Table of Content

22 July 2022, Volume 52 Issue 7 Previous Issue    Next Issue

Basic research

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Study on the influencing factors of phase behavior of SDBS/（C12-4-C12）Br2 microemulsion Liao Jianjun,Li Huabin,Deng Jinpin,He Gang,Guo Chengfei 2022, 52 (7):  689-695.  doi: 10.3969/j.issn.1001-1803.2022.07.001 Abstract ( 244 )   HTML ( 22 )   PDF (1154KB) ( 226 )   Microemulsions are widely used in tertiary oil recovery, cosmetics, food industry and other fields due to their excellent properties. By mixing anionic and cationic surfactants, a microemulsion system with excellent performance could be prepared. The factors influencing the phase behavior of the microemulsion system of mixed anionic/cationic surfactants, such as the molar ratio of SDBS to （C12-4-C12）Br2, salinity, surfactant mass fraction, and oil-water ratio, were studied. The results show that, for the SDBS-（C12-4-C12）Br2/n-butanol/NaCl/water/kerosene system, the solubilization parameter shows a trend of first increase and then decrease with the increase of the molar ratio. The optimal molar ratio of SDBS to （C12-4-C12）Br2 is 0.7∶1. In the experiments to investigate the effects of salt, the oil-water ratio was fixed to 1∶1, and the mass fractions of mixed surfactants were 2%, 3%, 4% and 5%, respectively. With the increase of NaCl mass fraction, all systems show the phase transition from Winsor Ⅰ→Winsor Ⅲ→Winsor Ⅱ. In the experiments to investigate the effects of oil, the mass fraction of mixed surfactants was fixed to 4%, and the mass fractions of NaCl were 0.50%, 1.30% and 1.65%, respectively. With the increase of the oil-water ratio, when the NaCl mass fraction was 0.50%, the system changed from micellar solution to Winsor Ⅰ type; when the NaCl mass fractions were 1.30% and 1.65%, the two systems showed the phase transition from Winsor Ⅱ→Winsor Ⅲ→Winsor Ⅰ. When the NaCl mass fraction was fixed to 1.30% and the mass fractions of mixed surfactants were 3%, 4% and 5% respectively, with the increase of the oil-water ratio, all systems showed the phase transition from Winsor Ⅱ→Winsor Ⅲ→Winsor Ⅰ. In addition, the amounts of oil required for the formation and disappearance of Winsor Ⅲ microemulsion increased with the mass fractions of NaCl and mixed surfactants. Figures and Tables | References | Related Articles | Metrics

Lecture of science and technology

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Common cosmetic preparation technologies（Ⅰ）Oil-water mixture: Emulsions Feng Yun,Shi Jing,Bao Jie,Hao Yang,Xu Guiyun,Fan Jinshi 2022, 52 (7):  696-703.  doi: 10.3969/j.issn.1001-1803.2022.07.002 Abstract ( 365 )   HTML ( 37 )   PDF (1029KB) ( 531 )   Emulsions are generally made out of two immiscible fluids, one being dispersed in the other, in the presence of surface-active agents. They are obtained by shearing two immiscible fluids, leading to the fragmentation of one phase into the other. The droplet volume fraction may vary from zero to almost one. From diluted to highly concentrated, emulsions exhibit very different internal dynamics and mechanical properties. Emulsion droplets of oil-in-water or water-in-oil typically fall in the range of 0.1-10 μm, whereas microemulsion droplets are in the 0.01-0.1 μm size range. Usually used as the carrier or matrix of active and functional ingredients, emulsions have been widely applied to daily chemical industry, textiles, leather, papermaking, oil-recovery, pesticides, polymerization, food, medicine and other industries. With the people’s concept of environment-friendly, the concern of ecology, and the demand for high quality and healthy life, eco-friendly functional emulsions with good biocompatibility and biodegradability have becoming more and more valued. Herein, the composition and types of emulsions, the principles and methods of selecting emulsifiers, the mechanism of emulsion preparation, and the various influence factors of emulsifying process are introduced. Furthermore, some special applications of emulsion in cosmetics and daily chemical industry in recent years are also mentioned. Figures and Tables | References | Related Articles | Metrics

