On the Relation between the Viscoelastic Properties of Granular Hydrogels and Their Performance as Support Materials in Embedded Bioprinting.

Granular hydrogels, formed by jamming microgels suspension, are promising materials for three-dimensional bioprinting applications. Despite their extensive use as support materials for embedded bioprinting, the influence of the particle's physical properties on the macroscale viscoelasticity on one hand and on the printing performance on the other hand remains unclear. Herein, we investigate the linear and nonlinear rheology of κ-carrageenan granular hydrogel through small- and large-amplitude oscillatory shear measurements.

Comparative analysis of classic network vs. nanogel junction network in konjac glucomannan/kappa carrageenan hybrid hydrogels.

The three-dimensional network architecture of hydrogels significantly influences their mechanical and physical properties; therefore, understanding them is essential for designing optimized hydrogel-based biomaterials. This study presents a comparative analysis of two hybrid hydrogels composed of konjac glucomannan (KGM) and kappa carrageenan (KCAR) with the same stiffness (5.2-5.

Print-and-Grow within a Novel Support Material for 3D Bioprinting and Post-Printing Tissue Growth.

3D bioprinting holds great promise for tissue engineering, with extrusion bioprinting in suspended hydrogels becoming the leading bioprinting technique in recent years. In this method, living cells are incorporated within bioinks, extruded layer by layer into a granular support material followed by gelation of the bioink through diverse cross-linking mechanisms. This approach offers high fidelity and precise fabrication of complex structures mimicking living tissue properties.

A mucoadhesive patch loaded with freeze-dried liposomes for the local treatment of oral tumors.

Oral cancers affect millions of people globally, with increasing incidences among adults aged 35 and above. Poor drug uptake by lesions in the oral cavity following systemic administration, as well as limited localized treatment modalities for oral tumors, result in poor patient quality of life and high mortality. Here, we describe a solid, dissolvable, bioadhesive alginate patch containing freeze-dried doxorubicin-loaded liposomes as a local treatment for oral tumors located on the tongue.

Insights into the formation mechanisms and properties of pectin hydrogel physically cross-linked with chitosan nanogels.

This study explores hydrogels based on the physical interaction between soluble pectin and chitosan nanogels. A simple technique for creating chitosan nanogels of controllable size was developed based on a two-step process: physical cross-linking with tripolyphosphate (TPP) and chemical cross-linking with genipin. The particles were stable at acidic pH, which allowed hydrogel formation.

Hybrid Acrylated Chitosan and Thiolated Pectin Cross-Linked Hydrogels with Tunable Properties.

We developed and characterized a new hydrogel system based on the physical and chemical interactions of pectin partially modified with thiol groups and chitosan modified with acrylate end groups. Gelation occurred at high pectin thiol ratios, indicating that a low acrylated chitosan concentration in the hydrogel had a profound effect on the cross-linking. Turbidity, Fourier transform infrared spectroscopy, and free thiol determination analyses were performed to determine the relationships of the different bonds inside the gel.

Inclusion of Cross-Linked Elastin in Gelatin/PEG Hydrogels Favourably Influences Fibroblast Phenotype.

The capacity of a biomaterial to innately modulate cell behavior while meeting the mechanical property requirements of the implant is a much sought-after goal within bioengineering. Here we covalently incorporate soluble elastin into a gelatin-poly (ethylene glycol) (PEG) hydrogel for three-dimensional (3D) cell encapsulation to achieve these properties. The inclusion of elastin into a previously optimized gelatin-PEG hydrogel was then evaluated for effects on entrapped fibroblasts, with the aim to assess the hydrogel as an extracellular matrix (ECM)-mimicking 3D microenvironment for cellular guidance.

The effect of freeze-drying on mucoadhesion and transport of acrylated chitosan nanoparticles.

Nanoparticle-based mucosal drug delivery is a promising method to increase the residence time of a drug in the mucosa. It is known that the stability of polysaccharide-based nanoparticles in aqueous solutions is limited, due to hydrolysis; hence the long-term stability of a formulation is usually improved by freeze-drying. The aim of this study was to investigate the effect of cryoprotection and freeze-drying on the physical and chemical properties of mucoadhesive acrylated chitosan (ACS) nanoparticles including the potential of these carriers to deliver drugs.

