Temperature-sensitive biodegradable mixed star-shaped block copolymers hydrogels for an injection application

Accelerated, injectable, self-healing, scarless wound dressings using rGO reinforced dextran/chitosan hydrogels incorporated with PDA-loaded asiaticoside

The process of wound healing is intricate and complex, necessitating the intricate coordination of various cell types and bioactive molecules. Despite significant advances, challenges persist in achieving accelerated healing and minimizing scar formation. Herein, a multifunctional hydrogel engineered via dynamic Schiff base crosslinking between oxidized dextran and quaternized chitosan, reinforced with reduced graphene oxide (rGO) is reported. The resulting OQG hydrogels demonstrated injectability to aid in conforming to irregular wound geometries, rapid self-healing to maintain structural integrity and adhesion for intimate integration with wound beds. Moreover, the developed hydrogels possessed antioxidant and antibacterial activities, mitigating inflammation and preventing infection. The incorporation of conductive rGO further facilitated the transmission of endogenous electrical signals, stimulating cell migration and tissue regeneration. In addition, the polydopamine-encapsulated asiaticoside (AC@PDA) nanoparticles were encapsulated in OQG hydrogels to reduce scar formation during in vivo evaluations. In vitro results confirmed the histocompatibility of the hydrogels to promote cell migration. The recovery of the full-thickness rat wounds revealed that these designed OQG hydrogels with the incorporation of AC@PDA nanoparticles could accelerate wound healing, reduce inflammation, facilitate angiogenesis, and minimize scarring when implemented. This multifunctional hydrogel system offers a promising strategy for enhanced wound management and scarless tissue regeneration, addressing the multifaceted challenges in wound care.

Injectable, self-healing, transparent, and antibacterial hydrogels based on chitosan and dextran for wound dressings

One major shortcoming of biopolymeric based wound dressing so far is the lack of an integrated multi-functional system that could provide suitable mechanical strength, fast self-healing, transparency, antibacterial and antioxidant effects. Benefiting from the dynamic and rapid reaction between glycidyl trimethyl ammonium chloride-graft- chitosan (QCS) and aldehyde-dextran (ODex) under physiological conditions, we designed hydrogels (QCS-ODex) with fast in situ gel-forming (< 70 s), porous structure (300-350 μm), stable storage modulus and the loss modulus, suitable swelling capacity (2.465 folds of chitosan), tissue adhesion, transmission property, free radical scavenging capacity, good self-healing behavior, and injectability, inherent antibacterial (against E. coli and S. aureus) and biocompatibility. Furthermore, Baicalein could be in situ encapsulated into QCS-ODex hydrogels, and the release behavior of Baicalein could be regulated by adjusting the ratio of QCS and ODex. The Baicalein-loaded QCS-ODex hydrogel further facilitated free radical scavenging and antibacterial bioactivities due to the cooperative therapeutic effects between QCS-ODex and Baicalein. This study may provide new insights into designing multi-functional QCS-ODex hydrogels with multiple therapeutic effects as a wound dressing.

MSCs-laden silk Fibroin/GelMA hydrogels with incorporation of platelet-rich plasma for chondrogenic construct

Repair of osteochondral defects and regeneration of cartilage is a major challenge. In this work, the mesenchymal stem cells (MSCs)-laden hydrogel was designed using silk fibroin (SF) and gelatin methacrylate (GelMA), to encapsulate platelet-rich plasma (PRP). Initially, GelMA was synthesized, and SF was prepared using silkworm cocoon, then MSCs-laden SF/GelMA (SG) hydrogel was fabricated. The physicochemical properties of the hydrogels were evaluated using Fourier-transform infrared spectroscopy, scanning electron microscope, and rheometry. After hydrogel preparation, the viability of MSCs in the hydrogels was investigated via CCK-8 analysis and fluorescent images. The MSCs-laden SG hydrogel containing PRP was subsequently injected into the cartilage defect area in Sprague Dawley rats. Hematoxylin and eosin (H&E), Masson staining, and Mankin scores evaluation confirmed the new cartilage formation in 8 weeks. The results presented in the study, therefore, showed that the prepared MSCs-laden SG hydrogel loaded with PRP has the potential for cartilage reconstruction, which is crucial to the treatment of knee osteoarthritis.