Development and application

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Study on the improvement effects of Saussurea involucrata polysaccharide on atopic dermatitis in mice by external application Liu Guangrong,Gan Xiaoshuang,Tai Meiling,Han Ping,Akber Aisa Haji,Du Zhiyun 2022, 52 (7):  704-709.  doi: 10.3969/j.issn.1001-1803.2022.07.003 Abstract ( 222 )   HTML ( 24 )   PDF (1050KB) ( 238 )   The therapeutic effect and its possible mechanism of Saussurea involucrata polysaccharide on atopic dermatitis （AD） in mice were studied. The polysaccharide of Saussurea involucrata was obtained by water extraction and alcohol precipitation process. The content of crude polysaccharide was determined. The atopic dermatitis model in mice was established with topical 2, 4-dinitrofluorobenzene （DNFB）. 40 Mice were randomly divided into blank group, model group, prednisolone positive group, and low-dose and high-dose Saussurea involucrata polysaccharide groups （100 and 500 μg/mL, respectively）. The skin lesions of each group of mice were recorded; the transepidermal water loss of the mice was tested; the lesions were stained with hematoxylin-eosin to observe the pathological characteristics; the expression levels of IL-6, IL-4, IL-13, Ig E, TNF-α, NOD 1, TLR-2 and CRAMPS in the skin lesions were determined by ELISA method. The results show that the content of Saussurea involucrata polysaccharide prepared in this experiment is 28.23%. Saussurea involucrate polysaccharide could effectively alleviate the skin symptoms of mice with DNFB-induced atopic dermatitis. The transepidermal water loss and the thickness of the epidermal layer are both reduced. The high-dose group of Saussurea involucrata polysaccharide was selected for cytokine detection. Compared with the model group, the expression levels of Th2-related cytokines IL-6 （P<0.01）, IL-4 （P<0.01）, IL-13 （P<0.01） and Ig E in the skin of mice （P<0.01） are effectively reduced for the Saussurea involucrate polysaccharide group. Meanwhile, the Saussurea involucrate polysaccharide group regulates the cytokines of the innate immune pathway, significantly reduces the expression levels of TLR-2 （P<0.01）, NOD1 （P<0.01） and TNF-α （P<0.01）, and significantly increases the expression level of CRAMPS （P<0.05）. The present study shows that, through inhibiting the cytokines IL-4 and IL-13 in Th2 inflammatory response process in atopic dermatitis, and through regulating the secretion and release of the innate immunity regulator of TLR-2, the inflammatory response in AD model mice is thereby inhibited. Figures and Tables | References | Related Articles | Metrics

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Preparation and characterization of PR-CS/γ-PGA nanocapsules Zhang Wanping,Wu Kaixiang,Jiang Wen,Zhang Dongmei 2022, 52 (7):  710-716.  doi: 10.3969/j.issn.1001-1803.2022.07.004 Abstract ( 184 )   HTML ( 17 )   PDF (1319KB) ( 232 )   Encapsulated phenylethyl resorcinol chitosan/polyglutamic acid （PR-CS/γ-PGA） nanocapsules were prepared by ionic gelation method with chitosan （CS） and polyglutamic acid （γ-PGA） as wall materials. The effects of the mass concentration of γ-PGA, the pH of the CS solution and the mass concentration of PR on the particle size, Zeta potential and encapsulation rate of PR-CS/γ-PGA nanocapsules were studied. The results showed that, with the increase of γ-PGA concentration, the particle size of the suspension of PR-CS/γ-PGA nanocapsules was decreased, and the Zeta potential was also decreased. The encapsulation rate of PR-CS/γ-PGA nanocapsules was first decreased and then increased （the encapsulation rate was the largest when the mass concentration of γ-PGA was 0.27 mg/mL）, and if the mass concentration of γ-PGA was further increased, the encapsulation rate was not significantly changed. With the increase of PR mass concentration, the particle size of the suspension of PR-CS/γ-PGA nanocapsules was increased and the Zeta potential was decreased. The encapsulation rate of PR-CS/γ-PGA nanocapsules was reduced. As the pH of the CS solution was increased, the particle size of the suspension of PR-CS/γ-PGA nanocapsules was first decreased and then increased （the particle size was the smallest when pH=4.5）, and the Zeta potential was decreased. The encapsulation rate of PR-CS/γ-PGA nanocapsules was not significantly changed. When the CS concentration in the system was 1.33 mg/mL, the optimized conditions for preparing PR-CS/γ-PGA nanocapsules were as follows: the pH of CS solution was 4.5, the mass concentration of γ-PGA was 0.27 mg/mL, the mass concentration of PR was 0.4 mg/mL, the magnetic stirring speed was 400 r/min during the reaction, the speed of adding γ-PGA was 0.5 mL/min, and the reaction time was 1 h. Systematic characterization of the PR-CS/γ-PGA nanocapsules was made. TEM results showed that the PR-CS/γ-PGA nanocapsules were spherical. FT-IR analysis showed that the electrostatic interaction between CS and γ-PGA formed CS/γ-PGA nanocapsules, and the PR-CS/γ-PGA nanocapsules contained PR. The TGA curve showed that CS/γ-PGA nanocapsules could improve the thermal stability of PR, and PR-CS/γ-PGA nanocapsules successfully encapsulated PR. Figures and Tables | References | Related Articles | Metrics

