ACS Applied Bio Materials最新文献

Nanofibers, with their high surface area-to-volume ratio, elasticity, and mechanical strength, significantly enhance scaffold structures for skin tissue engineering. The present study introduces a unique method of combining solution blow spinning (SBS) and freeze casting to fabricate biomimetic hybrid nanofibroporous scaffolds (BHNS) using polycaprolactone (PCL) and chitosan (CH). The developed scaffolds mimic the fibrous porous natural extracellular matrix (ECM) architecture, promoting cell adhesion, proliferation, and matrix deposition. The combined SBS and freeze-casting processes resulted in scaffolds with high porosity and optimal mechanical strength, crucial for effective skin regeneration. Scanning electron microscopy (SEM) confirmed the uniform, nonwoven, and beadless architecture of the PCL fibers and the fibroporous nature of the PCL/CH scaffolds. The scaffolds exhibited excellent swelling behavior, controlled degradation rates, and enhanced mechanical properties. In vitro cell studies demonstrated scaffold cell-supportive properties in terms of cell attachment, proliferation, and migration. This innovative layer-by-layer fabrication technique, integrating nanofibers with freeze-cast scaffolds, represents a significant advancement in skin tissue engineering, promising improved outcomes in wound healing and regenerative medicine.

In 2023, around 850 million people globally were affected by chronic kidney disease, which leads to the retention of uremic toxins and excess fluid in the blood. This study examines the adsorption of these toxins to poly(ethylene oxide) (PEO) films, known for their low-fouling properties. The gold surfaces were treated with 5 mM end-thiolated methoxy-terminated PEO (m-PEO) and analyzed using dynamic contact angle measurements, X-ray photoelectron spectroscopy, and spectroscopic ellipsometry to confirm the PEO film's presence and determine chain density. The adsorption of 25 different uremic toxins to m-PEO films was evaluated by using liquid chromatography-mass spectrometry (LC/MS), focusing on their binding affinity and adsorption dynamics. Results showed the effective modification of surfaces with m-PEO, with a notable change in contact angles and chain density (∼0.5 and 0.8 chains/nm²). Interestingly, pyruvic acid showed significant adsorption, whereas other toxins, such as hippuric acid, creatinine, and xanthosine had minimal interactions with the film. This indicates that the adsorption of these toxins is not primarily concentration driven and is rather dependent on the chemical structure of each toxin. These findings provide important insights for designing low-fouling coatings for biomedical devices.

Monitoring enzyme activity is crucial in both scientific research and clinical applications. However, abnormalities in a single enzyme's activity can indicate multiple diseases, limiting the specificity of single enzyme activity monitoring in clinical diagnosis. We developed a dynamic DNA walker that can be sequentially activated by two enzymes, enabling the monitoring and imaging of both enzyme activities within cells. Initially, the DNA walker contains a site for apurinic/apyrimidinic endonuclease 1 (APE1). Upon APE1 activation, the DNA walker forms specific structures recognized and cleaved by Flap endonuclease 1 (FEN1). The temporal disparity between the activities of APE1 and FEN1 allows for the sequential monitoring and imaging of both enzymes, reducing the likelihood of false-positive results. To enhance local concentration and decrease reaction time, the DNA walk sequence was attached to the surface of gold nanoparticles (AuNPs). The fruition of this endeavor will facilitate the investigation and advancement of multiple enzyme activity monitoring and imaging methods and technologies, while simultaneously broadening the domains of application for DNA nanotechnology.

Developing implantable medical materials with excellent comprehensive performance has important practical applications. Cardiovascular and bile ducts are characterized by various forms of diseases and high morbidity and mortality. One of the effective treatment modalities for such diseases is replacement surgery. Since commercially available materials for tubular organ sites are in short supply and the number of autologous and natural grafts is limited, the study of implantable materials that can be prepared in tubes is of great significance. This study reports on an implantable medical polyurethane material (IBP-PU) with a binary soft segment structure prepared by microwave synthesis. The material exhibits excellent mechanical properties (with a mechanical strength of 33.00 ± 4.02 MPa and a strain at break of 519.93 ± 53.44%), and stable thermomechanical properties (T_d5% > 250 °C). The excellent biocompatibility of IBP-PU (hemolysis rate = 2.55% and cell survival on the fifth day over 100%, etc.) makes it suitable for implantable medical applications. Its appropriate degradation rate allows for slow in vivo degradation with the generation of tissues, and the degradation products are nontoxic and do not require removal by secondary surgery. Additionally, the material has been successfully prepared using electrostatic spinning technology, resulting in a 5 mm caliber. It is significant for small-caliber cardiovascular, bile duct, and other in vivo tubular grafts.

