Cationic β‑Lactoglobulin Nanoparticles as a Bioavailability Enhancer: Protein Characterization and Particle Formation

Cationic β-lactoglobulin (CBLG) was developed as a bioavailability enhancer for poorly absorbed bioactives. At most 11 anionic amino acid residues of β-lactoglobulin (BLG) were substituted by ethylenediamine (EDA), resulting in a highly positive surface charge (zeta potential up to 39 mV at pH 7.0) and significantly increased surface hydrophobicity. These changes conferred CBLG with desirable water solubility and improved mucoadhesion by at most 252%, according to quartz crystal microbalance (QCM) study. Furthermore, CBLG inherited the unique resistance to gastric digestion from BLG, while the digestion under simulated intestinal condition was significantly improved. The latter was possibly due to the formation of aspartic acid-EDA conjugates, together with the randomization of protein conformation related with decreased percentage of β-sheet. Compared to BLG, CBLG formed smaller (75–94 nm), more uniform nanoparticles by the acetone-desolvation method. These merits made CBLG a useful material that provides desirable solubility, controlled release, and enhanced absorption to nutraceuticals or drugs

Understanding the Dissolution of α‑Zein in Aqueous Ethanol and Acetic Acid Solutions

Zein is a corn prolamin that has broad industrial applications because of its unique physical properties. Currently, the high cost of extraction and purification, which is directly related to the dispersion of zein in different solvents, is the major bottleneck of the zein industry. Solution behaviors of zein have been studied for a long time. However, the physical nature of zein in different solvents remains unclear. In this study, small-angle X-ray scattering (SAXS), static light scattering (SLS), and rheology were combined to study the structure and protein–solvent interaction of α-zein in both acetic acid and aqueous ethanol solutions. We found that the like-dissolve-like rule, the partial unfolding, and the protonation of zein are all critical to understanding the solution behaviors. Zein holds an elongated conformation (i.e., prolate ellipsoid) in all solutions, as revealed from SAXS data. There is an “aging effect” for zein in aqueous ethanol solutions, as evidenced by the transition of Newtonian rheological profiles for fresh zein solutions to the non-Newtonian shear thinning behavior for zein solutions after storage at room temperature for 24 h. Such shear thinning behavior becomes more pronounced for zein solutions at higher concentrations. The SLS results clearly show that acetic acid is a better solvent to dissolve zein than aqueous ethanol solution, as supported by a more negative second virial coefficient. This is majorly caused by the protonation of the protein, which was further verified by the dissolution of zein in water (a nonsolvent for zein) with the addition of acids

Self-Assembly with Orthogonal-Imposed Stimuli To Impart Structure and Confer Magnetic Function To Electrodeposited Hydrogels

A magnetic nanocomposite film with the capability of reversibly collecting functionalized magnetic particles was fabricated by simultaneously imposing two orthogonal stimuli (electrical and magnetic). We demonstrate that cathodic codeposition of chitosan and Fe₃O₄ nanoparticles while simultaneously applying a magnetic field during codeposition can (i) organize structure, (ii) confer magnetic properties, and (iii) yield magnetic films that can perform reversible collection/assembly functions. The magnetic field triggered the self-assembly of Fe₃O₄ nanoparticles into hierarchical “chains” and “fibers” in the chitosan film. For controlled magnetic properties, the Fe₃O₄-chitosan film was electrodeposited in the presence of various strength magnetic fields and different deposition times. The magnetic properties of the resulting films should enable broad applications in complex devices. As a proof of concept, we demonstrate the reversible capture and release of green fluorescent protein (EGFP)-conjugated magnetic microparticles by the magnetic chitosan film. Moreover, antibody-functionalized magnetic microparticles were applied to capture cells from a sample, and these cells were collected, analyzed, and released by the magnetic chitosan film, paving the way for applications such as reusable biosensor interfaces (e.g., for pathogen detection). To our knowledge, this is the first report to apply a magnetic field during the electrodeposition of a hydrogel to generate magnetic soft matter. Importantly, the simple, rapid, and reagentless fabrication methodologies demonstrated here are valuable features for creating a magnetic device interface