Journal of biomedical materials research. Part A最新文献

Human liver models grown in the lab are used for testing drug metabolism and toxicity, studying liver diseases, and developing new therapies. Induced pluripotent stem cell (iPSC)-derived hepatocyte-like cells (HLCs) provide a renewable alternative to scarce primary human hepatocytes (PHHs), but they remain functionally immature compared to adult liver cells. The extracellular matrix (ECM) is a key regulator of liver cell behavior, yet how its biochemical makeup, stiffness, and structural organization work together to influence HLC maturation is not well understood. Here, we engineered electrospun nanofibers from collagen I, chitosan, porcine liver ECM (PLECM), and blends of these materials. Over 3 weeks of differentiation, HLCs cultured on ECM nanofibers showed more advanced functional maturation than those grown on standard Geltrex-coated substrates. Importantly, chitosan/collagen nanofibers promoted greater HLC function than either hydrogels of similar stiffness or proteins adsorbed to glass, highlighting the importance of nanoscale topography. By contrast, stiffer polyvinyl alcohol nanofibers of comparable size failed to enhance HLC maturation, a result linked to higher nuclear activity of the mechanosensor Yes-associated protein 1 (YAP). These findings demonstrate that ECM nanofibers drive more mature iPSC-HLCs and advance the development of predictive human liver models for drug discovery, disease modeling, and regenerative medicine.

Titanium-copper (Ti-Cu) alloys are gaining attention for their dual functionality in promoting osteogenesis while providing antimicrobial protection, making them ideal candidates for dental and orthopedic implants. Copper's ability to enhance bone cell activity and inhibit bacterial growth could help address two critical challenges: successful osseointegration and the prevention of peri-implant infections. This study investigated the cellular and molecular mechanisms by which copper, when incorporated into titanium alloys, stimulates both pro-osteogenic behavior and inhibits bacterial viability. MG-63 osteoblast-like cells were cultured on Ti-5Cu alloy surfaces, and osteogenic activity was assessed through alkaline phosphatase (ALP) activity, collagen deposition, and mineralization assays. Gene expression analysis using qPCR and protein expression via band densitometry provided insights into key pathways, including copper homeostasis and bone matrix formation. The antimicrobial effects of Ti-5Cu were evaluated against common pathogens such as Escherichia coli and Staphylococcus aureus, as well as oral bacteria such as Streptococcus oralis and Fusobacterium nucleatum. Bacterial gene expression was analyzed using qPCR and RNA sequencing. Osteoblast-like cells cultured on Ti-5Cu surfaces showed enhanced ALP activity, increased collagen production, and significant gene upregulation of RUNX2, Osteonectin, Alkaline phosphatase, and BMP-2, driving bone matrix formation. Copper homeostasis proteins, such as CTR1 and ATP7A/ATP7B, were modulated to prevent cytotoxicity while supporting osteogenesis. Ti-5Cu alloys also exhibited broad-spectrum antimicrobial effects, significantly reducing bacterial viability. In S. oralis, stress response genes, CsoR and SOD, were upregulated in response to copper exposure, indicating oxidative stress and disruption of copper homeostasis. Transcriptome analysis found that the alloys induce oxidative stress and disrupt metal homeostasis in commensal bacteria such as S. oralis and Actinomyces naeslundii. The study demonstrates that Ti-5Cu alloys effectively promote osteoblast differentiation and mineralization while preventing bacterial colonization through copper-induced stress responses. These findings support the potential of Ti-5Cu alloys for clinical applications, particularly in dental implants, where both regenerative bone formation and infection prevention are critical for long-term success.

Silver (Ag⁺) ions are field-emitted under atmospheric pressure from a sharpened Ag⁺ ion-conductive glass by applying a high voltage. This study investigates the antibacterial efficacy of emitted Ag⁺ ions. When Ag⁺ ions are irradiated onto hydroxyapatite (HAP) for 5 min, an antibacterial effect against Escherichia coli is clearly observed. Furthermore, Ag⁺ ion irradiation directly into the E. coli suspension results in a significant reduction in viable E. coli after 24 h of incubation, compared to immediately after ion irradiation. Although Ag⁺ ions are expected to rapidly lose energy upon collision with air molecules, penetration exceeding 100 μm into the hydrated agar gel is confirmed. When Ag⁺ ions are irradiated onto the surface of an artificial skin (3D reconstructed human epidermis model), fungal cells located beneath the skin are successfully eliminated. These results demonstrate, for the first time, that field-emitted Ag⁺ ions under atmospheric conditions exhibit potent antimicrobial activity.

