 0.467 |
| 431 | 0.330 | 0.554 | 0.508 | 0.386 | 549 | 0.436 | 0.565 | 0.536 | 0.468 |
| 434 | 0.328 | 0.555 | 0.503 | 0.385 | 552 | 0.437 | 0.570 | 0.534 | 0.471 |
| 437 | 0.325 | 0.554 | 0.497 | 0.384 | 555 | 0.438 | 0.571 | 0.533 | 0.472 |
| 440 | 0.333 | 0.553 | 0.503 | 0.390 | 558 | 0.437 | 0.566 | 0.534 | 0.471 |
| 444 | 0.347 | 0.555 | 0.511 | 0.399 | 561 | 0.437 | 0.561 | 0.536 | 0.471 |
| 447 | 0.359 | 0.557 | 0.516 | 0.408 | 565 | 0.439 | 0.559 | 0.538 | 0.472 |
| 450 | 0.372 | 0.560 | 0.520 | 0.419 | 568 | 0.442 | 0.559 | 0.540 | 0.474 |
| 453 | 0.384 | 0.564 | 0.525 | 0.430 | 571 | 0.443 | 0.559 | 0.541 | 0.475 |
| 456 | 0.395 | 0.566 | 0.528 | 0.439 | 574 | 0.446 | 0.560 | 0.543 | 0.477 |
| 459 | 0.404 | 0.567 | 0.531 | 0.447 | 577 | 0.447 | 0.560 | 0.543 | 0.477 |
| 462 | 0.411 | 0.568 | 0.533 | 0.453 | 580 | 0.446 | 0.560 | 0.543 | 0.475 |
| 465 | 0.417 | 0.569 | 0.536 | 0.458 | 583 | 0.444 | 0.559 | 0.541 | 0.471 |
| 468 | 0.422 | 0.569 | 0.537 | 0.462 | 586 | 0.442 | 0.559 | 0.540 | 0.469 |
| 471 | 0.425 | 0.569 | 0.538 | 0.464 | 589 | 0.445 | 0.560 | 0.540 | 0.470 |
| 475 | 0.428 | 0.568 | 0.539 | 0.466 | 592 | 0.453 | 0.565 | 0.545 | 0.478 |
| 478 | 0.430 | 0.568 | 0.539 | 0.467 | 596 | 0.466 | 0.571 | 0.552 | 0.491 |
| 481 | 0.432 | 0.569 | 0.540 | 0.469 | 599 | 0.484 | 0.580 | 0.563 | 0.508 |
| 484 | 0.433 | 0.569 | 0.541 | 0.470 | 602 | 0.505 | 0.589 | 0.575 | 0.527 |
| 487 | 0.434 | 0.568 | 0.540 | 0.471 | 605 | 0.525 | 0.599 | 0.588 | 0.546 |
| 490 | 0.436 | 0.570 | 0.539 | 0.473 | 608 | 0.545 | 0.609 | 0.600 | 0.565 |
| 493 | 0.439 | 0.571 | 0.539 | 0.476 | 611 | 0.565 | 0.619 | 0.612 | 0.583 |
| 496 | 0.442 | 0.572 | 0.540 | 0.479 | 614 | 0.582 | 0.627 | 0.622 | 0.598 |
| 499 | 0.446 | 0.573 | 0.543 | 0.483 | 617 | 0.598 | 0.634 | 0.632 | 0.612 |
| 503 | 0.449 | 0.572 | 0.544 | 0.486 | 620 | 0.612 | 0.642 | 0.638 | 0.624 |
| 506 | 0.452 | 0.573 | 0.546 | 0.488 | 624 | 0.632 | 0.660 | 0.646 | 0.643 |
| 509 | 0.455 | 0.571 | 0.548 | 0.490 | 627 | 0.641 | 0.664 | 0.652 | 0.651 |
| 512 | 0.457 | 0.571 | 0.549 | 0.491 | 630 | 0.645 | 0.661 | 0.658 | 0.654 |
| 515 | 0.460 | 0.571 | 0.551 | 0.493 | 633 | 0.651 | 0.662 | 0.663 | 0.658 |
Table 4.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured across the full spectral range 636–897 nm.
