Stability Of Nanoemulsions Research Articles

Formulation process, physical stability and herbicidal activities of Cymbopogon nardus essential oil-based nanoemulsion

Essential oil-based bioherbicides are a promising avenue for the development of eco-friendly pesticides. This study formulated nanoemulsions containing citronella (Cymbopogon nardus) essential oil (CEO) as an herbicidal product using a high-pressure homogenization method with hydrophilic-lipophilic balance (HLB) values ranging 9–14.9 for the surfactant mixture (Tween 60 and Span 60). The CEO was high in monoterpene compounds (36.333% geraniol, 17.881% trans-citral, 15.276% cis-citral, 8.991% citronellal, and 4.991% β-citronellol). The nanoemulsion at HLB 14 was selected as optimal due to having the smallest particle size (79 nm, PI 0.286), confirmed by transmission electron microscopy. After 28 days of storage, particle size in the selected formulation changed to 58 and 140 nm under 4 °C and 25 °C, respectively. Germination and seedling growth assays with Echinochloa crus-galli showed that the nanoemulsion exerted a significant dose-dependent inhibitory effect at all tested HLBs (9–14.9) and concentrations (100–800 µL/L). The inhibitory effect was greatest at HLB 14. Treatment of E. cruss-galli seed with the HLB 14 nanoemulsion significantly reduced seed imbibition and α-amylase activity. Our findings support that CEO nanoemulsions have a phytotoxic effect and hence herbicidal properties for controlling E. cruss-galli. Accordingly, this nanoemulsion may have potential as a bioherbicide resource.

Impact of high hydrostatic pressure on the micellar structures and physicochemical stability of casein nanoemulsion loading quercetin.

Natural casein is a highly structured protein and the characteristic of self-assembly makes the formation of micelles, thus negatively limiting the applications. High hydrostatic pressure (HHP), as a novel non-thermal process, can modify the structures of protein and improve the related functionalities. In this study, micellar casein was subjected to HHP treatment from 100 to 500MPa, which then loaded quercetin and formed the nanoemulsion. The thermal, pH, ions and physical stability of nanoemulsion were comprehensively investigated. The results showed 300-500MPa could effectively disintegrate the micellar structures of natural casein by dissociating colloidal calcium phosphate, which significantly improved the emulsifying activity and encapsulation efficiency. However, 500MPa caused the nanoemulsion loading most quercetin and subsequently showed the better physical and ions stability in comparison with control and 100-400MPa. Therefore, HHP is expected to modify the high-order structure of casein, which becomes the ideal nano-vehicles for hydrophobic bioactive substances.

Nanoemulsions with sea buckthorn oil and κ-carrageenan

The structure, stability, and rheological properties of nanoemulsions with droplets of sea buckthorn oil stabilized with Tween 80 and Span 80 and κ-carrageenan in the aqueous phase were investigated. The fast flocculation and coalescence of oil droplets occurred in nanoemulsions without κ-carrageenan. The nanoemulsion stability was significantly improved in the presence of the gel network at κ-carrageenan concentrations ≥ 0.5 mass%. TEM analysis showed that oil droplet flocs were trapped in the polymer gel network, so the further floc compaction and creaming were prevented. Nanoemulsions without κ-carrageenan and 0.25 mass% κ-carrageenan displayed the Newtonian-like rheological behavior whereas nanoemulsions with 0.5–5.0 mass% κ-carrageenan demonstrated the non-Newtonian flow of the pseudoplastic type. Oscillatory measurements showed that the values of G′ were higher than the corresponding G″ for nanoemulsions with 0.5 and 2 mass% κ-carrageenan in the investigated range of angular frequencies. However, the G′/G″ crossover was detected for nanoemulsion with 5 mass% κ-carrageenan. The structure relaxation was not observed for this nanoemulsion because the gel in the aqueous phase was irreversibly broken under shear. In nanoemulsions with lower κ-carrageenan concentration, the disintegrated structure was recovered with time after shearing. Apparently, the destruction of the oil droplet flocs under the shear was reversible and the elastic structure of the gel was not destroyed.

