Journal of biomedical materials research. Part A最新文献

Coatings of silver compounds with higher dissolution rates than metallic silver offer a promising approach for delivering Ag⁺ ions to prevent medical implant device-associated infections. In this study, we investigate the synthesis and characterization of single-phase, silver (I) oxide (Ag₂O) and silver (II) oxide (AgO) for potential antimicrobial applications. The synthesis of these materials leverages the higher stability of Ag₂O in comparison to AgO. The formation of AgO requires a low landing energy of the adatoms, achieved through gas phase scattering and rapid quenching when landing. Alternatively, higher landing energies cause re-sputtering of oxygen, which favors the formation of Ag₂O. Higher chamber pressures during deposition increase the number of inelastic collisions, thereby reducing the energy of the adatoms influencing phase formation. A combination of energy dispersive spectroscopy, microstructural imaging, X-ray diffraction (XRD), and high-temperature XRD confirms this result. To evaluate antimicrobial potential, silver ion release (elution) was measured in water, Luria-Bertani broth, and tryptic soy broth. Elution rates were highest in water, but in all media, both oxides elute significantly more Ag⁺ ions than metallic silver coatings. Antimicrobial assays clearly show potent and broad-spectrum activity of silver oxides against both clinical and multidrug-resistant bacteria, confirming their potential as effective antimicrobial coatings for implanted devices.

In this study, we developed a piezoelectric-polydimethylsiloxane (pz-PDMS) composite by blending poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) with PDMS to create a biocompatible, mechanoelectrical responsive material. The pz-PDMS was synthesized with varying piezoelectric concentrations (0%, 1%, 3%, and 5%) and characterized for visual properties, mechanical properties, mechanoelectrical sensitivity, and biocompatibility. Compression testing showed no significant change in mechanical strength with the addition of piezoelectric particles, while mechanolectrical sensitivity testing revealed a non-linear increase in voltage response, with 5% pz-PDMS producing the highest sensitivity. Fatigue testing demonstrated no change in sensitivity after 7 days of cyclic displacement. Additionally, microcantilever experiments demonstrated the high fidelity of the 5% pz-PDMS to mechanical deformation. In parallel, human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes cultured on both 0% pz-PDMS and 5% pz-PDMS substrates exhibited comparable cell viability, attachment, and maturation, as confirmed by MTS assays and immunofluorescence imaging. The results suggest that 5% pz-PDMS offers a promising platform for bioelectronic applications, combining piezoelectric functionality with long-term biocompatibility.

Few clinical solutions exist for cardiac fibrosis, creating the need for a tunable in vitro model to better understand fibrotic disease mechanisms and screen potential therapeutic compounds. Here, we combined cardiomyocytes, cardiac fibroblasts, and exogenous extracellular matrix (ECM) proteins to create an environmentally mediated in vitro cardiac fibrosis model. Cells and ECM were combined into 2 types of cardiac tissues—aggregates and tissue rings. The addition of collagen I had a drastic negative impact on aggregate formation, but ring formation was not as drastically affected. In both tissue types, collagen and other ECM did not severely affect contractile function. Histological analysis showed direct incorporation of collagen into tissues, indicating that we can directly modulate the cells' ECM environment. This modulation affects tissue formation and distribution of cells, indicating that this model provides a useful platform for understanding how cells respond to changes in their extracellular environment and for potential therapeutic screening.

Development of synthetic biomaterials for skeletal reconstruction has progressed rapidly, driven partly by demand to reduce dependency on allografts. One class of materials, biopolymer nanocomposites, has shown promise when combined with additive manufacturing for these applications. The driving goal for the development of 3D-printable biopolymer nanocomposites composed of methacrylated monomers (triglycerides and triethylene glycol) and hydroxyapatite (HA) is to produce structurally robust and degradable customizable grafts. These materials must be able to withstand the loading conditions found in vivo while allowing for degradation and remodeling processes. This study focused on the degradation potential of previously developed HA-containing biopolymer nanocomposites and the resulting consequences of degradation on their mechanical performance. One of the means to study a material's in vivo degradation performance is to assess its susceptibility to oxidative degradation, as oxidation is naturally occurring in cell metabolism, inflammatory responses, and osteoclast resorption. Two in vitro models of oxidative degradation were trialed: aqueous solutions of either hydrogen peroxide or neutral hypochlorous acid. Hypochlorous acid was shown to be a useful in vitro assessment for the degradation potential of biomaterials to different reactive oxygen species. The biopolymer nanocomposites were clearly susceptible to oxidative degradation, demonstrating significant changes in mass and surface morphology. Mechanical performance was reduced under these testing conditions. This was attributed to three main factors: swelling and water absorption effects, chemical modifications, and loss of structure. Overall, this study provides insights into the effects of oxidative degradation on biomaterial functionality and highlights the importance of exploring relevant physiological effects on mechanical properties when developing biomaterials.