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Study on preparation method of magnetic carbon-based solid acid and its application in glycoside synthesis Yu Hongmei,Zhou Feng,Hua Ping,Li Jianhua,Qian Feng 2022, 52 (7):  717-723.  doi: 10.3969/j.issn.1001-1803.2022.07.005 Abstract ( 159 )   HTML ( 13 )   PDF (1349KB) ( 188 )   Fe3O4/C-SO3H（A） and Fe3O4/C-SO3H（B） were magnetic carbon-based solid acid catalysts. Fe3O4/C-SO3H（A） was synthesized by step-by-step method. Fe3O4/C-SO3H（B） was synthesized by one-step method. They were prepared by ferric oxide, biomass carbon and sulfonic acid source. Ferric oxide was the magnetic core, while soluble starch was the matrix, and p-toluenesulfonic acid was the source of sulfonic acid group. The structure of the catalysts was characterized by SEM, XRD,FT-IR, TG and Vibrating Sample Magnetometer （VSM）. The synthesis of octyl glucoside was used as a probe. The activity of the catalyst was measured by the conversion of glucose and catalyst acid content. The activity of two catalysts was compared, the catalyst with good activity was applied to the synthesis of octyl glucoside, and the synthesis conditions of octyl glucoside were optimized. The optimization factors were investigated, such as the amount of catalyst, the mole ratio of octanol to glucose, the reaction temperature, the structure of octyl glucoside and the repeatability of catalyst. The results show that the crystal structure of Fe3O4 magnetic particles has not changed significantly after carbonization and sulfonation. Fe3O4 magnetic particles still retain good magnetic properties, and can be quickly separated from the system under the action of external magnetic field. Catalyst Fe3O4/C-SO3H（A） is a core-shell structure with a particle size of about 30 nm. Fe3O4/C-SO3H（B） is amorphous particles with porous structure. Both catalysts have good thermal stability and magnetic properties. The acid content of Fe3O4/C-SO3H（A） is 1.17 mmol/g, and the glucose conversion rate in the probe reaction is 97.9%. The acid content of Fe3O4/C-SO3H（B） is 0.91 mmol/g, and the glucose conversion rate in the probe reaction is 95.4%. Compared with Fe3O4/C-SO3H （B）, Fe3O4/C-SO3H （A） has better performance in acid content, and glucose conversion. Therefore, Fe3O4/C-SO3H（A） is selected as the catalyst for the synthesis of octyl glucoside. Fe3O4/C-SO3H（A） is used for octyl glucoside process optimization. When the amount of Fe3O4/C-SO3H（A） is 7% （w/%） of glucose, the molar ratio of n-octanol to glucose is 9 to 1, and the reaction temperature is 140 ℃, the conversion rate of glucose can reach 98.5%. The catalyst can be reused by simple magnetic field separation. After repeated using 3 times, the conversion rate of the glucose reaches more than 92%. Figures and Tables | References | Related Articles | Metrics