A Comparative Study on Inhibition of Breast Cancer Cells and Tumors in Mice by Carotenoid Extract and Nanoemulsion Prepared from Sweet Potato (Ipomoea batatas L.) Peel.

The objectives of this study were to determine carotenoid composition in sweet potato (TNG66) peel and prepare carotenoid nanoemulsion to study its inhibition effect on breast cancer cells MCF-7 and tumors in mice. Results showed that a total of 10 carotenoids were separated within 30 min by employing a YMC C30 column and a gradient mobile phase of methanol/acetonitrile/water (74:14:12, v/v/v) and dichloromethane (B) with a flow rate of 1 mL/min, column temperature of 25 °C, and detection wavelength of 450 nm. Following quantitation, all-trans-β-carotene was present in the highest amount (663.8 μg/g). The method validation data demonstrated a high accuracy and precision of this method. The carotenoid nanoemulsion was prepared by mixing an appropriate proportion of carotenoid extract, Tween 80, PEG 400, soybean oil and deionized water with the mean particle size being 15.7 nm (transmission electron microscope (TEM)), polydispersity index 0.238, encapsulation efficiency 97% and zeta potential −69.8 mV. A high stability of carotenoid nanoemulsion was shown over a 90-day storage period at 25 °C and during heating at 100 °C for 2 h. The release percentage of total carotenoids from carotenoid nanoemulsion under gastric and intestinal condition was 18.3% and 49.1%, respectively. An antiproliferation study revealed that carotenoid nanoemulsion was more effective than carotenoid extract in inhibiting the growth of human breast cancer cells MCF-7. Following treatments of paclitaxel (10 μg/mL), carotenoid nanoemulsion (20 and 10 μg/mL) and carotenoid extract (20 and 10 μg/mL), the tumor weight of mice respectively decreased by 77.4, 56.2, 40.3, 36.1 and 18.7%, as well as tumor volume of mice by 75.4, 65.0, 49.7, 46.7 and 26.5%. Also, both carotenoid extract and nanoemulsion could reduce the levels of epidermal growth factor (EGF) and (vascular endothelial growth factor (VEGF) in serum, with the latter being more effective. This finding suggested that carotenoid nanoemulsion was more effective than carotenoid extract in inhibiting tumor growth in mice.

Effect of Curcuma Extract and Surfactant Concentration on o/w Curcuma Extract Nanoemulsion Characteristics

Curcuma extract contains curcumin, which is known to have antiinflammation, anti-tumor and anti-microbial properties. Curcumin has relatively a low bioavailability and bioactivity since it is poorly water-soluble and easily degraded during digestion. The objective of this study was to investigate the effect of curcuma extract and surfactant concentration on the nanoemulsion characteristics of curcuma extract dispersed in red palm oil. Experiment was conducted using Response Surface method, by examining two factors: temulawak extract concentration (the lower limit: 2%, the upper limit: 5%), and surfactant (Tween 20 and Tween 80) concentration (the lower limit: 1%, upper: 2%). Nanoemulsion was produced using a high pressure homogenizer (1500psi, 7 cycles). Results showed that nanoemulsion with 5.94 % curcuma extract, 1.5 % tween 80, and 1.5% tween 20 had the best nanoemulsion stability (99 %), with droplet size of 74.7 nm and Polydispersity index (PDI) value 0.272. Both nanoemulsion stability and droplet size were significantly influenced by curcuma extract concentration. The results will be useful for designing effective nanoemulsion delivery systems for curcuma extract and other lipophilic bioactives for food, beverage, and pharmaceutical applications.

