Use Of Nanoemulsions Research Articles

Nanoemulsions: Synthesis, Characterization, and Application in Bio-Based Active Food Packaging.

The increasing demands for foods with fresh-like characteristics, lower synthetic additive and preservative contents, and low environmental footprint, but still safe to consume, have guided researchers and industries toward the development of milder processing technologies and more eco-friendly packaging solutions. As sustainability acquires an increasingly critical relevance in food packaging, bio-based and/or biodegradable materials stand out as suitable alternatives to their synthetic counterparts. In this context, the use of nanoemulsions has represented a step forward for improving the performance of sustainable food packaging devices, especially for the successful incorporation of new compounds and functionalities into conventional films and coatings. This class of emulsions, featuring unique optical stability and rheological properties, has been developed to protect, encapsulate, and deliver hydrophobic bioactive and functional compounds, including natural preservatives (such as essential oils from plants), nutraceuticals, vitamins, colors, and flavors. This article presents the surfactants (including naturally occurring proteins and carbohydrates), dispersants, and oil-soluble functional compounds used for designing food-grade nanoemulsions intended for packaging applications. The improved kinetic stability, bioavailability, and optical transparency of nanoemulsions over conventional emulsions are discussed considering theoretical concepts and real experiments. Bottom-up and top-down approaches of nanoemulsion fabrication are described, including high-energy (such as high-pressure homogenizers, microfluidics, ultrasound, and high-speed devices) and low-energy methods (for instance, phase inversion and spontaneous emulsification). Finally, incorporation of nanoemulsions in biopolymer matrixes intended for food packaging applications is also addressed, considering current characterization techniques as well as their potential antimicrobial activity against foodborne pathogens.

Development of triptolide-nanoemulsion gels for percutaneous administration: physicochemical, transport, pharmacokinetic and pharmacodynamic characteristics

BackgroundThis work aimed to provide useful information on the use of nanoemulsions for the percutaneous administration of triptolide. Lipid nanosystems have great potential for transdermal drug delivery. Nanoemulsions and nanoemulsion gels were prepared to enhance percutaneous permeation. Microstructure and in vitro/in vivo percutaneous delivery characteristics of triptolide (TPL)-nanoemulsions and TPL-nanoemulsion gels were compared. The integrity of the nanoemulsions and nanoemulsion gels during transdermal delivery and its effects on the surface of skin were also investigated. The penetration mechanisms of nanoemulsions and nanoemulsion gels were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The transport characteristics of fluorescence-labelled nanoemulsions were probed using laser scanning confocal microscopy. A chronic dermatitis/eczema model in mice ears and the pharmacodynamic of the TPL-nanoemulsion gels were also investigated.ResultsCompared to TPL gels, significantly greater cumulative amounts of TPL-nanoemulsion gels and TPL-nanoemulsions penetrated rat skin in vitro. The in vivo microdialysis showed the concentration–time curve AUC0–t for TPL-NPs is bigger than the TPL-gels. At the same time, TPL-NPs had a larger effect on the surface of skin. By hydrating keratin and changing the structure of both the stratum corneum lipids and keratin, nanoemulsions and nanoemulsion gels influence skin to promote percutaneous drug penetration. Both hairfollicles and the stratum corneum are also important in this transdermal drug delivery system. Moderate and high dosages of the TPL-nanoemulsion gels can significantly improve the symptoms of dermatitis/eczema inflammation and edema erythematic in mice ears and can reduce the expression of IFN-γ and IL-4. Moreover, the TPL-nanoemulsion gels cause less gastrointestinal damage than that of the Tripterygium wilfordii oral tablet does.ConclusionsNanoemulsions could be suitable for transdermal stably releasing drugs and maintaining the effective drug concentration. The TPL-nanoemulsion gels provided higher percutaneous amounts than other carriers did. These findings suggest that nanoemulsion gels could be promising percutaneous carriers for TPL. The TPL-nanoemulsion gels have a significant treatment effect on dermatitis/eczema in the mice model and is expected to provide a new, low-toxicity and long-term preparation for the clinical treatment of dermatitis/eczema in transdermal drug delivery systems.