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Optimization and emulsification mechanism of emulsified viscosity reducer with high temperature resistance for heavy oil in Henan Oilfield Zhao Yilu,Cheng Hongxiao,Xu Lina,Wang Xiaodong,Zhao Changxi,Li Xindan,Ren Hong 2022, 52 (7):  724-730.  doi: 10.3969/j.issn.1001-1803.2022.07.006 Abstract ( 172 )   HTML ( 13 )   PDF (1187KB) ( 230 )   With the widely exploitation and development of conventional oil reservoirs, the heavy oil has become the important resources in oil production and attracted great attentions to be the solution of the energy crisis in our country. The heavy oil is usually exploited by thermal and emulsification methods to decrease the viscosity, which require the emulsified viscosity reducer with excellent performance under high temperature conditions. Therefore, aimed at the problems of high viscosity and poor fluidity for heavy oil in Henan Oilfield, several emulsified viscosity reducers were investigated at different types and concentrations to obtain an optimum formula. Then, the emulsification performance of the optimum viscosity reducer under high temperature was further tested to study its temperature resistance ability. Finally, the emulsification mechanisms were explored by investigating the pH values, surficial tensions （SFT） and oil/water interfacial tensions （IFT）. The results show that the optimum formulation of emulsion viscosity reducer is BY-2 with the mass fraction of 0.4%. The emulsified viscosity reduction rate of the heavy oil can reach up to 97.36% under the reservoirs conditions of 50 ℃ and oil/water volume ratio of 7∶3. Moreover, the viscosity reducer exhibits excellent ability of high temperature resistance. It can maintain effective oil/water interfacial activity and emulsification ability after aging 6 h at 300 ℃, which is beneficial to apply in thermal recovery process for heavy oil. The alkaline components in the emulsified viscosity reducer can form the in-situ surfactant with petroleum acids in heavy oil, thereby producing synergistic effects to significantly reduce the SFT, oil/water IFT and improve the emulsification performance. Consequently, this study can provide technical support for the research and development of emulsified viscosity reducer with properties of efficient viscosity reduction and high temperature resistance for heavy oilfields. Figures and Tables | References | Related Articles | Metrics

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Preparation and antioxidant properties of Elaeagnus mollis Diels seed oil nanoemulsions Zhao Zhijuan,Gong Peilong,Wang Xiahui,Yu Jiahui,Liu Xiaomei 2022, 52 (7):  731-736.  doi: 10.3969/j.issn.1001-1803.2022.07.007 Abstract ( 204 )   HTML ( 19 )   PDF (1069KB) ( 327 )   Nanotechnology has practical and potential application value in various fields. Recently, the nanoemulsion, a spontaneous emulsification delivery system has attracted increasing attention, which is composed of oil phase, surfactant, cosurfactant and water phase. An Elaeagnus mollis Diels seed oil nanoemulsion was constructed by self-nanoemulsifying method and its characterization and antioxidant activity were evaluated. The appearance, particle size, particle size distribution and pH value of the nanoemulsion were all showed that the nanoemulsion was qualified. The stability determination of nanoemulsion was tested under different conditions respectively, and the change in particle size was not obvious, and no delamination, turbidity and precipitation occurred, which suggested that the nanoemulsion possessed a good stability. DPPH radical scavenging experiment and hydroxyl radical scavenging experiment were conducted to verify the antioxidant activity of the nanoemulsion. The scavenging ability of Elaeagnus mollis Diels seed oil nanoemulsion and Elaeagnus mollis Diels seed oil to DPPH free radical was increased with the concentration increasing, and the scavenging ability of the nanoemulsion was better than that of the oil. At the same time, the scavenging ability of the nanoemulsion to hydroxyl radicals was significantly stronger than that of Elaeagnus mollis Diels seed oil. Nanoemulsion has smaller particle size, larger specific surface area, which is beneficial to the improvement of drug solubility, stability and antioxidant activity. Nanoemulsion is a promising delivery system, which can provide experimental basis for the application of Elaeagnus mollis Diels seed oil. Figures and Tables | References | Related Articles | Metrics