Improving encapsulating efficiency, stability, and antioxidant activity of catechin nanoemulsion using foam mat freeze-drying: The effect of wall material types and concentrations

This study investigated the effect of wall material types and concentrations on hygroscopicity, solubility, encapsulation efficiency (EE), flavonoid recovery (FR), and antioxidant activity of catechin nanoemulsion (CaNE) powder produced by foam mat freeze-drying. CaNE containing 0.4 g/100 g green tea catechins was ultrasonically fabricated and foamed with hydroxypropyl methylcellulose, as a foaming agent, and three different types of wall materials (maltodextrin [MD], gum arabic [GA], or a mixture of MD and GA [M + G]), at two concentration levels (5 and 10 g/100 g), before being freeze-dried at −50 °C for 48 h. The wall materials increased the hygroscopicity of CaNE powder while improving its water solubility by up to 92%. CaNE containing GA and M + G had higher EE and FR values than that containing MD. MD and M + G samples had higher antioxidant activity than GA. The antioxidant activity of the powder decreased as the concentration of wall material increased. CaNE powder with high EE and FR values, good solubility, and high antioxidant activity can be obtained when using M + G at 5 g/100 g. The findings are significant in providing an efficient method for developing CaNE powder as an effective ingredient for functional foods or beverages.

A novel formulation of simvastatin nanoemulsion gel for infected wound therapy: In vitro and in vivo assessment

Simvastatin, a well-known antihyperlipidemic drug, has antibacterial activity against a broad range of bacteria, especially Staphylococcus aureus. In present study, a nanoemulsion gel-based formulation containing Simvastatin was developed for infected wound therapy. Therefore, different formulations of Simvastatin nanoemulsion were prepared. Based on droplet size, polydispersity index and zeta potential, the best nanoemulsion formulation containing Simvastatin was selected for development of nanoemulsion gel formulation of drug using carbomer 934 as gelling agent. Thermodynamic stability of Simvastatin nanoemulsion was assessed at different conditions. The in vitro antibacterial activity against S. aureus as well as in vivo wound healing efficacy of both Simvastatin nanoemulsion and its nanoemulsion gel formulation were assessed.The droplet size, PDI, and zeta potential of selected Simvastatin nanoemulsion formulation were 75 nm, 0.3, and −29.4, respectively. The physical characteristics of nanoemulsion such as droplet size, charge and PDI did not change significantly in nanoemulsion gel formulation with viscosity of 11.12 Pas. Selected formulations of nanoemulsion and nanoemulsion gel of simvastatin were stable at 4 and 25 °C for 72 days and Minimum Inhibitory Concentration values of both nanoemulsion and nanoemulsion gel of drug against pathogenic strains S. aureus was 15.52 μg/ml which is two-fold lower than drug solution (31.25 μg/ml). Histological findings in mouse animal model of wound healing demonstrated the superiority of nanoemulsion gel belong other formulations.

Effect of pectin on the properties of nanoemulsions stabilized by sodium caseinate at neutral pH

The effect of different concentrations of low methoxyl pectin (LMP) on lipid oxidation and physical stability of sodium caseinate (CAS) stabilized nanoemulsions under neutral pH was investigated. The addition of pectin at low concentration (≤ 0.10 wt%) had no significant effect on the average size of nanoemulsions, but a slight size increase and phase separation were observed at higher concentrations of pectin (≥ 0.25 wt%). This result suggests that LMP can not adsorb at the oil/water interfacial CAS membrane at neutral pH. However, in the presence of LMP, the physical stability of nanoemulsions against high salt concentrations and freeze-thaw cycles was significantly enhanced. Moreover, nanoemulsions containing pectin have a better ability to inhibit lipid and protein oxidation than nanoemulsions without pectin after 3 weeks, and the lowest lipid hydroperoxide content was observed for nanoemulsions containing 0.25 wt% pectin.

Effect of Emulsifiers and Wall Materials on Particle Size Distribution and Stability of the Blended Essential Oils Nanoemulsions

In the present work, microencapsulation of the essential oil blend (clove + lemon peel + thyme) was successfully used to produce a product that can be used as food additives or in the pharmaceutical industry for the manufacture of a food supplement or so-called nutraceutical of plant origin. The characterization of the powder of the microcapsules made it possible to observe that the essential oil was successfully incorporated into the coating matrix. This was designed by the wall material, namely maltodextrin represented a barrier allowing the protection of the active principle, the control of its release and the property retention of the encapsulated essential oil for a long time. This powder of microcapsules of essential oil mixture can be successfully used for medical purposes to remedy certain pathologies, in particular for its antioxidant, antibacterial and anti-inflammatory properties.

