Modulating size and surface charge of ethylcellulose nanoparticles through the use of cationic nano-emulsion templates

Polymer nanoparticles from low-energy nanoemulsions for biomedical applications

The formulation of nanoemulsions by low-energy strategies, particularly by the phase inversion composition method, and the use of these nanoemulsions as templates for the preparation of polymer nanoparticles for biomedical applications are reviewed. The methods of preparation, nature of the components in the formulation, and their impact on the physicochemical properties, drug loading, and drug release are discussed. We highlight the utilization of ethyl cellulose, poly(lactic-co-glycolic acid), and polyurethane/polyurea in the field of nanomedicine as potential drug delivery systems. Advances are still needed to achieve better control over size distribution, nanoparticle concentration, surface functionalization, and the type of polymers that can be processed.

In situ and in vitro evaluation of the bioavailability of rumen-protected methionine with coating prototypes

Rumen protected amino acids are supplements that can enhance ruminal performance, yet the coating designed to protect the amino acids might also lead to different effects. Methionine is an essential methyl donor to synthesize protein, and little data exists on the effects of coating materials on its bioavailability. The purpose of this study was to estimate the effect of rumen-protected methionine (RPM) coatings with different ratios of acrylic resin IV (AR), ethyl cellulose (EC), and a mixture of AR and EC (AREC). Fifteen RPMs were prepared according to a single factor design, with 5 proportions each of AR, EC, and AREC to DL-methionine (DL-Met). Twelve hybrid small-tailed Han sheep with rumen fistula were utilized to evaluate in situ escape of RPMs, followed by in vitro abomasum-intestinal release of the RPMs. The results showed a regular variation in both ruminal disappearance and gastrointestinal release of RPMs with different coating prototypes and retention time. The RPMs that were EC and AREC coated presented high bioavailability compared to those with AR. Bioavailability of RPMs was optimal with the 2:20 AREC: DL-Met ratio, when the proportion of AR:EC is 1:1. Additionally, RPMs with a 1:3 ratio of AR:EC confirmed the optimum effect for the RPM of 2:20 AREC: DL-Met. In conclusion, an RPM with a lower AREC ratio coating can achieve better bioavailability and is synergistic to those with EC and AR.

Ethylcellulose nanoparticles prepared from nano-emulsion templates as new folate binding haemocompatible platforms

Ethylcellulose is a biocompatible polymer attracting increasing interest for biomedical applications. In the present work, the formation of folate-ethylcellulose nanoparticle complexes from nano-emulsion templates prepared by a low-energy approach, using aqueous components suitable for biomedical applications has been investigated. The composition of the aqueous component is shown to be crucial for the formation of stable nano-emulsions and influences the zeta potential values. The ethylcellulose nanoparticles with mean sizes around 100 nm were obtained from the nano-emulsions by solvent evaporation and showed positive zeta potential values above +20 mV due to the presence of the cationic surfactant. The nanoparticles were successfully complexed with folate, as evidenced by both particle size and zeta potential measurements. The complexes prepared with HEPES buffered glucose solution showed excellent haemocompatibility, which make them promising for parenteral therapeutic applications and also for those in which easy access to systemic circulation may occur, like in lungs.

Bio-Based Nanoparticles as a Carrier of β-Carotene: Production, Characterisation and In Vitro Gastrointestinal Digestion

β-carotene loaded bio-based nanoparticles (NPs) were produced by the solvent-displacement method using two polymers: zein and ethylcellulose. The production of NPs was optimised through an experimental design and characterised in terms of average size and polydispersity index. The processing conditions that allowed to obtain NPs (<100 nm) were used for β-carotene encapsulation. Then β-carotene loaded NPs were characterised in terms of zeta potential and encapsulation efficiency. Transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction analysis were performed for further morphological and chemical characterisation. In the end, a static in vitro digestion following the INFOGEST protocol was performed and the bioaccessibility of β-carotene encapsulated in both NPs was determined. Results show that the best conditions for a size-controlled production with a narrow size distribution are lower polymer concentrations and higher antisolvent concentrations. The encapsulation of β-carotene in ethylcellulose NPs resulted in nanoparticles with a mean average size of 60 ± 9 nm and encapsulation efficiency of 74 ± 2%. β-carotene loaded zein-based NPs resulted in a mean size of 83 ± 8 nm and encapsulation efficiency of 93 ± 4%. Results obtained from the in vitro digestion showed that β-carotene bioaccessibility when encapsulated in zein NPs is 37 ± 1%, which is higher than the value of 8.3 ± 0.1% obtained for the ethylcellulose NPs.

Ethylcellulose nanoparticles as a new "in vitro" transfection tool for antisense oligonucleotide delivery

Oil-in-water nano-emulsions have been obtained in the HEPES 20 mM buffer solution / [Alkylamidoammonium:Kolliphor EL = 1:1] / [6 wt% ethylcellulose in ethyl acetate] system over a wide oil-to-surfactant range and above 35 wt% aqueous component at 25 °C. The nano-emulsion with an oil-to-surfactant ratio of 70/30 and 95 wt% aqueous component was used for nanoparticles preparation. These nanoparticles (mean diameter around 90 nm and zeta potential of +22 mV) were non-toxic to HeLa cells up to a concentration of 3 mM of cationic species. Successful complexation with an antisense phosphorothioate oligonucleotide targeting Renilla luciferase mRNA was achieved at cationic/anionic charge ratios above 16, as confirmed by zeta potential measurements and an electrophoretic mobility shift assay, provided that no Fetal Bovine Serum is present in the cell culture medium. Importantly, Renilla luciferase gene inhibition shows an optimum efficiency (40%) for the cationic/anionic ratio 28, which makes these complexes promising for "in vitro" cell transfection.