Hence, it may be possible to design more effective BPP-loaded colloidal particles by carefully controlling these parameters

Hence, it may be possible to design more effective BPP-loaded colloidal particles by carefully controlling these parameters. their loading capacity, encapsulation O-Phospho-L-serine efficiency, protective properties, retention/release properties, and stability. Different kinds of colloidal delivery systems suitable for encapsulation of BPPs are then reviewed, such as microemulsions, emulsions, solid lipid particles, liposomes, and microgels. Finally, some examples of the use of colloidal delivery systems for delivery of specific BPPs are given, including hormones, enzymes, vaccines, antimicrobials, and ACE inhibitors. An emphasis is on the development of food-grade colloidal delivery systems, which could be used in functional or medical food applications. The knowledge presented should facilitate the design of more effective vehicles for the oral delivery of bioactive proteins and peptides. pH profile (Figure 2). Open in a separate window Figure 2 The electrical potential of biopolymers, such as proteins and polysaccharides, changes appreciably with pH due to ionization/deionization of charged groups. Information about the electrical attributes of BPPs is often essential for the design of an efficacious CDS. As an example, the retention/release of BPPs from biopolymer microgels is strongly influenced by the electrical interactions between the proteins and the biopolymer network inside the microgels. BPPs are electrostatically attracted to anionic biopolymers, like alginate, carrageenan, or pectin, when the pH is less than their isoelectric point, but they are electrostatically repelled when the pH is above their isoelectric point [21,22]. As a result, they may be retained at low pH values, but released under high pH values due to the change in electrostatic interactions. The opposite phenomenon occurs for cationic biopolymers, such as chitosan or polylysine. The magnitude of O-Phospho-L-serine any electrostatic interactions in aqueous solutions is reduced when dissociable salts are added as a result of electrostatic screening, i.e., accumulation of salt counter-ions around charged groups on the proteins [23]. This has important practical implications because it means that it may be challenging to keep BPPs trapped within the interior of biopolymer hydrogels using electrostatic attraction in commercial products that contain salts. Conversely, it means that it may O-Phospho-L-serine be possible to develop CDSs that can release proteins in response Rabbit Polyclonal to B-Raf to changes in the ionic strength of their environment. Beyond net charge considerations, it is important to note that the complex chemical and physical nature of many BPPs means that the spatial arrangement of the charges can also be O-Phospho-L-serine important in dictating their interactions with CDSs [24,25,26]. For example, serum proteins such as bovine serum albumin (BSA) tend to have O-Phospho-L-serine a uniform charge distribution, while lysozyme has a cluster of cationic residues on its surface. This clustering of cationic charge has been shown to drive nearly 100-fold higher loading of lysozyme into microgels formed from equimolar mixtures of oppositely-charged polymers than for BSA [27]. 2.3. Polarity, Solubility, and Surface Activity The polarity of BPPs is another critical factor influencing their ability to be encapsulated, since it impacts their three-dimensional structure, solubility, surface activity, and molecular interactions. BPPs may be predominantly polar, nonpolar, or amphiphilic depending on the number and distribution of hydrophilic and hydrophobic amino acids in the polypeptide chain, which in turn influences their structural arrangement in aqueous solutions. Polar groups are able to form dipole-dipole interactions with water, whereas nonpolar ones are not. A major driving force for protein folding is the tendency to reduce the number of hydrophobic nonpolar groups exposed to water [28]. As a result, BPPs may be either soluble or insoluble in aqueous solutions depending on their surface polarities. The surface activity of BPPs depends on the distribution of polar and non-polar groups on their surfaces. Many polypeptides are amphiphilic molecules that are able to adsorb.