Shear thinning pectin hydrogels physically cross-linked with chitosan nanogels.

The development of a polymer-nanogel hydrogel based on a pair of polysaccharides is reported for the first time. This new hydrogel exhibits self-healing properties due to physical interactions between soluble pectin chains and chitosan nanogels. The nanogels act as crosslinking agents between pectin chains, leading to the formation of thermos-responsive hydrogel.

Mucoadhesive Hybrid Polymer/Liposome Pastes Based on Modified Polysaccharides.

Mucoadhesive hybrid polymer/liposome paste is a new drug delivery system presenting controllable and tailorable delivery mechanism. By using mucoadhesive material, the delivery can be more specific and local. Here, we present a study investigating the effect of polymer type, concentration, functional end group, and cross-linking on the release profile of nanoliposomes from polymer pastes.

Acrylated Chitosan Nanoparticles with Enhanced Mucoadhesion.

The aim of this study was to investigate the effect of acrylate modification on the mucoadhesion of chitosan at the nanoscale. Nanoparticles were fabricated from acrylated chitosan (ACS) via ionic gelation with tripolyphosphate and were characterized in terms of size, zeta potential, stability, and nanoparticle yield. Chitosan (CS) nanoparticles, serving as a control, were fabricated using the same procedure.

Mucoadhesive alginate pastes with embedded liposomes for local oral drug delivery.

Oral cancers are extremely common among adults with increasing incidences due to human papillomavirus, while treatment modalities are limited. This study aims to develop a new oral mucoadhesive delivery system based on the combination of alginate and liposomes. The polymer provides adhesion properties and induces local release of the drug-loaded carriers, while the liposomes protect the drug from degradation and improve its absorption into the cells.

Alginate modified with maleimide-terminated PEG as drug carriers with enhanced mucoadhesion.

The goal of this study was to generate a new mucoadhesive carbohydrate-based delivery system composed of alginate (Alg) backbone covalently attached to polyethylene glycol (PEG) modified with a unique functional end-group (maleimide). The immobilization of PEG-maleimide chains significantly improved the mucoadhesion properties attributed to thioether bonds creation via Michael-type addition and hydrogen bonding with the mucus glycoproteins. Mucoadhesion studies using tensile and rotating cylinder assays revealed a 3.

Curcumin Protects Skin against UVB-Induced Cytotoxicity via the Keap1-Nrf2 Pathway: The Use of a Microemulsion Delivery System.

Curcumin was found to be beneficial in treating several skin pathologies and diseases, providing antioxidant protection due to its reducing properties and its electrophilic properties (the ability to activate the Nrf pathway and induce phase II cytoprotective enzymes). Nevertheless, clinical applications of curcumin are being hampered by its insufficient solubility, chemical instability, and poor absorption, leading to low efficacy in preventing skin pathologies. These limitations can be overcome by using a nanotechnology-based delivery system.

Pectin-chitosan physical hydrogels as potential drug delivery vehicles.

Pectin-chitosan hydrogels are intriguing and relatively new type of physically crosslinked hydrogels. Here we present for the first time a study exploring the suitability of pectin-chitosan hydrogels to serve as drug carriers and the mechanism controlling the release patterns. Using drug release assays, we demonstrated sustained release of three model drugs (mesalamine, curcumin and progesterone) over a period of 24h in physiological conditions.

A novel role of topical iodine in skin: Activation of the Nrf2 pathway.

For a long time iodine has been used as an active dermal agent in the treatment of inflammatory, immune-mediated and infectious diseases. Moreover, topical iodine application has been reported to provide protection against sulfur-mustard-induced skin lesions, heat-induced and acid-induced skin burns in both haired guinea-pigs and mouse ear swelling models. However, the exact mechanism of action underlying these benefits of iodine has not yet been elucidated.

Acrylated chitosan for mucoadhesive drug delivery systems.

