A novel fullerene composite material for directional oil control and antioxidant

There are very few cosmetic ingredients that can target oil control and extend the wear time. Fullerenes have been reported to have excellent antioxidant capacity and a variety of biological activities, such as quenching free radicals, inhibiting lipid peroxidation, and promoting lipid flocculation.


| INTRODUC TI ON
At present, for the demand of the cosmetics market, consumers have changed from simply "the beauty of makeup" to "how to maintain the beauty of makeup," and "oil control" is the core demand.Oil control, which involves the absorption of oil by certain means and the preservation of oil from oxidation.
Almost all of the methods can only absorb oil and then control the level of oil on the skin surface, but cannot solve the problem of oil oxidation.However, excessive oil control will lead to a series of problems such as difficulty in putting on makeup, unconformity and creasing of makeup, dry feeling, and so on.Excessive skin oil secretion or excessive oil control will cause consumers trouble.
Fullerenes have a strong ability to accept electrons due to their large π bond conjugated system composed of multiple P orbitals, and it was named "radical sponge" 7 for its excellent free radical scavenging performance and antioxidant ability.So that it has been widely studied in cosmetic materials, biomedicine, and other aspects.In the field of skin care, fullerenes have the functions of antioxygen, 8 anti-wrinkle, 9,10 whitening, 11 protective barrier, anti-inflammatory, acne removal, rad fading, 12 shrinking pores, and so on.In addition, the scientists have found that fullerenes have excellent therapeutic effects on parkinson's disease, 13,14 enteritis, 15 diabetes, pulmonary fibrosis, 16 and reduced side effects in the process of radiotherapy and chemotherapy significantly. 17droxyapatite is safe and nontoxic, and has good compatibility with biological tissues.Therefore, hydroxyapatite has been studied and applied in environmental treatment, antitumor materials, 18 hard tissue materials, 19 drug slow, controlled release carriers, etc.
Hydroxyapatite has a large specific surface area, high biosafety, and strong availability, which was especially suitable as a carrier. 20erefore, this study selected hydroxyapatite as a carrier to form a complex with fullerenes.
In this paper, hydroxyapatite was selected as dispersion matrix to form stable complex with fullerenes.This compound can adsorb the oil by skin secretly, but it hardly adsorbs the oil in cosmetics, so it can control the oil without drying the skin effectively.
When the fullerene content is 1, 2, 3, and 4 mg/kg, the quenching rates are 25.02%, 39.57%, 49.75%, and 62.24%, respectively.The quenching effect was enhanced with the increase of fullerene content, and it had strong long-term antioxidant properties.It can also be proved that C 60 -hydroxyapatite composites have strong antioxidant capacity through antioxidant experiments.The peroxide value of oleic acid on Day 0 was 2.8, and after 7 days of UV irradiation, the peroxide values of blank control, hydroxyapatite group, C 60 -hydroxyapatite composite containing 0.5% and 1% fullerenes four groups of materials were 8.02 meq O 2 /kg, 7.98 meq O 2 /kg, 7.11 meq O 2 /kg, and 6.87 meq O 2 / kg, respectively.The cell activity was 20.94% and 99.2% after the cells were cultured for 24 h using C 60 -hydroxyapatite composite and hydroxyapatite extracts, respectively, and the addition of fullerene was able to significantly increase the cell activity.

| Structural characterization
The powder was light beige; a schematic diagram of fullerene embedded on the surface of hydroxyapatite (Figure 1).The C 60hydroxyapatite composite has a porous structure (Figure 2A), but pure hydroxyapatite has no significant loose porous structure (Figure 2B).As can be seen from the UV-Vis diffuse reflection absorption spectrum (Figure 2C), the C 60 -hydroxyapatite composite not only maintains the characteristic absorption peak of hydroxyapatite, but also has obvious fullerene absorption (about 340 nm and 450 nm), indicating that the composite contains the components of two materials.However, there is no absorption of fullerenes in the mixture because the content of fullerenes is low and is submerged in hydroxyapatite powder, rather than forming a chimeric complex structure.This demonstrate that C 60 has been uniformly dispersed over the surface of hydroxyapatite.
In addition, it can be seen from the Raman spectrum that the fullerenes has characteristic Raman signal at 1200-1600 cm −1 , and the fullerene hydroxyapatite composite has obvious characteristic signals of fullerenes at 1500 cm −1 , indicating that the two components in the composite have strong interaction.XRD spectra also show that the composite retains the characteristic signals of hydroxyapatite and fullerenes, indicating that the composite contains fullerenes (Figure 3).It is consistent with the previous conclusion of structural characterization.

