Thermosensitive chitosan hydrogels—renewable, biocompatible materials—have many applications as injectable biomaterials for localized drug delivery in the treatment of a variety of diseases. To combat infections such as Staphylococcus aureus osteomyelitis, localized antibiotic delivery would allow for higher doses at the site of infection without the risks associated with traditional antibiotic regimens. Fosfomycin, a small antibiotic in its own class, was loaded into a chitosan hydrogel system with varied beta-glycerol phosphate (β-GP) and fosfomycin (FOS) concentrations. The purpose of this study was to elucidate the interactions between FOS and chitosan hydrogel. The Kirby Bauer assay revealed an unexpected concentration-dependent inhibition of S. aureus, with reduced efficacy at the high FOS concentration but only at the low β-GP concentration. No effect of FOS concentration was observed for the planktonic assay. Rheological testing revealed that increasing β-GP concentration increased the storage modulus while decreasing gelation temperature. NMR showed that FOS was removed from the liquid portion of the hydrogel by reaction over 12 h. SEM and FTIR confirmed gels degraded and released organophosphates over 5 days. This work provides insight into the physicochemical interactions between fosfomycin and chitosan hydrogel systems and informs selection of biomaterial components for improving infection treatment.

Hemorrhage causes millions of deaths and hundreds of billions of dollars in medical costs every year, and a large percentage of trauma bleeding–associated deaths occur in the prehospital setting. Bleeding is typically treated with transfused blood products, but this is difficult in the prehospital setting due to limitations in transportation and storage, especially in rural and remote military settings. Advancements in cold-stored platelets and lyophilized blood products have the potential to address some of these limitations. However, devising novel products that continue to improve shelf life, portability, scalability, cost, and safety for patients experiencing bleeding in prehospital settings could greatly improve treatment options and patient outcomes. This review primarily focuses on rational design of material-based approaches to develop novel hemostatic agents that strive to meet limitations of current blood products, especially for use in the prehospital setting. Key topics of consideration include how material design can lead to identification of effective therapies that stop bleeding as well as strategies to iterate on existing designs to enhance healing after cessation of bleeding. Improving performance and functionality of existing and emerging materials could be achieved through the incorporation of transglutaminases, growth factors, cellular components, or inorganic molecules. Finally, consideration of patient-specific factors that influence bleeding, such as patient sex and age, through evaluation of therapies in specific populations and/or design of materials targeted for specific patient populations, is a key area for development of next-generation hemostatic materials.

(1) Background: Musculoskeletal trauma from combat wounds, accidents, or surgeries is highly associated with infections and hospitalization. The current “gold standard” for such injuries when access to hospitals is limited is administering antibiotics and opioids; however, they are not ideal treatments due to their contributions to antibiotic resistance and the opioid epidemic. Electrospun chitosan acylated with lipids and loaded with hydrophobic drugs has been shown to release the therapeutics systemically and to prevent infections. (2) Methods: Electrospun chitosan membranes (ESCMs) were fabricated and acylated using decanoyl chloride. FTIR was used to confirm acylation through the presence of ester bonds and acyl chains. ESCMs were loaded with the quorum-sensing molecule cis-2-decenoic acid (C2DA) and the local anesthetic bupivacaine and then implanted in rat femurs for 3 days. Afterward, the rats were euthanized, and CFUs were measured on retrieved bone, tissue, and treatment material. (3) Conclusions: While ESCMs prevented bacterial growth on the surface of the material, controls outperformed treatment groups. This is possibly due to bupivacaine’s role in inhibiting sodium channels, which favors the production of Th2-type cytokines associated with immune response suppression. Furthermore, ESCMs provide a large surface area for bacteria to grow on and form bridges between nanofibers.