Thermogelling 3D Systems towards Stem Cell-Based Tissue Regeneration Therapies

Fluorescent antimicrobial hydrogel based on fluorophore N-doped carbon dots originated from cellulose nanocrystals

The current study represents a unique fabrication strategy for preparation of fluorescent hydrogels via incorporation of fluorescent quantum dots (QDs) as fluorophore entities into chitosan as a gelling matrix. QDs identified as carbon quantum dots (CQDs) & nitrogen containing carbon quantum dots (NCQDs) were preliminary synthesized from cellulose nanocrystals (CNCs) and cationic cellulose nanocrystals (CCNCs), respectively. Cationic CNCs was prepared via chemical grafting with poly-di-allyl dimethyl ammonium chloride (CNCs-g-poly-DADMAC) through free chain polymerization reaction. Additionally, both of the prepared CQDs & NCQDs were impregnated in 3D interpenetrating network of chitosan for preparation of microbicide/florescent hydrogels (CQDs@Chs hydrogel & NCQDs@Chs hydrogel). The represented data revealed that, exploitation of cationic CNCs resulted in preparation of NCQDs with more controllable size and superior photoluminescence. Moreover, the increment in concentration of CNCs reflected in nucleation of enlarged QDs, at variance of CCNCs, whereas, increment of concentration resulted in significantly smaller-sized QDs. Size distribution of CQDs ingrained from 2% CNCs was estimated to be 8.2 nm, while, NCQDs ingrained from 2% CCNCs exhibited with size distribution of 3.8 nm. The prepared florescent CQDs@Chs hydrogel & NCQDs@Chs hydrogel showed excellent antimicrobial performance and the diameter of inhibition zone was estimated to be 31 mm, 26 mm & 22 mm against E. Coli, S. Aureus & C. Albicans with CQDs@Chs, respectively. Whereas, treatment of the as-mentioned microbial strains with NCQDs@Chs resulted in detection of inhibition zone diameter to be significantly higher as 34 mm, 28 mm & 25 mm for E. Coli, S. Aureus & C. Albicans, respectively. In a conclusion, cationic CNCs showed seniority in nucleation of QDs with significantly higher photoluminescence and microbicide activities.

3D culture applied to reproduction in females: possibilities and perspectives

In vitro cell culture is a well-established technique present in numerous laboratories in diverse areas. In reproduction, gametes, embryos, and reproductive tissues, such as the ovary and endometrium, can be cultured. These cultures are essential for embryo development studies, understanding signaling pathways, developing drugs for reproductive diseases, and in vitro embryo production (IVP). Although many culture systems are successful, they still have limitations to overcome. Three-dimensional (3D) culture systems can be close to physiological conditions, allowing greater interaction between cells and cells with the surrounding environment, maintenance of the cells' natural morphology, and expression of genes and proteins such as in vivo. Additionally, three-dimensional culture systems can stimulated extracellular matrix generating responses due to the mechanical force produced. Different techniques can be used to perform 3D culture systems, such as hydrogel matrix, hanging drop, low attachment surface, scaffold, levitation, liquid marble, and 3D printing. These systems demonstrate satisfactory results in follicle culture, allowing the culture from the pre-antral to antral phase, maintaining the follicular morphology, and increasing the development rates of embryos. Here, we review some of the different techniques of 3D culture systems and their applications to the culture of follicles and embryos, bringing new possibilities to the future of assisted reproduction.

Injectable PTHF-based thermogelling polyurethane implants for long-term intraocular application

BACKGROUND

Hydrogels show great potential to be used for intraocular applications due to their high-water content and similarity to the native vitreous. Injectable thermosensitive hydrogels through a small-bore needle can be used as a delivery system for drugs or a tamponading substitute to treat posterior eye diseases with clear clinical potential. However, none of the currently available thermosensitive hydrogels can provide intraocular support for up to 3 months or more.

METHOD

In this study, an injectable polytetrahydrofuran (PTHF)-based thermosensitive hydrogel was synthesized by polyurethane reaction. We examined the injectability, rheological properties, microstructure, cytotoxicity, and in vivo compatibility and stability of the hydrogels in rabbit eyes.

