Dendritic Hydrogels with Robust Inherent Antibacterial Properties for Promoting Bacteria-Infected Wound Healing

All-Aqueous Microfluidics Fabrication of Multifunctional Bioactive Microcapsules Promotes Wound Healing

Wound healing involves multiple stages of body responses, including hemostasis, inflammation, cell proliferation, and tissue remodeling. New material design satisfying all demands throughout different stages of wound healing is cherished but rarely discussed. Here we introduce all-aqueous multiphase microfluidics as a novel strategy to fabricate self-assembled, multifunctional alkylated chitosan/alginate microcapsules (SAAMs) as novel therapeutic materials for rapid blood coagulation and wound healing. SAAMs are structurally distinguished by their ultrathin shells with polycationic surface for rapid activation of clotting cascade and their internal porous dextran-rich cores for fast absorption of blood and exudate. These features endow SAAMs with excellent hemostatic properties for acute hemorrhage. Moreover, the alkylated chitosan within the microcapsules exhibits persistent antimicrobial activities against bactericidal infections due to their amphiphilic and cationic surfaces. Besides, cytokines can be safely loaded into the organic-solvent-free microcapsules and released precisely to promote the proliferation of epidermal cells, supporting the subsequent development of granulation tissue and suppression of inflammation in the last stages of wound healing. With the ability to fabricate size-tailored soft microcapsules and to realize time-sequential functions for tissue repairing, the presented "all-aqueous microfluidics generation of multifunctional bioactive SAAMs" create a versatile and robust paradigm for wound treatment.

Effect of Currently Available Nanoparticle Synthesis Routes on Their Biocompatibility with Fibroblast Cell Lines

Nanotechnology has acquired significance in dental applications, but its safety regarding human health is still questionable due to the chemicals utilized during various synthesis procedures. Titanium nanoparticles were produced by three novel routes, including Bacillus subtilis, Cassia fistula and hydrothermal heating, and then characterized for shape, phase state, size, surface roughness, elemental composition, texture and morphology by SEM, TEM, XRD, AFM, DRS, DLS and FTIR. These novel titanium nanoparticles were tested for cytotoxicity through the MTT assay. L929 mouse fibroblast cells were used to test the cytotoxicity of the prepared titanium nanoparticles. Cell suspension of 10% DMEM with 1 × 104 cells was seeded in a 96-well plate and incubated. Titanium nanoparticles were used in a 1 mg/mL concentration. Control (water) and titanium nanoparticles stock solutions were prepared with 28 microliters of MTT dye and poured into each well, incubated at 37 °C for 2 h. Readings were recorded on day 1, day 15, day 31, day 41 and day 51. The results concluded that titanium nanoparticles produced by Bacillus subtilis remained non-cytotoxic because cell viability was >90%. Titanium nanoparticles produced by Cassia fistula revealed mild cytotoxicity on day 1, day 15 and day 31 because cell viability was 60−90%, while moderate cytotoxicity was found at day 41 and day 51, as cell viability was 30−60%. Titanium nanoparticles produced by hydrothermal heating depicted mild cytotoxicity on day 1 and day 15; moderate cytotoxicity on day 31; and severe cytotoxicity on day 41 and day 51 because cell viability was less than 30% (p < 0.001). The current study concluded that novel titanium nanoparticles prepared by Bacillus subtilis were the safest, more sustainable and most biocompatible for future restorative nano-dentistry purposes.

Preparation of biodegradable carboxymethyl cellulose/dopamine/Ag NPs cryogel for rapid hemostasis and bacteria-infected wound repair

Massive hemorrhage caused by accident or surgery is a major factor in accidental death. In addition, bacterial infection is also an important threat after bleeding. Cryogels with interpenetrating macroporous structures pose great application prospects in rapid hemostasis and infected wound repair. In this study, cryogels with different pore size are prepared by carboxymethyl cellulose (CMC) and dopamine (DA). The CMC grafted with different DA amounts is crosslinked by free DA through oxidative polymerization at low temperatures to form cryogels with different pore sizes. And the CMC/DA-3 cryogel is chosen as the optimal group for its high porosity, suitable mechanical, and good hemostatic ability. CMC/DA-3 cryogel is loaded with silver nanoparticles (Ag NPs) to prepare hemostatic cryogel with antibacterial properties. Antibacterial tests and animal hemostasis experiments confirm that the CMC/DA-3/Ag cryogel has good antibacterial properties and can finish rapid hemostasis. In the S. aureus infection skin defect model, the wound healing is significantly improved compared with commercial gelatin sponge. In summary, the novel cryogel has great potential in rapid hemostasis and infected wound healing.