Hyperuricemia is a common disorder induced by purine metabolic abnormality, which will further cause chronic kidney disease, cardiovascular disease, and gout. Its main pathological characteristic is the high uric acid (UA) level in the blood, so that the detection of UA is highly important for hyperuricemia diagnosis and therapy. Herein, we report a biocompatible and minimally invasive microneedle electrode patch (MEP) for continuous UA monitoring and diet management in hyperuricemia. The composite of graphene oxide and carboxylated multiwalled carbon nanotubes was modified on the microneedle electrode surface to enhance its sensitivity, selectivity, and stability, thus realizing the continuous detection of UA in the interstitial fluid to accurately predict the UA level in the blood. This further allowed us to study the hypouricemic effect of anthocyanins on the hyperuricemia model mouse. It was found that anthocyanins extracted from blueberry can effectively inhibit the activity of xanthine oxidase to reduce the production of UA. The UA level of hyperuricemia model mice fed with anthocyanins is ∼1.7 fold lower than that of the control group. We believe that this MEP offers enormous promise for continuous UA monitoring and diet management in hyperuricemia.

We fabricated composite membranes containing inorganic nanosheets (NSs) and polymers and demonstrated their outstanding antibacterial performance against several opportunistic pathogens. Layered α-zirconium phosphate [Zr(HPO₄)₂, α-ZrP] as a pristine compound of NS was exfoliated by ion-exchanging protons in the interlayer space of α-ZrP with bulky tetraalkylammonium ions (TRA⁺: R = butyl, hexyl, and octyl). During the exfoliation process, TRA⁺ was electrostatically adsorbed onto α-ZrP NS with a negative surface charge (ZrP-TRA-NS). The produced PMMA membrane including α-ZrP NS (PM-ZrP-TRA-NS) was optically transparent and prohibited bacterial growth, and the effect was stronger for Gram-positive Staphylococcus aureus than Gram-negative Escherichia coli. The antibacterial activity of PM-ZrP-TRA-NS was based on physical damage induced by both 2D ceramic NSs and sharp alkyl chains of TRA⁺. Despite the inherent flexibility of alkyl chains, when adsorbed onto the NSs, they can act in a manner that effectively pierces the bacterial cell wall. The piercing force of TRA⁺ was greater for the longer alkyl chains (TBA⁺ < THA⁺ < TOA⁺). Focusing on the difference in the cell wall structure between these bacteria, the growth of Gram-positive S. aureus with loose peptidoglycan layers as an outer membrane could be easily inhibited by contact with the composite film. In contrast, Gram-negative bacteria E. coli, surrounded by a relatively dense outer cell wall composed of peptidoglycan and lipopolysaccharide layers, could not be damaged easily. In this study, the antibacterial mechanism of PM-ZrP-TRA-NS membranes was elucidated, and their usefulness as antimicrobial coatings for existing solid surfaces was demonstrated.

Exosomes are small extracellular vesicles (EVs) constituting fully biological, cell-derived nanovesicles with great potential in cell-to-cell communication and drug delivery applications. The current gold standard for EV labeling and tracking is represented by fluorescent lipophilic dyes which, however, importantly lack selectivity, due to their unconditional affinity for lipids. Herein, an alternative EV fluorescent labeling approach is in-depth evaluated, by taking advantage of green fluorescent protein (GFP) farnesylation (GFP-f), a post-translational modification to directly anchor GFP to the EV membrane. The performance of GFP-f is analyzed, in terms of selectivity and efficiency, in several typical EV experimental setups such as delivery in recipient cells, surface engineering, and cargo loading. First, the capability of GFP and GFP-f to label exosomes was compared, showing significantly higher GFP protein levels and fluorescence intensity in GFP-f- than in GFP-labeled exosomes, highlighting the advantage of directly anchoring the GFP to the EV cell membrane. Then, the GFP-f tag was further compared to Vybrant DiD lipophilic dye labeling in exosome uptake studies, by capturing EV intracellular fluorescence in a time- and concentration-dependent manner. The internalization assay revealed a particular ability of GFP-f to monitor the uptake of tagged exosomes into recipient cells, with a significant peak of intensity reached 12 h after administration by GFP-f but not Vybrant-labeled EVs. Finally, the GFP-f labeling capability was challenged in the presence of a surface modification of exosomes and after transfection for siRNA loading. Results showed that both procedures can influence GFP-f performance compared to naïve GFP-f exosomes, although fluorescence is importantly maintained in both cases. Overall, these data provide direct insight into the advantages and limitations of GFP-f as a tagging protein for selectively and accurately tracking the exosome route from isolation to uptake in recipient cells, also in the context of EV bioengineering applications.