Superior Fluorescent Nanoemulsion Illuminates Hepatocellular Carcinoma for Surgical Navigation.

Hepatocellular carcinoma (HCC), the fifth most common cancer worldwide, poses a severe threat to public health. Intraoperative fluorescence imaging provides a golden opportunity for surgeons to visualize tumor-involved margins, thereby implementing precise HCC resection with minimal damage to normal tissues. Here, a novel-acting contrast agent, which facilely bridges indocyanine green (ICG) and lipiodol using self-emulsifying nanotechnology, was developed for optical surgical navigation. Compared to clinically available ICG probe, our prepared nanoemulsion showed obviously red-shifted optical absorption and enhanced fluorescence intensity. Further benefiting from the shielding effect of lipiodol, the fluorescence stability and anti-photobleaching ability of nanoemulsion were highly improved, indicating a great capacity for long-lasting in vivo intraoperative imaging. Under the fluorescence guidance of nanoemulsion, the tumor tissues were clearly delineated with a signal-to-noise ratio above 5-fold, and then underwent a complete surgical resection from orthotopic HCC-bearing mice. Such superior fluorescence performances, ultrahigh tumor-to-liver contrast, as well as great bio-safety, warrants the great translational potential of nanoemulsion in precise HCC imaging and intraoperative navigation.

Garlic essential oil-based nanoemulsion carrier: Release and stability kinetics of volatile components.

An O/W nanoemulsion of garlic essential oil (GEO) at different oil‐to‐emulsion (O/E) ratios (5%, 10%, 15%, and 25%) was formulated to protect the volatile components of GEO. The effects of O/E ratios on the encapsulation efficiency (EE%) of volatile compounds and droplet size of nanoemulsions were studied. The results showed that with increasing in E/O ratio, droplet size increased while EE% decreased so that the droplet size was below 100 nm for all samples and the EE% was almost above 80% for most samples. The effects of various factors such as temperature (5°C–45°C), pH values (3–7), ionic strength (0–500 mM), and O/E ratios (5%–25%) on kinetic of nanoemulsions stability were studied. Reducing pH values and raising the temperature, ionic strength, and O/E ratios intensified the instability process and constant rate of instability in all nanoemulsions. The effects of temperature and O/E ratios on the release kinetics of volatile components were evaluated over time, and kinetic parameters such as release rate constant (k), Q10, and activation energy (Ea) were calculated in which results showed a zero‐degree model to describe the release kinetic behavior of most nanoemulsions. Both temperature and O/E ratios factors as well as their interaction (which had a synergistic effect) had a significant effect on increasing the release rate of volatiles so that the degree of reaction rate was changed from zero to the first order at simultaneous high levels of both factors. FT‐IR spectroscopy was carried out to study interactions among nanoemulsion ingredients. The presence of sulfur‐containing functional groups of garlic oil (thiosulphate, diallyl trisulfide, etc.) in nanoemulsions was confirmed by FT‐IR.

Novel Bioengineered Antibacterial and Anticancer ZnO Nanoparticles.

