Novel fava bean 11S nanofiber gels for sustained ergothioneine delivery: a calcium ion and κ-carrageenan approach

Abstract

This study explores the development of a novel delivery system for the potent antioxidant ergothioneine (ET) using fava bean globulin nanofibers (FPF). FPF were generated from a 6 % fava bean 11S solution under controlled acid-heat treatment (pH 2.0, 85 °C). Increasing treatment duration triggered FPF formation through hydrolysis of the protein into peptides, which subsequently self-assembled. This process significantly altered particle size, secondary structure, viscosity, surface hydrophobicity, and free sulfhydryl group content. Notably, a 24-h reaction yielded FPF with optimal viscosity properties. The FPF-based delivery system was constructed by combining FPF, calcium ions (Ca²⁺), and κ-carrageenan (KC) to form a gel matrix loaded with ET. Analyses using advanced techniques like Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) revealed the formation mechanism. Calcium bridges facilitated gel formation through electrostatic interactions between Ca²⁺ and FPF. Furthermore, the addition of KC promoted cross-linking: sulfate ions from KC coordinated with Ca²⁺, and electrostatic interactions occurred between FPF and KC. Following simulated gastrointestinal digestion, the FPF-Ca²⁺-KC-ET composite gel retained its fibrous structure, enabling the sustained release of ET. This controlled release effect was superior to a similar gel formulation lacking the FPF component (FP-Ca²⁺-KC-ET). In conclusion, this research not only advances our understanding of protein nanofiber formation but also offers a promising approach for designing carriers for bioactive substances.