Living systems have some of the most sophisticated reaction circuits in the world, realizing many incredibly complex functions through a variety of simple molecular reactions, in which the most notable feature that distinguishes them from artificial molecular reaction networks is the precise control of reaction times and programmable expression. Here, we exploit the hydrolysis-directed nature of λ exonuclease and the programmed responses of the dynamic nanotechnology of nucleic acids to construct a simple, complete, and powerful set of temporally programmed circuits. This system can arbitrarily regulate the degradation rate of the blocker, thereby delaying the nucleic acid chain substitution reaction with less signal leakage. In addition, the powerful dynamic reaction network of nucleic acids enabled us to control the programmed execution of a wide range of reactions in different fields. We have developed a simple strategy to introduce precise control of the time dimension into nucleic acid reaction circuits, which greatly enriches the functionality and applicability of the reaction programs, which can be easily used as timers, compilers, converters, etc. The simplicity, precision, stability, and versatility of such dynamic temporal programming circuits greatly expand the potential of artificial molecular reaction networks for more complex practical applications in biochemistry and molecular biology.

Medical devices composed of titanium (Ti) should exhibit antibacterial and osteogenic activities to achieve both infection prevention and rapid bone reconstruction. Here, a Ti surface was modified by performing magnetron sputtering (MS) using pure Mg or Mg–30Ca alloy targets for surface functionalization. MC0, prepared with a pure Mg target, had a crystalline metallic-Mg coating layer, whereas MC30, prepared with an Mg–30Ca alloy target, had an amorphous coating composed of Mg and Ca. Both samples rapidly dissolved when immersed in a cell culture medium and exhibited antibacterial activities against methicillin-resistant Staphylococcus aureus and cytotoxicity against MC3T3-E1 cells. Furthermore, MC30 promoted the proliferation and calcification of MC3T3-E1 cells because of the subsequent deposition of calcite on the surface after rapid dissolution. Our findings are the first to reveal that MS performed by using an Mg–30Ca alloy target endowed Ti surfaces with functional changes from antibacterial to osteogenic activities over time. Our results provide fundamental insights into the surface design of Ti-based medical devices for enhanced bone reconstruction and infection prevention and offer possibilities for biomedical applications of Mg-based coatings.

Creatinine is indeed a crucial biomarker for kidney diseases. In this work, a novel electrochemical biosensor based on a copper-hemin metal organic framework [Cu-hemin metal–organic framework (MOF)] nanoflake decorated with palladium (Pd) (Pd/Cu-hemin MOF) was fabricated and incorporated with creatinine deiminase (CD) on a glassy carbon electrode (GCE) for creatinine detection. The formation of a Pd/Cu-hemin MOF composite was confirmed by X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The formation of the composite as nanoflakes is evident from the scanning electron microscopy image. The transmission electron microscopy image clarifies the decoration of palladium nanoparticles on Cu-hemin MOF surfaces. Thus, the proposed biosensor (Pd/Cu-hemin MOF/CD/GCE) electrochemical performances were studied with cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. As a result, the Pd/Cu-hemin MOF/CD/GCE-based electrochemical detection of creatinine exhibits a broad linear range from 0 to 130 μM (R² = 0.99), a low limit of detection 0.08 μM, and an excellent sensitivity of 3.2 μA μM^–1 cm^–2. The biosensor also determines creatinine in samples of human urine with a good recovery from 99.4 to 100.8%. Thus, in this study, an electrochemical biosensing platform based on Pd/Cu-hemin MOF/CD/GCE has been designed practically for creatinine.