Enzymatically crosslinked hydrogel based on tyramine modified gelatin and sialylated chitosan

The enzymatically crosslinked hydrogel could replicate the cellular microenvironment for biomedical applications. In the present study, to improve the cytocompatibility of chitosan (CS), sialic acid (SA) was introduced to CS to synthesize sialylated CS (CS-SA), and the tyramine (TA) was grafted to gelatin (G) to obtain TA modified gelatin (G-TA). The successful synthesis of CS-SA and G-TA was confirmed using¹H NMR and UV-Vis absorption spectra. The interpenetrating polymer networks G-TA/CS-SA (GC) hydrogel was then fabricated via blending G-TA and CS-SA solutions and crosslinked using horseradish peroxidase. The storage modulus (G') of the fabricated GC hydrogels with different ratios of G-TA/CS-SA greatly varied during the formation and strain of hydrogels. With the increase of CS-SA concentration from 0% to 2%, the storage modulus of GC hydrogels was also observed to decrease from 1500 Pa to 101 Pa; the water uptake capacity of GC hydrogels increased from 1000% to 4500%. Additionally, the cell counting kit-8 and fluorescent images demonstrated the excellent cytocompatibility of GC hydrogels after culturing with NIH 3T3 cells. The obtained results indicated that the fabricated GC hydrogels might have potential in biomedical fields, such as wound dressing.

Bio-Inspired Hydrogels via 3D Bioprinting

Many soft tissues of the human body such as cartilages, muscles, and ligaments are mainly composed of biological hydrogels possessing excellent mechanical properties and delicate structures. Nowadays, bio-inspired hydrogels have been intensively explored due to their promising potential applications in tissue engineering. However, the traditional manufacturing technology is challenging to produce the bio-inspired hydrogels, and the typical biological composite topologies of bio-inspired hydrogels are accessible completed using 3D bioprinting at micrometer resolution. In this chapter, the 3D bioprinting techniques used for the fabrication of bio-inspired hydrogels were summarized, and the materials used were outlined. This chapter also focuses on the applications of bio-inspired hydrogels fabricated using available 3D bioprinting technologies. The development of 3D bioprinting techniques in the future would bring us closer to the fabrication capabilities of living organisms, which would be widely used in biomedical applications.

Injectable Vaginal Hydrogels as a Multi-Drug Carrier for Contraception

Injectable intravaginal hydrogels could deliver drugs systemically without hepatic first pass effect. This paper focuses on the contraceptive function of an injectable temperature-sensitive four-arm star-shaped poly(D,L-lactic-co-glycolic acid)-b-methoxy poly(ethylene glycol) (4sPLGA-mPEG) block copolymer hydrogels as a carrier of three drugs. In vitro controlled release profiles were investigated via HPLC, and it showed that the cumulative release amounts of indomethacin (IMC), gestodene (GSD), and ethinyl estradiol (EE) from copolymer hydrogels could be regulated by adjusting the lactide/glycolide (LA/GA) mol ratio. In addition, in vitro release profiles of IMC, GSD, and EE well corresponded to Higuchi model. The acute toxicity of copolymer hydrogels loaded with different dosage contents multi-drug was evaluated in vivo. As to the high dosage group, the uterus was hydropic at day 1 and ulcerated at day 5, followed with intestinal adhesion. Regarding the middle dosage group, no festering of tissues was observed and, blood coagulum existed in the uterus at different days. For low dosage group, no significant tissue necrosis was found. Finally, the antifertility experiments confirmed that hydrogels loaded with the multi-drug had an excellent contraceptive effect. The above results indicated that injectable copolymer hydrogel as a multi-drug carrier was promising as a novel contraception method.