Multifunctional hydrogel based on dopamine-modified hyaluronic acid, gelatin and silver nanoparticles for promoting abdominal wall defect repair

Abdominal wall defects are often accompanied by severe infections and complications, creating a significant challenge for clinicians. There is an urgent need to develop a novel wound dressing that can effectively prevent intra-abdominal infection and promote the healing of defective abdominal walls. Based on a hydrogel dressing containing hyaluronic acid (HA) and gelatin (GT), herein we integrated dopamine with a catechol structure to enhance its antioxidant and adherent properties. HA is oxidized to form an aldehyde group, and subsequently grafted with dopamine. The dopamine-modified HA undergoes amidation reaction with GT at different concentrations. In addition, silver nanoparticles (AgNPs) were introduced to the hydrogel to enhance the antibacterial properties. The in vitro studies on GT/DA-HA demonstrated excellent physical and chemical properties, biodegradability, and biocompatibility. In a rat full-thickness skin defect model and a full-thickness abdominal wall defect model, the GT/DA-HA hydrogel could accelerate the healing process by improving wet adhesion, reducing wound inflammation, and promoting angiogenesis and formation of granulation tissues. The multifunctional hydrogel developed in this study shows great potential for treating full-thickness abdominal wall defects.

Progress in Antibacterial Hydrogel Dressing

Antibacterial hydrogel has excellent antibacterial property and good biocompatibility, water absorption and water retention, swelling, high oxygen permeability, etc.; therefore, it widely applied in biomedicine, intelligent textiles, cosmetics, and other fields, especially for medical dressing. As a wound dressing, the antibacterial hydrogel has the characteristics of absorbing wound liquid, controlling drug release, being non-toxic, being without side effects, and not causing secondary injury to the wound. Its preparation method is simple, and can crosslink via covalent or non-covalent bond, such as γ-radiation croFsslinking, free radical polymerization, graft copolymerization, etc. The raw materials are easy to obtain; usually these include chondroitin sulfate, sodium alginate, polyvinyl alcohol, etc., with different raw materials being used for different antibacterial modes. According to the hydrogel matrix and antibacterial mode, the preparation method, performance, antibacterial mechanism, and classification of antibacterial hydrogels are summarized in this paper, and the future development direction of the antibacterial hydrogel as wound dressing is proposed.

Bioactivity of star-shaped polycaprolactone/chitosan composite hydrogels for biomaterials

Recently, our group reported the synthesis and fabrication of composite hydrogels of chitosan (CS) and star-shaped polycaprolactone (stPCL). The co-crosslink of modified stPCL with carboxyl at the end chain (stPCL-COOH) provided good mechanical properties and stability to the composite hydrogels. This research presents the bioactivities of composite hydrogels showing a potential candidate to develop biomaterials such as wound dressing and bone tissue engineering. The bioactivities were the antibacterial activity, cell viability, skin irritation, decomposability, and ability to attach ions for apatite nucleation. The results showed that all the composite hydrogels were completely decomposed within 2 days. The composite hydrogels had better antibacterial activity and higher efficiency to Gram-negative (Escherichia coli) than to Gram-positive (Staphylococcus epidermidis) bacteria. The composite hydrogels were studied for cell viability based on MTT assay and skin irritation on rabbit skin. The results indicated high cell survival more than 80% and no skin irritation. In addition, the results showed that calcium and phosphorous were preferentially attached to the composite hydrogel surface to grow apatite crystal (Ca/P ratio 1.86) compared to attaching to the chitosan hydrogel (Ca/P ratio 1.48) in 21 days of testing.