Nanoemulsion: process selection and application in cosmetics – a review

In recent decades, considerable and continuous growth in consumer demand in the cosmetics field has spurred the development of sophisticated formulations, aiming at high performance, attractive appearance, sensorial benefit and safety. Yet despite increasing demand from consumers, the formulator faces certain restrictions regarding the optimum equilibrium between the active compound concentration and the formulation base taking into account the nature of the skin structure, mainly concerning to the ideal penetration of the active compound, due to the natural skin barrier. Emulsion is a mixture of two immiscible phases, and the interest in nanoscale emulsion has been growing considerably in recent decades due to its specific attributes such as high stability, attractive appearance and drug delivery properties; therefore, performance is expected to improve using a lipid‐based nanocarrier. Nanoemulsions are generated by different approaches: the so‐called high‐energy and low‐energy methods. The global overview of these mechanisms and different alternatives for each method are presented in this paper, along with their benefits and drawbacks. As a cosmetics formulation is reflected in product delivery to consumers, nanoemulsion development with prospects for large‐scale production is one of the key attributes in the method selection process. Thus, the aim of this review was to highlight the main high‐ and low‐energy methods applicable in cosmetics and dermatological product development, their specificities, recent research on these methods in the cosmetics and consideration for the process selection optimization. The specific process with regard to inorganic nanoparticles, polymer nanoparticles and nanocapsule formulation is not considered in this paper.     

Influence of nanostructure composition on its morphometric characterization by different techniques

Morphometric characterization of nanoparticles is crucial to determine their biological effects and to obtain a formulation pattern. Determining the best technique requires knowledge of the particles being analyzed, the intended application of the particles, and the limitations of the techniques being considered. The aim of this article was to present transmission (TEM) and scanning (SEM) electron microscopy protocols for the analysis of two different nanostructures, namely polymeric nanoemulsion and poly(lactic‐co‐glycolic acid) (PLGA) nanoparticles, and to compare these results with conventional dynamic light scattering (DLS) measurements. The mean hydrodynamic diameter, the polydispersity index, and zeta potential of the nanostructures of polymeric nanoemulsion were 370.5 ± 0.8 nm, 0.133 ± 0.01, and ?36.1 ± 0.15 mV, respectively, and for PLGA nanoparticles were 246.79 ± 5.03 nm, 0.096 ± 0.025, and ?4.94 ± 0.86 mV, respectively. TEM analysis of polymeric nanoemulsion revealed a mean diameter of 374 ± 117 nm. SEM analysis showed a mean diameter of 368 ± 69 nm prior to gold coating and 448 ± 70 nm after gold coating. PLGA nanoparticles had a diameter of 131 ± 41.18 nm in TEM and 193 ± 101 nm in SEM. Morphologically, in TEM analysis, the polymeric nanoemulsions were spherical, with variable electron density, very few showing an electron‐dense core and others an electron‐dense surface. PLGA nanoparticles were round, with an electron‐lucent core and electron‐dense surface. In SEM, polymeric nanoemulsions were also spherical with a rough surface, and PLGA nanoparticles were round with a smooth surface. The results show that the “gold standards” for morphometric characterization of polymeric nanoemulsion and PLGA nanoparticles were, respectively, SEM without gold coating and TEM with negative staining. Microsc. Res. Tech. 77:691–696, 2014. © 2014 Wiley Periodicals, Inc.     

柠檬醛纳米乳液对鲅鱼鱼糜凝胶品质及贮藏稳定性的影响

目的 为了改善鱼糜制品的品质及其贮藏稳定性,添加不同浓度柠檬醛纳米乳液（0.35%-0.55%,添加量为3%）制备鲅鱼鱼糜。方法 测定鱼糜的凝胶性能、微观结构、挥发性盐基氮（total volatile basic nitrogen,TVB-N）值、氧化稳定性以及菌落总数。结果 柠檬醛纳米乳液的添加提高新鲜鲅鱼鱼糜的凝胶强度、持水性以及质构特性 (P < 0.05),降低蒸煮损失率 (P < 0.05),且凝胶网络结构致密有序,孔洞较小,表面光滑。当柠檬醛纳米乳液浓度为0.45%时,新鲜鱼糜凝胶品质最好。此外,在贮藏过程中,各处理组鱼糜的持水性、蒸煮损失、氧化稳定性、TVB-N值和菌落总数均优于对照组,表现最佳为0.45%组。结论 柠檬醛纳米乳液的加入能够提高鲅鱼鱼糜的凝胶性能,增强鱼糜在贮藏过程中的氧化稳定性,抑制鱼糜中微生物的生长,为进一步鱼糜凝胶品质的改善提供参考。     