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Preparation and application of highly purified illite He Guangwen,Yan Shaowei,Yu Bin 2022, 52 (7):  737-743.  doi: 10.3969/j.issn.1001-1803.2022.07.008 Abstract ( 333 )   HTML ( 16 )   PDF (1236KB) ( 225 )   A kind of highly purified illite was successfully prepared via the wet purification. The purification process was optimized by investigating grinding concentration, inlet flow rate, primary settling time and secondary settling time. The safety of illite was confirmed by heavy metal detection. Scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and particle size analysis were used to observe the structure and properties of purified illite. A mud mask was prepared with the purified illite, and the skin sensation and efficacy of the mud mask were investigated. The content of purified illite was increased from 41% to 94% when the grinding concentration （mass ratio of ore to water） was 80%, the inlet flow rate was 15 m3/h, the primary settling time was 24 hours and the secondary settling time was 72 hours. The results of heavy metal detection indicated that the content of heavy metals in the illite obtained was obviously below the limit value, indicative of excellent safety. The SEM and FT-IR results showed that the purified illite had a typical scaly structure and the impurities were effectively removed. The XRD results confirmed that the content of purified illite was 94%. The skin sensation and efficacy results illustrated that, the purified illite had the potential and prospect in preparing mud masks. Figures and Tables | References | Related Articles | Metrics

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Effect of gold microneedle combined with Kefumei mask on symptoms, skin physiological function and prognosis of patients with rosacea Cui Xiuhua,Gao Weitao,Wu Qingmei,Su Zixin,Sun Chongqiu 2022, 52 (7):  744-749.  doi: 10.3969/j.issn.1001-1803.2022.07.009 Abstract ( 297 )   HTML ( 12 )   PDF (977KB) ( 238 )   To investigate the effect of gold microneedle combined with Kefumei mask on symptoms, skin physiological function and prognosis of patients with rosacea were studied. A total of 142 patients with rosacea in our hospital from August 2019 to August 2021 were selected and randomly divided into different groups, with 71 cases in each group. The control group took gold micro-needling, while the observation group took Kefumei mask after gold micro-needling treatment, and both were treated for 4 weeks. The treatment effect, adverse reactions, symptom scores before and after treatment were recorded, including skin physiological indexes （transepidermal water loss （TEWL）, epidermal water content, oil）, stratum corneum integrity indexes （mucoprotein content, serine protein activity）, and Acne-specific quality of life scale （Acne-QOL）. The total effective rate of treatment in the observation group was higher than that in the control group （P<0.05）. After 2 weeks and 4 weeks of treatment, the scores of erythema, flushing and telangiectasia in the observation group were lower than those in the control group （P<0.05）. After 4 weeks of treatment, the contents of TEWL, serine protein activity and mucoprotein in the observation group were lower than those in the control group, and the oil and epidermal water contents were higher than those in the control group （P<0.05）. There was no significant difference in the incidence of adverse reactions between the observation group and the control group （P>0.05）. After 4 weeks of treatment, the Acne-QOL scores in both groups were higher than those before treatment （P<0.05）. Gold microneedle combined with Kefumei mask can help to improve the physiological function of the skin in patients with rosacea, repair the stratum corneum, relieve clinical symptoms, improve the prognosis, and has high safety. Figures and Tables | References | Related Articles | Metrics

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A study on the lip and perioral aging via fast optical in vivo topometry of human skin Jia Xueting,Yue Zhang,Li Jingjing,Zhang Chenyang,Yang Li,Su Ning 2022, 52 (7):  750-755.  doi: 10.3969/j.issn.1001-1803.2022.07.010 Abstract ( 255 )   HTML ( 13 )   PDF (1337KB) ( 437 )   The lip and perioral skin aging was evaluated by the fast optical in vivo topometry of human skin （referred to as AEVA-HE）. In the experiment, 20 eligible healthy female volunteers were selected to participate in the test. The volunteers were divided into a youth group and an elderly group, and each with 10 people. Based on the fast optical in vivo topometry of human skin technology, the 3D topography of all volunteers’ skin of lip and perioral skin was collected, and the physiological parameters of the lip and perioral skin were measured, and the skin texture and morphological changes were also statistically analyzed. The perioral wrinkles: compared with the elderly group, the youth group’s perioral skin is more delicate, and the results of wrinkles’ roughness （Ra, Rz） show significant difference by statistics analysis （P<0.05）. The wrinkles of lower lip: as for comparing the wrinkles of lower lip between the youth and the elderly groups, the parameters of skin smoothness （Stm, Sa） show no significant difference. However, from the data trend and 3D topography, it is observed that the elderly group performs worse. The wrinkles of lip corners: the lip corner wrinkles’ roughness, wrinkle depth, volume and area were compared between the youth group and the elderly group. The results of wrinkles’ roughness and mean depth show significant difference by statistics analysis （P<0.05）. The morphological change of lip: the results show that the youth group has plump lips combined with the parameters of positive volume, positive area and 3D topography. But no significant difference is shown between the youth group and the elderly group. This study shows that the AEVA-HE system can characterize the changes in the skin texture and morphology of the lips and perioral skin’s aging through the objective data and 3D topography, which will provide strong technical support for cosmetic companies and research institutions. Figures and Tables | References | Related Articles | Metrics