Conventional treatments for oral candidiasis often fail due to the complexities of the oral environment and the increasing antifungal drug resistance. Therefore, there is a growing demand for new therapies that optimize drug bioavailability, allowing for lower therapeutic doses while enhancing cytocompatibility, maintaining antifungal, anti-inflammatory, and wound healing efficacy. This study investigated the antifungal activity, cytocompatibility, wound healing potential, and mucosal adhesion of novel mucoadhesive formulations containing nystatin (NYS) or chlorhexidine (CHX) complexed with β-cyclodextrin (βCD), compared with the drug-free formulation (GEL) and the standard treatment with 2% miconazole gel (DK—Daktarin). Efficacy against Candida albicans was evaluated by measuring the metabolic activity, whereas cytocompatibility with human gingival fibroblasts (HGFs) was analyzed for viability, morphology, lactate dehydrogenase (LDH) release, and apoptosis. Additionally, wound healing potential was investigated by assessing cell migration efficacy, anti-inflammatory activity, and reactive oxygen species (ROS) scavenging activity. Mucoadhesion was evaluated using mucin discs and a texture analyzer. Mucoadhesive gels containing βCD-complexed NYS or CHX exhibited significantly higher antifungal activity when compared to the GEL and DK groups (p < 0.05). Compared to fibroblast control cultures, those exposed to drug-complexed gels exhibited similar viability (p > 0.05) and morphological parameters, lower LDH release (p < 0.05), and similar apoptosis rates (p > 0.05). Additionally, exposure to the βCD-modified gels was associated with complete wound closure (p > 0.05), significant anti-inflammatory effect, with downregulation of pro-inflammatory gene expression (p < 0.05), and higher ROS scavenging activity (p < 0.05). The developed formulations showed no difference in mucoadhesiveness (p > 0.05), which was superior to that of DK (p < 0.05). Therefore, the proposed drug-complexed mucoadhesives are promising therapeutic options for oral candidiasis.

The incorporation of functional molecular switches into smart materials imparts dynamic material properties, gaining deeper insight into how molecular structure affects the functionality of these materials and aiding the development of novel sensor devices. To enable mechanochromic biomaterials capable of sensing shape changes, we explored the incorporation of spiropyran (SP) mechanophores into a polyurethane (PUR) shape memory polymer (SMP). SPs reversibly generate variations in fluorescence and visual colors due to conversion from inactivated SP to activated merocyanine (MC) in response to force. We hypothesized that SP-containing PUR (PUR-SP) could undergo simultaneous shape and color changes. Small quantities of SP were dissolved in control PUR solutions with different hard-to-soft segment ratios, and PUR-SP films were formed by solvent-casting. The effect of SP incorporation on material properties, including mechanical, shape memory, thermal, and cytocompatibility, was studied. Mechanochromic behavior was analyzed by straining the films and imaging using a camera and fluorescence microscopy. We also employed a previously developed bacterial protease-responsive PUR SMP to confirm that SP incorporation enables simultaneous shape and color changes in the presence of bacteria. Strained samples showed increased fluorescence (up to 56%, p < 0.05), which was reversed upon shape recovery. Mechanochromic behavior was affected by the hard-to-soft segment ratio of the PUR, SP concentration, and strain percentage. Bacteria-responsive PURs with SP showed reduction in fluorescence and complete biofilm removal after incubation with Staphylococcus aureus for 24 h, which conveyed the potential to use SP in PURs as a molecular force probe with color-based bacteria detection. This technology could be expanded to include a range of other stimuli-responsive functionalities in future work to enable shape and color changes based on environmental cues.