Advanced molecular interaction in Cu2+-alginate beads with high M/G ratio for the intercalation of Li+ and Mg2+ ions

Mechanism of the G/M ratio and zein in enhancing the mechanical and hydrophobic properties of sodium alginate films

This study developed an edible film based on calcium-crosslinked sodium alginate (SA) using the casting method. The investigation assessed how the α-L-guluronic acid/β-D-mannuronic acid (G/M ratio) and zein addition influence the film's physicochemical properties. Fourier transform infrared spectroscopy and scanning electron microscopy findings suggest that the G/M ratio modulates the film's physicochemical characteristics by altering SA molecular cross-linking strength and the film's network structure density. At a G/M ratio of 0.85, the film exhibits a more uniform network structure, enhanced moisture resistance, hydrophobicity, and mechanical properties. Zein, evenly dispersed within the film matrix, establishes strong hydrogen bonds and electrostatic interactions with SA, enhancing the film's network structure and boosting its thermophysical, mechanical, and moisture resistance characteristics. The study demonstrates that modifying the G/M ratio and incorporating zein enhances the film's mechanical and hydrophobic properties, broadening its potential applications in food packaging.

Calcium Alginate as an Active Device Component for Light-Triggered Degradation of 2D MoS2-Based Transient Electronics

Transient electronics technology has enabled the programmed disintegration of functional devices, paving the way for environmentally sustainable management of electronic wastes as well as facilitating the exploration of novel device concepts. While a variety of inorganic and/or organic materials have been employed as media to introduce transient characteristics in electronic devices, they have been mainly limited to function as passive device components. Herein, we report that calcium (Ca) alginate, a natural biopolymer, exhibits multifunctionalities of introducing light-triggered transient characteristics as well as constituting active components in electronic devices integrated with two-dimensional (2D) molybdenum disulfide (MoS2) layers. Ca2+ ions-based alginate electrolyte films are prepared through hydrolysis reactions and are subsequently incorporated with riboflavin, a natural photosensitizer, for the light-driven dissolution of 2D MoS2 layers. The alginate films exhibit strain-sensitive triboelectricity, confirming the presence of abundant mobile Ca2+ ions, which enables them to be active components of 2D MoS2 field-effect transistors (FETs) functioning as electrolyte top-gates. The alginate-integrated 2D MoS2 FETs display intriguing transient characteristics of spontaneous degradation upon ultraviolet-to-visible light illumination as well as water exposure. Such transient characteristics are demonstrated even in ambient conditions with natural sunlight, highlighting the versatility of the developed approach. This study emphasizes a relatively unexplored aspect of combining naturally abundant polymers with emerging near atom-thickness semiconductors toward realizing unconventional and transformative device functionalities.

Release of encapsulated bioactives influenced by alginate viscosity under in-vitro gastrointestinal model

The physicochemical properties of alginate can affect the release profile of encapsulated bioactives, but this is poorly understood. The influence of alginate viscosity (low- A1, medium- A2 and high- A3) and molecular weight (kDa) on the release of encapsulated bioactives (seaweed and spirulina powder) was investigated in an in-vitro gastrointestinal (GSI) model. Beads encapsulated with A2 at 1% (w/v) have overall higher release of bioactives (protein, phlorotannins and antioxidants) but A3 at 0.5% (w/v) was able to release and absorb similar amount of bioactives with ~10% difference with A2. The relative release of protein, phlorotannins and antioxidant was 96%, 111% and 43% respectively from A2 in gastric digestion. In contrast, protein (165%) and phlorotannins (234%) release was highest from A3 in intestinal phase. These results establish the importance of physicochemical properties of the encapsulating matrix on water retention capacity and their interaction with bioactive material to release into the system.

Subtle influence on alginate gel properties through host–guest interactions between covalently appended cyclodextrin and adamantane units

Host–guest interactions between functionalized alginate chains modulate the physico-chemical properties of alginate gels.