Actuating, shape reconstruction, and reinforcement of galactomannan-based hydrogels by coordination bonds induced metal ions capture

Progress in galactomannan-based materials for biomedical application

Galactomannan-based biomaterials display a unique behavior in aqueous media due to their mechanical, rheological and solubility properties, which are increasingly attracting their applicability into the biomedical area. The physical-chemical features of galactomannans extracted from different botanical sources provide diverse applicability for the developed systems, which can deliver active substances and be applied in wound healing and bone replacement. Galactomannans have an essential biological role and can be easily chemically modified due to their reactive chemical structure. Besides, their biocompatibility and capacity to be applied in the form of film, hydrogel, micro, nanoparticles, and printed material, could revolutionize personalized medicine. Scientists are investigating ways to functionalize galactomannans with bioactive molecules to enhance their biological performance. This is the first review of galactomannans that combines their chemical modifications with biological activities, presenting various biomaterial possibilities with a focus on biomedical applications. The rising demand for renewable-source materials in the medical field underscores their importance, driving ongoing research to explore their full capabilities. As studies progress, the scope of clinical applications for galactomannan-based materials is expected to broaden. To maximize the bioactive potential of galactomannan-based materials, emphasis should be placed on clinical translation to facilitate its effective incorporation into biomedical applications.

Pullulan fermented by Aureobasidium melanogenum TZ-FC3 for the preparation of self-healing, adhesive, injectable and antibacterial pullulan/PVA/borax hydrogel

Natural polymer hydrogels, such as pullulan-based hydrogels, offer significant advantages over synthetic materials due to their thermal stability, film-forming capacity, solubility, adhesiveness, and antioxidant properties. In this study, the strain Aureobasidium melanogenum TZ-FC3, which produces a high level of pullulan, was successfully isolated from the mangrove ecosystems of Guangdong Province, China. 66.01 ± 1.10 g/L pullulan without melanin was produced by the TZ-FC3 strain within 120 h at flask level. Pullulan fermented by A. melanogenum TZ-FC3 was added to enhance the hydrogen bond network within the pullulan/PVA/borax hydrogels (P-2, P-3 and P-4 hydrogels) to improve mechanical strength and crosslinking density of PVA/borax hydrogel (P-1 hydrogel). Compared to the P-1 hydrogel, the P-2 hydrogel exhibited a 65.4 % increase in tensile strain, a remarkable 694.03 % increase in tensile strength and improved the degree of internal crosslinking. Additionally, the pullulan/PVA/borax hydrogels demonstrated excellent self-healing properties, adhesion, injectability, and antibacterial activity. The preparation process of pullulan/PVA/borax hydrogels is straightforward and effective, suggesting broad industrial applicability and underscoring their potential as next-generation materials for advanced healthcare solutions.

Biomimetic construction of environmental-tolerant composite hydrogels based on galactomannan for tough, flexible and conductive sensors

Sustainable composite hydrogel materials with harsh environmental adaption and tolerance capability have received considerable interests but still remain as challenges. In this work, biomimetic strategy was adapted for construction of three-dimensional galactomannan (GM) hydrogels with intercalation of flexible polymer chains polyethyleneimine (PEI), biomacromolecules tannin acid (TA) and CeO2 nanoparticles (NPs). The hydrogels cross-linked with double-networks (DN) present not only pH-responsive water absorption property, but also boosted mechanical strength with highest toughness of 326 kJ/m3 and Young's modulus of 220 kPa. Self-healing and anti-freezing capabilities were revealed for the hydrogels by maintaining of fracture elongation (23 %) and fracture strength (250 kPa). TA, CeO2 NPs as well as the amide groups in PEI of the hydrogels introduced excellent bacterial prohibition performance on both Bacillus subtilis (B. subtilis) and Escherichia coli (E. coli). Also, due to the existence of the free ions, the hydrogels exhibited electric conductive properties, with wide-range high sensitivity and long-time conductive stability. In addition, various tensile strain degrees were related to the conductive resistance values, and the great recovery performance was proved by cyclic tensile-conductive tests for 3000 times. Therefore, the proposed GM-based hydrogels displayed great potentials as strain sensors that are adaptable and tolerant to various environmental conditions.

Stretchable and fatigue resistant hydrogels constructed by natural galactomannan for flexible sensing application

Exploration of sustainable and functional materials from biomolecules has received much interest, while the limited mechanical property and possible bacterial contamination were proved to be their major shortages. Here, we proposed novel double network (DN) hydrogels based on galactomannan (GM) polysaccharide as backbone. Folic acid (FA) and polyacrylamide (PAM) were introduced to form hydrogen bond linkages and covalent bond networks respectively. The three-dimensional hydrogel networks showed greatly improved mechanical strength. Impressive compressive fatigue resistance was present for 100 cycles' compression forming only 0.7 % shape deformation. The phenomenon was mainly attributed to promoted stress-bearing and energy dissipation from the DN cross-linking. The GM hydrogels also exhibited good electronic conductivity and excellent anti-bacterial capabilities with inhibition against more than 80 % of E. coli., attributing to the tunable attachments of FA. Thus, we provided multi-functional hydrogels of high potential serving as anti-fatigue/bacterial and conductive strain sensors on the fields of wearable devices.

Diffusion of water and protein drug in 1,4-butanediol diglycidyl ether crosslinked galactomannan hydrogels and its correlation with the physicochemical properties

The aim of the present study was to obtain a better and safer galactomannan-based material for drug release applications. A novel epoxy-crosslinked galactomannan hydrogel (EGH) was prepared from guar gum using 1,4-butanediol diglycidyl ether as a crosslinking agent. The diffusion rate constant of water molecules in freeze-dried EGH positively correlated with water uptake/equilibrium swelling rate (WU/ESR), and the water molecules participated in Fickian diffusion. The ESR, WU/ESR, and bovine serum albumin (BSA) loading capacity of a customized EGH with a crosslinking density of 48.9% were 48.7 ± 0.15 g/g, 95.3%, and 56.4 mg/g, respectively. The release of BSA from freeze-dried EGH was affected by the WU/ESR and the pH; the release equilibrium time was ~40 h at pH 1.2, decreasing to ~24 h at pH 7.4. Furthermore, the cumulative release rate increased from 63.5% to 80.7% and the t₅₀ decreased from 59 to 41 min upon changing from the acidic to basic pH. The release process conformed to the Ritger-Peppas and Hixson-Crowell models, and represented Fickian diffusion and chain relaxation. The EGH showed no cytotoxicity toward HeLa cells. Together, these results demonstrate the properties of a novel galactomannan-based hydrogel that can potentially be employed as a vehicle for drug delivery.