Gene editing of MPS I human fibroblasts by co-delivery of a CRISPR/Cas9 plasmid and a donor oligonucleotide using nanoemulsions as nonviral carriers

Mucopolysaccharidosis type I (MPS I) is an inherited disease caused by the deficiency of alpha-L-iduronidase (IDUA). This study shows the use of nanoemulsions co-complexed with the plasmid of CRISPR/Cas9 system and a donor oligonucleotide aiming at MPS I gene editing in vitro. Nanoemulsions composed of MCT, DOPE, DOTAP, DSPE-PEG, and water were prepared by high-pressure homogenization. The DNA was complexed by adsorption (NA) or encapsulation (NE) of preformed DNA/DOTAP complexes with nanoemulsions at +4/−1 charge ratio. The incubation in pure DMEM or supplemented with serum showed that the complexation with DNA was stable after 1 h of incubation, but the complexes tended to release the adsorbed DNA after 24 h of incubation, while the encapsulated DNA remained complexed in the oil core of the nanoemulsions even 48 h after incubation with DMEM. The treatment of MPS I patient’s fibroblasts homozygous for the p.Trp402∗ mutation led to a significant increase in IDUA activity at 2, 15, and 30 days when compared to MPS I untreated fibroblasts. Flow cytometry and confocal microscopy demonstrated that there was a reduction in the area of lysosomes to values similar to normal, an indicator of correction of the cellular phenotype. These results show that the nanoemulsions co-complexed with the CRISPR/Cas9 system and a donor oligonucleotide could effectively transfect MPS I p.Trp402∗ patient’s fibroblasts, as well as enable the production of IDUA, and represent a potential new treatment option for MPS I.

Use of nanoemulsions of plant essential oils as aphid repellents

It is believed that climate change will greatly impact the relative importance of pests. The bird cherry-oat aphid, Rhopalosiphum padi L. is probably the major pest of temperate cereal crops on a world scale, it attacks all the major cereals and pasture grasses. The organic sector is in need of alternative aphicides or products that can repel this pest. In spite of the properties of plant volatiles that allow them to act as insect repellents, there is a lack of such products on the market for the agricultural sector. In this work, we tested a group of essential oils and pure compounds in a laboratory choice bioassay with R. padi (20 replications per product) and the repellency index (R.I.) was computed after 24h. At 0.15μl/cm2, aniseed, peppermint and lemongrass essential oils were repellent for apterous females. trans-Anethole and caryophyllene exhibited volatile toxicity to the insects (LD50=0.11μl/cm2). R.I. values ranging from 68.8 to 100 were obtained using farnesol, geraniol, cis-jasmone, citral, linalool, estragole, pulegone and caryophyllene. Water emulsions of the active products were obtained (nanoemulsions with oil droplets less than 100nm via ultrasounds for 10min) and applied at increasing volumes using a computer-controlled spraying apparatus for the bioassay, and a dose response was obtained. Some products were active: carvone increased mobility, whilst cis-jasmone repelled R. padi at a very low dose (0.02μl/cm2 of the treated leaf). Zetasizer measurements indicated that the smaller the particle size within the nanoemulsion, the higher the activity. Using lecithin (1:2) or lecithin plus glycerol (1:2:1) in addition to a bioactive produced larger negative Z-potential values and therefore more stable formulations without any evident effect on activity.

Emulsion versus nanoemulsion: how much is the formulative shift critical for a cosmetic product?

