Nucleoside-Based Cross-Linkers for Hydrogels with Tunable Properties

A Gas Therapy Strategy for Intestinal Flora Regulation and Colitis Treatment by Nanogel-Based Multistage NO Delivery Microcapsules

Current approaches to treating inflammatory bowel disease focus on the suppression of overactive immune responses, the removal of reactive intestinal oxygen species, and regulation of the intestinal flora. However, owing to the complex structure of the gastrointestinal tract and the influence of mucus, current small-molecule and biologic-based drugs for treating colitis cannot effectively act at the site of colon inflammation, and as a result, they tend to exhibit low efficacies and toxic side effects. In this study, nanogel-based multistage NO delivery microcapsules are developed to achieve NO release at the inflammation site by targeting the inflammatory tissues using the nanogel. Surprisingly, oral administration of the microcapsules suppresses the growth of pathogenic bacteria and increases the abundance of probiotic bacteria. Metabolomics further show that an increased abundance of intestinal probiotics promotes the production of metabolites, including short-chain fatty acids and indole derivatives, which modulate the intestinal immunity and restore the intestinal barrier via the interleukin-17 and PI3K-Akt signaling pathways. This work reveals that the developed gas therapy strategy based on multistage NO delivery microcapsules modulates the intestinal microbial balance, thereby reducing inflammation and promoting intestinal barrier repair, ultimately providing a new therapeutic approach for the clinical management of colitis.

In Situ Transglutaminase Cross-Linking Improves Mechanical Properties of Self-Assembling Peptides for Biomedical Applications

The development of three-dimensional (3D) biomaterials that mimic natural tissues is required for efficiently restoring physiological functions of injured tissues and organs. In the field of soft hydrogels, self-assembled peptides (SAPs) stand out as distinctive biomimetic scaffolds, offering tunable properties. They have garnered significant attention in nanomedicine due to their innate ability to self-assemble, resulting in the creation of fibrous nanostructures that closely mimic the microenvironment of the extracellular matrix (ECM). This unique feature ensures their biocompatibility and bioactivity, making them a compelling area of study over the past few decades. As they are soft hydrogels, approaches are necessary to enhance the stiffness and resilience of the SAP materials. This work shows an enzymatic strategy to selectively increase the stiffness and resiliency of functionalized SAPs using transglutaminase (TGase) type 2, an enzyme capable of triggering the formation of isopeptide bonds. To this aim, we synthesized a set of SAP sequences and characterized their cross-linking via rheological experiments, atomic force microscopy (AFM), thioflavin-T binding assay, and infrared spectroscopy (ATR-FTIR) tests. The results showed an improvement of the storage modulus of cross-linked SAPs at no cost of the maximum stress-at-failure. Further, in in vitro tests, we examined and validated the TGase capability to cross-link SAPs without hampering seeded neural stem cells (hNSCs) viability and differentiation, potentially leaving the door open for safe in situ cross-linking reactions in vivo.

Characterization of gelling agents in callus inducing media: Physical properties and their effect on callus growth

In plant tissue culture, callus formation serves as a crucial mechanism for regenerating entire plants, enabling the differentiation of diverse tissues. Researchers have extensively studied the influence of media composition, particularly plant growth regulators, on callus behavior. However, the impact of the physical properties of the media, a well-established factor in mammalian cell studies, has received limited attention in the context of plant tissue culture. Previous research has highlighted the significance of gelling agents in affecting callus growth and differentiation, with Agar, Phytagel, and Gelrite being the most used options. Despite their widespread use, a comprehensive comparison of their physical properties and their subsequent effects on callus behavior remains lacking. Our study provides insights into optimizing plant tissue culture media by analyzing the physical properties of gelling agents and their impact on callus induction and differentiation. We compared the phenotypes of calli grown on media composed of these different gelling agents and correlated them to the physical properties of these media. We tested water retention, examined pore size using cryo-SEM, measured the media mechanical properties, and studied diffusion characteristics. We found that the mechanical properties of the media are the only quality correlated with callus phenotype.

Nanogel Particles Based on Modified Nucleosides and Oligosaccharides as Advanced Delivery System

This work addresses the challenge of delivering bioactive molecules by designing biocompatible nanogel particles (NGPs) utilizing rationally modified nature-sourced building blocks: capryl-oligochitosan and oxidized inosine. Capryl substituents endowed the resultant NGPs with membrane-penetration capabilities, while purine-containing inosine allowed H-bond/π-π/π-cation interactions. The prepared NGPs were complexed with carboxyfluorescein-labeled single-stranded oligonucleotide (FAM-oligo) and DsRed-encoding plasmid DNA. The successful delivery of FAM-oligo to the cell cytoplasm of the Nicotiana benthamiana plant was observed. Alexa 555-labeled bovine serum albumin (Alexa 555-BSA) was also efficiently encapsulated and delivered to the plant. In addition to delivering FAM-oligo and Alexa 555-BSA separately, NGPs also successfully co-delivered both biomolecules to the plant. Finally, NGPs successfully encapsulated the drug amphotericin B and reduced its toxicity while maintaining its efficacy. The presented findings suggest that NGPs may become a promising platform for the advanced delivery of bioactive molecules in various applications.

Oligochitosan and oxidized nucleoside-based bioderived hydrogels for wound healing

Herein, we report biocompatible hydrogel for wound healing that was prepared using nature-sourced building blocks. For the first time, OCS was employed as a building macromolecule to form bulk hydrogels along with the nature-sourced nucleoside derivative (inosine dialdehyde, IdA) as the cross-linker. A strong correlation was obtained between the mechanical properties and stability of the prepared hydrogels with a cross-linker concentration. The Cryo-SEM images of IdA/OCS hydrogels showed an interconnected spongy-like porous structure. Alexa 555 labeled bovine serum albumin was incorporated into the hydrogels matrix. The release kinetics studies under physiological conditions indicated that cross-linker concentration could also control the release rate. The potential of hydrogels in wound healing applications was tested in vitro and ex vivo on human skin. Topical application of the hydrogel was excellently tolerated by the skin with no impairment of epidermal viability or irritation, determined by MTT and IL-1α assays, respectively. The hydrogels were used to load and deliver epidermal growth factor (EGF), showing an increase in its ameliorating action, effectively enhancing wound closure inflicted by punch biopsy. Furthermore, BrdU incorporation assay performed in both fibroblast and keratinocyte cells revealed an increased proliferation in hydrogel-treated cells and an enhancement of EGF impact in keratinocytes.