A new mucoadhesive polymer was synthesized by conjugating chitosan to poly(ethylene glycol)diacrylate (PEGDA) via the Michael type reaction. The product was characterized using NMR. Higher PEGDA grafting efficacy was observed with low molecular weight PEGDA (0.

Synthesis of stiffness-tunable and cell-responsive Gelatin-poly(ethylene glycol) hydrogel for three-dimensional cell encapsulation.

Biosynthetic poly(ethylene glycol) (PEG)-based hydrogels have been extensively investigated as extracellular matrix (ECM) mimicking gels as they retain the benefits of both ECM (biological cues) and synthetic hydrogels (tunable mechanical properties). In this article, we developed and characterized a new gelatin-PEG (GP) hydrogel that retains the benefits of gelatin and synthetic hydrogels. In this strategy, the thiolation of gelatin was accomplished by reacting with Traut's reagent; the thiolated gelatin was then conjugated to one end of PEG diacrylate (PEGDA) by Michael-type addition reaction.

PEGDA hydrogels as a replacement for animal tissues in mucoadhesion testing.

Utilization of animal parts in ex-vivo mucoadhesion assays is a common approach that presents many difficulties due to animal rights issues and large variance between animals. This study examines the suitability of two PEGDA (poly(ethylene glycol) diacrylate) based hydrogels to serve as tissue mimetics for mucoadhesion evaluation. One hydrogel, termed PEGDA-QT, was composed of pentaerythritol tetrakis (3-mercaptopropionate) and PEG and contained free thiol groups mimicking those found in natural mucosa.

Mucoadhesive acrylated block copolymers micelles for the delivery of hydrophobic drugs.

Blockpolymer micelles having acrylated end groups were fabricated for the development of mucoadhesive drug loaded vehicle. The critical micelle concentration (CMC) of Pluronic(®) F127 modified with acrylate end groups (F127DA) was found to be similar to that of the unmodified Pluronic(®) F127 (F127). Small angle X-ray scattering verified existence of micelles with an inner core of 4.

Composite chitosan hydrogels for extended release of hydrophobic drugs.

A composite chitosan hydrogel durable in physiological conditions intended for sustained release of hydrophobic drugs was investigated. The design is based on chitosan crosslinked with genipin with embedded biocompatible non-ionic microemulsion (ME). A prolonged release period of 48 h in water, and of 24h in phosphate buffer saline (PBS) of pH 7.

A modified emulsion gelation technique to improve buoyancy of hydrogel tablets for floating drug delivery systems.

The use of buoyant or floating hydrogel tablets is of particular interest in the sustained release of drugs to the stomach. They have an ability to slow the release rates of drugs by prolonging their absorption window in the upper part of the gastrointestinal (GI) tract. In this study we synthesized bioactive hydrogels that have sustainable release rates for drugs in the stomach based on a hydrogel preparation technique that employs emulsifying surfactants.

Designing a biocompatible hydrogel for the delivery of mesalamine.

A new design for nanocomposite hydrogels based on cross-linked chitosan for the delivery of mesalamine is presented. To enhance drug loading in chitosan, the mineral montmorillonite was incorporated into the matrix. The exfoliated silica montmorillonite nanosheets form interactions with both chitosan and mesalamine, which affect the hydrogel's drug release mechanism and swelling properties.

Nitroxide delivery system for Nrf2 activation and skin protection.

Cyclic nitroxides are a large group of compounds composed of diverse stable radicals also known as synthetic antioxidants. Although nitroxides are valuable for use in several skin conditions, in in vivo conditions they have several drawbacks, such as nonspecific dispersion in normal tissue, preferential renal clearance and rapid reduction of the nitroxide to the corresponding hydroxylamine. However, these drawbacks can be easily addressed by encapsulating the nitroxides within microemulsions.

The dramatic effect of small pH changes on the properties of chitosan hydrogels crosslinked with genipin.

We report on intriguing new phenomena related to the creation of chitosan hydrogels crosslinked with genipin. We found that the reaction between chitosan and genipin is very slow, sometimes requiring more than four days until completed. Further, we discovered that altering the pH within the small range of 4.