Nano-encapsulated Essential Oils Research Articles

Advancements in Nanoparticle-Based Strategies for Enhanced Antibacterial Interventions.

The escalating global threat of antibiotic resistance underscores the urgent need for innovative antimicrobial strategies. This review explores the cutting-edge applications of nanotechnology in combating bacterial infections, addressing a critical healthcare challenge. We critically assess the antimicrobial properties and mechanisms of diverse nanoparticle systems, including liposomes, polymeric micelles, solid lipid nanoparticles, dendrimers, zinc oxide, silver, and gold nanoparticles, as well as nanoencapsulated essential oils. These nanomaterials offer distinct advantages, such as enhanced drug delivery, improved bioavailability, and efficacy against antibiotic-resistant strains. Recent advancements in nanoparticle synthesis, functionalization, and their synergistic interactions with conventional antibiotics are highlighted. The review emphasizes biocompatibility considerations, stressing the need for rigorous safety assessments in nanomaterial applications. By synthesizing current knowledge and identifying emerging trends, this review provides crucial insights for researchers and clinicians aiming to leverage nanotechnology for next-generation antimicrobial therapies. The integration of nanotechnology represents a promising frontier in combating infectious diseases, underscoring the timeliness and imperative of this comprehensive analysis.

Chitosan-Based Nanoencapsulated Essential Oils: Potential Leads against Breast Cancer Cells in Preclinical Studies.

Since ancient times, essential oils (EOs) derived from aromatic plants have played a significant role in promoting human health. EOs are widely used in biomedical applications due to their medicinal properties. EOs and their constituents have been extensively studied for treating various health-related disorders, including cancer. Nonetheless, their biomedical applications are limited due to several drawbacks. Recent advances in nanotechnology offer the potential for utilising EO-loaded nanoparticles in the treatment of various diseases. In this aspect, chitosan (CS) appears as an exceptional encapsulating agent owing to its beneficial attributes. This review highlights the use of bioactive EOs and their constituents against breast cancer cells. Challenges associated with the use of EOs in biomedical applications are addressed. Essential information on the benefits of CS as an encapsulant, the advantages of nanoencapsulated EOs, and the cytotoxic actions of CS-based nanoencapsulated EOs against breast cancer cells is emphasised. Overall, the nanodelivery of bioactive EOs employing polymeric CS represents a promising avenue against breast cancer cells in preclinical studies.

Comparison of Emulsion Stabilizers: Application for the Enhancement of the Bioactivity of Lemongrass Essential Oil.

Recent focus on cellulose nanomaterials, particularly biodegradable and biocompatible cellulose nanocrystals (CNCs), has prompted their use as emulsion stabilizers. CNCs, when combined with salt, demonstrate enhanced emulsion stabilization. This study explored three emulsion stabilizers: Tween 80, soybean CNCs with salt (salted CNCs), and a combination of salted CNCs with Tween 80. Soybean CNCs, derived from soybean stover, were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Antifungal testing against Aspergillus flavus revealed increased bioactivity in all lemongrass essential oil (EO)-loaded emulsions compared to pure essential oil. In addition, all three emulsions exhibited a slight reduction in antifungal activity after 30 days of room temperature storage. The release experiment revealed that the EO-loaded nanoemulsion exhibited a slow-release profile. The nanoemulsion stabilized by salted CNCs and Tween 80 exhibited significantly lower release rates when compared to the nanoemulsion stabilized solely by Tween 80, attributed to the gel network formed by salted CNCs. The findings of this study highlight the efficacy of cellulose nanocrystals procured from soybean byproducts in conjunction with synthetic surfactants to create nanoencapsulated essential oils, resulting in improved antimicrobial efficacy and the achievement of sustained release properties.