Table 4.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured across the full spectral range 636–897 nm.
| Md | Q1 | Q3 | Min | Max | Mean | SD | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| Skin | 0.729 | 0.718 | 0.740 | 0.658 | 0.758 | 0.724 | 0.023 | |||
| T < 5 | 0.718 | 0.711 | 0.723 | 0.665 | 0.739 | 0.713 | 0.017 | Skin vs. T < 5 μm * | ||
| T < 100 | 0.725 | 0.716 | 0.733 | 0.668 | 0.742 | 0.720 | 0.017 | Skin vs. T < 100 nm * | T < 5 μm vs. T < 100 nm * | |
| Skin | 0.726 | 0.714 | 0.739 | 0.664 | 0.754 | 0.722 | 0.021 | Skin vs. Cream * | T < 5 μm vs. Cream * | T < 100 nm vs. Cream ns |
* p < 0.05, ns—Not Significant.
Table 5.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured in the spectral range 636–897 nm for each of the selected wavelengths. The greatest intensity of green colour indicates the highest reflectance value.
Table 5.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured in the spectral range 636–897 nm for each of the selected wavelengths. The greatest intensity of green colour indicates the highest reflectance value.
| λ [nm] | Skin | T < 5 | T < 100 | Cream | λ [nm] | Skin | T < 5 | T < 100 | Cream |
|---|---|---|---|---|---|---|---|---|---|
| 636 | 0.658 | 0.665 | 0.668 | 0.664 | 766 | 0.732 | 0.719 | 0.728 | 0.727 |
| 639 | 0.662 | 0.667 | 0.671 | 0.668 | 769 | 0.729 | 0.718 | 0.726 | 0.725 |
| 642 | 0.667 | 0.670 | 0.675 | 0.672 | 772 | 0.728 | 0.718 | 0.725 | 0.723 |
| 645 | 0.671 | 0.672 | 0.678 | 0.675 | 776 | 0.727 | 0.717 | 0.724 | 0.721 |
| 648 | 0.674 | 0.673 | 0.681 | 0.678 | 779 | 0.726 | 0.718 | 0.724 | 0.721 |
| 651 | 0.677 | 0.675 | 0.684 | 0.680 | 782 | 0.727 | 0.719 | 0.725 | 0.723 |
| 655 | 0.680 | 0.678 | 0.687 | 0.683 | 785 | 0.727 | 0.719 | 0.724 | 0.722 |
| 658 | 0.682 | 0.680 | 0.689 | 0.685 | 788 | 0.726 | 0.719 | 0.724 | 0.722 |
| 661 | 0.686 | 0.682 | 0.692 | 0.688 | 791 | 0.729 | 0.721 | 0.727 | 0.724 |
| 664 | 0.688 | 0.684 | 0.694 | 0.690 | 794 | 0.733 | 0.724 | 0.729 | 0.728 |
| 667 | 0.690 | 0.687 | 0.697 | 0.692 | 797 | 0.739 | 0.728 | 0.732 | 0.734 |
| 670 | 0.693 | 0.688 | 0.699 | 0.694 | 800 | 0.739 | 0.727 | 0.733 | 0.735 |
| 673 | 0.694 | 0.690 | 0.700 | 0.695 | 803 | 0.742 | 0.729 | 0.733 | 0.737 |
| 676 | 0.697 | 0.692 | 0.702 | 0.698 | 807 | 0.743 | 0.730 | 0.734 | 0.739 |
| 679 | 0.700 | 0.695 | 0.705 | 0.700 | 810 | 0.745 | 0.731 | 0.735 | 0.741 |
| 682 | 0.702 | 0.697 | 0.706 | 0.703 | 813 | 0.744 | 0.730 | 0.734 | 0.741 |
| 686 | 0.706 | 0.700 | 0.710 | 0.707 | 816 | 0.748 | 0.732 | 0.737 | 0.744 |
| 689 | 0.711 | 0.704 | 0.714 | 0.712 | 819 | 0.754 | 0.735 | 0.739 | 0.748 |
| 692 | 0.714 | 0.705 | 0.715 | 0.716 | 822 | 0.758 | 0.739 | 0.742 | 0.754 |
| 695 | 0.718 | 0.708 | 0.718 | 0.720 | 825 | 0.751 | 0.734 | 0.738 | 0.750 |
