Highly-hydrophobic nanofiber mat for efficient colonic delivery of lactoferrin: Preparation, characterization and release mechanism

Preparation of Eudragit S100-pullulan/hydroxypropyl-β-cyclodextrin complex-Eudragit S100 multilayer nanofiber film for resveratrol colon delivery

Cyclodextrin-based electrospun nanofibers are promising for encapsulating and preserving unstable compounds, but quick dissolution of certain nanofibers hinders their delivery application. In this study, hydroxypropyl-β-cyclodextrin (HPβCD) was used as an effective carrier of resveratrol (RSV) to obtain the RSV/HPβCD inclusion complex (HPIC), which was then incorporated into pullulan nanofibers. For enhancement of RSV release toward colon target, multilayer structure with a pullulan/HPIC film sandwiched between two layers of hydrophobic Eudragit S100 (ES100) nanofibers was employed. The relationship between the superiority of the ES100-pullulan/HPIC-ES100 film and its multilayer structure was verified. The intimate interactions of hydrogen bonds between two adjacent layers enhanced thermal stability, and the hydrophobic outer layers improved water contact resistance. According to release results, multilayer films also showed excellent colon-targeted delivery property and approximately 78.58 % of RSV was observed to release in colon stage. In terms of release mechanism, complex mechanism best described RSV colonic release. Additionally, ES100-pullulan/HPIC-ES100 multilayer films performed higher encapsulation efficiency when compared to the structures without HPIC, which further increased the antioxidant activity and total release amount of RSV. These results suggest a promising strategy for designing safe colonic delivery systems based on multilayer and HPIC structures with superior preservation for RSV.

Regulation of the colon-targeted release rate of lactoferrin by constructing hydrophobic ethyl cellulose/pectin composite nanofibrous carrier and its effect on anti-colon cancer activity

In order to modify colonic release behavior of lactoferrin (Lf), a hydrophobic composite nanofibrous carrier (CNC) was constructed by emulsion coaxial electrospinning. Ethylcellulose/pectin based water-in-oil emulsion and Lf-contained polyvinyl alcohol solution were used as shell and core fluids, respectively. An electrospinning diagram was first constructed to screen out suitable viscosity (51-82 cP) and conductivity (960-1300 μS/cm) of the dispersed phase of pectin solution for successful electrospinning of shell emulsion. Varying mass fraction of pectin solution (5 %-20 %) of shell emulsion during emulsion coaxial electrospinning obtained CNCs with different micro-structures, labeled as 5&95 CNC, 10&90 CNC, 15&85 CNC, 20&80 CNC. These CNCs all achieved colonic delivery of Lf (>95 %), and the time for complete release of Lf in simulated colon fermentation process were 10, 7, 5 and 3 h, respectively. That is, the greater the pectin content in CNC, the faster the release rate of stabilized Lf in colon. Lf release in simulated colon fermentation fluid involved complex mechanisms, in which diffusion release of Lf was dominant. Increasing colonic release rate of Lf enhanced its regulation effect on the expression levels of cell cycle arrest and apoptosis-related protein and promote its effective inhibition on the proliferation of HCT116 cell.

Fabrication of colon-targeted ethyl cellulose/gelatin hybrid nanofibers: Regulation of quercetin release and its anticancer activity

A colon-targeted delivery system that can efficiently deliver and release quercetin is essential to improve its bioavailability. We previously found that hydrophobic ethyl cellulose (EC) nanofibers could efficiently deliver quercetin to colon, but the release of quercetin was limited. To address this problem, hydrophilic gelatin (GN) was used as a regulator, and quercetin-loaded nanofibers with different mass ratios of EC to GN (3:1, 1:1, 1:2, 1:3) were fabricated by electrospinning. All nanofibers had a cylindrical morphology and high encapsulation efficiency (over 94 %), and there existed molecular interactions among quercetin, EC, and GN. The high GN content reduced the thermal stability of nanofibers but increased their surface wettability. Besides, these nanofibers had good stability in acidic and aqueous foods. Importantly, the release of quercetin in the simulated gastrointestinal fluid was <3 %. The addition of GN was beneficial to the release of quercetin in colon, and nanofibers with EC to GN being 1:3 had a more preferable release performance. The anticancer activity of nanofibers against HCT-116 cells was proved by inhibiting cell viability through the induction of apoptosis. Therefore, these nanofibers are potential carriers for efficient colon-targeted delivery of bioactive compounds in the food industry.