Reviews

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Visual design of cosmetic packaging based on simple aesthetic elements Zhong Jiao,Gao Tao 2022, 52 (7):  756-761.  doi: 10.3969/j.issn.1001-1803.2022.07.011 Abstract ( 207 )   HTML ( 14 )   PDF (966KB) ( 217 )   In recent years, more and more consumers are pursuing personalized products, hoping to have unique items. The visual design of cosmetic packaging is an important link in cosmetics marketing and production, and it is an important factor to enhance consumers’ desire to purchase and obtain higher benefits. In order to enhance the visual effect of cosmetic packaging and enhance consumers’ desire to purchase, cosmetic packaging based on simple aesthetic elements is proposed visual design. The acceleration of the current pace of life makes people pursue a more natural and simple design style, and the simple aesthetic elements start a new trend of aesthetics that replace “existence” with “nothing”. It expresses the visual simplicity and aesthetic elements of cosmetic packaging-colors, shapes and graphics in a simple, clear and regular way. Analyzing the definition and performance of simple aesthetic elements, it can be seen that simple aesthetic elements can be embodied by the combination relationship and order of visual design elements, which can be understood as the coordination of visual design elements under the simple aesthetic elements; therefore, from the unity and change of form, contrast and harmony, proceeding from the three aspects of organization and dynamics, the coordination of colors, shapes and graphics in the visual design of cosmetic packaging under the simple aesthetic elements is realized. Analyzing the application of simple aesthetic elements, comprehensive case analysis shows that the use of simple graphics in the visual design of cosmetics packaging is diverse, and different colors also have different meanings. As another main form of disseminating visual language to the outside world, color affects people. The emotions of people have a greater impact, but the ultimate goal is to coordinate the content of the layout, enhance the visual effect, and attract the attention of consumers. Finally, the purpose of using simple aesthetic elements to enhance the visual effect of cosmetic packaging is realized. Figures and Tables | References | Related Articles | Metrics

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Preparation of liquid crystal emulsion and its application in cosmetics Liu Huimin,Ma Xiaoyuan,Zhao Yonghong 2022, 52 (7):  762-769.  doi: 10.3969/j.issn.1001-1803.2022.07.012 Abstract ( 1368 )   HTML ( 65 )   PDF (1117KB) ( 827 )   Liquid crystal emulsion has a wide range of applications in the field of cosmetics, showing a variety of excellent properties. This article first introduces the microscopic morphology of the liquid crystal structure. Secondly, it summarizes the liquid crystal emulsifiers and the factors that affect the preparation of liquid crystal emulsion, including formula ingredients, emulsification method and emulsification process. Finally, the application advantages of liquid crystal emulsion in cosmetics are summarized, including the safety, efficacy, sensory and stability of cosmetics. Safety is mainly reflected in the packaging and sustained release of some active ingredients. The liquid crystal structure isolates the irritating active ingredients from the skin and interacts slowly with the skin. In terms of efficacy, the liquid crystal structure can encapsulate actives, thereby protecting unstable actives, slow-release actives, and promoting the penetration of actives on the skin. In terms of sensory properties, due to the layered structure of the lamellar liquid crystal, the layered structure can slide during the application process because it can improve the smearing feeling of the cosmetics during use. Finally, the application of liquid crystal emulsion in cosmetics with different efficacies, including moisturizing products and sunscreen products, is introduced, which aims to provide a theoretical basis for the preparation and application of liquid crystal emulsion. Figures and Tables | References | Related Articles | Metrics

