Preparation and Characterization of Semi-IPN Cryogels Based on Polyacrylamide and Poly(N,N-dimethylaminoethyl methacrylate); Functionalization of Carrier with Monochlorotriazinyl-β-cyclodextrin and Release Kinetics of Curcumin

Structural, mechanical, antioxidant and antibacterial properties of double cross-linked chitosan cryogels as hosts for thymol

The practical applications of essential oils (EOs) are limited by their hydrophobicity, volatility and instability. To overcome these drawbacks, the incorporation of EOs into porous materials is recommended. Chitosan (CS)-based composite cryogels as hosts for thymol as a volatile model terpenoid were developed using a double cross-linking of CS with glutaraldehyde (GA) and monochlorotriazinyl-β-cyclodextrin (MCT-β-CD), either in one-pot synthesis or through sequential cross-linking, first with GA and then with MCT-β-CD, resulting in CSCAV composites. Cross-linking with GA occurred under cryogelation conditions, while cross-linking with MCT-β-CD took place by heating at 60-80 °C. The composite cryogels were characterized by FTIR, 13C NMR, SEM, EDX, swelling kinetics, and uniaxial compressive tests. The mechanical, antioxidant, and antibacterial properties of composites were optimized by adjusting the concentrations of CS and GA, the initial CS to MCT-β-CD ratio, and the temperature regime. The novel CS-based biocomposites demonstrated sustained compression over 74 %, characteristic of porous materials obtained through cryogelation process. The antioxidant activity of the CSCAV composites revealed almost all composites exhibited over 85 % 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity. The thymol-loaded composites displayed strong antibacterial effectiveness (up to 100 %) towards both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria, with greater inhibition activity observed against S. aureus.

Experimental and Modelling Study of Controlled Release from Dextran-Based Cryogels

In this work, five different dextran-based cryogels for controlled drug release are investigated. Vitamin B12 was used as a model drug for in vitro release tests. Two different drug-loading procedures were adopted, leading to very different drug release curves. Indeed, a fast Fickian release was observed when freeze-dried samples of DEX40PEG360MA and DEX40PEG500MA were infused with the drug after cryogel formation. On the contrary, a slowed highly non-Fickian behavior arises when the drug is loaded before the low-temperature crosslinking step, leading to the cryogel formation. The non-Fickian drug release, observed for all the five different dextran-based cryogels investigated, is actually due to the cryoconcentration phenomenon, modeled with a two-step release process. The proposed transport model accurately predicts experimental release curves characterized by a long lag time, confirming that dextran-based cryogels are suitable for controlled release.

Cryogels: Advancing Biomaterials for Transformative Biomedical Applications

Cryogels, composed of synthetic and natural materials, have emerged as versatile biomaterials with applications in tissue engineering, controlled drug delivery, regenerative medicine, and therapeutics. However, optimizing cryogel properties, such as mechanical strength and release profiles, remains challenging. To advance the field, researchers are exploring advanced manufacturing techniques, biomimetic design, and addressing long-term stability. Combination therapies and drug delivery systems using cryogels show promise. In vivo evaluation and clinical trials are crucial for safety and efficacy. Overcoming practical challenges, including scalability, structural integrity, mass transfer constraints, biocompatibility, seamless integration, and cost-effectiveness, is essential. By addressing these challenges, cryogels can transform biomedical applications with innovative biomaterials.

Chitosan Sponges with Instantaneous Shape Recovery and Multistrain Antibacterial Activity for Controlled Release of Plant-Derived Polyphenols

Biomass-derived materials with multiple features are seldom reported so far. Herein, new chitosan (CS) sponges with complementary functions for point-of-use healthcare applications were prepared by glutaraldehyde (GA) cross-linking and tested for antibacterial activity, antioxidant properties, and controlled delivery of plant-derived polyphenols. Their structural, morphological, and mechanical properties were thoroughly assessed by Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and uniaxial compression measurements, respectively. The main features of sponges were modulated by varying the CS concentration, cross-linking ratio, and gelation conditions (either cryogelation or room-temperature gelation). They exhibited complete water-triggered shape recovery after compression, remarkable antibacterial properties against Gram-positive (Staphylococcus aureus (S. aureus), Listeria monocytogenes (L. monocytogenes)) and Gram-negative (Escherichia coli (E. coli), Salmonella typhimurium (S. typhimurium)) strains, as well as good radical scavenging activity. The release profile of a plant-derived polyphenol, namely curcumin (CCM), was investigated at 37 °C in simulated gastrointestinal media. It was found that CCM release was dependent on the composition and the preparation strategy of sponges. By linearly fitting the CCM kinetic release data from the CS sponges with the Korsmeyer-Peppas kinetic models, a pseudo-Fickian diffusion release mechanism was predicted.

