Effects of Span surfactants on the preparation and properties of fish oil-loaded sodium alginate-stabilized emulsions and calcium alginate-stabilized capsules

Complex coacervation of low methoxy pectin with three types of gelatins for the encapsulation of fish oil

Herein, the complex coacervation of low methoxy pectin (LMP) with three types of gelatins was explored to encapsulate fish oil. The fish oil@gelatin-LMP complex coacervates with good precipitation separation could be obtained at low gelatin concentrations (Fish gelatin, FG: 10-80 mg/mL; porcine skin gelatin, PSG: 10-40 mg/mL; bovine skin gelatin, BSG: 10-80 mg/mL), high gelatin: fish oil mass ratios (4:1-1:1), appropriate gelatin: LMP mass ratios (3:1-12:1 for FG and PSG, 6:1 for BSG), and appropriate pH (FG: 4.90-5.50; PSG: 4.80-5.40; BSG: 4.10-4.50). FG induced similar loading ability, lower encapsulation ability, and comparable peroxide values to the mammalian gelatins. FG induced higher or similar free fatty acid released percentages to mammalian gelatins in the in vitro gastrointestinal model at low gelatin concentrations (10-40 mg/mL). These results provided useful information to understand the protein-polysaccharide complex coacervation to encapsulate oil-based bioactive substances.

Fish oil-loaded multicore submillimeter-sized capsules prepared with monoaxial electrospraying, chitosan-tripolyphosphate ionotropic gelation, and Tween blending

In order to load fish oil for potential encapsulation of fat-soluble functional active substances, fish oil-loaded multicore submillimeter-sized capsules were prepared with a combination method of three strategies (monoaxial electrospraying, chitosan-tripolyphosphate ionotropic gelation, and Tween blending). The chitosan-tripolyphosphate/Tween (20, 40, 60, and 80) capsules had smaller and evener fish oil cores than the chitosan-tripolyphosphate capsules, which resulted from that Tween addition induced smaller and evener fish oil droplets in the emulsions. Tween addition decreased the water contents from 56.6 % to 35.0 %-43.4 %, increased the loading capacities from 10.4 % to 12.7 %-17.2 %, and increased encapsulation efficiencies from 97.4 % to 97.8 %-99.1 %. In addition, Tween addition also decreased the highest peroxide values from 417 meq/kg oil to 173-262 meq/kg oil. These properties' changes might result from the structural differences between the chitosan-tripolyphosphate and chitosan-tripolyphosphate/Tween capsules. All the results suggested that the obtained chitosan-tripolyphosphate/Tween capsules are promising carriers for fish oil encapsulation. This work also provided useful knowledge to understand the preparation, structural, and physicochemical properties of the chitosan-tripolyphosphate capsules.

Effects of gelatin type and concentration on the preparation and properties of freeze-dried fish oil powders

The effects of gelatin type (porcine skin gelatin, PSG; bovine skin gelatin, BSG; fish gelatin, FG; or cold-water fish skin gelatin, CFG) and concentration on the preparation and properties of fish oil powders were investigated in this work. The oil powders were prepared using the combination method of gelatin-sodium hexametaphosphate complex coacervation with starch sodium octenyl succinate (SSOS)-aided freeze-drying. Compared with the other gelatins, CFG-with an unobvious isoelectric point, a lower molecular weight, more hydrogen bonds, and longer gel formation time-could not form complex coacervates, which are necessary to prepare oil powders. For oil powders obtained from the other gelatins, gelatin type and concentration did not have obvious effects on microscale morphologies; they did, however, have significant effects on physicochemical properties. The highest peroxide values of the oil powders were mainly dependent on the gelatins, expressed in the following manner: PSG (153 ± 5 - 168 ± 3 meq/Kg oil) < BSG (176 ± 5 - 188 ± 1 meq/Kg oil) < FG (196 ± 11 - 201 ± 22 meq/Kg oil). Acidic and neutral pH could not dissolve the complex coacervates. However, the oil powders could be quickly dissolved to form emulsion droplets in the gastric phase, and that SSOS increased coacervate stability and promoted oil digestion during the in vitro gastrointestinal process. In sum, this study contributes fundamental information to understanding the development of fish oil solid encapsulation preparations.

The effects of Lactobacillus reuteri microcapsules on radiation-induced brain injury by regulating the gut microenvironment

A radiation-induced brain injury (RIBI) is a major adverse event following radiotherapy of malignant tumors. RIBI would affect cognitive function, leading to a series of complications and even death. However, the pathogenesis of RIBI is still unclear, and it still lacks specific therapeutic drugs. The gut-brain bidirectional communication may be mediated by various microbiota and metabolites in the gastrointestinal tract. Probiotics are closely related to physiological health. The theory of the gut-brain axis provides us with a new idea to improve the gut microenvironment by supplementing probiotics against RIBI. Here, Lactobacillus reuteri microcapsules (LMCs) were prepared, which were predominantly irregular spheres with a rough surface under a scanning electron microscope and a narrow size distribution ranging from 20 to 700 μm. The transmission electron microscopy images showed that the structure of microcapsules containing Lactobacillus reuteri (L. reuteri) was a core and shell structure. The survival of L. reuteri in microcapsules was significantly more than that of free L. reuteri in the simulated stomach environment of pH 1.2. 16S rDNA sequencing showed that LMCs observably increased the relative abundance of Lactobacillus in RIBI mice. More importantly, compared with the RIBI model mice, the behavior of RIBI mice treated with LMCs was significantly improved. In addition, LMCs greatly alleviated the pathological damage of the hippocampus and intestines in the mice after irradiation and reduced the level of TNF-α and IL-6 in vivo. Generally, LMCs are a promising oral preparation, which provide new ideas and methods for the treatment of RIBI.

Tween emulsifiers improved alginate-based dispersions and ionic crosslinked milli-sized capsules

The blending of surfactants might change the properties of alginate-based oil encapsulation preparations. Herein, the effects of Tween series (Tween 20, 40, 60, and 80) blending on the fish oil-encapsulated sodium alginate dispersions and calcium alginate capsules were studied. The results suggested Tween 80 showed better emulsifying properties than Span 80 for the alginate/surfactant emulsions. All the Tween series induced higher creaming stability than the sodium alginate-stabilized dispersion. Tween series blending did not change the sizes, decreased the water contents, and induced similar particle-like protrusions of calcium alginate capsules. Loading capacity and encapsulation efficiency of fish oil were dependent on the hydrophilic heads and fatty acid moieties of the Tween series. Tween series blending could increase the fish oil oxidative stability of the capsules. In the in vitro digestion process, Tween with saturated fatty acid moieties increased the free fatty acid release percentages. This work provided potential innovative processing technologies for improving the biological potency of fish oil.

Inflammation-modulating antibacterial hydrogel sustained release asiaticoside for infection wound healing

Wound infection and persistent inflammation are considered to be the main reasons for hindering wound healing. In this study, we developed an innovative hydrogel dressing, EPL-DA/ODEX/AMs, as a platform to inhibit bacteria and inflammation and promote wound healing. Polylysine (EPL) has cationic properties and can effectively disrupt bacterial cell membranes for antibacterial purposes. Polylysine-grafted levodopa (EPL-DA) with abundant amino and catechol groups can be cross-linked with oxidized dextran through Schiff base reaction to form antibacterial hydrogels with good adhesion and mechanical properties. In addition, asiaticoside, which can effectively inhibit inflammation and promote collagen regeneration, is made into PLGA microspheres to effectively deliver asiaticoside to the wound. The innovative antibacterial hydrogel of EPL-DA/ODEX/AMs may become a competitive wound dressing for infected wound.