Fabrication and finite element simulation of antibacterial 3D printed Poly L-lactic acid scaffolds coated with alginate/magnesium oxide for bone tissue regeneration.

This study proposes 3D-printed Poly L-lactic acid (PLA) scaffolds coated with alginate/MgO, and includes three different cellular topologies. Three unique scaffold models were considered: Perovskite type 1 (P1), Perovskite type 2 (P2), and IWP. Each scaffold was coated with alginate/MgO at the concentrations of 0 wt%, 5 wt%, 10 wt%, 15 wt%, and 20 wt%. For morphological and phase study, the microstructure of fabricated scaffolds was characterized using a Field Emission Scanning Electron Microscope (FESEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analysis. Besides, the biological characteristics of scaffolds, such as biocompatibility, antibacterial activity, and cell survival were studied after 21 days of soaking in the simulated body fluid (SBF). The results of biological studies indicate that the apatite layer covered the majority of composite scaffold's surface and sealed the pores' surface. The material properties of Alginate/MgO RVEs were evaluated under PBC, and it described that the elastic modulus enhanced from 100 (pure Alginate) to 130 MPA by adding 20 wt% MgO nanoparticles. The presented findings were compared to the results obtained by the experimental procedure and revealed satisfactory agreement. RVE-achieved material properties were used in the additional studies on the scaffolds to find the best candidate due to the material properties and architectures. Furthermore, experiment and finite element simulation were used to evaluate the mechanical properties of scaffolds under the compressive deformation. According to the results, the compressive strength of structures follows the order σPerovskite type 1>σPerovskite type 2 >σIWP. The results indicate that increasing MgO content from 0 wt% to 20 wt% enhances each structure's compressive strength and elastic modulus. In conclusion, based on the biological findings and simulation results, PLA scaffold with Perovskite type 1 (P1) architecture coated with Alginate/ 20 wt% MgO had the best response which is the final research candidate.

Fabrication of chitosan-gelatin films incorporated with thymol-loaded alginate microparticles for controlled drug delivery, antibacterial activity and wound healing: In-vitro and in-vivo studies.

Previously, studies have demonstrated the unique characteristics of chitosan-gelatin films as wound dressings applications. However, their application has been limited due to their inadequacy of antimicrobial and anti-inflammatory characteristics. To improve the intended multifunctional characteristics of chitosan-gelatin film, in this study, we designed a novel composite film with the capability of controlled and prolonged release of thymol as a natural antioxidant and antimicrobial drug. Here, thymol-loaded ALG MPs (Thymol-ALG MPs) were prepared by electrospraying method and incorporated into the chitosan-gelatin film. The composite wound dressings of Thymol-ALG MPs incorporated in chitosan-gelatin film (CS-GEL/Thymol-ALG MPs) were characterized by in vitro and in vivo evaluations. The Thymol-ALG MPs demonstrated spherical and uniform morphology, with high encapsulation efficiency (88.9 ± 1.1 %). The CS-GEL/Thymol-ALG MPs exhibited high antibacterial activity against both Gram-positive and Gram-negative bacteria and no cytotoxicity for the L929 fibroblast cells. The release trend of thymol from CS-GEL/Thymol-ALG MPs and Thymol-ALG MPs followed a pseudo-Fickian diffusion mechanism. This wound dressing effectively accelerates the wound healing process at rats' full-thickness skin excisions. Also, the histological analysis demonstrated that the CS-GEL/Thymol-ALG MPs could significantly enhance epithelialization, collagen deposition, and induce skin regeneration. The present antibacterial composite film has promising characteristics for wound dressings applications.

Carboxymethyl chitosan-alginate hydrogel containing GSNO with the ability to nitric oxide release for diabetic wound healing.

Despite significant progress in developing diabetic wound dressing, the fabrication of an ideal one that fulfills all virtual criteria, such as promoting angiogenesis, is still lacking. Given the low vascularization in chronic diabetic wounds, they have a severe and non-healing nature. In this study, Nitric oxide (NO) was used as an angiogenic agent, which also has antibacterial properties. Briefly, S-nitrosoglutathione (GSNO) as a NO-donor was physically loaded into the carboxymethyl chitosan (CMC)/sodium alginate (ALg) composite film (CMC-ALg-GSNO). The morphological evaluation via scanning electron microscope confirms the homogeneous and porous structure of the wound dressing. The water uptake and water vapor transmission for the wound dressing were 4354.1% ± 179.3% and 2753.8 ± 54.6 g m-2per day, respectively. Anin-vitrorelease study showed a continuous delivery of NO during 168 h. Besides, the result from thein-vivotest reveals that the CMC-ALg-GSNO wound dressing developed diabetic wound healing in a rat model compared to the CMC-ALg and gauze. Thus, this study showed that CMC-ALg-GSNO wound dressing could lead to novel therapeutic invasions to treat diabetic wounds.