Development of a mucilage coating including nanoencapsulated essential oils for extending shelf life of button mushrooms (Agaricus bisporus)

The shelf life of mushrooms is limited, which prevents distribution and marketing as a fresh product. The aim of present research is to coat Agaricus bisporus mushroom by chia seed mucilage containing encapsulated essential oils for Ferula gummosa Boiss. (FG) and Ziziphora clinopodioides Lam. (ZC) with 100 and 500 ppm concentrations in order to extend during 16 days. The results for technological assays illustrated that coatings including FG and ZC essential oils at 500 ppm level caused to reduction in respiration rate, lose weight, browning degree and microbial population and also enhanced firmness feature, total phenol, antioxidant attributes and vitamin C compared to control during shelf life. Microscopy analysis confirmed that formation of a uniform structure was observed. Overall, results suggest that a coating chia seed mucilage containing encapsulated essential oils for FG and ZC can be a promising approach and suitable factor to prolong shelf life of perishable mushroom.

Halquinol and nanoencapsulated essential oils: A comparative study on growth performance, intestinal morphology and meat quality in broiler chickens

Diets supplemented with halquinol and/or nanoencapsulated essential oils (N-EOs) have shown positive effects on the productive parameters of broiler chickens. However, there is limited comparative evidence between these two products. This study aimed to investigate and compare the efficacy of N-EOs blends with halquinol as dietary supplements for broiler chickens. A total of 500 male Cobb 500 broiler chickens were randomly assigned to five dietary groups. The control group received a conventional diet supplemented with halquinol (60%), while the experimental groups received supplementation with N-EOs blends derived from soursop (S), lemon (L), and eucalyptus (E) in different proportions: T1 (S:33.33%, L:33.33%, E:33.33%), T2 (S:50%, L:25%, E:25%), T3 (S:25%, L:50%, E:25%), and T4 (S:25%, L:25%, E:50%). The trial lasted for 42 days. The results showed that the T1 and T4 groups obtained the highest values (p < 0.05) for average daily growth rate and breast yield. The feed conversion ratio was significantly lower in groups T1 and T4 (p < 0.05). All N-EOs supplemented groups exhibited higher carcass yield (p < 0.05). At day 42, the T1 group displayed increased villus height and villus height/crypt depth ratio in the duodenum (p < 0.01), while all experimental groups showed increased villus width in the jejunum and ileum (p < 0.05). Texture analysis revealed that N-EOs-treated groups had texture values similar to halquinol, except for the T1 group, which significantly increased hardness (p < 0.05). Bromatological analysis showed that the T4 group significantly improved the percentage of crude protein, fat, and ash compared to the halquinol-supplemented group (p < 0.05). Additionally, the T1 and T4 groups exhibited lower levels of lipid peroxidation (p < 0.05). In conclusion, dietary supplementation with N-EOs holds promise as a potential alternative to halquinol, with the added advantage of improved oxidative stability.

Protection and Disinfection Activities of Oregano and Thyme Essential Oils Encapsulated in Poly(ε-caprolactone) Nanocapsules.

The biocolonization of building materials by microorganisms is one of the main causes of their degradation. Fungi and bacteria products can have an undesirable impact on human health. The protection and disinfection of sandstone and wood materials are of great interest. In this study, we evaluated the protection and disinfection activity of oregano and thyme essential oils encapsulated in poly(ε-caprolactone) nanocapsules (Or-NCs, Th-NCs) against four types of environmental microorganisms: Pleurotus eryngii, Purpureocillium lilacinum (fungal strains), Pseudomonas vancouverensis, and Flavobacterium sp. (bacterial strains). The surfaces of sandstone and whitewood samples were inoculated with these microorganisms before or after applying Or-NCs and Th-NCs. The concentration-dependent effect of Or-NCs and Th-NCs on biofilm viability was determined by the MTT reduction assay. The results showed that Or-NCs and Th-NCs possess effective disinfection and anti-biofilm activity. Diffuse reflectivity measurements revealed no visible color changes of the materials after the application of the nanoencapsulated essential oils.

Biotechnological Applications of Nanoencapsulated Essential Oils: A Review.