Transition metal oxide NPs have delivered wide applications in various fields. Therefore, in this study, a novel fungus, Alternaria sp. (NCBI Accession No: MT982648) was isolated and characterized from the vicinity of medicinal plants. Eventually, in this method extracted proteins from isolated fungus were utilized to synthesize highly biocompatible zinc nanoparticles (ZnO NPs). The various physical techniques including UV-visible spectroscopy, TEM, HR-TEM, XRD, DLS, zeta potential, and FTIR were used to characterize particles. The UV-visible absorption (λMax) and binding energy for the as-synthesized particles were found to be 329 nm and 3.91 eV, respectively. Further, the polydispersed particles were revealed to have regular crystallinity with hexagonal wurtzite phase of ZnO with the spacing of ~2.46 Å under XRD and HR-TEM. The average size of a particle under TEM was found to be ~18 nm. The evaluation of various surface functional groups of particles was done by FTIR. The average hydrodynamic diameter of particles was found to be ~57 d. nm with 0.44 particle distribution index whereas the nanoemulsion stability was explained by Zeta potential (-9.47 mV). These particles were found to exhibit potential antibacterial and anticancer activities. They were found to be bactericidal against S. abony (MIC 5.73 μg/mL); B. pumilis (MIC 6.64 μg/mL); K. pneumonia (MIC 14.4 μg/mL); E. coli (MIC 8.7 μg/mL); B. subtilis (MIC 5.63 μg/mL) and S. aureus (MIC 12.04 μg/mL). Further, they are also found to be concentration-dependent anticancer and inhibited the growth of A549 cells (IC50-65.3 μg/mL) whereas they were found to demonstrate no any cytotoxicity against NRK normal kidney cell line. The internalization of particles into the nucleus (i.e., nuclear fragmentation and DNA damage) was confirmed by DAPI staining. The intracellular particles were found to generate excessive ROS. Further, the anticancer potential was also estimated by noticing a hike in oxidative stress parameters, cell viability, cell morphology, and change in mitochondrial membrane potential. We effectively synthesized potentially potent antibacterial and anticancer novel bioengineered ZnO NPs.

Aggregative Stability of Nanoemulsions in eLiposomes: Analysis of the Results of Mathematical Simulation

Aggregative Stability of Nanoemulsions in eLiposomes: Analysis of the Results of Mathematical Simulation

Long-term Stability of Cationic Phytosphingosine Nanoemulsions as Delivery Systems for plasmid DNA

The case of ready to use gene delivery systems like cationic nanoemulsions is not reflecting the truth. Thus, delivery systems for applicating genes like nucleic acids have to be prepared freshly before each application. This study is focused on the preparation and characterization of cationic nanoemulsions using phytosphingosine for plasmid DNA delivery. Repurposing of cationic agents guided us to phytosphingosine, previously used for enhanced interaction with negatively charged surfaces. It was reported that phytosphingosine may act anti-apoptotic, but without using it in an appropriate delivery system like nanoemulsions. This gap attracted our interest about preparing and characterizing long-term stable cationic nanoemulsions and their cytotoxic effects on MDA-MB-231 and MCF-7 breast cancer cells using phytosphingosine. The cationic nanoemulsions 1, 2, and 3 were prepared and characterized in terms of droplet size, polydispersity index, and zeta potential, long-term stability after storage at 25 and 40 °C, complexation with pDNA, release and cytotoxicity on MDA-MB-231 and MCF-7 cells. The CNEs showed appropriate properties like a small droplet size (+30 mV). Unfortunately, each cationic nanoemulsion showed some disadvantages. Cationic nanoemulsion 1 decreased the viability of cancer cells to only 25 %. Phase separation was observed for cationic nanoemulsion 2 after storage of six months at 40 °C. And cationic nanoemulsion 3 was not able to form a complex with pDNA.
 However, cationic nanoemulsion 1 is more appropriate than the other cationic nanoemulsions for delivering pDNA.

Sustainable and effective Chitosan-based edible films incorporated with OEO nanoemulsion against apricots’ black spot

Black spot rot caused by Alternaria alternata is one of apricots’ (Prunus armeniaca L.) main postharvest diseases. This disease has caused considerable losses during fruit storage in recent years. This study aimed to produce a safe, convenient and commercially viable film material to preserve apricots by inhibiting the growth of Alternaria alternata. Oregano essential oil (OEO) has a good inhibitory effect on Alternaria alternata. In this study, OEO was added to chitosan-based films in the form of nanoemulsions acquired through ultrasonic emulsification to prolong its antifungal effect. The influence of the OEO concentration (2%, 4%, 6% (w/v)) and ultrasound time (0, 5, 10, 20, 30 min) on the stability and antifungal properties of the OEO nanoemulsions were investigated. Furthermore, the structure and properties of the chitosan-based edible films incorporated with OEO nanoemulsions (0, 0.2%, 0.5%, 1%, 1.5% v/v) were studied. Results revealed that the 4% (w/v) OEO nanoemulsion with 20 min of ultrasound treatment exhibited the best antifungal property and emulsion stability. The chitosan film incorporated with 1% (v/v) of 4% (w/v) OEO nanoemulsion (CS-1%OEO) significantly improved the antifungal properties in vitro. The incidence of apricot inoculated with Alternaria alternata in the presence of the CS-1%OEO film was 42.86% lower than that of control (without film) at three days, indicating the effectively controlled of black spot disease on apricots. Furthermore, the safety of the CS-1%OEO film was confirmed by the zebrafish model. The results obtained in the study showed the potential of the CS-1%OEO film in the disease resistance of apricots from the black spot caused by Alternaria alternata.

