No abstract

Emulsion gels are now emerging as a new class of biomaterials for controlled-release applications. Novel food-grade emulsion gels consisting of indomethacin-loaded vegetable oil droplets dispersed within genipin-cross-linked gelatin-based hydrogels were characterized for their physical and drug-release properties. Varying the weight ratio of the aqueous and oil phases between 5:1 and 5:5 was used to modulate construct swelling and drug release. The dispersed oil droplets generally became larger, more polydispersed and aggregated with an increase in oil fraction. Cross-linking with genipin increased the puncture strength of the gels vs. their uncross-linked counterparts and was necessary to prevent breakdown. Swelling of the emulsion gels demonstrated Fickian behaviour at all gelatin: oil ratios. Indomethacin release followed Fickian diffusion at higher oil fractions only, demonstrating coupled Fickian and super-Case-II transport at lower oil ratios (5:1, 5:2 and 5:3). Overall, the introduction of a dispersed oil phase within a hydrogel was exploited for the release of hydrophobic bioactive compounds, with tailoring of composition used to significantly alter release kinetics.

This article is a continuation of a series of reviews on the presence and the role of intrinsic disorder in milk proteins in the journal of Current Protein and Peptide Science. The focus of this article is on casein phosphopeptides, which are liberated during digestion of the milk protein casein. Structurally these phosphopeptides have multiphosphorylated regions making them highly charged. The high degree of charge coupled with relatively low instances of hydrophobic amino acids makes them intrinsically disordered. These peptides have anticariogenic, antimicrobial, immunomodulatory, and cytomodulatory properties. Recent work using in vivo and in vitro models suggests that in addition to transporting calcium, these peptides can also enhance its bioaccessibility. The mechanism of this enhancement has yet to be determined. We review the current state of their structure, function, and isolation of these peptides.

The β-casein phosphopeptide 1-25 (βCPP) is involved in calcium binding, cellular transduction, and dental remineralization. Though the net charge of 13e suggests an intrinsically disordered peptide, it has been shown to possibly maintain partial structure. To investigate the nature and extent of its conformational disorder, 100 independent molecular dynamics simulations (cumulative time of 30 μs) were conducted in explicit water with 0.1 M sodium chloride. βCPP adopted an ensemble of conformations (Rg = 8.61 ± 0.06 Å) stabilized primarily by ionic interactions and less so by hydrogen bonding (HB). Intramolecular contact maps showed a lack of interaction between the peptide's head (RELEELNVPGEIVEΣ) and tail (ΣΣΣEESITR) segments, suggesting their conformational independence. While many backbone HB interactions were observed between the amino acids in each segment, there was no persistent secondary structure evident. Our findings provide a framework for further investigation of βCPP's conformation and mechanism of action upon binding to calcium phosphate.

No abstract