Essential oils (EOs) are complex mixtures of volatile and semi-volatile organic compounds that originate from different plant tissues, including flowers, buds, leaves and bark. According to their chemical composition, EOs have a characteristic aroma and present a wide spectrum of applications, namely in the food, agricultural, environmental, cosmetic and pharmaceutical sectors. These applications are mainly due to their biological properties. However, EOs are unstable and easily degradable if not protected from external factors such as oxidation, heat and light. Therefore, there is growing interest in the encapsulation of EOs, since polymeric nanocarriers serve as a barrier between the oil and the environment. In this context, nanoencapsulation seems to be an interesting approach as it not only prevents the exposure and degradation of EOs and their bioactive constituents by creating a physical barrier, but it also facilitates their controlled release, thus resulting in greater bioavailability and efficiency. In this review, we focused on selecting recent articles whose objective concerned the nanoencapsulation of essential oils from different plant species and highlighted their chemical constituents and their potential biotechnological applications. We also present the fundamentals of the most commonly used encapsulation methods, and the biopolymer carriers that are suitable for encapsulating EOs.

Nano-Encapsulated Essential Oils as a Preservation Strategy for Meat and Meat Products Storage

Consumers today demand the use of natural additives and preservatives in all fresh and processed foods, including meat and meat products. Meat, however, is highly susceptible to oxidation and microbial growth that cause rapid spoilage. Essential oils are natural preservatives used in meat and meat products. While they provide antioxidant and antimicrobial properties, they also present certain disadvantages, as their intense flavor can affect the sensory properties of meat, they are subject to degradation under certain environmental conditions, and have low solubility in water. Different methods of incorporation have been tested to address these issues. Solutions suggested to date include nanotechnological processes in which essential oils are encapsulated into a lipid or biopolymer matrix that reduces the required dose and allows the formation of modified release systems. This review focuses on recent studies on applications of nano-encapsulated essential oils as sources of natural preservation systems that prevent meat spoilage. The studies are critically analyzed considering their effectiveness in the nanostructuring of essential oils and improvements in the quality of meat and meat products by focusing on the control of oxidation reactions and microbial growth to increase food safety and ensure innocuity.

Antifungal activity of poly(ε-caprolactone) nanoparticles incorporated with Eucalyptus essential oils against Hemileia vastatrix.

Coffee (Coffea L.) is one of the main crops produced globally. Its contamination by the fungus Hemileia vastatrix Berkeley and Broome has been economically detrimental for producers. The objective of this work was to extract and characterize the essential oils from Eucalyptus citriodora Hook, Eucalyptus camaldulensis Dehn and Eucalyptus grandis Hill ex Maiden, produce and characterize nanoparticles containing these essential oils and evaluate the invivo and invitro antifungal activity of free and nanoencapsulated essential oils. The principal constituent of the essential oil from E. citriodora was citronellal; that from E. grandis was α-pinene; and that from E. camaldulensis was 1,8-cineol. The invitro antifungal activity against the fungus H. vastatrix was 100% at a concentration of 1000 μl l-1 for all the oils and nanoparticles containing these natural products. The sizes of the nanoparticles produced with the essential oils from E. citriodora, E. camaldulensis and E. grandis were 402·13 nm, 275·33 nm and 328·5 nm, respectively, with surface charges of -11·8 mV, -9·24 mV and - 6·76 mV, respectively. Fourier transform infrared analyses proved that the encapsulation of essential oils occurred in the polymeric matrix of poly(ε-caprolactone). The incorporation of essential oils into biodegradable poly(ε-caprolactone) nanoparticles increased their efficiency as biofungicides in the fight against coffee rust, decreasing the severity of the disease by up to 90·75% after treatment with the nanoparticles containing the essential oil from E. grandis.