Premix membrane emulsification for the preparation of curcumin-loaded nanoemulsions

In order to overcome limitations of conventional methods, premix membrane emulsification (ME) using Shirasu porous glass (SPG) membranes was investigated for the preparation of O/W food-grade nanoemulsions. In this study, the effects of major emulsification process variables, formulation and membrane parameters on the mean droplet diameter and polydispersity (PDI) were systematically investigated. Stability of curcumin-loaded nanoemulsions with different size was also investigated during 28 days storage period. The results revealed that surfactant type and concentration, and medium-chain triglyceride (MCT) concentration played an important role on droplet size and PDI values, while premix quality, flow rate and cycle number had a minor effect on the droplet size. Moreover, there was a linear relationship between the membrane pore size and mean droplets size of nanoemulsions. Curcumin-loaded nanoemulsions with high encapsulation efficiency (>94%) had a good stability (>96% retention rate) after 28 days of storage at 4 °C. Also, there were no major differences on the retention rate of curcumin for nanoemulsions with different droplet size when they were stored at 4 °C, 25 °C and 37 °C under both pH 3 and pH 7. These results indicated that premix ME can be successfully used for the preparation of food-grade nanoemulsions with controlled droplet sizes and narrow droplet size distributions. • Premix ME using SPG membranes was used for the nanoemulsions preparation. • The influence of formulation, operating and membrane parameters were investigated. • Curcumin concentration had no effect on the droplet size and PDI values of nanoemulsions. • Curcumin-loaded nanoemulsions had high encapsulation efficiency. • Premix ME could be successfully used for the preparation of food-grade nanoemulsions.

Physical and Chemical Characterisation of Conventional and Nano/Emulsions: Influence of Vegetable Oils from Different Origins.

The processes of oil production play an important role in defining the final physical and chemical properties of vegetable oils, which have an influence on the formation and characteristics of emulsions. The objective of this work was to investigate the correlations between oils’ physical and chemical properties with the stability of conventional emulsions (d > 200 nm) and nanoemulsions (d < 200 nm). Five vegetable oils obtained from different production processes and with high proportion of unsaturated fatty acids were studied. Extra virgin olive oil (EVOO), cold-pressed rapeseed oil (CPRO), refined olive oil (OO), refined rapeseed oil (RO) and refined sunflower oil (SO) were used in this study. The results showed that the physicochemical stability of emulsion was affected by fatty acid composition, the presence of antioxidants, free fatty acids and droplet size. There was a significant positive correlation (p < 0.05) between the fraction of unsaturated fatty acids and emulsion oxidative stability, where SO, OO and EVOO showed a significantly higher lipid oxidative stability compared to RO and CPRO emulsions. Nanoemulsions with a smaller droplet size showed better physical stability than conventional emulsions. However, there was not a significant correlation between the oxidative stability of emulsions, droplet size and antioxidant capacity of oils.

