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Trees grow by coupling the transpiration‐induced nutrient absorption from external sources and photosynthesis‐based nutrient integration. Inspired by this manner, we designed a class of polyion complex (PIC) hydrogels containing isolated liquid‐filled voids for growing texture surfaces. The isolated liquid‐filled voids were created via irreversible matrix reconfiguration in a deswelling‐swelling process. During transpiration, these voids reversibly collapse to generate negative pressures within the matrices to extract polymerizable compounds from external sources and deliver them to the surface of the samples for photopolymerization. This growth process is spatial‐controllable and can be applied to fabricate complex patterns consisting of different compositions, suggesting a new strategy for making texture surfaces. [ABSTRACT FROM AUTHOR]

Developing a novel approach for the administration of catechin that ensures sustained bioactivity, even at low doses, is crucial. In this regard, hydrogels were synthesized by polyion complexation of carboxymethyl cellulose (CMC) and chitosan (CS) grafted with epigallocatechin gallate (EGCG-g-CS), which can maintain enduring antioxidant activity. We initially synthesized grafted chitosan with various grafting ratios using a free-radical grafting method. Polyionic complexes were formed by ionic bonding of the amino groups in EGCG-g-CS with the carboxyl groups in CMC. After lyophilization, a hydrogel with a porous structure was obtained. Scanning electron microscopy (SEM), thermogravimetric differential thermal analysis (TG–DTA), and Fourier transform infrared (FT-IR) analyses of the gel structures were conducted. The swelling properties and porosity of the hydrogels were affected by the grafting ratio. The hydrogel gradually released EGCG under low pH conditions owing to chitosan solubilization, resulting in hydrogel disintegration. Additionally, the hydrogels demonstrated cell adhesion and viability. This study suggests that bio-based materials have potential as pH-dependent catechin-releasing materials. Preparation of hydrogel using catechin-grafted chitosan and carboxymethyl cellulose [ABSTRACT FROM AUTHOR]

Hydrogels are biomaterials frequently used as carrier systems for wound care, tissue engineering, and local drug applications. Our study aimed to prepare and characterize hydrogels using chitosan and sodium alginate through pH modification. Mechanical properties (hardness, adhesiveness, cohesiveness, compressibility, and elasticity), viscosity, surface morphology, and cytotoxicity of polyion complex hydrogels containing different ratios of sodium alginate and chitosan were investigated. Mechanical properties were determined with a texture analyzer. The viscosity values of hydrogels varied between 12235 and 40743.3 cP. Hydrogel samples absorbed water up to 1000 – 1400% of their weight. The effect of pH and polymer concentration on the structural and mechanical properties of alginate-chitosan hydrogels was demonstrated. The findings showed that the decrease in pH improved the mechanical properties of alginate-chitosan hydrogels and increased the viscosity. The concentrations of chitosan and sodium alginate also altered the properties of hydrogels depending on pH. The formulation H5, which had the highest polymer ratio (3%) and lower pH, showed the highest hardness (0.285 ± 0.018 N), adhesiveness (0.824 ± 0.042 N. s), and compressibility (1.334±0.020 N.mm) values. The results showed that the prepared alginate-chitosan hydrogels are not cytotoxic (cell viability of over 80% in L-929 cell line) and safe for use in living organisms. [ABSTRACT FROM AUTHOR]

Herein, we report the fabrication of a polyion complex hydrogel from two oppositely charged derivatives of cellulose nanofibrils (CNF). CNF was produced from dissolving pulp through subsequent periodate oxidation, chemical modification, and microfluidization. Three different durations for periodate oxidation (30 min, 120 min, and 180 min) resulted in three different aldehyde contents. Further, two types of chemical modifications were introduced to react with the resulting aldehydes: chlorite oxidation to yield anionic CNF with carboxylic acid groups (DCC) and imination with Girard’s reagent T to yield cationic CNF containing quaternary ammonium groups (CDAC). Functional group contents were assessed using conductometric titration and elemental analysis, while nanofibril morphologies were assessed using atomic force microscopy (AFM). Longer durations of periodate oxidation did not yield different width profile but was found to decrease fibril length. The formation of self-standing hydrogel through mixing of DCC and CDAC dispersions was investigated. Oscillatory rheology was performed to assess the relative strengths of different gels. Self-standing hydrogels were obtained from mixture of DCC180 and CDAC180 dispersions in acetate buffer at pH 4 and 5 at a low concentration of 0.5% w/w that displayed approximately 10-fold increase in storage and loss moduli compared to those of the individual dispersions. Self-standing gels containing doxorubicin (an anticancer drug) displayed pH-responsive release profiles. At physiological pH 7.4, approximately 65% of doxorubicin was retained past a burst release regime, while complete release was observed within 5 days at pH 4. Biocompatibility of DCC180, CDAC180, and their mixture were investigated through quantification of the metabolic activity of NIH3T3 cells in vitro . No significant cytotoxicity was observed at concentrations up to 900 µg/mL. In short, the nanocellulose-based polyion complex hydrogels obtained in this study are promising nature-derived materials for biomedical applications. Statement of Significance We demonstrate that polyion complex can be formed between two cellulose nanofibrils containing complementary charges. To the best of our knowledge, this is the first time that polyion complex formation between complementarily-modified cellulose nanofibrils has been reported, and the results may lead to new ideas on applications of the very promising nanocellulosic materials. The polyion complex helps form a self-standing network that is demonstrated to provide controlled and pH-responsive release of doxorubicin. Particularly, the report explores the connection between the physical properties of functionalizable nanocellulosic materials and their potential biomedical applications. Thus, the study encompasses several broad fields of materials science and engineering, chemistry, and biomedical science that we believe is in line with the readers’ interests. [ABSTRACT FROM AUTHOR]

A novel hyaluronic acid (HA)-based hydrogel was prepared through polyion complex (PIC) formation between cationic polylactide (PLA)-based microspheres (MS+) and hyaluronic acid (HA-) as an anionic polyelectrolyte. The MS+ and HA formed a biodegradable PIC hydrogel (HA-/MS+) when mixed in aqueous media. The swelling behavior and mechanical properties of the PIC hydrogel could be controlled by changing the charge ratio between HA- and MS+. In addition, the HA-/MS+ PIC hydrogel resulted in a lower inflammatory response compared with a collagen hydrogel in vivo. [ABSTRACT FROM AUTHOR]