Investigation into potential allergenicity of DBD plasma-treated casein digestion products based on immunoglobulin E linear epitopes and the sensitized-cell model

The study aimed to investigate the allergenicity change in casein treated with dielectric barrier discharge (DBD) plasma during in vitro simulated digestion, focusing on the immunoglobulin E (IgE) linear epitopes and utilizing a sensitized-cell model. Results indicated that prior treatment with DBD plasma treatment (4 min) before simulated digestion led to a 10.5% reduction in the IgE-binding capacity of casein digestion products. Moreover, the release of biologically active substances induced from KU812 cells, including β-HEX release rate, human histamine, IL-4, IL-6, and TNF-α, decreased by 2.1, 28.1, 20.6, 11.6, and 17.3%, respectively. Through a combined analysis of LC-MS/MS and immunoinformatics tools, it was revealed that DBD plasma treatment promoted the degradation of the IgE linear epitopes of casein during digestion, particularly those located in the α-helix region of αs1-CN and αs2-CN. These findings suggest that DBD plasma treatment prior to digestion may alleviate casein allergic reactions.

Polylactic Acid/Polyaniline Nanofibers Subjected to Pre- and Post-Electrospinning Plasma Treatments for Refined Scaffold-Based Nerve Tissue Engineering Applications

Composite biopolymer/conducting polymer scaffolds, such as polylactic acid (PLA)/ polyaniline (PAni) nanofibers, have emerged as popular alternative scaffolds in the electrical-sensitive nerve tissue engineering (TE). Although mimicking the extracellular matrix geometry, such scaffolds are highly hydrophobic and usually present an inhomogeneous morphology with massive beads that impede nerve cell-material interactions. Therefore, the present study launches an exclusive combinatorial strategy merging successive pre- and post-electrospinning plasma treatments to cope with these issues. Firstly, an atmospheric pressure plasma jet (APPJ) treatment was applied on PLA and PLA/PAni solutions prior to electrospinning, enhancing their viscosity and conductivity. These liquid property changes largely eliminated the beaded structures on the nanofibers, leading to uniform and nicely elongated fibers having average diameters between 170 and 230 nm. After electrospinning, the conceived scaffolds were subjected to a N₂ dielectric barrier discharge (DBD) treatment, which significantly increased their surface wettability as illustrated by large decreases in water contact angles for values above 125° to values below 25°. X-ray photoelectron spectroscopy (XPS) analyses revealed that 3.3% of nitrogen was implanted on the nanofibers surface in the form of C-N and N-C=O functionalities upon DBD treatment. Finally, after seeding pheochromocytoma (PC-12) cells on the scaffolds, a greatly enhanced cell adhesion and a more dispersive cell distribution were detected on the DBD-treated samples. Interestingly, when the APPJ treatment was additionally performed, the extension of a high number of long neurites was spotted leading to the formation of a neuronal network between PC-12 cell clusters. In addition, the presence of conducting PAni in the scaffolds further promoted the behavior of PC-12 cells as illustrated by more than a 40% increase in the neurite density without any external electrical stimulation. As such, this work presents a new strategy combining different plasma-assisted biofabrication techniques of conducting nanofibers to create promising scaffolds for electrical-sensitive TE applications.

Influence of mild oxidation induced through DBD-plasma treatment on the structure and gelling properties of glycinin

The effects of dielectric-barrier discharge (DBD) plasma treatment (20 s to 120 s treatment time with 40 kV, 12 kHz) induced mild oxidation on the gelling properties, and related structural changes of glycinin were investigated. The gelling ability of glycinin was improved by the mild oxidation induced by the plasma treatment. Treated glycinin gels exhibited a continuous and uniform network microstructure. Samples treated for 120 s had a 2.07-, 3.99- and 2.03-fold increase in hardness, chewiness, and resilience compared to the 20 s treated samples. Structural analyses showed that primary and secondary structures of glycinin were unaffected. The tertiary structure was shifted, accompanied by a decrease in free sulfhydryl (-SH) content. At the same time, carbonyl content and average particle diameter were increased by DBD treatment. The DBD treatment facilitated the generation/exchange of intermolecular disulfide bonds and enhanced gelling properties of glycinin. It is concluded that controlled plasma-induced protein oxidation can improve protein functionality.

Dielectric-barrier discharge (DBD) plasma treatment reduces IgG binding capacity of β-lactoglobulin by inducing structural changes

The present study investigated the effects of dielectric-barrier-discharge (DBD) plasma treatment (12 kHz, 40 kV) at 1, 2, 3, and 4 min on the reduction of the immunoglobulin G (IgG) binding capacity of β-lactoglobulin (β-LG). The IgG binding capacity of β-LG was reduced by 58.21% following a plasma treatment time of 4 min, as confirmed by western-blot and ELISA analyses. The reduction in IgG binding capacity of β-LG was directly related to a stepwise change in its structure. The initial drop in the IgG binding capacity of β-LG was found to be caused by conformational alteration, free sulfhydryl exposure and cross-linkage of molecules induced by oxidation of NH-/NH₂- functional groups of peptide bonds and of sensitive amino acid residues (Tyr, Trp) as confirmed by SDS-PAGE, surface hydrophobicity and multi-spectroscopic analyses. Plasma treatment of more than 3 min resulted in cleavage of disulfidebonds and fragmentation of β-LG that was confirmed by LC-MS/MS analysis, which resulted a further decline in the IgG binding capacity of β-LG. Plasma treatment therefore has great potential as a substitute treatment for enzymatic hydrolysis for the production of hypoallergenic milk protein-based products.

Oxidation induced by dielectric-barrier discharge (DBD) plasma treatment reduces soybean agglutinin activity

In this study, potential of dielectric-barrier discharge (DBD) plasma treatment (40 kV, 12 kHz at 1, 2, 3 and 4 min) to eliminate soybean agglutinin (SBA) activity was investigated in a SBA model system and soymilk. The plasma treatment decreased the SBA in the model system and hemagglutination activity was decreased by 87.31%. SDS-PAGE analysis confirmed the degradation of the SBA polypeptide chain. The multi-spectroscopic analysis revealed a two-stage structure alteration in the SBA upon exposure to the plasma treatment. Oxidation of NH-/NH₂- at the peptide bond disrupted the hydrogen bonds and altered the secondary structure of SBA. Further oxidation of aromatic amino acid, cleavage of peptide bonds and the breakage of polypeptide led to the SBA fragmentation and complete unfolding of the protein. The SBA inactivation by the plasma treatment was confirmed in soymilk. Plasma treatment is a promising technology for the elimination of SBA in soybean product.