Extracellular Vesicles and Hydrogels: An Innovative Approach to Tissue Regeneration

Extracellular vesicles have emerged as promising tools in regenerative medicine due to their inherent ability to facilitate intercellular communication and modulate cellular functions. These nanosized vesicles transport bioactive molecules, such as proteins, lipids, and nucleic acids, which can affect the behavior of recipient cells and promote tissue regeneration. However, the therapeutic application of these vesicles is frequently constrained by their rapid clearance from the body and inability to maintain a sustained presence at the injury site. In order to overcome these obstacles, hydrogels have been used as extracellular vesicle delivery vehicles, providing a localized and controlled release system that improves their therapeutic efficacy. This Review will examine the role of extracellular vesicle-loaded hydrogels in tissue regeneration, discussing potential applications, current challenges, and future directions. We will investigate the origins, composition, and characterization techniques of extracellular vesicles, focusing on recent advances in exosome profiling and the role of machine learning in this field. In addition, we will investigate the properties of hydrogels that make them ideal extracellular vesicle carriers. Recent studies utilizing this combination for tissue regeneration will be highlighted, providing a comprehensive overview of the current research landscape and potential future directions.

Curcumin-loaded alginate hydrogels for cancer therapy and wound healing applications: A review

Hydrogels have emerged as a versatile platform for a numerous biomedical application due to their ability to absorb a huge quantity of biofluids. In order to design hydrogels, natural polymers are an attractive option owing to their biocompatibility and biodegradability. Due to abundance in occurrence, cost effectiveness, and facile crosslinking approaches, alginate has been extensively investigated to fabricate hydrogel matrix. Management of cancer and chronic wounds have always been a challenge for pharmaceutical and healthcare sector. In both cases, curcumin have been shown significant improvement and effectiveness. However, the innate restraints like poor bioavailability, hydrophobicity, and rapid systemic clearance associated with curcumin have restricted its clinical translations. The current review explores the cascade of research around curcumin encapsulated alginate hydrogel matrix for wound healing and cancer therapy. The focus of the review is to emphasize the mechanistic effects of curcumin with its fate inside the cells. Further, the review discusses different approaches to designed curcumin loaded alginate hydrogels along with the parameters that regulates their release behavior. Finally, the review is concluded with emphasize on some key aspect on increasing the efficacy of these hydrogels along with novel strategies to further develop curcumin loaded alginate hydrogel matrix with multifacet applications.

Modulation of hydrogel networks by metal ions

Self-assembling hydrogels are receiving great attention for both biomedical and technological applications. Self-assembly of protein/peptides as well as organic molecules is commonly induced in response to external triggers such as changes of temperature, concentration, or pH. An interesting strategy to modulate the morphology and mechanical properties of the gels implies the use of metal ions, where coordination bonds regulate the dynamic cross-linking in the construction of hydrogels, and coordination geometries, catalytic, and redox properties of metal ions play crucial roles. This review aims to discuss recent insights into the supramolecular assembly of hydrogels involving metal ions, with a focus on self-assembling peptides, as well as applications of metallogels in biomedical fields including tissue engineering, sensing, wound healing, and drug delivery.

Hydrogels: Properties and Applications in Biomedicine

Hydrogels are crosslinked polymer chains with three-dimensional (3D) network structures, which can absorb relatively large amounts of fluid. Because of the high water content, soft structure, and porosity of hydrogels, they closely resemble living tissues. Research in recent years shows that hydrogels have been applied in various fields, such as agriculture, biomaterials, the food industry, drug delivery, tissue engineering, and regenerative medicine. Along with the underlying technology improvements of hydrogel development, hydrogels can be expected to be applied in more fields. Although not all hydrogels have good biodegradability and biocompatibility, such as synthetic hydrogels (polyvinyl alcohol, polyacrylamide, polyethylene glycol hydrogels, etc.), their biodegradability and biocompatibility can be adjusted by modification of their functional group or incorporation of natural polymers. Hence, scientists are still interested in the biomedical applications of hydrogels due to their creative adjustability for different uses. In this review, we first introduce the basic information of hydrogels, such as structure, classification, and synthesis. Then, we further describe the recent applications of hydrogels in 3D cell cultures, drug delivery, wound dressing, and tissue engineering.

A facile gelator based on phenylalanine derivative is capable of forming fluorescent Zn-metallohydrogel, detecting Zn2+ in aqueous solutions and imaging Zn2+ in living cells

Supramolecular hydrogels are attracting soft materials with potential applications. In this study, we synthesized a facile gelator (named 2-QF) based on phenylalanine derivative with a Quinoline group. 2-QF can assemble to form hydrogels at room temperature in different colors under low pH values. Moreover, 2-QF was triggered to form a yellow metallohydrogel (2-QF-Zn) at high pH by the coordination between 2-QF and Zn²⁺. 2-QF-Zn metallohydrogel showed excellent multi-stimuli responsiveness, especially the reversible "on-off" luminescence switching, as induced by base/acid. In addition, at a low concentration, 2-QF can selectively and visibly identify Zn²⁺ through fluorescence enhancement, and can detect Zn²⁺ at physiological pH as a chemosensor. Remarkably, 2-QF and 2-QF-Zn exhibited an excellent biocompatibility without cell cytotoxicity, and 2-QF is able to penetrate live HeLa cells and image intracellular Zn²⁺ by a turn-on fluorescent response, which makes it a potential candidate for biomedical applications.