| Directional oil absorption test
The oil was dissolved in n-hexane and stirred evenly.After standing for 18 h, the excess oil was removed, Gc-MS was used to detect the adsorbed oil content.As shown in the Figure 4, the adsorption rates of C 60 -hydroxyapatite composites for oleic acid, phenyl trimethicone, caprylic capric glyceride, isooctyl palmitate, mineral oil, olive oil, and dimethicone were 60.5%, 9.3%, 9.15%, 5.24%, 2.94% 1.01%, and 0%, respectively.The reason may be that most skin oils are unsaturated components, and the C 60 -hydroxyapatite composite has a porous structure with a larger surface area, and the composite can be in full contact with fatty acids, and the free fatty acids in the system can form complexes with the composite, or the fatty acids may exist in the form of ions and Ca 2+ fatty acids on the surface of the composite undergo ion exchange and thus be adsorbed.

| Artificial sebum absorption ability test
A simple artificial sebum was prepared by adding 2.4 g water and 4.8 g oleic acid in a 10 mL bottle.The C 60 -hydroxyapatite composite and C 60 -hydroxyapatite mixture were added to the vial with artificial sebum of equal mass respectively, then sealed, shook violently for 20 times, stood for 1 min, and observed the flow state of the solution.The quality of material added when the solution appears to be about to flocculate is recorded.

| Oil oxidation resistance test
There are three stages of grease oxidation, namely induction, development and termination.The induction stage is when a small amount of fat is photocatalyzed to dissociate one H atom of the methylene carbon atom adjacent to its double bond, forming an unstable free  For the cytotoxicity examination, HACAT cells were cultured in 96-well plates at 37°C for 24 h.When the cell growth fused to 80%, 100 μL of C 60 -hydroxyapatite composite sample extract was added to the culture dish respectively in the dark for 24 h.After that, the cell viability was detected using a Cell Counting Kit-8.The absorption value at 450 nm was detected by 96-well plate reader (iMark microplate reader, Bio-RAD, USA) to determine the cell viability.
Hydroxyapatite extract was tested in the above manner.
As shown in Figure 7, the cell activity of the C 60 -hydroxyapatite composite and the hydroxyapatite extracts was 99.2% and 20.94%, respectively.Indicating that hydroxyapatite has a strong toxicity effect on the cells, whereas the fullerene-containing C 60hydroxyapatite composite is not only nontoxic but also has a protective effect on the cells.

| CON CLUS ION
Using hydroxyapatite as a solid dispersant, and fullerenes were evenly dispersed on the surface to form a composite.This compound has the excellent ability of directional adsorption of skin oil.
Its quenching ability for free radical was excellent, and reduced the oxidation degree of skin oil effectively.The hydroxyapatite fullerene composite in this study is a kind of makeup material with great application value.
ture flocculates 5.9 g of artificial sebum, while a gram of C 60hydroxyapatite composite flocculates 24.2 g.The results showed F I G U R E 1 The schematic diagram of C 60 -hydroxyapatite composite powder.that C 60 -hydroxyapatite composite have a strong ability to absorb artificial sebum.
Hydroxyl radical (• OH), the most common ROS in the body, was chosen as a model to evaluate the capability of eliminating ROS by the samples using an electron paramagnetic resonance (EPR) method.Hydroxyl radicals were generated by H 2 O 2 , following irradiation with ultraviolet light (UV).As shown in Figure 5a, detection of hydroxyl radical scavenging capacity of C 60 -hydroxyapatite composites with different fullerene contents, tested at 4 min.The results demonstrated that C 60 -hydroxyapatite composite has excellent quenching ability for hydroxyl radicals, and when the fullerene content was 1 mg/kg, 2 mg/ kg, 3 mg/kg, and 4 mg/kg, the quenching percentage was 25.02%, 39.57%, 49.75%, and 62.24% respectively, and the quenching effect was enhanced with the increase of fullerenes content.To further verify the continuous antioxidant capacity of C 60hydroxyapatite composite, detection of hydroxyl radical scavenging capacity of VC and C 60 -hydroxyapatite composites were tested at 4 and 40 min.The Figure 5b showed that the ESR signal of C 60hydroxyapatite composite (contains 4 mg/kg fullerene) weakened with time extension, while there was no reduction in the signal in the vitamin C(1000 mg/kg) group.These results demonstrated that C 60hydroxyapatite composite has strong long-term oxidation resistance.

F I G U R E 2
Figure 6, the peroxide value of oleic acid on Day 0 was 2.8, and after 7 days of UV irradiation, the peroxide values of the four groups of solutions were Blank-8.02,A-7.98, B-7.11, and C-6.87, respectively.It can be found that the addition of fullerene can significantly reduce the oxidation of oleic acid, and the inhibition effect rises with the increase of fullerene content.

3. 6 |
Cell culture and cytotoxicity testC 60 -hydroxyapatite composite and hydroxyapatite were weighed 25 mg respectively, and added to 1 mL of culture medium containing 10% FBS and mixed well.Then placed in a constant temperature incubator at 37°C for 24 h.The C 60 -hydroxyapatite composite and hydroxyapatite were and obtained from the filtered extracts, respectively.
Table 1 serge oil-water ratio is the best flocculation phenomenon.As shown in Table 1, a gram of C 60 -hydroxyapatite mix-