Modulation of physicochemical properties of lipid droplets using soy protein isolate and lactoferrin interfacial coatings

In order to improve the physicochemical stability of soy protein isolate (SPI) emulsion, lactoferrin (LF) was used to modify the interface layer. The stable multilayer emulsion can be formed when the content of lactoferrin is 0.5% at pH 5. The emulsion with good stability was at pH 3-7, and it was also stable to temperature change. The FFAs release of SPI emulsion and LF-SPI emulsion was 103.9% and 103.7%, respectively. The results showed that the lactoferrin layer did not hinder the digestion of oil and the bioaccessibility of carotenoids, but lactoferrin layer improved the physicochemical stability of SPI emulsions. This work provides information valuable in the design of emulsion formulations for applications in the food, pharmaceutical, and personal care industries.

Tri-Layer Core-Shell Fibers from Coaxial Electrospinning for a Modified Release of Metronidazole

Polymers are the backbone of drug delivery. Electrospinning has greatly enriched the strategies that have been explored for developing novel drug delivery systems using polymers during the past two decades. In this study, four different kinds of polymers, i.e., the water-soluble polymer poly (vinyl alcohol) (PVA), the insoluble polymer poly(ε-caprolactone) (PCL), the insoluble polymer Eudragit RL100 (ERL100) and the pH-sensitive polymer Eudragit S100 (ES100) were successfully converted into types of tri-layer tri-polymer core-shell fibers through bi-fluid coaxial electrospinning. During the coaxial process, the model drug metronidazole (MTD) was loaded into the shell working fluid, which was an emulsion. The micro-formation mechanism of the tri-layer core-shell fibers from the coaxial emulsion electrospinning was proposed. Scanning electron microscope and transmission electron microscope evaluations verified the linear morphology of the resultant fibers and their obvious tri-layer multiple-chamber structures. X-ray diffraction and Fourier transform infrared spectroscopy measurements demonstrated that the drug MTD presented in the fibers in an amorphous state and was compatible with the three polymeric matrices. In vitro dissolution tests verified that the three kinds of polymer could act in a synergistic manner for a prolonged sustained-release profile of MTD in the gut. The drug controlled-release mechanisms were suggested in detail. The protocols reported here pioneer a new route for creating a tri-layer core-shell structure from both aqueous and organic solvents, and a new strategy for developing advanced drug delivery systems with sophisticated drug controlled-release profiles.

Research Advances of Lactoferrin in Electrostatic Spinning, Nano Self-Assembly, and Immune and Gut Microbiota Regulation

Lactoferrin (LF) is a naturally present iron-binding globulin with the structural properties of an N-lobe strongly positively charged terminus and a cage-like structure of nano self-assembly encapsulation. These unique structural properties give it potential for development in the fields of electrostatic spinning, targeted delivery systems, and the gut-brain axis. This review will provide an overview of LF's unique structure, encapsulation, and targeted transport capabilities, as well as its applications in immunity and gut microbiota regulation. First, the microstructure of LF is summarized and compared with its homologous ferritin, revealing both structural and functional similarities and differences between them. Second, the electrostatic interactions of LF and its application in electrostatic spinning are summarized. Its positive charge properties can be applied to functional environmental protection packaging materials and to improving drug stability and antiviral effects, while electrostatic spinning can promote bone regeneration and anti-inflammatory effects. Then the nano self-assembly behavior of LF is exploited as a cage-like protein to encapsulate bioactive substances to construct functional targeted delivery systems for applications such as contrast agents, antibacterial dressings, anti-cancer therapy, and gene delivery. In addition, some covalent and noncovalent interactions of LF in the Maillard reaction and protein interactions and other topics are briefly discussed. Finally, LF may affect immunological function via controlling the gut microbiota. In conclusion, this paper reviews the research advances of LF in electrostatic spinning, nano self-assembly, and immune and gut microbiota regulation, aiming to provide a reference for its application in the food and pharmaceutical fields.