Biointerphases最新文献

Hydrolytic and enzymatic degradation of linear segmented polyurethanes with differing compositions were studied by atomic force microscopy and time-of-flight secondary ion mass spectroscopy. Poly (ester urethane urea)s (PEUUs) with two different molecular ratios of polycaprolactone diol (PCL) soft segments and L-lysine diisocyanate/hydrazine hard segments were exposed to aqueous conditions (water or phosphate buffered saline), and the changes in their surface chemistry and morphology were studied. It was found that polymer surface roughness in aqueous conditions is significantly affected by its bulk composition. After soaking in an aqueous buffer solution, the surface of PEUU with higher PCL concentration became significantly rougher compared to PEUU with lower PCL concentration. This surface roughening can be attributed to PCL lost from the surface during hydrolytic degradation. Despite the surface roughness changes, the rate of the hydrolytic degradation of PEUUs was found to be independent of bulk polymer composition. Enzymatic degradation of a linear segmented PEUU containing an oligopeptide segment [poly(peptide urethane urea) (PPUU)] in a collagenase solution was also investigated. The PPUU oligopeptide segment contained proline, hydroxyproline, and glycine amino acids. In a collagenase solution, the PPUU polymer exhibited a significantly higher degradation rate and surface roughness compared to a PEUU polymer that did not contain the oligopeptide segment.

High-speed atomic force microscopy (HS-AFM) was used to directly visualize the single-molecule adsorption dynamics of fibrinogen (FG) and bovine serum albumin (BSA) on atomically smooth mica and on silica nanoparticle (SiNP) coatings. By capturing the motion of individual proteins against a static background, HS-AFM enables the resolution of key dynamic processes, including surface diffusion, conformational adaptation, binding and unbinding events, and interfacial fluctuations on nanostructured surfaces. The results revealed two distinct, protein-specific adsorption mechanisms on SiNP coatings. BSA adsorbed via strong protein-surface interactions that promoted conformational adaptation and localized shell-like coverage of individual nanoparticles-progressively occupying interparticle interstices but leaving the overall nanoparticle topography visible. In contrast, FG adsorption followed a concentration-dependent, two-stage process; proteins first adsorbing directly to the nanoparticle surface, and at higher coverages, associated via protein-protein interactions, producing a secondary, dynamic, and loosely bound outer layer. This FG protein layer reduced the root-mean-square roughness of the underlying surface from a peak of ∼13.2 to ∼7.8 nm while introducing pronounced molecular-level fluctuations at the interface, as inferred from tip-induced smearing in HS-AFM images. These findings demonstrate that the relevant biological interface is not a static substrate, but a dynamic, structurally defined protein layer, whose properties are dictated by both nanoscale surface topography and the characteristics of the adsorbing proteins.

Bacterial strains can be divided into pathogenic and nonpathogenic strains. Distinguishing between the characteristics of these two types will help us understand the mechanisms that bacteria use to cause infections. Thus, the differences in the adhesion to a model hydrophilic silicon nitride surface and in the conformational properties between pathogenic and nonpathogenic Listeria species were probed using atomic force microscopy (AFM). The AFM force-distance approach curves were fitted to two steric models, the steric model and the extended-steric model, which assume the presence of one or two brushes on the bacterial cell surface, respectively. Our results indicated that no significant differences were noticed in the mean adhesion forces measured for pathogenic and nonpathogenic strains using the silicon nitride model surface. However, a larger number of adhesion peaks was found in the AFM retraction curves of the pathogenic strains. Similarly, when the conformational properties, represented by the mean thickness and the mean grafting density of the biopolymer brush, were determined using the steric model, no significant differences were observed between the pathogenic and nonpathogenic strains. However, when the conformational properties, represented by the mean thickness and the mean grafting density of the two brush layers, were quantified using the extended-steric model, it was found that the pathogenic strains had a lower mean grafting density for the first long brush and a higher mean grafting density for the second short brush. Thus, our findings demonstrate that the extended-steric model provides a more detailed view of the conformational properties of Gram-positive Listeria strains and allows for the detection of existing differences.

