ACS Biomaterials Science & Engineering最新文献

Polyhydroxyalkanoates (PHAs) are biopolyesters that accumulate as cytosolic cell inclusions in many bacteria, enhancing resistance to environmental stresses. However, the structure, spatial localization, plasticization effects, and mechanical properties of PHA granules in vivo remain underexplored. Here, Cupriavidus necator H16 grown under nutrient-rich and limited conditions was investigated across a 72 hour accumulation cycle using orthogonal techniques including atomic force microscopy infrared (AFM-IR) spectroscopy, contact resonance mechanical analysis, optical photothermal infrared spectroscopy, nano-thermal analysis, and proteomics to map polyhydroxybutyrate (PHB) granule evolution. Across the PHB production cycle, the PHB content increased from 34 to 69% after 72 hours in minimal media, while in vivo crystallinity reached a maximum of 20% compared to 42–63% when extracted. Ester carbonyl band shifts (1720–1740 cm^–1) indicated mostly amorphous PHB in vivo, while contact resonance mapping showed that the granules were mechanically softer than the surrounding cellular matrix. Notably, AFM-IR revealed membrane patterning consistent with spinodal decomposition, representing the first reported observation of spinodal-like membrane organization in C. necator. Proteomics identified increased production of PHB biosynthesis, regulation, and phasin proteins during the stationary phase, supporting phasin-assisted suppression of crystallization. Whole-pathway analysis further revealed stronger perturbations in formate oxidation and polyphosphate metabolism than in PHB biosynthesis alone, highlighting broader metabolic shifts. This study establishes a link between PHB accumulation, crystallinity, mechanical softness, and granule-associated protein production in C. necator, yielding a plasticized intracellular polymer state relevant to flexible bioplastic and biomedical material design.

Osteoporosis (OP) is a prevalent skeletal disorder characterized by decreased bone mass and increased fragility, leading to fractures and chronic pain. Nerve growth factor (NGF) plays a pivotal role in bone homeostasis and neuro-regeneration but paradoxically exacerbates pain. This study investigated the therapeutic potential of engineered, bone-targeting exosomes derived from NGF-pretreated Schwann cells (NGF-Exo-Pep) for the treatment of OP. We demonstrated that NGF-Exo-Pep effectively promoted osteogenic differentiation and mineralization of bone marrow mesenchymal stem cells (BMSCs) in vitro, while also enhancing Schwann cell proliferation, migration, and neurotrophic factor secretion. Mechanistically, miRNA sequencing revealed that NGF-Exo-Pep was enriched in osteogenic miRNAs. In vivo, NGF-Exo-Pep treatment in ovariectomized mice significantly improved bone microarchitecture, increased osteoblast activity, reduced osteoclast activity, and neurotization of bone tissue. Notably, NGF-Exo-Pep alleviated pain-related behaviors by downregulating pain mediators and reducing c-Fos expression in the spinal cord. This study presented a novel and promising strategy for OP treatment, harnessing the pro-regenerative properties of NGF while mitigating its pain-inducing side effects.

Probiotic oral delivery is constrained by harsh gastrointestinal conditions and antibiotic exposure. This paper presents a single-cell nanoencapsulation strategy that assembles protective Fe³⁺-benzene-1,3,5-tricarboxylate (BTC; trimesic acid) metal—organic nanoshells around individual probiotics, including Lactobacillus acidophilus, to create cell-in-shell nanobiohybrids. Nanoencapsulated cells exhibit markedly enhanced viability relative to native counterparts under diverse gastrointestinal stressors. Under strongly acidic conditions (pH 2.0), cell-in-shell nanobiohybrids retain 7.45 log CFU/mL after 3 h, compared with 6.00 log CFU/mL for native cells, while maintaining 7.09 log CFU/mL in simulated gastric fluid where native cells are completely inactivated. Enhanced tolerance is also observed under tetracycline exposure (7.59 vs 7.00 log CFU/mL) and bile salts-trypsin treatment (6.88 vs 4.00 log CFU/mL). The Fe³⁺-BTC nanoshells provide a cytocompatible platform that enhances probiotic resilience against multiple gastrointestinal stressors and is broadly applicable to other therapeutically relevant cells.