The use of nanoemulsions in cosmetic products has been enlarged in the last decades because of several formulative advantages (e.g., the improved self-life stability, better texture properties). In addition, nanoemulsions seemed to improve the penetration of active ingredients through the human skin, comparing to conventional emulsion. In this contest, the risk of a higher systemic exposure of consumer to active ingredients, due to the ability of nanoemulsion to enhance permeation, results a critical attribute that should be evaluated for assuring the consumer safety. The aim of this work was the evaluation of how an oil-in-water (O/W) nanoemulsion can influence the in vitro skin permeation profiles of two model active ingredients with different polarity (i.e., caffeine and ethyl ximenynate). Preliminarily, since both selected molecules influenced the physical stability of nanoemulsion, formulative studies were carried out to identify the most stable formulation to perform in vitro permeation studies. The overall results demonstrated that nanoemulsions could significantly influence the permeation profiles of molecules as a function of their physicochemical properties. In particular, O/W nanoemulsions significantly improved the permeation profiles of apolar active ingredients in comparison to conventional emulsions, whereas no differences were observable for polar molecules. Considering such findings, it is worth observing that there is room for reconsidering the risk assessment of nanoemulsion-based cosmetic products.

Enhanced Bioavailability of Curcumin Nanoemulsions Stabilized with Phosphatidylcholine Modified with Medium Chain Fatty Acids.

Curcumin is a natural, oil-soluble polyphenolic compound with potent anticancer, anti-inflammatory, and antioxidant activities. In its free form, it is very poorly absorbed in the gut due to its very low solubility. The use of nanoemulsions as carrier is a feasible way for improving curcumin bioavailability. To this end, the choice of emulsifying agent for stabilizing the nanoemulsions is of the upmost importance for achieving a desired functionality. Phosphatidylcholine (PC) and phosphatidycholine enriched (PCE) with medium chain fatty acids (42.5 mol %) in combination with glycerol as co-surfactant, were used for preparing oil-in water nanoemulsions coded as NEPC and NEPCE, respectively. NEPCE displayed significantly smaller mean droplet size (30 nm), equal entrapment efficiency (100%), better droplet stability and suffered lower encapsulation efficiency loss (3%) during storage time (120 days, 4ºC) than NEPC. Bioavailability, measured in terms of area under the curve of curcumin concentration versus time, and maximum curcumin plasma concentration, was in general terms significantly higher for NEPCE than for NEPC, and for curcumin coarse aqueous suspension (CCS). Also, NEPCE produced significantly higher curcumin concentrations in liver and lung than NEPC and CCS. These data support the role of phosphatidylcholine enriched with medium chain fatty acids to increase the bioavailability of nanoemulsions for therapeutic applications.

The combined impact of nanoemulsion based on commercial oils and vacuum packing on the fatty acid profiles of sea bass fillets

The effects of oil-in-water nanoemulsions using different commercial oils on the fatty acid composition of vacuum packed sea bass (Dicentrarchus labrax) fillets stored at 2 ± 2 °C were investigated. The highest SFA content was obtained from the control (21.89%) and among treated groups sunflower (20.13%) followed by olive group (19.90%) because of oxidation at the end of storage period. The total amount of MUFA were in the range of 36–41.52% during storage period. PUFA ranged from 19.31 to 30.11% in which EPA is present from 2.07 to 4.54% and DHA ranges from 2.58 to 7.07%. Hazelnut gave the highest PUFA content (24.35%), followed by canola (24.21%) and soybean (24.15%) at the end of storage since nanoemulsion and vacuum packing prevented the lipid oxidation. Application of nanoemulsion in combination with vacuum packing maintained the PUFA content of fish, especially hazelnut, canola, and soybean groups and can be used as a preservative for fish. Practical applications Lipid oxidation is undesirable in most foods because it causes to the development of undesirable off-flavors known as rancidity. This study indicated that both application of nanoemulsion and vacuum packing maintained the PUFA content of fish. Lipid oxidation process in fish meat may be retarded by the use of nanoemulsions which have potential as a preservative for fish oil.