Nano-encapsulated with mesoporous silica enhanced the antifungal activity of essential oil against Botrytis cinerea (Helotiales; Sclerotiniaceae) and Colletotrichum nymphaeae (Glomerellales; Glomerellaceae)

One of the most prevalent and practical uses of nanotechnology is encapsulating active chemicals in mesoporous silica SBA-15 to improve their functional performance. Encapsulation techniques can be used to increase the potency of essential oils (EOs), making them more commercially viable. The general objective of this work was to encapsulate peppermint (Mentha aquatica L.) essential oils in mesoporous silica SBA-15 and to assess their antifungal efficacy against the phytopathogens Botrytis cinerea and Colletotrichum nymphaeae. The EOs extracted from the leaves of peppermint very effectively inhibited C. nymphaeae and B. cinerea mycelium at 5, 10 and 15 days after incubation. Encapsulating the M. aquatica L. EOs increased the inhibition of mycelium growth of C. nymphaeae by 16.8, 32.5, and 66.3% after 5, 10, and 15 days of incubation, respectively. Meanwhile, mesoporous silica-encapsulated EOs decreased mycelium growth by 35.20, 8.12, 10.40, and 8.15% at concentrations of 100, 1000, 1500, and 2000 ppm. Our work reveals that when nano-encapsulated EOs are administered, significant morphological changes occur in the fungal mycelium. d-limonene (4.904%), menthone (30.18%), p-menthone (7.03%), and menthol (52.11%) were identified as the primary components in M. piperita EOs using GC-MS analysis. In conclusion, the encapsulation of peppermint EO with SBA-15 was demonstrated to be efficient in controlling B. cinerea and C. nymphaeae growth and can be comparably applied as eco-friendly and safe antifungal agents to the management of plant diseases.

Nanoparticles Loaded with Essential Oil from Zanthoxylum riedelianum Engl. Leaves: Characterization and Effects on Bemisia tabaci Middle-East Asia Minor 1.

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Middle-East Asia Minor 1 is a major pest of agricultural production systems. It is controlled by synthetic insecticides. Essential oils are promising eco-friendly alternatives. This study developed and characterized nanoparticles loaded with essential oils of Zanthoxylum riedelianum Engl. (Rutaceae) leaves and evaluated their potential for B. tabaci management. The essential oil exhibited an average yield of 0.02% (w w-1) and showed as major components γ-elemene (24.81%), phytol (18.16%), bicyclogermacrene (16.18%), cis-nerolidol (8.26%), and D-germacrene (6.52%). Characterization of the nanoparticles showed a pH between 4.5 and 6.7, a zeta potential of approximately - 25mV, particle-size distribution ranging from 450 to 550nm, and encapsulation efficiency close to 98%. The nanoencapsulation was an efficient process that provided photostability against photodegradation. Bioassays with crude and nanoencapsulated essential oils significantly reduced the number of nymphs and eggs of B. tabaci, with the best results observed at concentrations of 5 and 2% (v v-1). Our results demonstrated that essential oils from Z. riedelianum can be nanoformulated resulting in a stable product while maintaining their biological activity against B. tabaci Middle-East Asia Minor 1.

Rosmarinus officinalis essential oil incorporated into nanoparticles as an efficient insecticide against Drosophila suzukii (Diptera: Drosophilidae)

AbstractThe effective control of an insect pest such as Drosophila suzukii (Diptera: Drosophilidae) has been challenging because its attack on red fruits can cause losses in production of up to 80% worldwide. The objective of this work was to extract and characterise the essential oil from rosemary (Rosmarinus officinalis), produce and characterise nanoparticles incorporated with this essential oil, evaluate the in vivo insecticide activity of free and nanoencapsulated essential oil against D. suzukii, and evaluate the effect of that oil on the enzyme acetylcholinesterase. The nanoparticles produced with the essential oil from rosemary had a particle size and surface charge of 236.6 nm and −11.8 mV, respectively. According to the FTIR data, the essential oil was incorporated into the polymeric matrix of poly(ε‐caprolactone). Through in vivo toxicity analysis, the free and nanoencapsulated essential oils were found to possess insecticidal activity, with an LD50 close to 9.1 g/L. The maximum anticholinesterase activity for the essential oil was 75% at a concentration of 0.10 mg/mL. The incorporation of the essential oil from R. officinalis into biodegradable nanoparticles of poly(ε‐caprolactone) potentiated and prolonged its in vivo insecticidal activity against D. suzukii.