Intervertebral disc (IVD) degeneration is a leading cause of low back pain (LBP), primarily originating in the nucleus pulposus (NP). Regenerative strategies combining mesenchymal stem cells (MSCs) with biomaterials offer great potential for NP repair by replenishing cells and restoring extracellular matrix (ECM). However, key translational challenges remain, including limited stem cell differentiation, poor cell survival in the harsh degenerative niche, and insufficient biomaterial support. While matrix viscoelasticity has been shown to influence adipose-derived stem cell (ASC) discogenic differentiation, its interplay with cell-adhesive ligands for IVD regeneration remains unclear. Moreover, most current hydrogels fail to replicate the ultrafast stress relaxation properties of native non-degenerative human NP tissue. Here, we developed viscoelastic ECM peptide-functionalized hydrogels (VEPH), specifically designed to mimic healthy human NP biomechanics and promote ASC differentiation for NP regeneration. We biochemically conjugated NP ECM-derived adhesive peptides (IKVAV, hA5G26, CHAD) through maleimide-thiol click chemistry, achieving hydrogels with significantly faster stress relaxation (∼25 s) compared to conventional viscoelastic alginate hydrogels (>100 s). Our results demonstrated that VEPH supported >95% ASC viability and robust metabolic activity over 21 days in 3D culture. Notably, the IKVAV-functionalized hydrogel significantly enhanced ASC cell-matrix interactions, upregulated NP marker expression (KRT18, HIF-1α, ITGA3, and CD24), and promoted type-II collagen secretion, indicating an NP-committed cell fate. Our findings highlight the synergistic roles of matrix viscoelasticity and NP-specific biochemical cues in directing ASC discogenic differentiation and advancing novel biomaterial design for IVD regeneration.

Bioinspired and biomimetic membranes represent a rapidly advancing class of materials for biomedical and life-science applications by emulating the structure and function of natural biological systems. This review represents the current progress in these technologies, including membrane-coated nanoparticles, tissue-engineering scaffolds, and related constructs, and classifies them into four complementary functional categories. It further elaborates on material selection, fabrication methods, biomedical uses, translational barriers, and future directions. Natural biodegradable polymers contribute to biocompatibility and intrinsic bioactivity, whereas synthetic polymers afford adjustable mechanical properties and controlled degradation. Lipid-based formulations and cell membrane–mimetic nanostructures enhance functionality through improved targeting, immune evasion, and regulated drug release. Precise architectural control is achieved using advanced fabrication approaches such as electrospinning, layer-by-layer assembly, self-assembly, biomineralization, and 3D bioprinting. These membranes have shown in vitro experiments and preclinical animal studies, and for certain selected systems, such as dialysis membranes and liposomal systems, they have already reached clinical use for drug delivery, tissue regeneration, biosensing, and antimicrobial applications. Despite advances in recapitulating biological form and function, important obstacles remain, notably scalable manufacturing, long-term stability under physiological conditions, and cost-effectiveness. Nevertheless, owing to their selective molecular transport, adaptive behavior, and enhanced biointerface compatibility, bioinspired and biomimetic membranes are suitable materials for next-generation biomedical technologies.