Antimicrobial activity of nanoemulsions containing essential oils and high methoxyl pectin during long-term storage

The antimicrobial activity against Escherichia coli and Listeria innocua of nanoemulsions containing oregano, thyme, lemongrass or mandarin essential oils and high methoxyl pectin was assessed during a long-term storage period (56 days). On one hand, a higher antimicrobial activity was detected against E. coli compared to L. innocua regardless the EO type. Transmission Electron Microscopy (TEM) images showed a significant damage in the E. coli cells for both the cytoplasm and cytoplasmic membrane, led to cell death. The antimicrobial activity of the nanoemulsions was found to be strongly related to the EO type rather than to their droplet size. The lemongrass-pectin nanoemulsion had the smallest droplet size (11 ± 1 nm) and higher antimicrobial activity reaching 5.9 log reductions of the E. coli population. Nevertheless, the freshly made oregano, thyme and mandarin EO-pectin nanoemulsion led to 2.2, 2.1 or 1.9 E. coli log-reductions, respectively. However, the antimicrobial activity decreased significantly during storage regardless the EO type, which was related to the loss of volatile compounds over time according to our results. The current work provides valuable information in order to make progress in the use of nanoemulsions containing EOs as decontaminating agents in food products.

Evaluation of effects of nanoemulsion based on herb essential oils (rosemary, laurel, thyme and sage) on sensory, chemical and microbiological quality of rainbow trout (Oncorhynchus mykiss) fillets during ice storage

Antimicrobial and antioxidant effects of nanoemulsions containing herb oils (rosemary, laurel, thyme and sage) on the quality of rainbow trout were investigated. Fish fillets were immersed for 3 min in the nanoemulsions prepared with different oils. During 24 days of storage, sensory (raw and cooked), chemical (TBA (thiobarbituric acid), pH, TVB-N (total volatile basic nitrogen), PV (peroxide value), FFA (free fatty acids)) and microbiological quality (total mesophilic aerobic and psychrophilic aerobic bacteria, Enterobacteriaceae count) of rainbow trout fillets in ice at 2 ± 2 °C were carried out. Nanoemulsions of essential oils enhanced organoleptic quality of rainbow trout. Shelf life of rainbow trout was found as 14 days for the control, 17 days for the treatment groups. The use of nanoemulsions based on all essential oils reduced the values of the biochemical parameters and slowed down the growth of bacteria. TVB-N values were lower in all samples than limit value. FFA and PV developed at a slower rate in the treated groups, especially in the rosemary group. The lowest bacterial numbers were obtained from rosemary followed by thyme group. Among the essential oils, it can be concluded that rosemary and thyme can be recommended for nanoemulsion as a preservative for fish fillets.

Dental unit water lines decontamination with the aid of nanotechnology.

This article reviews the issue of dental unit waterline (DUWL) contamination which affects all the clinical and hospital settings. The contaminating microorganisms commonly isolated from these settings and the most pathogenic among them have serious consequences. Over the years several measures are inculcated for decontamination of water, their advantages and shortcomings have been addressed. Options using nanotechnology which are available in the market are described briefly. A manual and electronic search was conducted. Google and PubMed were searched for relevant material from studies up to 2013. Medical Subject Headings words looked for were "Nanotechnology," "Water purification," and "Biofilms." Reviewed findings were summarized by topic, using the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement for reporting. Seventy articles were shortlisted for articles pertaining to our topic of discussion. A systematic approach was followed by two independent reviewers and included eligibility criteria for study inclusion, data extraction, data synthesis, and drawing of conclusion. Dental waterline contamination is widespread in any type of dental setting having serious implications on clinicians and patients alike, especially elderly and immune-compromised. Hence, international bodies like center for disease and control and American Dental Association have come up with stringent measures for maintenance of water quality. A gamut of procedures has been tried to overcome this problem ranging from chlorinated products, water filters to the usage of distilled water. The use of nanoemulsions, nanofilters, nanomembranes, etc., and their applicability for routine usage is discussed. Biofilm formation in DUWLs is inevitable with the subsequent release of part of microbiota into the otherwise sterile dental settings. These consequences can be quite serious on clinicians and dental patients. Though conventional measures in water decontamination have been partly successful, the quest for more foolproof methods has led to the use of latest technology, i.e., nanotechnology. The most practical option has to be chosen based on the ease of their usage.