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Advances in size control of micro and nano silica particles Niu Hongbo,Yan Yongli,Dou Longlong,Jiang Xuanxuan,Zhang Xiao,Zhang Peiliang 2022, 52 (7):  770-777.  doi: 10.3969/j.issn.1001-1803.2022.07.013 Abstract ( 239 )   HTML ( 12 )   PDF (1387KB) ( 360 )   Micro/nano-SiO2 particles are important inorganic non-metallic materials, and their good properties are concerned by researchers. They are also ideal building blocks for assembling functional nanostructured materials, and play an important role in rubber, photonic crystals, biomedicine, cosmetics and other fields. Therefore, the synthesis of nano-silica particles with controllable particle size is of great significance. Since Stöber et al. successfully prepared silica nanoparticles with different size by adjusting appropriate reaction parameters in 1968, a series of important progress has been made in the synthesis of silica nanoparticles. However, how to control the particle size of SiO2 more effectively remains to be further developed. Herein, three preparation methods of SiO2 particles are briefly introduced, including Stöber method, microemulsion method and precipitation method, with emphasis on the particle size control mechanism and its influencing factors in the preparation of SiO2 particles. The particle size control mechanism of SiO2 particles prepared by Stöber method and microemulsion method is mainly based on the reaction kinetics of TEOS hydrolysis and condensation, while the particle size control mechanism of SiO2 particles prepared by precipitation method is mainly based on the theory of silicic acid polymerization. The research progress has shown that by using Stöber method, by adjusting the type and concentration of catalysts, solvent polarity, synthesis process and other factors, the particle size of SiO2 particles can be adjusted in the range of 10 nm-4.5 μm; by microemulsion method, by adjusting the content of reactants, hydrophobic carbon chain length of surfactants and other factors, the particle size of SiO2 particles can be adjusted in the range of 20-100 nm; by means of precipitation method, by adjusting the content of reactants, pH of solution, synthesis process and other factors, SiO2 particles with the smallest particle size of 2 nm can be obtained. Finally, the problems and development direction of micro/nano-SiO2 particle size control technology are pointed out to provide some reference for application. Figures and Tables | References | Related Articles | Metrics

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Assessment of sensitive skin condition Cheng Lin,Ding Meihua,Liu Qi,Zhao Hua 2022, 52 (7):  778-784.  doi: 10.3969/j.issn.1001-1803.2022.07.014 Abstract ( 396 )   HTML ( 28 )   PDF (955KB) ( 437 )   Sensitive skin is a series of skin symptoms of unpleasant subjective feelings caused by the slight stimulation of skin response. It may produce a series of subjective and objective manifestations such as tingling, itching, erythema, tingling, and burning. Its main characteristics are subjectivity and responsiveness. It is a highly reactive skin condition, which is not a skin disease, but it is more likely to occur with skin disease, and it can be considered as a skin manifestation of some skin diseases. Sensitive skin may occur in various parts of the body and is not necessarily accompanied by objective signs such as erythema. Sensitive skin may be precipitated by various factors that its occurrence mechanism is complicated and unclear, involving skin barrier, nervous system, immune response, vascular system and many other aspects. The occurrence of sensitive skin is closely related to the TRP family, especially the TVPR1 receptor, which is generally accompanied by damage to the skin barrier and （or） nervous system disorders. The evaluation methods of sensitive skin condition can be divided into subjective evaluation methods, semi-subjective evaluation methods and objective evaluation methods. The lactic acid sting test and the measurement of transdermal water loss are the mostly used. At present, lots of researchers are exploring more objective and accurate evaluation methods for sensitive skin. However, due to the random occurrence and unclear mechanism, many evaluation methods have the limitations of poor consistency, low recognition rate, and difficulty in repeatability. The incidence of sensitive skin in the population is relatively high which about 40%, and there are differences in the incidence of different countries. At the same time, as cosmetics companies pay more attention to sensitive skin, it is showing a blowout trend in the market that more and more cosmetics claim suiting for sensitive skin. The efficacy claim of cosmetics should have sufficient scientific basis. The “Evaluation standard of cosmetic efficacy declaration” requires that specifically declared cosmetics should be evaluated by human efficacy evaluation test or consumer use test if they claim to apply to sensitive skin. Therefore, it is very important to accurately assess the condition of sensitive skin. Starting from the precipitating factors and occurrence mechanism of sensitive skin, this paper elaborates the subjective and objective identification and grading methods of sensitive skin, aiming to provide a theoretical basis for establishing a sound evaluation system of applicability and efficacy of sensitive skin cosmetics. Figures and Tables | References | Related Articles | Metrics