Fungal and mycotoxin contamination of herbal raw materials and their protection by nanoencapsulated essential oils: An overview

Presently, consumption of herbal raw materials (HRMs) has been an emerging concern owing to therapeutic potential against broad range of human diseases. However, there are various cases available reporting the fungal and mycotoxin contaminations. These HRMs after collection undergo severe extent of deterioration, leading to degradation of their active principles. Different chemical preservatives have been frequently used to protect HRMs from fungal and mycotoxin contamination, however, their indiscriminate use could lead to adverse effects on human health and environment due to residual toxicity. The use of essential oils (EOs) based formulations has been recommended as a green alternative of synthetic preservatives having greater safety profile and biodegradable nature. Nanoencapsulation maintains the stability of EOs and facilitate the controlled delivery with improvement in maintenance of bioactive principles of HRMs against fungal and mycotoxin mediated biodeterioration to boost pharmaceutical sectors. This review summarizes the pharmacological properties of some HRMs, the extent of degradation by fungal and mycotoxin contamination, preservation through nanoencapsulated EOs, mode of action, patenting of EOs as preservatives, and finally future opportunities to mitigate the associated problems.

Inhibition of bacterial growth on marble stone of 18th century by treatment of nanoencapsulated essential oils

Controlling of cultural heritage biodeterioration is a serious problem in the world. Chemical biocides, used to kill unwanted microorganism, can represent a risk for human health and environment, and interfere with the restoration material. Natural biocides could represent a valid alternative to conventional ones. In this study we report the use of nanocapsules suspensions (NCs) loaded with Origanum vulgare and Thymus capitatus essential oils (EOs) to contrast the development of bacterial growth of two microrganisms (Escherichia coli and Kokuria rhizophila) on the marble stone from 18th century church altar. No structural change was observed on the stone after treatment with the aqueous suspension containing nanoparticles as evidenced by SEM-EDX analysis. The nanostructurate systems (EO-NCs) were able to inhibit the bacterial grow on the stone pretreated with bacterial inoculum as showed by agar discs contact test. Nanocapsules, based on biodegradable and biocompatible polymer (poly(ε-caprolactone)), loaded with thyme EO are more efficient than nanocapsules loaded with oregano EO. The obtained results evidenced the potential of these natural biocides in the treatment of biodeteriorated cultural heritage.

Nano silver-encapsulation of Thymus daenensis and Anethum graveolens essential oils enhances antifungal potential against strawberry anthracnose

Nanotechnology is an eco-friendly strategy in managing plant diseases. In combination with existing practices nanotechnology can enhance the protection of agricultural products and food. For example, essential oils (EOs) of thyme (Thymus daenensis L.) and dill (Anethum graveolens L.) have an antimicrobial potential and this potential may be enhanced by certain nanoparticle systems. Here we demonstrate that encapsulating EOs of thyme and dill in silver nanoparticles increases their fungicidal activity against Colletotrichum nymphaeae, causing anthracnose in many horticultural crops. Using GC-MS analysis, we identified p-cymene, thymol, carvacrol and (E)-caryophyllene as the main EOs of thyme and limonene, cis-dihydrocarvone, cyclohexanon, and carvone as the main EOs of dill. When the EOs of the two sources were encapsulated in silver nanoparticles, synergistic effects against C. nymphaeae were observed, resulting in more than 80% inhibition of mycelium growth of C. nymphaeae. Moreover, conidia germination was suppressed by nano-encapsulated EOs. We also observed considerable morphological changes in the fungal hyphae when nano-encapsulated EOs were applied. Our study demonstrates the potential of encapsulated EOs in controlling pathogens that can be very applicable as antifungal agents.