Nano-Formulated Hydroxyurea Enhances Drug Delivery in K562 Cells

The vasculopathy of sickle cell disease (SCD), characterized by a chronic hemolytic anemia, endothelial dysfunction and recurrent vaso-occlusive events, underlies most of the clinical complications. Hydroxyurea (HU), the only FDA approved medication to treat patients with SCD, acts via the induction of fetal hemoglobin (HbF) production. Recent studies suggest that HU increases endothelial nitric oxide (NO) production and reduces adhesion molecule expression as another potential mechanism for the observed reduction in vaso-occlusive events and improved survival in SCD. Despite its benefits, HU is currently under-utilized and we hypothesize that improved targeted drug delivery may increase its usage. The use of nano-emulsions, a class of stable emulsions formed by a monolayer of phospholipids and/or biodegradable material, is a mechanism by which to enhance targeted cellular delivery of therapeutics. We hypothesized that a nano-formulation of HU would enhance drug delivery to the bone marrow and this may be a direct way of impacting HbF expression in SCD. Nano-formulated HU (NHU) was developed using a phospholipid approach and this compound was found to be biologically stable for > 6 months.Chronic myelogenous leukemia bone marrow (K562) cells were treated with a NHU or HU suspension in concentrations ranging from 25µM to 250µM over a course of 4, 5 and 6 days. Cells were harvested for RNA isolation and qPCR was performed using primers for HbF and basal cell adhesion molecule (BCAM, a cellular adhesion molecule on red and white blood cells. On day 5, when HbF expression in K562 cells peaks, there was a five-fold increase in HbF expression treated with lower concentrations of NHU compared to untreated cells and a two-fold increase in expression compared with HU treated cells. With increasing concentrations of NHU and HU, HbF expression became similar. This suggests that the use of NHU can provide increased HbF expression at a lower concentration with likely less toxicity. Treatment of K562 cells with NHU and HU resulted in decreased BCAM expression on day 6 of treatment. Treatment with NHU produced a four-fold decrease in BCAM expression compared to the same concentration of a HU suspension which supports the concept that NHU can impact gene expression at lower doses than unformulated HU. Nanoformulated HU produces a molecule which is highly stable, and able to achieve higher intracellular concentrations with increased efficacy in K562 cells. This suggests a potential novel therapeutic for patients with sickle cell disease. DisclosuresKlings:Pfizer: Consultancy; Actelion Pharmaceuticals: Research Funding.

Nanoemulsions as an effective medium for encapsulation and stabilization of cholesterol/β-cyclodextrin inclusion complex.

Inclusion complex formation between β-cyclodextrin (β-CD) and suitable guest molecules such as cholesterol (Ch) has regularly been exploited to design self-assembled structures. In the present study an effective nanoemulsion medium (lecithin/Tween 80/ethyl oleate/water) was selected for solubilizing and stabilizing Ch and Ch/β-CD inclusion complex. Phase solubility, spectroscopic, thermodynamic, Z-average diameter and morphological analyses were conducted. Phase solubility data analysis demonstrated an increase in Ch solubility at low β-CD concentrations (0.01-0.35 mmol L(-1) ). Transmission electron microscopy and Z-average diameter data indicated the spherical nature of the droplets and confirmed the formation of nanoemulsions with an average size of less than 50 nm. The negative value of ΔG obtained during analysis further indicated that the binding was spontaneous in nature. Primarily, this research demonstrates the use of nanoemulsions as a medium in food matrices, instead of water, for hosting Ch in β-CD.