Analytical methods and testing

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Rapid screening and determination of eight nitrosamines in cosmetics by liquid chromatography-quadrupole-time-of-flight mass spectrometry Jiang Yaqi,Gao Tianyang,Yu Haiying,Li Qiyan,Li Jun,Xie Yaping 2022, 52 (7):  785-790.  doi: 10.3969/j.issn.1001-1803.2022.07.015 Abstract ( 191 )   HTML ( 16 )   PDF (1060KB) ( 244 )   A rapid screening and determination method was developed for eight nitrosamines in cosmetics by liquid chromatography-quadrupole-time-of-flight mass spectrometry. Cosmetics were well dispersed by saturated sodium chloride solution and extracted by vortex mixer using dichloromethane. After dichloromethane was dried under nitrogen, the residuums were redissolved by methanol; the separation of 8 target compounds was performed on an Agilent Poroshell 120 SB-C18 column with gradient elution using methanol and water as mobile phases. Detection was achieved by atmospheric pressure chemical ionization in the positive mode, and rapid screening could be achieved using high-resolution mass spectrometry database which was created and acquired by Library view 1.3.1 software. Sample pretreatment methods were optimized, and the determination method for 8 nitrosamines in cosmetics was established through methodological study. The results showed that: this sample pretreatment method had purifying effect and had a better recovery compared with other pretreatment methods; the eight nitrosamines all showed good linear relationship （r≥0.999） in the range of 5-100 ng/mL under the optimized conditions; the average recoveries were in the range of 85.1%-113.1% at three spiked levels （0.03, 0.10, 0.50 mg/kg） with relative standard deviations （RSDs） of 1.4%-6.6%; limits of detection （LODs） were in the range of 0.001 0-0.020 0 mg/kg, and limits of quantitation （LOQs） were in the range of 0.003 0-0.060 0 mg/kg. This method was simple and timesaving for rapid screening of target compounds even in case of lack of standards, and the method also had high sensitivity and accuracy, which was suitable for trace detection of nitrosamines in cosmetics. Figures and Tables | References | Related Articles | Metrics

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Simultaneous determination and usage analysis of six functional ingredients in whitening cosmetics Yan Jun,Wang Rong,Li Zehua,Zhang Liyuan,Cheng Qiaoyuan,Yan Linqi 2022, 52 (7):  791-796.  doi: 10.3969/j.issn.1001-1803.2022.07.016 Abstract ( 351 )   HTML ( 22 )   PDF (1139KB) ( 267 )   A high performance liquid chromatography method to determine six functional ingredients in whitening cosmetics was established for the simultaneous detection of α-arbutin, β-arbutin, deoxyarbutin, nicotinamide, hydroquinone and phenol in water-based, emulsion and cream cosmetics. For satisfactory sensitivity, stability and precision, the effects of detection wavelength, chromatographic column, mobile phase, extraction solvents, injection volume and column temperature were explored. Finally, the samples were extracted by 70% methanol solution, then the extract was separated on Waters HSS T3-C18 （250×4.6 mm, 5 μm） column using methanol-water as the mobile phase with a flow rate of 1.0 mL/min, and qualitative and quantitative analysis was performed by high performance liquid chromatography with diode array detector at the detection wavelength of 220 nm. The results show that there are good linear relationships for 6 compounds in certain concentration range, with correlation coefficients （r2） larger than 0.999. The limits of detection （LOD） and limits of quantitation （LOQ） are in the range of 6-12 mg/kg and 20-40 mg/kg, respectively. The spiked recoveries for six compounds are in the range of 93.4%-109.6% with relative standard deviations （RSD） of 0.2%-3.8%. 150 batches of samples were determined. No deoxyarbutin, hydroquinone or phenol was detected. The content of nicotinamide, β-arbutin and α-arbutin range from 0.10% to 5.26%, 0.01% to 3.32% and 0.01% to 0.57%, respectively. The developed method is accurate, sensitive and simple for the determination of the six components in cosmetics. It is not only an effective method to detect deoxyarbutin in cosmetics, but also provides basis for simultaneous determination of these six components. Figures and Tables | References | Related Articles | Metrics