A multi-responsive self-healing hydrogel for controlled release of curcumin

A multi-responsive self-healing hydrogel for the controlled release of curcumin has been developed using dynamic boronic acid ester linkages.

Evaluating the role of a urea-like motif in enhancing the thermal and mechanical strength of supramolecular gels

Enhanced thermal and mechanical strength in semicarbazone gels with a urea-like motif obtained by modifying the hydrogen bonding motif of the hydrazone compound.

DAP derived fatty acid amide organogelators as novel carrier for drug incorporation and pH-responsive release

Low-molecular mass fatty acid amide gelators were synthesized using 2,6-diaminopyridine as a linker and alkyl chains of varying lengths. The prepared organogel-elusions are able to trap and release ibuprofen molecule without changing its structure and activity.

Balancing connectivity with function in silver(i) networks of pyridyltriazole (tzpa) ligands results in the formation of a metallogel

A new flexible and divergent 1,2,3-triazol-4-yl-picolinamide (tzpa) ligand 2 and the half-equivalent model ligand 1, both functionalised with pendant 3-pyridyl groups, are reported and their coordination behaviour with silver(i) ions is explored, both in the crystalline phase and through the formation of a supramolecular metallogel. The self-assembly of tzpa ligand 1 with AgCF3SO3 resulted in the formation of a 1D coordination polymer, binding in a bidentate fashion through the pyridyl and triazole nitrogen atoms of the tzpa binding site and a pendant pyridyl nitrogen atom of an adjacent ligand. Doubling the number of metal binding sites in ligand 2, while retaining the same metal binding domain, gives rise to the formation of a supramolecular metallogel on reaction with AgBF4 at 5 wt% in MeCN, possessing self-healing properties.

Fluorescent supramolecular hierarchical self-assemblies from glycosylated 4-amino- and 4-bromo-1,8-naphthalimides

The investigation into the self-assembly formation of the glycan based 4-amino- and 4-bromo-1,8-naphthalimide (Nap) structures1–3is presented.

Unexpected linkage isomerism in chiral tetranuclear bis-tridentate (1,2,3-triazol-4-yl)-picolinamide (tzpa) grids

The synthesis of a chiral bis-tridentate (1,2,3-triazol-4-yl)-picolinamide (tzpa) ligand is described and its coordination chemistry with Cu(NO3)2 and [Cu(MeCN)4]PF6 is explored in the crystalline phase as well as in solution. Chiral [2 × 2] tetranuclear square grid complexes [Cu4(H21)4](NO3)8 and [Cu4(H1)4](PF6)4 were observed, and crystallographically analysed, these being linkage isomers with N4O2 and N5O coordination spheres, respectively. These come about by an unusual in situ amide deprotonation and coordination, which accompanies a CuI → CuII oxidation process.

Glycosylated naphthalimides and naphthalimide Tröger's bases as fluorescent aggregation probes for Con A

We report the synthesis of glycosylated naphthalimide compounds and their application as fluorescent probes for Concanavalin A (Con A) lectin.

Supramolecular phenoxy-alkyl maleate-based hydrogels and their enzyme/pH-responsive curcumin release

Low molecular-weight hydrogelators as stimuli-responsive drug carrier agents in the pharmaceutical field.

Norbornene chaotropic salts as low molecular mass ionic organogelators (LMIOGs)

Phenylalanine functionalised norbornene (9:Na) functions as a potent, low molecular-mass (MW = 333 Da) ionic organogelator with a minimum gelating concentration of 0.5 wt% in THF, i-PrOH, 1,4-dioxane and n-BuOH. Fibrous crystals form in the gel and X-ray crystallography identified a cation mediated helical assembly process controlled by the chirality of the phenylalanine. In addition to excellent gelating properties 9:Na readily forms aqueous biphasic and triphasic systems.

Thermoresponsive double network cryogels from dendronized copolymers showing tunable encapsulation and release of proteins

Thermoresponsive double network cryogels were prepared from OEG-based dendronized copolymers with PVA, which can reversibly capture and release proteins.

Exploring the reversible host–guest chemistry of a crystalline octanuclear Ag(i) metallosupramolecular macrocycle formed from a simple pyrazinylpyridine ligand

High nuclearity Ag(i) assemblies are prepared from simple polytopic ligands, including an octanuclear metallomacrocycle which exhibits reversible and selective guest exchange.

One-step, green synthesis of a supramolecular organogelator based on mellitic triimide for the recognition of aromatic compounds

Mellitic triimide derivatives with N-benzyl groups form conformations with concave cavities, that are capable of including aromatic molecules such as benzene, nitrobenzene, etc. In addition, they act as supramolecular gelators, which enable the detection of aromatic molecules as a gel-sol phase transition.

One-pot facile synthesis of 4-amino-1,8-naphthalimide derived Tröger's bases via a nucleophilic displacement approach

We report here a novel one-pot synthetic strategy for the synthesis of a family of N-alkyl-1,8-naphthalimide derived Tröger's bases (in overall yield of 65–96%) via a nucleophilic substitution reaction.