Use of Nano-Formulated Hydroxyurea Enhances Drug Delivery to Pulmonary Artery Endothelial Cells

The vasculopathy of sickle cell disease (SCD), characterized by a chronic hemolytic anemia, endothelial dysfunction and recurrent vasoocclusive events, underlies most of the clinical complications. Recent work has suggested that hydroxyurea (HU) enhances endothelial nitric oxide (NO) production and reduces adhesion molecule expression which may contribute to its associated observed reduction in vasoocclusive events and improved survival in SCD. However, clinically HU is under-utilized, at least in part related to medication related toxicity, stressing a need for enhanced drug delivery. The use of nano-emulsions, a class of stable emulsions formed by a monolayer of phospholipids and/or biodegradable material such as chitosan, is a mechanism by which to enhance targeted cellular delivery of therapeutics. We hypothesized that a nano-formulation of HU would enhance drug delivery to the endothelium and may be a direct way of targeting endothelial dysfunction in SCD. Nano-formulated HU (nano-HU) was developed using a phospholipid approach and this compound was found to be biologically stable for > 6 months. Human pulmonary arterial endothelial cells (HPAECs) were co-incubated with 25µM, 125µM and 250µM HU, nano-HU, or the empty nano-emulsification preparation for 48 hours. HPAEC were isolated, and stained with propidium iodide (PI) for cell cycle analysis by FACS. HPAEC treated with 25µM nano-HU demonstrated the highest level of cell viability (55%) and similar levels of S phase inhibition as HPAEC treated with 125µM HU (where 10-20% cell viability was observed). RNA isolation of treated HPAECs was performed and qPCR for VCAM1 and SLX4, a regulator of DNA damage which promotes S phase inhibition was performed. 25µM nano-HU significantly decreased VCAM1 and increased SLX4 expression compared with 25µM HU suggesting increased efficacy at lower levels of toxicity. The impact of nano-HU on endothelial gene expression is currently being evaluated by RNA-seq. Nano-formulation of HU produces a molecule which is highly stable, and able to achieve higher intracellular concentrations with lower rates of toxicity in HPAECs .which provides the opportunity to gain greater understanding of the impact of this medication on the vascular endothelium and the potential for a more targeted and better tolerated delivery of this therapeutic to patients with sickle cell disease. DisclosuresKlings:Pfizer: Consultancy.

Entrapment into nanoemulsions potentiates the anticancer activity of tocotrienols against the highly malignant (+SA) mouse mammary epithelial cells.

The highly malignant +SA mouse mammary epithelial cells were used as the model cell line over the years to establish the anticancer activity of tocotrienols. Tocotrienols, however, have poor oral bioavailability and were therefore entrapped into parenteral nanoemulsions for parenteral administration. The objective of this work was to test whether the activity of tocotrienols in lipid nanoemulsions against the +SA cells was retained. A secondary objective was to test whether stabilizing the nanoemulsions with poloxamer or sodium oleate would affect their activity. Nanoemulsions were found to be significantly more potent than tocotrienol/albumin conjugate. The IC50 values of the poloxamer and sodium oleate nanoemulsions were 3 and 6 microM, respectively, whereas the IC50 value of the conjugate was 10 microM. The antiproliferative activity of the nanoemulsions was also found to inversely correlate with particle size. No activity was observed with nanoemulsions loaded with alpha-tocopherol or vehicle, which confirmed the cytotoxic activity of tocotrienols and the potential use of nanoemulsions in cancer therapy.

Preparation and in vitro evaluation of α and β-amyrins loaded nanoemulsions.

The triterpenes α- and β-amyrins display important pharmacological activities. As a result of their high hydrophobia, they present low water solubility and reflect poor oral bioavailability. Different techniques can be used for the improvement of amyrins solubility, one of them is the use of nanoemulsions. Therefore, the method of direct emulsification was used to develop a nanoemulsion of these triterpenes and the resulting drug delivery system was characterized by an in vitro release assay. Encapsulation efficiency higher than 99% was achieved with total release around 30% in 24 h, which suggests that this system could be useful for the administration of α- and β-amyrins by different routes in an efficient way.