Preservation of meat and meat products using nanoencapsulated thyme and oregano essential oils

Among other plants, thyme and oregano are commonly used in Mediterranean cuisine, especially in meat dishes. Although the essential oils of these two plants possess great antimicrobial and antioxidative properties, their application as natural meat preservatives are limited due to hydrophobicity, sensitivity to external factors and interaction with food components. Furthermore, essential oils can have adverse impacts on meat’s organoleptic properties. A possible way to overcome these barriers is by incorporating essential oils into nanometric delivery systems. Nano-sizing essential oils increases their stability, protects them, and allows their controlled release. This enhances the bioavailability of the essential oils and reduces their possible adverse impact on meat products’ organoleptic properties by preventing their unwanted interactions with food components. The antibacterial and antioxidative effect of nanoencapsulated essential oils is confirmed in numerous studies, and some of them show that in this form, essential oils were potent in food models e.g. beef burgers, pâté and rainbow trout. However, a more promising way to introduce nano forms of essential oils into foods is incorporating them in packaging systems.

Chitosan nano-encapsulation improves the effects of mint, thyme, and cinnamon essential oils in broiler chickens

ABSTRACTThis study was conducted to evaluate the effects of chitosan nano-encapsulating mint (MEO), thyme (TEO) and cinnamon (CEO) essential oils (EOs) used in the diet on performance, immune responses and intestinal bacteria population in broiler chickens.A total of 600 mixed-sex, 1-d-old Ross 308 broiler chicks were used in a 2 × 4 factorial experiment as completely randomised design with 8 experimental groups (diets) with 5 replicates of 15 chicks each (totally 40 pens). The eight experimental diets consisted of no EO and free distiller water (control); no EO and chitosan nano-encapsulated (CNE) distiller water; and other six treatments with free or CNE form of MEO, TEO and CEO (added at 0.025%, 0.04% and 0.055% respectively to starter, grower and finisher diets).Both EOs and the CNE form had significant (P < 0.05) benefits on improving body weight gain, and feed conversion ratio in periods of 29–42 and 1–42 days. The highest effect was (P < 0.05) obtained in birds receiving TEO, which was intensified by nano-encapsulation. Breast percentage was improved by nano-encapsulation (P < 0.05). The EOs (especially TEO and CEO) and CNE form improved (P < 0.05) serum IgY and IgM concentrations (at 35 and 42 days) and intestinal Lactobacillus spp. and E. coli populations (at 42 days) in broilers. Nano-encapsulated EOs, especially TEO and CEO had (P < 0.05) the largest effect on increasing IgY42 concentrations and the microbial populations.The tested EOs, especially TEO, improved more of the evaluated traits in broiler chickens. Also, Chitosan nano-encapsulation because of its ideal properties can be an effective, suitable and inexpensive method for protecting bioactive compounds and improving effects of the herbal EOs especially thyme in broiler chickens.

Antimicrobial Activity of Some Essential Oils-Present Status and Future Perspectives.

Extensive documentation on the antimicrobial properties of essential oils and their constituents has been carried out by several workers. Although the mechanism of action of a few essential oil components has been elucidated in many pioneering works in the past, detailed knowledge of most of the compounds and their mechanism of action is still lacking. This knowledge is particularly important for the determination of the effect of essential oils on different microorganisms, how they work in combination with other antimicrobial compounds, and their interaction with food matrix components. Also, recent studies have demonstrated that nanoparticles (NPs) functionalized with essential oils have significant antimicrobial potential against multidrug- resistant pathogens due to an increase in chemical stability and solubility, decreased rapid evaporation and minimized degradation of active essential oil components. The application of encapsulated essential oils also supports their controlled and sustained release, which enhances their bioavailability and efficacy against multidrug-resistant pathogens. In the recent years, due to increasingly negative consumer perceptions of synthetic preservatives, interest in essential oils and their application in food preservation has been amplified. Moreover, the development of resistance to different antimicrobial agents by bacteria, fungi, viruses, parasites, etc. is a great challenge to the medical field for treating the infections caused by them, and hence, there is a pressing need to look for new and novel antimicrobials. To overcome these problems, nano-encapsulation of essential oils and exploiting the synergies between essential oils, constituents of essential oils, and antibiotics along with essential oils have been recommended as an answer to this problem. However, less is known about the interactions that lead to additive, synergistic, or antagonistic effects. A contributing role of this knowledge could be the design of new and more potent antimicrobial blends, and understanding of the interplay between the components of crude essential oils. This review is written with the purpose of giving an overview of current knowledge about the antimicrobial properties of essential oils and their mechanisms of action, components of essential oils, nano-encapsulated essential oils, and synergistic combinations of essential oils so as to find research areas that can facilitate applications of essential oils to overcome the problem of multidrug-resistant micro-organisms.

