Silver chloride nanoparticles embedded in self-healing hydrogels with biocompatible and antibacterial properties

Preparation of a Bi6O5(OH)3(NO3)5·2H2O/AgBr composite and its long-lasting antibacterial efficacy

A novel Bi₆O₅(OH)₃(NO₃)₅·2H₂O/AgBr (6535BBN/AgBr) composite with long-lasting antibacterial efficacy was prepared. The microstructure of the composite was characterized. AgBr nanoparticles (NPs) were sandwiched in 6535BBN nanosheets (NSs) or loaded on their surfaces. The utilization of 6535BBN as carriers contributed to the long-term lasting antibacterial activity of the composite after storage in water or 0.9% NaCl. The antibacterial activity was evaluated by inhibition zones against E. coli. The inhibition zone diameters of 6535BBN/AgBr stored in water for 0 h, 8 h, 16 h, and 48 h were measured as 22.50, 21.71, 20.43, and 20.29 mm, respectively. The activity of the composite after storage in water for 48 h remained 90.2% of that in the beginning. After storing in 0.9% NaCl for 16 h, the activity was determined to be 90.1% of that in the beginning. In comparison with the rapid decrease in the antibacterial activity of pure AgBr, the slow reduction of 6535BBN/AgBr after storage indicates long-lasting efficacy. The excellent dispersion states of 6535BBN/AgBr powders after storage in solutions were revealed, and the positive relationship between the dispersion state and its long-lasting antibacterial activity was suggested. Based on the unique load-on-carrier (LOC) structure, the long-lasting antibacterial performance was promoted by the synergy of the sharp-edge-cutting effect of 6535BBN NSs, prolonged ROS antibacterial effect, and restrained sterilization effects of silver ions caused by their slow release.

Strategies to design extrinsic stimuli-responsive dental polymers capable of autorepairing

Objectives

For many years, the requirements for dental polymers were limited to inertially filling the cavity and restoring form, function, and esthetics. Inorganic filler systems were widely enhanced to maximize the mechanical properties and optimize finishing and polishing procedures. The development of alternative photoinitiator systems also improved the carbon-carbon double bond conversion, increasing biocompatibility, wear, and stain resistance. However, despite laudable progress, the clinical life span of dental restorations is still limited, and their replacement is the most common procedure in dental offices worldwide. In the last few years, the development of materials with the potential to adapt to physiological stimuli has emerged as a key step to elevating dental polymers to a higher excellence level. In this context, using polymeric networks with self-healing properties that allow for the control of the propagation of microcracks is an appealing strategy to boost the lifetime of dental restorations. This review aims to report the current state-of-the-art of extrinsic self-healing dental polymers and provide insights to open new avenues for further developments. General classification of the self-healing polymeric systems focusing on the current extrinsic strategies used to inhibit microcracks propagation in dental polymers and recover their structural integrity and toughness are presented.

Search Strategy

An electronic search was perfomed using PubMed, Google Scholar, and Scopus databases. Only studies published in English on extrinsic self-healing polymeric systems were included.

Overall Conclusions

Self-healing materials are still in their infancy in dentistry, and the future possibilities are almost limitless. Although the mouth is a unique environment and the restorative materials have to survive chemical, physical, and mechanical challenges, which limits the use of some strategies that might compromise their physicochemical performance, there are countless untapped opportunities to overcome the challenges of the current systems and advance the field.

Synergic adhesive chemistry-based fabrication of BMP-2 immobilized silk fibroin hydrogel functionalized with hybrid nanomaterial to augment osteogenic differentiation of rBMSCs for bone defect repair

Bone defect repair and tissue engineering is specifically challenging process because of the distinctive morphological and structural behaviours of natural bone with complex healing and biochemical mechanisms. In the present investigation, we designed dopamine adhesive chemistry-based fabrication of silk fibroin hydrogel (SFD) with incorporation of nano-hydroxyapatite (nHA)-graphene oxide (GO) hybrid nanofillers with well-arranged porous morphology immobilized with bone morphogenic protein-2 (BMP-2) for the effective in vitro rabbit bone marrow derived mesenchymal stem cells loading compatibility and in vivo new bone regrowth and collagen deposition ability. We have achieved bone-specific hydrogel scaffolds with upgraded structural features, mechanical properties and particularly promoted in vitro osteogenic differentiation and compatibility of rabbit bone marrow mesenchymal stem cells (rBMSCs). Structural and microscopic analyses established greater distributions of components and well-ordered and aligned porous structure of the hydrogel network. In vivo result of new bone regrowth was promisingly higher in the Bm@nHG-SFD hydrogel (85%) group as compared to the other treatment groups of nHG-SFD (77%) and nH-SFD (64%) hydrogel. Overall, we summarized that morphologically improved hydrogel material with immobilization of BMP-2 could be have more attentions for new generation bone regeneration therapies.

Injectable nanofiber-polysaccharide self-healing hydrogels for wound healing

Injectable self-healing hydrogels of natural polysaccharides that mimic the extracellular matrix to promote cellular growth are attractive materials for wound healing. Here, a novel hydrogel was fabricated based on carboxymethyl chitosan (CS) and aldehyde functionalized sodium alginate via Schiff base reaction. To enhance the hydrogel's properties, carboxymethyl-functionalized polymethyl methacrylate (PMAA) short nanofibers were obtained through sodium hydroxide-treated polymethyl methacrylate nanofibers, and added to a CS solution. Gelation time was determined for different hydrogels including 0-5 mg/mL PMAA short nanofibers. The nanofiber hydrogels were tested for their injectability and self-healing abilities and were demonstrated to be easily injectable with excellent self-healing abilities. Additionally, in vitro cytocompatibility experiments, good interaction between the cultured cells and hydrogels was seen. Further, the polysaccharide hydrogel containing short PMMA nanofibers significantly facilitated wound healing in rats compared with the polysaccharide hydrogel and control groups. Thus, the developed hydrogel has great potential for wound healing applications.

Novel fabrication of antibiotic containing multifunctional silk fibroin injectable hydrogel dressing to enhance bactericidal action and wound healing efficiency on burn wound: In vitro and in vivo evaluations

The development of biologically active multifunctional hydrogel wound dressings can assist effectively to wound regeneration and also has influenced multiple functions on wound injury. Herein, we designed a carbon-based composited injectable silk fibroin hydrogel as multifunctional wound dressing to provide effective anti-bacterial, cell compatibility and in vivo wound closure actions. Importantly, the fabricated injectable hydrogel exhibit sustained drug delivery properties, anti-oxidant and self-healing abilities, which confirm that composition of hydrogel is highly beneficial to tissue adhesions and burn wound regeneration ability. Frequently, designed injectable hydrogel can be injected into deep and irregular burn wound sites and would provide rapid self-healing and protection from infection environment with thoroughly filled wound area. Meanwhile, incorporated carbon nanofillers improve injectable hydrogel strength and also offer high fluid uptake to hydrogel when applied on the wound sites. In vitro MTT cytotoxicity assay on human fibroblast cell lines establish outstanding cytocompatibility of the injectable hydrogel and also have capability to support cell growth and proliferations. In vivo burn wound animal model results demonstrate that the hydrogel dressings predominantly influenced enhanced wound contraction and also promoted greater collagen deposition, granulation tissue thickness and vascularization. This investigation's outcome could open a new pathway to fabricate multifunctional biopolymeric hydrogel for quicker burn wound therapy and effectively prevents microenvironment bacterial infections.