RESULTS

We found that the PTHF block type and PTHF component ratio could modulate thermogelation properties of the polyurethane polymers. The PTHF-based hydrogel implants retained normal retinal structure and function. Incorporating bioinert PTHF generated highly biocompatible and more stable thermogels in the vitreous cavity, with gel networks and the presence of polymer still observed after 3 months when other thermogels would have been completely cleared. Moreover, despite lacking hydrolytically cleavable linkages, the polymers could be most naturally removed from the native vitreous by bio-erosion without additional surgical interventions.

CONCLUSION

Our findings suggest the potential of incorporating hydrophobic bioinert blocks to enhance the in vivo stability of supramolecularly associated hydrogels for long-term intraocular applications.

15.4.5 Quinolinones and Related Systems (Update 2022)

Quinolinones, of which the quinolin-4(1H)-one ring system can be highlighted, represent an exciting class of nitrogen heterocycles. The quinolinone motif can be found in many natural compounds and approved drugs for several diseases. This chapter is a comprehensive survey of the methods for the synthesis of quinolin-2(1H)-ones, quinolin-4(1H)-ones, and their thio- and amino derivatives, and is an update to the previous Science of Synthesis chapter (Section 15.4), covering the period between 2003 and 2020.

Graphene-Induced Transdifferentiation of Cancer Stem Cells as a Therapeutic Strategy against Glioblastoma

Glioblastoma (GBM) is an extremely malignant tumor of the central nervous system, characterized by low response to treatments and reoccurrence. This therapeutic resistance is believed to arise mostly from the presence of a subpopulation of tumorigenic stem cells, known as cancer stem cells (CSCs). In addition, the surrounding microenvironment is known to maintain CSCs, thus supporting tumor development and aggressiveness. This review focuses on a therapeutic strategy involving the stem cell trans-differentiating ability of graphene and its derivatives. Graphene distinguishes itself from other carbon-based nanomaterials due to an array of properties that makes it suitable for many purposes, from bioengineering to biomedical applications. Studies have shown that graphene is able to promote and direct the differentiation of CSCs. In addition, potential usage of graphene in GBM treatment represents a challenge in respect to its administration method. The present review also provides a general outlook of the potential side effects (e.g., cell toxicity) that graphene could have. Overall, this report discusses certain graphene-based therapeutic strategies targeting CSCs, which can be considered as prospective effective GBM treatments.

Thermogelling chitosan-based polymers for the treatment of oral mucosa ulcers

Current treatments for oral mucosa-related ulcers use drugs to relieve pain and promote healing, but rarely consider drug resistance to bacterial infection in the microenvironment of the oral cavity or the prevention of bleeding from gingival mucosa ulcers. We herein report an injectable, thermogelling chitosan-based system to address these concerns. An aqueous solution of chitosan-based conjugates (chitosan-g-poly(N-isopropylacrylamide) [CS-g-PNIPAAM] including 1a [CS-g-PNIPAAM with less PNIPAAM] and 1b [CS-g-PNIPAAM with more PNIPAAM], and chitosan-g-poly(N-isopropylacrylamide)-g-polyacrylamide [CS-g-PNIPAAM-g-PAM] 3) could reversibly form semi-solid gels at physiological temperatures for easy application to oral cavity ulcer sites by injection. The chitosan-based conjugate thermogels prepared could inhibit both Gram-positive and Gram-negative bacteria and the two with higher chitosan and poly(N-isopropylacrylamide) contents (1a and 1b) promoted proliferation of gingival fibroblasts in vitro. These two thermogels also exhibited improved blood clotting in an in vivo rat study. Thermogels 1a and 1b effectively promoted ulcer healing and shortened ulcer healing times in an oral gingival mucosa ulcer model using Sprague Dawley (SD) rats. These thermogels showed no obvious toxicity to the main organs of SD rats undergoing gingival ulcer treatment. These results suggest that this antibacterial biomaterial could be a promising injectable therapeutic agent for the treatment for oral mucosa ulcers.

Sustained delivery of anti-VEGFs from thermogel depots inhibits angiogenesis without the need for multiple injections

Polyurethane thermogels show sustained delivery of bioactive anti-VEGFs therapeutics to the eye.