复合天然保鲜剂制备及对树仔菜保鲜效果研究

为了筛选出适于树仔菜的复合天然保鲜剂,本实验以海南树仔菜为实验材料,在单因素实验的基础上进行正交试验,考察壳聚糖、茶树油纳米乳液、茶皂素复配溶液处理对储存期间树仔菜叶绿素含量、V_C含量、感官品质及失重率的影响。再以蒸馏水处理组作对照,比较最佳配方的复合天然保鲜剂与传统化学保鲜剂（二氧化氯）对树仔菜的保鲜效果。结果表明,复合保鲜剂最佳配方为茶皂素2 mg/mL、茶树油纳米乳液4 mg/mL、壳聚糖15 mg/mL,用该配方处理树仔菜,储存6 d,其叶绿素和V_C损失较少,失重率低,能较好地保持其感官品质,保鲜效果的综合评分为86.05分。复合天然保鲜剂和化学保鲜剂的保鲜效果均明显优于对照组,且复合天然保鲜剂的保鲜效果略优于传统化学保鲜剂,尤其在保持叶绿素含量及减少失重方面效果更佳。本实验筛选的复合天然保鲜剂对树仔菜有良好的保鲜效果,在树仔菜的绿色保鲜上具有巨大的应用前景。     

Dimensional analysis of a novel low‐pressure device for the production of size‐tunable nanoemulsions

A novel low pressure device was used to generate nanoemulsions of methyl methacrylate. This device is based on a strong elongational flow known to be more efficient than the shear flow for dispersive mixing. The influence of process parameters (pressure drop number of cycles, number and size of holes) and composition parameters (monomer fraction, surfactant concentration, etc) on droplet size has shown that the average droplet size can be tailored in the range 30–200 nm by adjusting these parameters. The objective of the present paper is to find correlations that relate the obtained droplet size to the studied process and composition parameters. This model is based on a dimensional analysis using the Buckingham theorem in order to determine appropriate dimensionless numbers. This approach represents a first step for scaling up the device besides giving a set of parameters allowing to achieve a given droplet size. © 2014 American Institute of Chemical Engineers AIChE J, 61: 23–30, 2015     

Development of a nanoemulsion of Phyllanthus emblica L. branch extract

For potential topical administration, we formulated a nanoemulsion containing phenolic constituents of Phyllanthus emblica branch extract. The nanoemulsion has high entrapment efficiency, small particle size, is stable, and can release its main chemical components. Branches of P. emblica were extracted with 50% ethanol (EPE) with 5.4% yield. HPLC analysis indicated several phenolic compounds, including gallic acid, vanillic acid, epigallocatechin (EGC), epigallocatechin gallate (EGCG) and ellagic acid. These were selected as chemical markers of EPE in the nanoemulsion development. The nanoemulsion was prepared by microemulsion techniques with hot high pressure homogenization. A ternary phase diagram was constructed to obtain the optimized nanoemulsion. The obtained transparent EPE nanoemulsion is composed of isopropyl myristate (0.6% w/w), Brij® 78 (0.35% w/w), and 0.15% (w/w) EPE. The optimized EPE nanoemulsion had a median particle size of 191.63?±?4.07?nm with a narrow particle size distribution, a zeta potential of ?10.19?±?0.54?mV, high entrapment efficiency at 67.99?±?0.87% and good stability at 4?°C after 90?d of storage. The release of active ingredients from the EPE nanoemulsion was slower than that of the EPE aqueous formulation. The loading ratios of the five phenolic compounds were high, with relative order of EGC?>?EGCG?>?vanillic acid?>?gallic acid?>?ellagic acid, resulting in slow release profiles of EGC and EGCG in the EPE nanoemulsion. In conclusion, the obtained EPE nanoemulsion has good characteristics for future clinical trials.     

Development of dorzolamide hydrochloride in situ gel nanoemulsion for ocular delivery

Background: Several in situ gel-forming systems have been developed to prolong the precorneal residence time of a drug and to improve ocular bioavailability. Poloxamer 407 with its thermoreversible gelation and surface active properties was utilized to formulate a novel dorzolamide hydrochloride in situ gel nanoemulsion (NE) delivery system for ocular use. Objective: Improvement of both ocular bioavailability and duration of action for dorzolamide hydrochloride was the aim of this study. Methods: Physicochemical properties, in vitro drug release studies and biological evaluation of the prepared NEs were investigated. Results: The optimum formulation of in situ gel NE consisted of Triacetin (7.80%), Poloxamer 407 (13.65%), Poloxamer 188 (3.41%), Miranol C2M (4.55%), and water (70.59%). Biological evaluation of the designed dorzolamide formulation on normotensive albino rabbits indicated that this formulation had better biological performance, faster onset of action, and prolonged effect relative to either drug solution or the market product. The formula showed a superior pharmacodynamic activity compared to the in situ gel dorzolamide eye drops. This indicated the effectiveness of the in situ gel properties of poloxamer 407, besides formulating the drug in an NE form for improving the therapeutic efficacy of the drug. Conclusion: These results demonstrate the superiority of in situ gel NE to conventional ocular eye drops and in situ gels to enhance ocular drug bioavailability.