| 698 | 0.721 | 0.709 | 0.720 | 0.723 | 828 | 0.744 | 0.727 | 0.734 | 0.741 |
| 701 | 0.724 | 0.711 | 0.722 | 0.726 | 831 | 0.745 | 0.728 | 0.733 | 0.741 |
| 704 | 0.729 | 0.714 | 0.725 | 0.731 | 835 | 0.748 | 0.729 | 0.734 | 0.743 |
| 707 | 0.732 | 0.715 | 0.727 | 0.735 | 838 | 0.746 | 0.728 | 0.733 | 0.742 |
| 710 | 0.735 | 0.716 | 0.730 | 0.738 | 841 | 0.745 | 0.727 | 0.731 | 0.740 |
| 714 | 0.738 | 0.718 | 0.732 | 0.741 | 844 | 0.743 | 0.726 | 0.731 | 0.738 |
| 717 | 0.739 | 0.717 | 0.732 | 0.742 | 847 | 0.740 | 0.724 | 0.728 | 0.735 |
| 720 | 0.736 | 0.715 | 0.730 | 0.740 | 850 | 0.737 | 0.723 | 0.727 | 0.732 |
| 723 | 0.737 | 0.715 | 0.729 | 0.739 | 853 | 0.734 | 0.722 | 0.725 | 0.730 |
| 726 | 0.738 | 0.717 | 0.729 | 0.738 | 856 | 0.731 | 0.720 | 0.723 | 0.727 |
| 729 | 0.743 | 0.721 | 0.732 | 0.742 | 859 | 0.732 | 0.720 | 0.723 | 0.725 |
| 732 | 0.745 | 0.723 | 0.734 | 0.744 | 862 | 0.729 | 0.719 | 0.722 | 0.723 |
| 735 | 0.746 | 0.723 | 0.735 | 0.744 | 866 | 0.727 | 0.718 | 0.721 | 0.722 |
| 738 | 0.746 | 0.723 | 0.735 | 0.744 | 869 | 0.728 | 0.718 | 0.720 | 0.720 |
| 741 | 0.745 | 0.723 | 0.735 | 0.743 | 872 | 0.725 | 0.717 | 0.720 | 0.718 |
| 745 | 0.744 | 0.723 | 0.735 | 0.741 | 875 | 0.724 | 0.718 | 0.720 | 0.718 |
| 748 | 0.743 | 0.723 | 0.735 | 0.740 | 878 | 0.725 | 0.718 | 0.720 | 0.718 |
| 751 | 0.740 | 0.721 | 0.733 | 0.737 | 881 | 0.724 | 0.718 | 0.719 | 0.716 |
| 754 | 0.740 | 0.722 | 0.733 | 0.736 | 884 | 0.724 | 0.718 | 0.719 | 0.716 |
| 757 | 0.739 | 0.722 | 0.733 | 0.734 | 887 | 0.720 | 0.717 | 0.717 | 0.714 |
| 760 | 0.736 | 0.720 | 0.731 | 0.732 | 890 | 0.719 | 0.715 | 0.716 | 0.711 |
| 763 | 0.734 | 0.720 | 0.729 | 0.730 | 893 | 0.717 | 0.715 | 0.715 | 0.710 |
| 897 | 0.717 | 0.715 | 0.714 | 0.708 |
Table 6.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured across the full spectral range 900–1002 nm.
Table 6.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured across the full spectral range 900–1002 nm.
| Md | Q1 | Q3 | Min | Max | Mean | SD | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| Skin | 0.686 | 0.676 | 0.701 | 0.662 | 0.714 | 0.687 | 0.015 | |||
| T < 5 | 0.704 | 0.700 | 0.708 | 0.697 | 0.714 | 0.704 | 0.005 | Skin vs. T < 5 μm * | ||
| T < 100 | 0.686 | 0.681 | 0.702 | 0.671 | 0.712 | 0.689 | 0.013 | Skin vs. T < 100 nm ns | T < 5 μm vs. T < 100 nm * | |
| Cream | 0.685 | 0.666 | 0.698 | 0.653 | 0.707 | 0.682 | 0.017 | Skin vs. Cream ns | T < 5 μm vs. Cream * | T < 100 nm vs. Cream * |
* p < 0.05, ns—Not Significant.
Table 7.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured in the spectral range 900–1002 nm for each of the selected wavelengths. The greatest intensity of green colour indicates the highest reflectance value.
Table 7.