Rupture of the anterior cruciate ligament (ACL) is a common injury resulting in joint instability. Tendon autografts, the gold standard to reconstruct a ruptured ACL, contain dead or dying cells upon implantation that can initiate early localized catabolic and inflammatory events. This is hypothesized to contribute to detrimental remodeling, which may compromise graft stability and increase the risk of rupture. To address this, we propose using decellularized grafts. However, the cells used to reseed decellularized tendons cannot be detected anymore in vivo, potentially due to the dynamic loading conditions. Therefore, the repopulation efficiency of decellularized tendons under dynamic load was investigated using a custom developed bioreactor. As a proof of concept, human gracilis tendons were decellularized and reseeded with human dermal fibroblasts and cultured for 7 days dynamically (2%–6% strain at 1 Hz for 7 h a day) or statically. Thereafter, the viability and infiltration ability of the reseeded cells were assessed. The loading protocol used in this study demonstrated that the bioreactor could measure the transient response of tendon mechanical behavior and could detect changes in mechanical properties over time. The application of dynamic load to reseeded decellularized tendons had no significant effect on cell adhesion, viability, cell metabolism, and infiltration. In both loading groups, cell infiltration was localized rather than globally observed. As bioreactors can serve as an in vitro or ex vivo model to potentially predict in vivo outcomes, this bioreactor shows promising potential for future ACL graft research.

Hydrogels that can change shape on the application of an electric field are receiving increasing attention due to their potential to fulfill a range of functions in biomedicine, including the controlled release of therapeutic agents or the creation of replacements for contractile tissues. In this manuscript, a novel electroactive polymer was reported based on the copolymerisation of 2-acrylamido-2-methylpronane sulfonic acid and poly(ethylene glycol) diacrylate (AMPS-co-PEGDA), via free radical polymerization using UV light. It was shown that to enable curing and the production of a material that could repeatably actuate without cracking, 900 mJ/cm² (at 365 nm⁻¹) of UV exposure was optimal. Further increasing the curing time resulted in the production of a brittle material that cracked following actuation, preventing multiple actuations from occurring. The polymer that was cured for 900 mJ/cm² was shown to be non-cytotoxic to dermal fibroblast cells, showing potential in biomedical applications. Furthermore, it was shown that the optimized polymer could be structured using a process of suspended 3D printing, allowing for the manufacture of complex, electro-actuatable geometries. Processing in an agarose supporting bed resulted in a reduction in the Young's modulus of the printed polymer and an associated greater degree of bending. These results demonstrate that the optimized (AMPS-co-PEGDA) polymer is a promising electroactive material with tuneable properties and complex geometries, suitable for advanced biomedical applications.

Hybrid materials are gaining increasing attention for several applications since they properly combine biological and synthetic components, leveraging the advantages of both; thus, these materials can integrate with the host organism to support proper functions, offering new promising solutions, especially in the biomedical field. In this study, we developed hybrid membranes by combining decellularized porcine pericardium with a commercial polycarbonate urethane, available in two formulations: without (AR) and with microsilica particles (AR-LT). These membranes were characterized through chemical and physical analyses; their cytocompatibility was assessed in vitro via direct contact tests, and their biocompatibility was checked in vivo by implanting the materials in a subdermal pouch in a rat animal model. Three kinds of mechanical tests have been performed to check different mechanical features: tensile test to rupture, to measure the mechanical resistance in terms of elastic modulus, failure strain (FS), and ultimate tensile strength (UTS); cyclic tests to assess the effects of repetitive loadings on the mechanical resistance; and stress-relaxation tests to assess the time-dependent behavior. The physicochemical analyses demonstrated that the two components well adhere to each other, with traces of the polymer on the pericardial side of the membranes. Considering mechanical response, coupling pericardium with the polymer causes a reduction of FS and UTS compared to the individual components. Hybrid materials show a viscoelastic behavior while loading cycles do not cause significant changes in their tensile resistance. In vitro tests showed no cytotoxic effects, with cell proliferation observed for up to 7 days. In vivo, 8 weeks after implantation, the hybrid membranes exhibited better integration with host tissue compared to the polymer alone (control), and the polymeric component did not show any sign of degradation. The improved integration was demonstrated by increased neovascularization around the implant, reduced fibrotic capsule thickness, lower expression of interleukin-6 (IL-6), and stable body weight of the rats throughout the experiment. This study highlights the potential of the hybrid membranes for tissue engineering applications, combining favorable biocompatibility and adequate mechanical features.