Xingxun Liu

Although the mechanical strength of hydrogels has been significantly improved in recent years, failure still readily occurs with defects, indicating their low fracture toughness and restricted practical applications in flexible electronics and biomedicine. To obtain both high strength and high fracture toughness, a strategy is proposed inspired by the ancient Chinese flood‑control philosophy of “channeling rather than blocking”, in which a balance between chemical cross-linking and chain entanglements is established for chemically cross-linked single‑network hydrogels with high reliability. Polyacrylic acid hydrogel with low chemical cross-linking density and moderate entanglements is used as a model system to realize excellent notch resistance and puncture resistance. This self‑regulating hydrophilic polymer network can effectively channel stress concentration within the hydrogel, thereby blunting the notch and arresting crack propagation, thus ensuring the hydrogel reliability. Such hydrogels possess outstanding ultra‑stretchability and damage resistance, including a fracture toughness of 33,000 J/m2 and a centimeter-scale fractocohesive length of over 3 cm. Furthermore, the introduction of multifunctional physical cross-linking to replace partial entanglements can also yield high strength and damage tolerance without using high monomer content. The effect of monomer side groups on hydrogel reliability was also systematically investigated followed by proposing a general design strategy that a hydrophilic polymer network with chain flexibility is equally critical. This study demonstrates that the “channeling” strategy rather than “blocking” can effectively overcome the strength-toughness trade-off, providing a facile and effective method for preparing highly reliable hydrogels.

Resistant starch (RS) is a nondigestible carbohydrate that serves as a prebiotic and is fermented by colonic bacteria to produce short-chain fatty acids (SCFAs). Here, in vitro digestion-derived residues (RSs) from five high-amylose starches (HASs; four RS2 and one RS3) were evaluated for their effects on microbiota composition and SCFA production using a simulated colonic fermentation model inoculated with human fecal microbiota. RSs with more amorphous structures and lower short-range order generated the highest SCFA levels and promoted the growth of the primary RS degrader Bifidobacterium adolescentis. In contrast, RSs with higher resistance to digestion and retained B-type crystallinity favored propionate-associated taxa, including Veillonella spp. and Bacteroides spp., whereas less resistant RSs promoted butyrate-producing taxa such as Clostridium spp. These results suggest that structural features of RS are associated with differences in microbial composition and metabolic activity, providing insights into the design of HAS-based dietary fibers with targeted prebiotic functions.

The amphiphilic nature of octenyl succinic anhydride (OSA)[1]-modified starch enables effective emulsion stabilization through its balanced hydrophilic–hydrophobic structure. In this study, five new OSA-starches (OSA-1 to OSA-5) with distinct molecular characteristics were systematically characterized to evaluate their interfacial behaviors and encapsulation performance. Emulsions were subjected to single droplet drying (SDD) to simulate spray drying, and the influence of core-to-wall ratios and drying temperatures on particle formation and functional properties was investigated. Results shows that the core-to-wall ratio significantly affected particle morphology, while drying temperature modulated solubility and encapsulation efficiency. OSA-1 exhibited superior drying performance and encapsulation efficiency at a core-to-wall ratio of 1:3. A drying temperature of 70 °C was found to reduce core material precipitation and enhance solubility of the dried particles. These findings elucidate the structure–function relationship of OSA-starch emulsions during drying and provide practical guidance for the development of stable microcapsules using OSA-starch as a wall material.

Anthocyanins and starch are both important components of sweetpotato root tubers, and the effect of anthocyanin mutation on starch properties remains unknown. In this study, purple-fleshed sweetpotato Ningzishu4 and its natural mutant yellow-fleshed sweetpotato were selected for research to eliminate the interference of genotype background. Anthocyanin mutation increased soluble sugar content from 13.2 % to 19.9 % and starch content from 54.1 % to 60.5 %. Although there was no effect on starch morphology and crystalline type, the mutant significantly increased amylose content as well as the A chains and B3+ chains of amylopectin, while decreasing the granule size, relative crystallinity and lamellar peak intensity. The structural properties can be attributed to the changes of starch biosynthesis-related genes relative expression level. The starch from Ningzishu4 and its mutant had difference in gelatinization temperature, peak viscosity, final viscosity, and digestion properties. The present research demonstrated that anthocyanin mutation can significantly affect the starch physicochemical properties, potentially enhancing sweetpotato functionality for various applications.