Reflectance of skin, skin with cream containing titanium dioxide < 5 µm, skin with cream containing titanium dioxide < 100 nm, and skin with cream without titanium dioxide measured in the spectral range 900–1002 nm for each of the selected wavelengths. The greatest intensity of green colour indicates the highest reflectance value.
| λ [nm] | Skin | T < 5 | T < 100 | Cream | λ [nm] | Skin | T < 5 | T < 100 | Cream |
|---|---|---|---|---|---|---|---|---|---|
| 900 | 0.714 | 0.714 | 0.712 | 0.707 | 952 | 0.681 | 0.699 | 0.681 | 0.685 |
| 903 | 0.712 | 0.714 | 0.712 | 0.707 | 956 | 0.682 | 0.701 | 0.682 | 0.685 |
| 906 | 0.709 | 0.711 | 0.709 | 0.703 | 959 | 0.683 | 0.701 | 0.683 | 0.684 |
| 909 | 0.707 | 0.711 | 0.707 | 0.701 | 962 | 0.687 | 0.703 | 0.685 | 0.684 |
| 912 | 0.706 | 0.710 | 0.705 | 0.700 | 965 | 0.688 | 0.706 | 0.687 | 0.683 |
| 915 | 0.704 | 0.709 | 0.704 | 0.699 | 968 | 0.687 | 0.708 | 0.687 | 0.681 |
| 918 | 0.703 | 0.709 | 0.703 | 0.698 | 971 | 0.685 | 0.707 | 0.687 | 0.677 |
| 921 | 0.703 | 0.708 | 0.702 | 0.698 | 974 | 0.680 | 0.704 | 0.683 | 0.671 |
| 925 | 0.701 | 0.708 | 0.702 | 0.698 | 977 | 0.672 | 0.700 | 0.678 | 0.663 |
| 928 | 0.698 | 0.706 | 0.700 | 0.695 | 980 | 0.668 | 0.699 | 0.674 | 0.659 |
| 931 | 0.693 | 0.702 | 0.696 | 0.691 | 983 | 0.664 | 0.697 | 0.671 | 0.654 |
| 934 | 0.689 | 0.700 | 0.693 | 0.688 | 987 | 0.662 | 0.700 | 0.671 | 0.654 |
| 937 | 0.689 | 0.700 | 0.690 | 0.689 | 990 | 0.663 | 0.699 | 0.671 | 0.653 |
| 940 | 0.688 | 0.700 | 0.688 | 0.688 | 993 | 0.666 | 0.700 | 0.672 | 0.655 |
| 943 | 0.685 | 0.699 | 0.685 | 0.687 | 996 | 0.669 | 0.704 | 0.676 | 0.659 |
| 946 | 0.683 | 0.698 | 0.684 | 0.687 | 999 | 0.675 | 0.708 | 0.678 | 0.662 |
| 949 | 0.680 | 0.698 | 0.682 | 0.686 | 1002 | 0.676 | 0.711 | 0.681 | 0.666 |
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
MDPI and ACS Style
Stolecka-Warzecha, A.; Mickoś, E.; Śniecińska, D.; Malewicz-Skrabania, D.; Wilczyński, A.; Wilczyński, S. The Influence of Titanium Dioxide Particle Size on the Photo-Protective Properties of Pharmaceutical Preparations and Their Effectiveness Assessment Using Hyperspectral Imaging Methods. Cosmetics 2025, 12, 242. https://doi.org/10.3390/cosmetics12060242
AMA Style
Stolecka-Warzecha A, Mickoś E, Śniecińska D, Malewicz-Skrabania D, Wilczyński A, Wilczyński S. The Influence of Titanium Dioxide Particle Size on the Photo-Protective Properties of Pharmaceutical Preparations and Their Effectiveness Assessment Using Hyperspectral Imaging Methods. Cosmetics. 2025; 12(6):242. https://doi.org/10.3390/cosmetics12060242
Chicago/Turabian StyleStolecka-Warzecha, Anna, Elżbieta Mickoś, Daria Śniecińska, Dominika Malewicz-Skrabania, Adam Wilczyński, and Sławomir Wilczyński. 2025. "The Influence of Titanium Dioxide Particle Size on the Photo-Protective Properties of Pharmaceutical Preparations and Their Effectiveness Assessment Using Hyperspectral Imaging Methods" Cosmetics 12, no. 6: 242. https://doi.org/10.3390/cosmetics12060242
APA StyleStolecka-Warzecha, A., Mickoś, E., Śniecińska, D., Malewicz-Skrabania, D., Wilczyński, A., & Wilczyński, S. (2025). The Influence of Titanium Dioxide Particle Size on the Photo-Protective Properties of Pharmaceutical Preparations and Their Effectiveness Assessment Using Hyperspectral Imaging Methods. Cosmetics, 12(6), 242. https://doi.org/10.3390/cosmetics12060242
Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.