Neurodegenerative disorders of the central nervous system (CNS) remain a significant clinical challenge due to the limited regenerative capacity of neural tissues. Herein, bioactive scaffolds were developed from decellularized extracellular matrices (dECMs) derived from four CNS tissues: brain, spinal cord, spinal meninges, and optic nerve. The scaffolds were comprehensively characterized with respect to biochemical composition, mechanical properties, and biological performance. Optimized decellularization protocols efficiently removed cellular components while preserving key matrix constituents, including collagens and glycosaminoglycans (GAGs). The resulting dECM scaffolds exhibited distinct tissue-specific mechanical profiles; meninges (dM) and optic nerve (dO) scaffolds showed enhanced elasticity (>64% strain), whereas brain-derived (dB) scaffolds displayed higher stiffness in the lyophilized state. All scaffolds were highly porous (>60%) and hydrophilic, with swelling ratios exceeding 1000%. 3D culture studies using bEnd.3 endothelial and SH-SY5Y neuronal cells demonstrated favorable cytocompatibility (>65% viability) and tissue-dependent cellular responses. dM and dO scaffolds promoted slightly improved endothelial cell adhesion relative to dB and spinal cord (dC), while neuronal cell proliferation was more pronounced in dB, dC, and dO scaffolds. In addition, in ovo chick chorioallantoic membrane (CAM) assays confirmed the pro-angiogenic activity of all scaffold types. Collectively, these findings demonstrate that CNS-derived dECM scaffolds can support both angiogenic and neurogenic processes. This work provides the first comparative assessment of multiple CNS-derived dECMs in terms of their dual biofunctional potential and underscores the importance of tissue-specific ECM composition in guiding cell behavior for neurovascular tissue engineering applications.

Black extremotolerant fungi form persistent biofilms on a wide range of natural and engineered substrates. Able to weather minerals, affect stone monument surfaces, and colonize solar panels, they demonstrate a strong capacity to interact with and modify material surfaces, even under most extreme conditions. In this study, we establish a methodological workflow for the structural and mechanical characterization of melanized biofilms formed by the black fungus Knufia petricola. This species represents a broader group of resilient surface colonizers and provides a model for in‑depth investigation. When grown on the solid agar/air interface, this species predominantly forms a compact biofilm, composed of spherical cells, while retaining the capacity for filamentous growth, providing a suitable framework to explore morphology-dependent biomechanical responses. The proposed toolbox combines complementary analytical techniques spanning multiple spatial scales, including shear rheology to quantify bulk viscoelastic behavior, microindentation to resolve local stiffness of the biofilm surface, microcomputed tomography for nondestructive three-dimensional visualization of biofilm architecture, and cryogenic preparation methods and electron microscopy for high-resolution ultrastructural analysis. As a methodological case study, we applied this workflow to compare biofilms grown on two different nitrogen sources (NO₃⁻ vs NH₄⁺). Our results reveal nitrogen-associated differences in biofilm organization across multiple hierarchical levels, ranging from biofilm morphology and bulk mechanical behavior to cellular morphology and EPS distribution. NO₃⁻-grown biofilms presented more filaments with cells exhibiting budding-like morphologies and higher bulk viscoelastic moduli, whereas NH₄⁺-grown biofilms were thicker with meristematic-like morphologies and a softer, more shear-tolerant mechanical response. The successful application and combination of complementary methods originally developed for bacterial biofilm research demonstrates that quantitative multiscale characterization can be extended to melanized fungal biofilms. Ultimately, this multiscale toolbox will help in advancing the mechanistic understanding of fungal biofilms and biofilm−material interactions, with implications for geomicrobiology, material biodeterioration, and the design of bioinspired functional materials.

Thiol−ene gelatin-based hydrogels, particularly gelatin−norbornene (GelNB)-based hydrogels, are promising for extrusion-based three-dimensional (3D) bioprinting owing to their rapid oxygen-insensitive crosslinking and excellent biocompatibility. Dithiothreitol (DTT) is commonly used as a thiol crosslinker because of its efficient and well-characterized reaction kinetics and ability to fine-tune the mechanical properties of the resulting hydrogel with minimal changes to its composition. However, application of DTT in cell-laden constructs is limited by cytotoxicity arising from direct cellular exposure to its strong reducing activity. To address this limitation, we introduced an indirect DTT delivery approach, in which DTT was incorporated into a starch-based support material alternately deposited with a GelNB bioink, enabling interfacial diffusion-mediated thiol−ene crosslinking upon light irradiation while minimizing direct cellular exposure to free DTT. Incorporation of 64.8 mM DTT into a 16.7 w/w% starch-based support material produced constructs (10 w/v% GelNB) with mechanical properties, shape fidelity, and stability comparable to those fabricated using direct DTT premixing (6.5 mM). Fibroblasts encapsulated within the constructs prepared via indirect DTT supply exhibited enhanced cytocompatibility (up to a 47% increase in the cell viability), a significantly higher mitochondrial activity, and reduced reactive oxygen species generation compared with those in the constructs prepared via direct DTT premixing in the bioink. These improvements were consistently observed across multiple cell types. The proposed extrusion-based 3D bioprinting strategy offers a practical and cell-friendly approach for expanding the application scope of a DTT-mediated thiol−ene reaction for GelNB-based bioprinting and may be adapted to other bioink systems relying on cytotoxic crosslinkers.