We aimed to synthesize modified magnesium nanowire (Ti-NW-Mg) on the surface of titanium implants and to investigate its effects on bone binding by regulating macrophage polarization in vitro. The Ti-NW-Mg was synthesized from smooth titanium (CP-Ti) by hydrofluoric acid etching and high temperature alkalization, and then through the displacement reaction of magnesium sulfate solution with the titanium surface. The control groups were CP-Ti, sandblasted and etched with acid titanium (Ti-SLA), and only for micro/nano-modified titanium surfaces (Ti-NW). The physicochemical properties of the Ti-NW-Mg surface were examined. The biological effects of materials on RAW264.7 cells were compared, and the effects on osteogenesis by mediating RAW264.7 polarization were discussed. We observed the effect of the materials on osteogenesis through immunohistochemistry. In this experiment, the Ti-NW-Mg surface was interwoven into a nanotopological network, which released a specific concentration of magnesium ions and had good hydrophilicity. Compared to CP-Ti, Ti-SLA, and Ti-NW, Ti-NW-Mg reduced the proliferation of macrophages on the surface, inhibited inflammation, regulated macrophage polarization, and promoted bone formation. Ti-NW-Mg reduced the proliferation and adhesion of macrophages and decreased the release of inflammatory factors from macrophages. These results provide an essential experimental basis for the effect of Ti-NW-Mg on improving implant osteogenesis and increasing the implant success rate.

Vapor-deposited polymer films offer a solvent-free, scalable route to engineer optically functional biointerfaces with tunable geometry. Recently developed technologies, such as condensed droplet polymerization (CDP), enable the direct fabrication of polymer dome arrays (PDAs) with precise control over size, curvature, and array density, as key parameters for high-resolution imaging and cellular compatibility. This perspective highlights the unique advantages of CDP-based microlenses as solid immersion lenses for live-cell imaging, pointing to their potential integration into tissue scaffolds, point-of-care diagnostics, and drug delivery platforms. We further discuss how polymeric material selection could enable refractive index tuning, mechanical adaptability, and biocompatibility for diverse biological applications. These capabilities position CDP-fabricated microlenses as a multifunctional platform for high-resolution imaging and for exploring how precisely engineered surface curvatures influence curvature-mediated signaling, mechano-transduction, and intracellular communication.

The efficiency of enzymatic proteolysis is often attributed to the properties of the enzyme itself, with the substrate typically viewed as a passive participant. In this study, we demonstrate that the conformational state of the substrate critically influences proteolytic efficiency. Using human serum albumin (HSA) as a model substrate, papain as the enzyme, and urea as a controlled denaturing agent, we systematically investigated how substrate conformation might affect proteolysis. While papain maintains its structural and functional integrity across varying urea concentrations, HSA transitions through well-defined conformational states (native, compact intermediate, and unfolded), allowing us an opportunity to isolate the effects of the substrate structure. Utilizing site-specific fluorescent labeling and single-molecule fluorescence correlation spectroscopy, we monitor the progression of proteolysis. Our results show that digestion slows at 3M urea, where HSA adopts a compact form, and accelerates at 6M, where HSA takes on an unfolded state, compared to native HSA. These results reveal that substrate folding critically influences the digestion kinetics, probably by controlling protease accessibility and underscoring its importance in mechanistic enzymology and proteomics workflows.

Plasma-enhanced chemical vapor deposition is a versatile technology to control interactions at the biomaterial/biological environment interface. Plasma copolymerization is a related strategy that utilizes a mixed feedgas of two or more plasma precursors, whereby conformal coating surface properties can be controlled by simply varying the feedgas composition. This study reports a previously unexplored combination of plasma precursors-pentane and acrylic acid-to deposit coatings with tunable chemistry and wettability on silk fibroin constructs. Five pentane/acrylic acid feedgas compositions were utilized, ranging from 100%, 75%, 50%, 25%, to 0% pentane by pressure. Plasma-deposited coating properties were evaluated through water contact angle goniometry and x-ray photoelectron spectroscopy. Coating static water contact angle values were tunable between >90° and <55° depending on the feedgas composition. Plasma diagnostics and density functional theory were used to evaluate plasma precursor fragmentation. This library of plasma-modified silk-based materials can be used to design biomaterial surfaces that are "just right" for the intended biomedical setting.