Green synthesis and biological characterization of cerium oxide nanoemulsion against human HT-29 colon cancer cell line

ABSTRACT In this research, the cerium oxide nanoparticles (CeO2-NPs) were synthesized using Spirulina platensis microalgae. CeO2-NPs were nano-encapsulated based on ultrasonic emulsification method. Morphology, size, and stability of cerium oxide nanoemulsion (CeO2-NE) were verified by TEM, SEM, DLS, and zeta-potential. Antioxidant, antimicrobial against Escherichia coli and Staphylococcus aureus, and cytotoxic (on cancer cell line HT-29 and normal cell HFF) were performed comparatively between CeO2-NE and CeO2-NPs. Apoptotic and antioxidant related genes expression were determined in HT-29 treated cells with the CeO2-NE by Q-PCR. The CeO2-NE showed a much greater effect on anticancer activity, growth inhibition of two bacterial strains, antioxidant capacity, and reduction of ferric ions. Overexpression of caspase-3, caspase-8 and, caspase-9 of CeO2-NE confirmed apoptosis. Upregulation of superoxide dismutase attributed to the cellular redox potential of CeO2-NE in HT-29 cells. In conclusion, the CeO2-NE provides more efficient biological applications that could turn it into a promising factor for cancer treatment.

UV resistant wood coating based on zinc oxide and cerium oxide dispersed linseed oil nano-emulsion

Natural wood is susceptible to weathering deteriorations and hence needs application of coating to increase its service life during exterior use. Due to the environmental issues associated with synthetic wood coatings, the current focus is on development of environmentally safer options for wood protection. In this paper, we propose an UV resistant and environment friendly wood coating based on zinc oxide (ZnO) and cerium oxide (CeO2) nanoparticles embedded linseed oil nanoemulsion. Preparation of nanoparticle dispersed linseed oil nanoemulsion with tween 80 as a surfactant was carried out using homogenization and ultrasonication techniques. Nanoemulsions were characterized on the basis of particle size and polydispersity index measured using dynamic light scattering technique. Morphology of nanoemulsions was examined using optical and scanning electron microscopy. Storage stability of nano emulsion was evaluated by measuring effective particle size and zeta potential over a period 14 days. Pinus radiata wood specimens were coated with ZnO and CeO2 nanoparticles (concentration 0.5–2.0% w/v) dispersed linseed oil-water nanoemulsions and UV stability of coated wood was accessed in an accelerated weathering tester by evaluating color changes on wood surfaces using CIE color parameters. Fourier transform infrared spectroscopy was used to elucidate the chemical changes on the irradiated surfaces. The results (color changes and chemical degradation) indicate significant improvement in UV shielding of wood surfaces coated with oil nanoemulsion with nano particle dispersion.

Physicochemical properties and stability of nanoemulsions containing Clinacanthus nutans extract for postherpetic neuralgia

The leaf extract of Clinacanthus nutans (CNE), a medicinal plant widely distributed in South East Asia, has long been used in traditional medicine by applying topically for treatment of herpes zoster. Besides, it has an analgesic effects that could help relieve suffering from postherpetic neuralgia. The aims of this study were to develop nanoemulsions containing CNE obtained from extraction of dried leaves and evaluate their physicochemical properties, stability, and permeability. Forty formulations of oil-in-water emulsion bases containing various concentrations of sunflower oil and mixed emulsifiers were prepared by spontaneous emulsification and screened for further preparation of nanoemulsion bases by high presure homogenization. The results showed that particle sizes and viscosities of nanoemulsion bases were in the range of 85.9 – 120.9 nm and 339.4 – 1,362.0 cP, respectively. The content of vitexin, which was used as a marker in this study, in CNE and 4 %w/w CNE nanoemulsions were 0.130 and 0.005 %w/w, respectively. The 4 %w/w CNE nanoemulsions was found to be stable based on vitexin content under storage at 5 °C and 30 °C. The amount permeated of vitexin after 24-h permeation from 4 %w/w CNE nanoemulsion across Strat-M® membrane was 61.1 ± 1.95%. In conclusion, the promising formulation of nanoemulsions according to stability and permeability results was composed of 4 %w/w CNE, 20 %w/w sun flower oil, and 20 %w/w mixed emulsifiers of Span®80 and Brij®721 (weight ratio of 1.0:0.32), which could be a candidate as a herbal topical dosage form for postherpetic neuralgia.