Insecticidal activity of polycaprolactone nanocapsules loaded with Rosmarinus officinalis essential oil in Tribolium castaneum (Herbst)

AbstractIn this study, the opportunity to enhance the insecticidal activity of Rosmarinus officinalis essential oil was studied for effective management of the red flour beetle, Tribolium castaneum, as a stored product pest beetle. Nanoprecipitation method was used to prepare rosemary oil‐loaded nanocapsules. Bioassays were conducted at 27–30°C temperature and 70–75 % relative humidity in the dark. Fumigant toxicity of the non‐formulated oil and nanocapsules of R. officinalis were investigated at 13.20, 15.92, 19.12, 23.04, and 27.76 μL/L air after 24 and 72 h exposure and the contact toxicity of the non‐formulated oil and nanocapsules were investigated at 4.28, 3.55, 2.95, 2.45 and 2.36 μL/cm2 after 24 h exposure. The major constituents of the essential oil of rosemary were α‐Pinene, 1,8‐cineol, camphor, and cis‐verbenone. Nanocapsules presented an average size (145 ± 15 nm) (± standard error [SE]) with a polydispersity index below 0.3, a negative zeta potential (−11.0 ± 0.5 mV), and a high encapsulation efficiency (78.20 ± 0.93 %). Scanning electron microscope photomicrograph of rosemary oil‐loaded nanocapsules showed the presence of spherical nanocapsules with regular and homogeneous surfaces. In fumigant and contact toxicity, there were significant differences between non‐formulated and rosemary oil‐loaded nanocapsules in all the concentrations and times. The results suggested that nanoencapsulated essential oils from R. officinalis can be used for effective control in T. castaneum. When this technique is used, it can produce pesticides that have controlled‐release properties and reduce the concentration of the applied doses and number of applications.

Antimicrobial Activity of Nano-Encapsulated Essential Oils: Comparison to Non-Encapsulated Essential Oils

As fragile active components, essential oils should be encapsulated to solve several problems linked to their use, including toxicity, miscibility in aqueous medium, time-controlled release, formulations or preparations for various industries (pharmaceuticals, cosmetics, textiles, chemicals, food, etc.). Then, the aim of this study is to perform nano-encapsulation of selected essential oils and to compare their antimicrobial activities with the non-encapsulated ones. Essential oils of Thymus leptobotrys, Thymus satureoides, Pelargonium graveolens, Eugenia Caryophyllata and their major component Eugenol were first encapsulated by the nanoprecipitation technique using Eudragit RS 100 as coating polymer. This results in a final stable milky dispersion of essential oils nanocapsules having a final concentration of 4% (v/v). The formed nanoparticles have 110 nm averages in diameter particle size and possess positive zeta potential (approximately 81 mV). Chemical composition of these encapsulated essential oils was investigated by Gas Chromatography-Mass Spectrometry confirming similarities to the non-encapsulated ones. Antimicrobial assays against five bacterial strains, two yeasts and two moulds, confirm that the prepared nanoparticles exhibit, at a comparative concentration of 0.4% (v/v), relatively less antimicrobial activities (both bacteriostatic and fungistatic) than the non-encapsulated EOs. These results lead us to think to numerous applications of such essential oils particularly in the pharmaceutical and cosmetic domains.