Existing in vivo models for retinal pathologies are costly, time-consuming, and subject to regulatory challenges, promoting interest in advanced in vitro models that replicate the blood-retinal barrier. Challenges related to vascularization and structural multiscale interactions hinder the development of in vitro models, which are useful to study nutrient and drug exchange between the retina and systemic circulation. To address these issues, we developed a blood-retinal barrier in vitro model for studying retinal pathophysiology. It features an electrospun scaffold (Bruch’s membrane) placed between a culture chamber (vitreous humor) and a bioinspired microfluidic network (choroidal vasculature). The network, modelled from indocyanine green angiography of the human retina, is laser-engraved into a 15 mm PDMS disc with channels 70–800 μm wide. PLGA and gelatin electrospun scaffold were investigated to mimic Bruch’s membrane. The scaffold is fixed to the microfluidic network, assembled into a culture chamber, and integrated within a bioreactor. A peristaltic pump ensures a consistent flow in the channels. Biological validation included ARPE-19 cells cultured on Transwell, PLGA, or gelatin membranes, HUVECs within membrane-coupled microchannels, and dual-layer constructs. Cells were examined separately and together, allowing evaluation of epithelial, endothelial, and construct responses. All configurations showed progressive increases in metabolic activity and limited LDH release over 28 days. Cell-seeded constructs reduced FITC–dextran transport relative to acellular controls, with stable values between days 21 and 28. Blank-corrected TEER likewise increased during ARPE-19 culture and plateaued by day 21. PLGA constructs showed the greatest electrical and solute-transport resistance, although acellular controls confirmed a substantial material contribution. Confocal microscopy demonstrated HUVEC attachment and F-actin organization along the microchannels, while ARPE-19 monolayers exhibited continuous junction-associated ZO-1 staining that remained stable between days 21 and 28. Overall, the platform supported long-term epithelial–endothelial culture and provided a stable, perfusable system for studying oBRB transport and cellular interactions.

Titanium mesh-supported guided bone regeneration (TM-GBR) has emerged as a clinically effective strategy for alveolar bone augmentation in complex defects, primarily through its ability to preserve osteogenic space and correct bone volume deficiencies. However, due to the inherent biological inertness of titanium mesh (TM), insufficient osteoinductive at the interface of TM remains a pressing issue to be addressed in alveolar bone reconstruction. Herein, silicon nitride nanofilms with low (SiN55), medium (SiN65), and high (SiN75) nitrogen contents were fabricated on TM substrates via reactive magnetron sputtering, exhibiting favorable hydrophilicity, superior corrosion resistance, and antibacterial activity. Moreover, the SiN65 nanofilms significantly promoted the macrophage polarization from the pro-inflammatory M1 phenotype to the pro-regenerative M2 phenotype and enhanced osteogenic differentiation through immune regulation of macrophages in co-culture assays. Mechanistically, RNA-eq analysis revealed that the SiN65 nanofilms modulated macrophage differentially expressed genes and reprogrammed the protein−protein interaction network, accompanied by downregulation of TNF, JAK-STAT, and Toll-like receptor signaling pathways. Additionally, the SiN65 nanofilms promoted bone regeneration in rat calvarial defect models. This study presents the SiN65 nanofilms as a rationally engineered coating integrating immunomodulatory and osteogenic functions, effectively mitigating peri-implant fibrosis and providing a promising strategy to improve the long-term outcomes of TM-GBR.