Development and Study of Nanoemulsions and Nanoemulsion-Based Hydrogels for the Encapsulation of Lipophilic Compounds

Biocompatible nanoemulsions and nanoemulsion-based hydrogels were formulated for the encapsulation and delivery of vitamin D₃ and curcumin. The aforementioned systems were structurally studied applying dynamic light scattering (DLS), electron paramagnetic resonance (EPR) spectroscopy and viscometry.

In vitro studies were conducted using Franz diffusion cells to investigate the release of the bioactive compounds from the nanocarriers. The cytotoxicity of the nanoemulsions was investigated using the thiazolyl blue tetrazolium bromide (MTT) cell proliferation assay and RPMI 2650 nasal epithelial cells as in vitro model. DLS measurements showed that vitamin D₃ and curcumin addition in the dispersed phase of the nanoemulsions caused an increase in the size of the oil droplets from 78.6 ± 0.2 nm to 83.6 ± 0.3 nm and from 78.6 ± 0.2 nm to 165.6 ± 1.0 nm, respectively. Loaded nanoemulsions, in both cases, were stable for 60 days of storage at 25 °C. EPR spectroscopy revealed participation of vitamin D₃ and curcumin in the surfactants monolayer.

In vitro release rates of both lipophilic compounds from the nanoemulsions were comparable to the corresponding ones from the nanoemulsion-based hydrogels. The developed o/w nanoemulsions did not exhibit cytotoxic effect up to the concentration threshold of 1 mg/mL in the cell culture medium.

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Article Information: Demisli, S.; Mitsou, E.; Pletsa, V.; Xenakis, A.; Papadimitriou, V. Development and Study of Nanoemulsions and Nanoemulsion-Based Hydrogels for the Encapsulation of Lipophilic Compounds. Nanomaterials 2020, 10, 2464.

Materials: Polyoxyethylenesorbitan monooleate (Tween 80), pure, was purchased from Fisher BioReagents, NH, USA. Soybean lecithin (L-alpha phosphatidylcholine), 90% was from Alpha Aesar, Germany. Glycerol monolinoleate (Maisine® CC) HLB 1, Diethylene glycol monoethyl ether (Transcutol® HP) and Caprylocaproyl Polyoxyl-8 glycerides (Labrasol®) HLB 12, were kindly donated by Gattefossé, France. Extra virgin olive oil (EVOO) (acidity <0.4%) from the Amfissa Variety, Pelion, Magnesia, Greece, was kindly provided by “Myrolion” start-up company, Greece. Isopropyl tetradecanoate (IPM), 98% was from Alpha Aesar, Germany. 5- and 16-Doxyl stearic acid, free radicals were from Sigma-Aldrich Chemie Gmbh Munich, Germany. Curcumin was a product of Sigma-Aldrich Co., St. Louis, MO, USA. Chitosan (200–600 mPa·s, 0.5% in 0.5% Acetic Acid at 20 ◦C) was purchased from TCI, Belgium. Xanthan gum from Xanthomonas campestris and Hydroxypropyl methylcellulose (HPMC) were supplied from Sigma-Aldrich, Chemie Gmbh Munich, Germany. Dulbecco’s Modified Eagle’s Medium (DMEM), foetal bovine serum (FBS), 100 U/mL penicillin and 100 mg/mL streptomycin, phosphate-buffered saline (PBS) and trypsin-EDTA were purchased from Gibco (Life Technologies, Grand Island, NY, USA). Acetic Acid glacial 100% was from Merck, Darmstadt, Germany. Ethanol absolute, analytical grade was from Fisher Scientific, Loughborough, UK. Deionized water was used.