Development of Multifunctional Nanoencapsulated trans-Resveratrol/Chitosan Nutraceutical Edible Coating for Strawberry Preservation.

Phytochemical nanoencapsulation for nutrient delivery and edible coatings for perishable food preservation are two emerging technologies. Leveraging the strong antimicrobial function of phytochemical nutrients, we propose convergent research to integrate the two technologies by embedding phytochemical-encapsulated nanoparticles in an edible coating on fresh fruits to achieve multiple functions. In particular, we report the study of an edible coating on strawberries that is composited of trans-resveratrol (R)-encapsulated nanoparticles (RNPs) embedded in a chitosan (CS) matrix. The biodegradable and biocompatible RNPs significantly increased the aqueous solubility of R by 150-fold and bioavailability by 3.5-fold after oral administration. Our results demonstrated the abilities of the RNP-embedded CS edible coating to diminish dehydration, prevent nutrient loss, inhibit microbe growth, increase nutraceutical value, preserve strawberry quality, and extend shelf life during storage at both 22 and 4 °C. Such a phytochemical nanoencapsulation-based edible coating is promising for the dual purposes of enhancing nutrient delivery and preserving perishable foods.

Alginate hydrogel beads as a carrier of low density lipoprotein/pectin nanogels for potential oral delivery applications.

Alginate hydrogel beads have been extensively investigated as drug delivery systems due to promising gastric environment stability. In the present study, alginate hydrogel beads were prepared with Ca2+ or Fe3+ to serve as the loading vehicles for egg yolk low density lipoprotein (LDL)/pectin nanogels. Scanning electron microscope was carried out to confirm the successful incorporation of nanogels into the beads. The FT-IR spectra and swelling ratio analyses proved that incorporation of nanogels did not affect the physicochemical properties of the hydrogel beads. The developed hydrogel beads exhibited pH dependent release of curcumin pre-encapsulated in nanogels, with significant retention of curcumin in gastric condition compared to curcumin encapsulated in nanogels or alginate beads alone. Hydrogel beads prepared with low viscous alginate and Ca2+ showed limited swelling property and more sustained release of curcumin in simulated gastrointestinal conditions, compared to the beads prepared with high viscous alginate and Fe3+. Gradual dissociation of nanogels from the beads during incubation in simulated intestinal fluid was studied with transmission electron microscope. Our study demonstrated the promising potential of alginate beads as a carrier to protect LDL-based nanogels from destabilization in gastric condition, thus expanding their applications as oral delivery system.

Preparation of lipid nanoparticles with high loading capacity and exceptional gastrointestinal stability for potential oral delivery applications.

Exploitation of lipid nanoparticles for oral delivery of nutrients and drugs is limited by their poor stability under gastrointestinal tract and low loading capacity, unless a high concentration of synthetic surfactants is formulated. The main objective of present study is to design a series of new formulations for solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) that are suitable for potential oral delivery applications, using natural biopolymers, i.e. sodium caseinate (NaCas) as emulsifier and pectin as coating, with minimal addition of a synthetic surfactant, Tween 80. Effects of pectin coating, concentration of Tween 80, thermal treatment (80°C for 30min), as well as two chemical cross-linkers on the particulate characteristics, stability, encapsulation efficiency, controlled release and drying feasibility were comprehensively investigated. The intermolecular interactions and cross-linking reactions were studied using Fourier transform infrared spectroscopy. Tween 80 at 0.15% (w/v) together with 0.15% (w/v) NaCas was proved effective to obtain stable cross-linked pectin-coated SLN (PSLN) under 200nm with high loading capacity for curcumin, while NLC prepared under the same condition failed to pass storage stability test. The 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) cross-linked PSLN exhibited superior characteristics than glutaradehyde (GA) cross-linked PSLN, especially for the stability and controlled release under simulated gastrointestinal conditions, with curcumin studied as a model compound. The feasibility of both nano spray drying and freeze-drying technologies were both investigated to transform of colloidal lipid nanoparticles into dry powders. Our results demonstrated a novel strategy to prepare small and homogenous SLN with exceptional GI stability and high loading capacity as a potential oral delivery system.

A novel and organic solvent-free preparation of solid lipid nanoparticles using natural biopolymers as emulsifier and stabilizer.

In this work, a new and novel organic solvent-free and synthetic surfactant-free method was reported to fabricate stable solid lipid nanoparticles (SLNs) from stearic acid, sodium caseinate (NaCas) and pectin, as well as water. Melted stearic acid was directly emulsified into an aqueous phase containing NaCas and pectin, followed by pH adjustment and thermal treatment to induce the formation of a compact and dense polymeric coating which stabilized SLNs. The preparation procedures and formulations were comprehensively optimized. The inter- and intra-molecular interactions among three ingredients were characterized by fluorescence and Fourier transform infrared spectroscopies. The stability of as-prepared SLNs was evaluated under simulated gastrointestinal conditions, and compared with traditional SLNs prepared with organic solvents. Our results revealed that the SLNs prepared from this organic solvent-free method had superior physicochemical properties over the traditional SLNs, including smaller size and better stability. Furthermore, redispersible SLNs powders were obtained by nano spray drying, but only the SLNs prepared by organic solvent-free method had sub-micron scale, uniform and spherical morphology. The organic solvent-free preparation method was proved to be a promising approach to prepare stable and uniform SLNs for potential oral delivery applications.