Biodegradable Guar-Gum-Based Super-Porous Matrices for Gastroretentive Controlled Drug Release in the Treatment of Helicobacter pylori: A Proof of Concept

An increase in resistance to key antibiotics has made the need for novel treatments for the gastric colonization of Helicobacter pylori (H. pylori) a matter of the utmost urgency. Recent studies tackling this topic have focused either on the discovery of new compounds to ameliorate therapeutic regimes (such as vonoprazan) or the synthesis of gastroretentive drug delivery systems (GRDDSs) to improve the pharmacokinetics of oral formulations. The use of semi-interpenetrating polymer networks (semi-IPNs) that can act as super-porous hydrogels for this purpose is proposed in the present work, specifically those displaying low ecological footprint, easy synthesis, self-floating properties, high encapsulation efficiency for drugs such as amoxicillin (AMOX), great mucoadhesiveness, and optimal mechanical strength when exposed to stomach-like fluids. To achieve such systems, biodegradable synthetic copolymers containing acid-labile monomers were prepared and interpenetrated with guar gum (GG) in a one-pot polymerization process based on thiol-ene click reactions. The resulting matrices were characterized by SEM, GPC, TGA, NMR, and rheology studies, and the acidic hydrolysis of the acid-sensitive polymers was also studied. Results confirm that some of the obtained matrices are expected to perform optimally as GRDDSs for the sustained release of active pharmaceutical ingredients at the gastrointestinal level, being a priori facilitated by its disaggregation. Therefore, the optimal performance of these systems is assessed by varying the molar ratio of the labile monomer in the matrices.

Recent Advances in Polysaccharide-Based Physical Hydrogels and Their Potential Applications for Biomedical and Wastewater Treatment

Polysaccharides have been widely employed to fabricate hydrogels owing to their intrinsic properties including biocompatibility, biodegradability, sustainability, and easy modification. However, a considerable amount of polysaccharide-based hydrogels are prepared by chemical crosslinking method using organic solvents or toxic crosslinkers. The presence of reaction by-products and residual toxic substances in the obtained materials cause a potential secondary pollution risk and thus severely limited their practical applications. In contrast, polysaccharide-based physical hydrogels are preferred over chemically derived hydrogels and can be used to address existing drawbacks of chemical hydrogels. The polysaccharide chains of such hydrogel are typically crosslinked by dynamic non-covalent bonds, and the co-existence of multiple physical interactions stabilize the hydrogel network. This review focuses on providing a detailed outlook for the design strategies and formation mechanisms of polysaccharide-based physical hydrogels as well as their specific applications in tissue engineering, drug delivery, wound healing, and wastewater treatment. The main preparation principles, future challenges, and potential improvements are also outlined. The authors hope that this review could provide valuable information for the rational fabrication of polysaccharide-based physical hydrogel. The specific research works listed in the review will provide a systematic and solid research basis for the reliable development of polysaccharide-based physical hydrogel. This article is protected by copyright. All rights reserved.

Chitosan-Based Polyelectrolyte Complex Cryogels with Elasticity, Toughness and Delivery of Curcumin Engineered by Polyions Pair and Cryostructuration Steps

Chitosan (CS)-based drug delivery systems (DDSs) are often stabilized by chemical cross-linking. A much more friendly approach to deliver drugs in a controlled manner is represented by polyelectrolyte complexes (PECs) physically stabilized by spontaneous interactions between CS and natural or synthetic biocompatible polyanions. PECs with tunable structures, morphologies, and mechanical properties were fabricated in this paper by an innovative and sustainable strategy. Carboxymethyl cellulose (CMC) or poly(2-acrylamido-2-methylpropanesulfonate sodium salt) were used as aqueous solutions, while CS microparticles were evenly dispersed in the polyanion solution, at pH 6.5, where CS was not soluble. Cryostructuration of the dispersion in two steps (5 min at −196 °C, and 24 h at −18 °C), and freeze-drying at −55 °C, 48 h, conducted to pre-PEC cryogels. Next step was rearrangement of complementary polyions and the complex formation inside the pore walls of cryogels by exposure of the pre-PECs at a source of H⁺. PEC cryogels with impressive elasticity and toughness were engineered in this study by multiple-cryostructuration steps using CMC as polyanion with a molar mass of 250 kDa and an optimum concentration of polyanion and polycation. The performances of PEC cryogels in sustained delivery of anti-inflammatory drugs such as curcumin were demonstrated.

Self-Healing Behavior of Polymer/Protein Hybrid Hydrogels

The paper presents the viscoelastic properties of new hybrid hydrogels containing poly(vinyl alcohol) (PVA), hydroxypropylcellulose (HPC), bovine serum albumin (BSA) and reduced glutathione (GSH). After heating the mixture at 55 °C, in the presence of GSH, a weak network is formed due to partial BSA unfolding. By applying three successive freezing/thawing cycles, a stable porous network structure with elastic properties is designed, as evidenced by SEM and rheology. The hydrogels exhibit self-healing properties when the samples are cut into two pieces; the intermolecular interactions are reestablished in time and therefore the fragments repair themselves. The effects of the BSA content, loaded deformation and temperature on the self-healing ability of hydrogels are presented and discussed through rheological data. Due to their versatile viscoelastic behavior, the properties of PVA/HPC/BSA hydrogels can be tuned during their preparation in order to achieve suitable biomaterials for targeted applications.