In this study, the marine red seaweed Devaleraea mollis (commonly known as Pacific dulse) was investigated as a green, sustainable, and animal-free tissue scaffold alternative, owing to its extracellular matrix mimicking properties. A decellularization-recellularization approach was employed to develop cellulose-based scaffolds capable of supporting human cardiomyocyte growth. Native dulse samples were cleaned, dried, and decellularized using varying concentrations of sodium dodecyl sulfate (SDS) (3%, 5%, 7%, 10%, 12%, and 15%), with Triton X-100 (2%) and NaClO (0.2%). The resulting scaffolds were comprehensively characterized using light microscopy, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy, and Raman spectroscopy to identify the conditions that best preserved the fibrous, honeycombed architecture and cellulose-rich content of the native tissue scaffold. Among all treatments, scaffolds processed with 10%, 12%, and 15% SDS exhibited superior structural integrity and biochemical preservation, emerging as the most effective formulations. These selected scaffolds were then subjected to swelling analysis to evaluate biodegradation behavior, followed by in vitro cell culture to assess biocompatibility. All tested scaffolds demonstrated excellent compatibility with human cardiomyocytes, maintaining high cell viability and proliferation for one week of in vitro culture, as confirmed by SEM and immunohistochemistry. Notably, a 90% scaffold surface coverage by cardiac cells on day 6, accompanied by a 2.5 times normalized cell proliferation, indicated robust cell attachment and proliferation. Collectively, these findings highlight seaweed-derived cellulose as a highly promising, biocompatible, and eco-friendly biomaterial, posing itself as a novel interface for diverse biomedical applications and innovations in sustainable tissue engineering.

Tissue engineering offers a promising route to treat cartilage damage caused by trauma or aging due to factors that limit regenerative capacity, such as tissue avascularity, limited nerve fiber distribution, and low cell-to-matrix ratio. It aims to repair hyaline cartilage by introducing chondrocytes or chondrocyte-differentiated stem cells within biocompatible scaffold. This study aimed to develop a composite tissue scaffold with enhanced mechanical strength and the ability to mimic the extracellular matrix of cartilage tissue by forming chitosan and γ-polyglutamic acid (γ-PGA) polyelectrolyte complexes (PECs) in shredded bacterial cellulose (BC). PECs at C:P molar ratios of 30:70, 50:50, and 70:30 were combined with BC at 0.25% and 0.5% w/v. FTIR confirmed characteristic peaks of BC, chitosan, and γ-PGA in the scaffolds. Water-holding capacity (WHC) increased significantly in the BCn-50P50 scaffolds. BC incorporation modulated PEC pore size and distribution most prominently in C30P70 and C70P30, while, overall, scaffolds exhibited a predominant pore-size range of 50-300 μm. Mechanical testing showed bidirectional reinforcement: PECs enhanced the elastic modulus of the BC, and, conversely, BC increased the elastic modulus of PECs. In vitro, all composite scaffolds were biocompatible and BC0.5-C50P50 scaffolds exhibited the best chondrogenic differentiation at day 7 compared to control (p = 0.0015). To our knowledge, this is the first composite scaffold in which PEC forms within BC nanofibers. The composites improved mechanical performance and WHC, expand surface area for cell adhesion, and support chondrogenic differentiation of mesenchymal stem cells.

Protein-mediated underwater adhesion is vital for the survival of many aquatic organisms and plays central roles in biofouling and bioinspired material development. Metal ions are known to influence underwater adhesion by regulating cohesion between adhesive proteins and interactions at the underwater material interface. However, direct mechanistic evidence of Ca2+ involvement in adhesion of marine organisms remains insufficient. In this study, we investigated the role of Ca2+ in permanent underwater adhesion of ascidian adhesive protein 1 (AAP1), an adhesive protein identified from the ascidian Ciona robusta, a model marine invasive fouling species. Using in vitro experiments, we examined AAP1's cohesion and interfacial adhesion under varying Ca2+ concentrations (0, 1.0, 2.5, 5.0, 10.0, and 25.0 mM). Our results indicated that Ca2+ mediated both cohesion and interfacial adhesion in a concentration-dependent manner. Protein aggregation was induced at 10.0 and 25.0 mM, with denser aggregation at higher concentrations. Surface force apparatus measurements showed a peak in cohesion energy at 25.0 mM Ca2+, while interfacial adhesion energy reached a maximum at 10.0 mM. These results suggest that Ca2+ may facilitate cohesion via salt bridge formation and promote interfacial adhesion by mediating electrostatic interactions between AAP1 and material surfaces. Additionally, the cohesion of AAP1 may enhance molecular alignment on surfaces, contributing its interfacial adhesion. Overall, our results provide direct evidence for the involvement of Ca2+ in protein-mediated ascidian underwater adhesion. These findings will deepen our understanding of the mechanisms of underwater adhesion in aquatic organisms and guide the future development of antifouling strategies and bioinspired underwater adhesives.