Zein/caseinate/pectin complex nanoparticles: Formation and characterization.

In this study, pectin was used as coating material to form zein/caseinate/pectin complex nanoparticles through pH adjustment and heating treatment for potential oral delivery applications. The preparation conditions were studied by applying heating treatment at different pHs, either the isoelectric point of zein (pH 6.2) or caseinate (pH 4.6), or consecutively at both pHs. The particulate characteristics, including particle size, polydispersity index, and zeta potential were monitored for complex nanoparticles formed under different preparation conditions. The complex nanoparticles generally exhibited particle size smaller than 200nm with narrow distribution, spherical shape, and strong negative charge. Fourier transform infrared and fluorescence spectroscopy revealed that hydrophobic interactions and hydrogen bonds were involved in the formation of complex nanoparticles, in addition to electrostatic interactions. Fresh colloidal dispersion and freeze-dried powders varied in their morphology, depending on their preparation conditions. Our results suggested that heating pH and sequence significantly affected the morphology of complex nanoparticles, and pectin coating exerted stabilization effect under simulated gastrointestinal conditions. The present study provides insight into the formation of protein/polysaccharide complex nanoparticles under different preparation conditions.

Synthetic surfactant- and cross-linker-free preparation of highly stable lipid-polymer hybrid nanoparticles as potential oral delivery vehicles.

The toxicity associated with concentrated synthetic surfactants and the poor stability at gastrointestinal condition are two major constraints for practical applications of solid lipid nanoparticles (SLN) as oral delivery vehicles. In this study, a synthetic surfactant-free and cross-linker-free method was developed to fabricate effective, safe, and ultra-stable lipid-polymer hybrid nanoparticles (LPN). Bovine serum albumin (BSA) and dextran varying in molecular weights were first conjugated through Maillard reaction and the conjugates were exploited to emulsify solid lipid by a solvent diffusion and sonication method. The multilayer structure was formed by self-assembly of BSA-dextran micelles to envelope solid lipid via a pH- and heating-induced facile process with simultaneous surface deposition of pectin. The efficiency of different BSA-dextran conjugates was systematically studied to prepare LPN with the smallest size, the most homogeneous distribution and the greatest stability. The molecular interactions were characterized by Fourier transform infrared and fluorescence spectroscopies. Both nano spray drying and freeze-drying methods were tested to produce spherical and uniform pectin-coated LPN powders that were able to re-assemble nanoscale structure when redispersed in water. The results demonstrated the promise of a synthetic surfactant- and cross-linker-free technique to prepare highly stable pectin-coated LPN from all natural biomaterials as potential oral delivery vehicles.

Effects of different polysaccharides on the formation of egg yolk LDL complex nanogels for nutrient delivery.

Five polysaccharides, pectin, carboxymethyl cellulose (CMC), gum arabic, carrageenan and alginate, were studied to form complex nanogels with egg yolk low density lipoprotein (LDL). All nanogels were smaller than 85nm with high negative zeta potential, while LDL/carrageenan and LDL/alginate nanogels exhibited more heterogeneous size distribution. Fourier transform infrared spectrum suggested that hydrogen bonds, hydrophobic and electrostatic interactions were involved to form nanogels. Overall, significant expansion of nanogels was observed after encapsulation of curcumin, being studied as a model lipophilic nutrient. Fluorescence spectra evidenced that LDL provided non-polar microenvironment for curcumin and polysaccharides played an important role in the encapsulation process. All nanogels showed sustained release of curcumin under simulated gastrointestinal conditions. Furthermore, nanoscale, smooth and spherical ultrafine dry powders of nanogels were obtained by innovative nano spray drying technology. Our study indicated that LDL/polysaccharides may serve as potential oral delivery systems for lipophilic nutrients.

Antimicrobial eugenol nanoemulsion prepared by gum arabic and lecithin and evaluation of drying technologies.

The purpose of present work was to develop eugenol oil nanoemulsions using gum arabic and lecithin as food grade natural emulsifiers, and study their antimicrobial activity. In addition, our study also evaluated different drying techniques (spray drying and freeze drying) on the morphology and redispersibility of nanoemulsion powders. The optimal fabrication method, physicochemical and structural characterization, stability, and antimicrobial activity were investigated. Results showed that nanoemusions with a particle size of 103.6±7.5nm were obtained by mixing aqueous phase (0.5% gum arabic, 0.5% lecithin, w/v) and eugenol oil (1.25%, w/v), which was premixed with ethanol (as a co-surfactant), followed by high speed homogenization process. The molecular interactions among emulsifiers and eugenol were evidenced by Fourier transform infrared spectroscopy. Buchi B-90 Nano Spray Dryer was evaluated as a powerful tool to obtain ultrafine spherical powders with a size of less than 500nm, compared to flake-like aggregation obtained by freeze-drying. The dried powders exhibited excellent re-dispersibility in water and maintained their physicochemical properties after re-hydration. The nanoemulsions did not adversely affect the antimicrobial activity of eugenol against Listeria monocytogenes and Salmonella Enteritidis. Therefore, the nanoemulsions have the potential to be applied in the food industry as a food preservative or sanitizer.