Central nervous system toxicity due to an overdose of lidocaine was quickly reversed by intravenous lipid emulsion in our patient.

Bacterial infection and poor cell recruitment are among the main factors that prolong wound healing. To address this, a strategy is required that can prevent infection while promoting tissue repair. Here, we have created a silver nanoparticle-based hydrogel composite that is antibacterial and provides nutrients for cell growth, while filling cavities of various geometries in wounds that are difficult to reach with other dressings. Silver nanoparticles (AgNPs) were synthesized by chemical reduction and characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS), and inductively coupled plasma-mass spectroscopy (ICP-MS). Using varying concentrations of AgNPs (200, 400, and 600 ppm), several collagen-based silver–hydrogel nanocomposite candidates were generated. The impact of these candidates on wound healing was assessed in a rat splinted wound model, while their ability to prevent wound infection from a contaminated surface was assessed using a rat subcutaneous infection model. Biocompatibility was assessed using the standard MTT assay and in vivo histological analyses. Synthesized AgNPs were spherical and stable, and while hydrogel alone did not have any antibacterial effect, AgNP–hydrogel composites showed significant antibacterial activity both in vitro and in vivo. Wound healing was found to be accelerated with AgNP–hydrogel composite treatment, and no negative effects were observed compared to the control group. The formulations were non-cytotoxic and did not differ significantly in hematological and biochemical factors from the control group in the in vivo study. By presenting promising antibacterial and wound healing activities, silver–hydrogel nanocomposite offers a safe therapeutic option that can be used as a functional scaffold for an acceleration of wound healing.

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Introduction Burn wound infections are a serious complication of thermal injury. Among the many factors that may limit effective wound healing in patients with burn, bacterial infection and poor cell recruitment appear as the leading causes for prolonged healing. Thus, a novel strategy that aims to prevent bacterial infection within the wound, while at the same time providing structural scaffolding that promotes endogenous tissue repair, would be of great interest. As a nutritional protective barrier for the wound, we developed a thermosensitive collagen-based matrix called MeshFill (MF) that contains all nutrition required for cell growth with the ability to fill up all the cavities and void areas in wounds regardless of their geometry. In a previous study, MF was successfully combined with partial-thickness mesh grafted skin in a porcine model and improved healing and aesthetic outcomes. In the present work, we report on the development, and in vitro and in vivo testing of a new formulation of MF containing silver nanoparticles (AgNPs), which simultaneously prevent bacterial infection and promote skin regeneration. Methods We fabricated MF/Ag formulation by loading different concentrations of AgNPs in MF hydrogel. The antibacterial activity of MF/Ag formulation against Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PA) was examined in vitro. The wound healing efficacy of the formulation was evaluated in a silicon ring splinted delayed wound healing model in rats. The splinted full-thickness wounds were generated on the back of rats and treated with either MF or MF/Ag with different concentrations of AgNPs or were bandaged with no treatment (NT) as a control. The healing process was monitored for 18 days. Clinical wound measurements and histological assessments were performed to compare different treatment regimens Results The results of in vitro antibacterial study showed MF/Ag released a sufficient concentration of silver which caused a marked reduction in colony forming units (CFU) of MRSA and PA as compared to MF alone. MF/Ag did not show any cytotoxicity to human fibroblast. Moreover, the result of the animal study confirmed the safety and efficacy of applying different concentrations of AgNPs loaded in MF without compromising the healing outcome in our rat model. Conclusions These findings suggest that AgNPs loaded MF would be a safe, nutritional, flowable hydrogel that provides an ideal moisture environment for healing while protecting the wound from bacteria and can potentially be used as a functional scaffold in partial-thickness mesh grafted skin in burn patients.