Nanoemulsions for Skin Targeting: Present Status and Future Prospects

The use of nanoemulsions as a carrier system for skin targeting has attracted increased attention over recent years. Nanoemulsions can be intended for both topical and systemic delivery of the biologically active agents for controlled and targeted delivery. Nanoemulsion droplets fall within the size range of 20-200nm, typically below 100nm. Nanoemulsions have high surface area and ability to solubilize poorly soluble drugs. They are reported to have higher skin permeation and retention potential than other novel drug delivery systems like nanoparticles, liposomes, microemulsions etc. Use of nanoemulsions for skin targeting of drug is a current research scenario in the field of Pharmaceutics. This research area has generated immense interest from the Pharmaceutical industry and a number of nanoemulsion based cosmetics formulations like anti-aging creams, skin cleansing lotions etc. are available in the market. Recently, Zydus Cadilla launched the Oxalgin NanoGel™ diclofenac sodium nanoemulsion gel showing the importance of nanoemulsion as carrier system for skin targeting of drugs. This review embodies an in-depth discussion on composition, application, its mechanism of skin permeation and commercial aspects of nanoemulsions for skin targeting. Keywords: Anti-acne, skin targeting, nanoemulsion, NSAIDs, commercial products, anti-fungal, anti-cancer, TOPICAL DELIVERY, Anti-Cancer Drugs

Investigation of plaunoi-loaded micro/nanoemulsions for the treatment of dermatitis: formulation, évaluation and skin irritation studies

The main objective of this work was to formulate microemulsions and nanoemulsions as delivery vehicles for plaunoi extract (Croton stellatopilosus Ohba) to treat dermatitis. Plaunotol, a constituent of plaunoi, has been shown to possess antimicrobial activity. In this work, 2 % w/w plaunoi-loaded formulations were prepared and investigated for their physical property (size and viscosity), efficacy and safety. The plaunoiloaded microemulsions (ME1-P (w/o), ME2-P (o/w)) and nanoemulsion (NE-P (o/w)) had different average sizes and apparent viscosities. Using modified Franz diffusion cell and a synthetic membrane, the release rate of plaunotol from NE-P was found to be the highest. With regard to the in vitro skin penetration, only o/w microemulsion (ME2-P) could deliver plaunotol through the newborn pig skin into the receptor fluid. Unlike ME1-P, the accumulation of plaunotol within the excised newborn pig skin was observed in ME2-P and NE-P. The antimicrobial property of the formulations was further investigated using a cylinder- plate method. Staphylococcus aureus, Staphylococcus epidermidis and Propionibacterium acnes were the tested gram microorganisms. It was found that the plaunoi-loaded formulations exhibited somewhat improved antibacterial activity for S. aureus and S. epidermidis when compared with the blank formulations. The skin irritation was not observed in all treated rabbits for the nanoemulsion NE-P. Both ME1-P and ME2-P showed slight erythema. These results suggest a potential use of nanoemulsions for topical delivery of plaunoi extract.

Nanoemulsion Components Screening and Selection: a Technical Note

Nanoemulsions are isotropic, thermodynamically stable transparent (or translucent) systems of oil, water, and surfactants with a droplet size usually in the range of 10–100 nm (1,2). Their long-term stability, ease of preparation (spontaneous emulsification), and high solubilization of drug molecules make them promising as a drug delivery tool. They have found wide applications in oral drug delivery to enhance the solubility and bioavailability of the lipophilic drugs (3–5). Recently, there has been a surge in the exploration of nanoemulsions for transdermal delivery (6–8). They are also being investigated ardently for potential applications in ocular (9,10), pulmonary (11), nasal (12,13), vaginal (14,15), and parenteral drug delivery (16–18). The use of nanoemulsions in drug delivery has been reviewed, and it was noted that most studies have not been very systematic with regard to selection of surfactants and cosurfactants. The main objective of this study was to provide an efficient screening approach for the proper selection of oils, surfactants, and cosurfactants for the nanoemulsion formulation development. Ropinirole was selected as a model lipophilic drug for this purpose (Log P = 3.32). These systems often require high surfactant concentration, and this may lead to toxicity and irritancy problems. Therefore, judicious selection of surfactants along with their optimum concentration is required, which has been discussed in this report. Determination of the influence of the surfactant-to-cosurfactant mass ratio (Smix) on the nanoemulsion formation region also formed an important aspect of the study. Optimum selection would aid in better formulation with desirable attributes.