Fabrication of microparticle protein delivery systems based on calcium alginate

Microencapsulation of Piscirickettsia salmonis Antigens for Fish Oral Immunization: Optimization and Stability Studies

The development of fish oral vaccines is of great interest to the aquaculture industry due to the possibility of rapid vaccination of a large number of animals at reduced cost. In a previous study, we evaluated the effect of alginate-encapsulated Piscirickettsia salmonis antigens (AEPSA) incorporated in feed, effectively enhancing the immune response in Atlantic salmon (Salmo salar). In this study, we seek to characterize AEPSA produced by ionic gelation using an aerodynamically assisted jetting (AAJ) system, to optimize microencapsulation efficiency (EE%), to assess microparticle stability against environmental (pH, salinity and temperature) and gastrointestinal conditions, and to evaluate microparticle incorporation in fish feed pellets through micro-CT-scanning. The AAJ system was effective in obtaining small microparticles (d < 20 μm) with a high EE% (97.92%). Environmental conditions (pH, salinity and temperature) generated instability in the microparticles, triggering protein release. 62.42% of the protein content was delivered at the intestinal level after in vitro digestion. Finally, micro-CT-scanning images confirmed microparticle incorporation in fish feed pellets. In conclusion, the AAJ system is effective at encapsulating P. salmonis antigens in alginate with a high EE% and a size small enough to be incorporated in fish feed and produce an oral vaccine.

Biopolymer Microparticles Prepared by Microfluidics for Biomedical Applications

Biopolymers are macromolecules that are derived from natural sources and have attractive properties for a plethora of biomedical applications due to their biocompatibility, biodegradability, low antigenicity, and high bioactivity. Microfluidics has emerged as a powerful approach for fabricating polymeric microparticles (MPs) with designed structures and compositions through precise manipulation of multiphasic flows at the microscale. The synergistic combination of materials chemistry afforded by biopolymers and precision provided by microfluidic capabilities make it possible to design engineered biopolymer-based MPs with well-defined physicochemical properties that are capable of enabling an efficient delivery of therapeutics, 3D culture of cells, and sensing of biomolecules. Here, an overview of microfluidic approaches is provided for the design and fabrication of functional MPs from three classes of biopolymers including polysaccharides, proteins, and microbial polymers, and their advances for biomedical applications are highlighted. An outlook into the future research on microfluidically-produced biopolymer MPs for biomedical applications is also provided.

Design principles of food gels

Naturally sourced gels from food biopolymers have advanced in recent decades to compare favourably in performance and breadth of application to their synthetic counterparts. Here, we comprehensively review the constitutive nature, gelling mechanisms, design approaches, and structural and mechanical properties of food gels. We then consider how these food gel design principles alter rheological and tribological properties for food quality improvement, nutrient-modification of foods while preserving sensory perception, and targeted delivery of drugs and bioactives within the gastrointestinal tract. We propose that food gels may offer advantages over their synthetic counterparts owing to their source renewability, low cost, biocompatibility and biodegradability. We also identify emerging approaches and trends that may improve and expand the current scope, properties and functionalities of food gels and inspire new applications.

Delivery of synergistic polyphenol combinations using biopolymer-based systems: Advances in physicochemical properties, stability and bioavailability

When consumed at sufficiently high levels, polyphenols may provide health benefits, which is linked to their antidiabetic, antiinflamatory, antimicrobial, antioxidant, antitumor, and hypolipidemic properties. Moreover, certain polyphenol combinations exhibit synergistic effects when delivered together - the combined polyphenols have a higher biological activity than the sum of the individual ones. However, the commercial application of polyphenols as nutraceuticals is currently limited because of their poor solubility characteristics; instability when exposed to light, heat, and alkaline conditions; and, low and inconsistent oral bioavailability. Colloidal delivery systems are being developed to overcome these challenges. In this article, we review the design, fabrication, and utilization of food-grade biopolymer-based delivery systems for the encapsulation of one or more polyphenols. In particular, we focus on the creation of delivery systems constructed from edible proteins and polysaccharides. The optimization of biopolymer-based delivery systems may lead to the development of innovative polyphenol-enriched functional foods that can improve human health and wellbeing.

Designing food delivery systems: challenges related to the in vitro methods employed to determine the fate of bioactives in the gut

This review discussesin vitroavailable approaches to study delivery and uptake of bioactive compounds and the associated challenges.

Polymeric nanoparticles and microparticles for the delivery of peptides, biologics, and soluble therapeutics

Biologically derived therapeutics, or biologics, are the most rapidly growing segment of the pharmaceutical marketplace. However, there are still unmet needs in improving the delivery of biologics. Injectable polymeric nanoparticles and microparticles capable of releasing proteins and peptides over time periods as long as weeks or months have been a major focus in the effort to decrease the frequency of administration. These particle systems fit broadly into two categories: those composed of hydrophilic and those composed of hydrophobic polymeric scaffolds. Here we review the factors that contribute to the slow and controlled release from each class of particle, as well as the effects of synthesis parameters and product design on the loading, encapsulation efficiency, biologic integrity, and release profile. Generally, hydrophilic scaffolds are ideal for large proteins while hydrophobic scaffolds are more appropriate for smaller biologics without secondary structure. Here we also introduce a Flash NanoPrecipitation method that has been adopted for encapsulating biologics in nanoparticles (40-200nm) at high loadings (50-75wt.%) and high encapsulation efficiencies. The hydrophilic gel interior and hydrophobic shell provide an opportunity to combine the best of both classes of injectable polymeric depots.

Preparation and characterization of chitosan microsphere loading bovine serum albumin

To optimize the preparation process of chitosan microspheres and study its loading capacity, chitosan microsphere was prepared by crosslinking with glutaraldehyde, and bovine serum albumin (BSA) was absorbed onto chitosan microsphere. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FITR), TA instruments and zeta potentiometer analyzer were used to characterize the parameters with respect to size, thermal characters, morphology, and zeta potential of the microspheres. The loading capability and in vitro release tests were carried out. The results showed that chitosan microsphere with particle size less than 10 μm and positively charged (+25.97±0.56 mV) can be obtained under the aldehyde group to amino group ratio at 1:1. A loading capacity of BSA at 28.63±0.15 g/100 g with corresponding loading efficiency at 72.01±1.44% was obtained for chitosan microsphere. In vitro test revealed a burst release followed by sustained-release profile.

Entrapment of Saccharomyces cerevisiae and 3T3 fibroblast cells into blue light cured hydrogels

Hydrogels, containing yeast cells or fibroblast cells, were fabricated using blue light-induced polymerization technique. The cell-loaded prepolymer formulation was comprised of poly(ethyleneglycol) diacrylate (more than or equal to 50% v/v), 0.5 wt % Eosin Y and 0.5 wt % triethanolamine as the base oligomer, photo-initiator, and co-initiator, respectively. The two model cell lines, Saccharomyces cerevisiae and NIH 3T3 fibroblasts maintained high viability pre- and post-processing. Several bioassays have demonstrated the unaffected intracellular and extracellular activities of the cells entrapped within the hydrogels. Scanning electron microscopy confirmed the proliferation of S. cerevisiae cells that were entrapped and cultivated for 48 h in growth media, which validated the favorable microenvironment and nutrient transport in these gels. Upon entrapment, fibroblast cells remain viable upto 12 h, however they failed to attach within the crosslinked network, thus no further proliferation was observed. The tunable properties of this hydrogel system project it as a useful matrix for specialized biohybrids.