Smart Materials in Medicine最新文献

Brain injury often caused irreversible loss of neural tissue and resulted in serious neurological disability. Owing to the extreme complexity of the brain, it is still challenging to regenerate the brain tissue from injury and restore its normal function. Growth factors are critical signaling molecules that promote endogenous neural stem/progenitor cells (NSPCs) proliferation, migration and differentiation, resulting in functional brain recovery from injury. However, the labile nature of growth factor motivated us to develop advanced growth factor delivery strategies to precisely control over its release profile in vivo. In this review, we will discuss growth factor delivery via biomaterials for brain regeneration after injury. This review begins with an overview of some major forms of brain injury. The characteristic properties of growth factors are described to provide a biological basis for their use in the brain regeneration. The specific biomaterials that generally used for delivering growth factor to treat brain injury are also detailed summarized. In particular, we focus on an engineering strategy that promote endogenous repair by creating growth factor concentration gradients in vivo. The last part of the review introduces current challenges and perspectives for growth factor delivery via biomaterials.

Three-dimensional (3D) printing can construct products with accurate complex architecture. Engineered bone tissues that can promote vascularization and regulate directed differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) are considered as an ideal substitute the healing of bone for bone defects treatment. Herein, we fabricated a 3D printed BMSCs-laden scaffold using methacrylated gelatin and methacrylated silk fibroin (GelMA/SFMA) based bioinks along with localized sustained release of a small molecule drug fingolimod (FTY-720) for the synergistic interactions of vascularization and osteogenesis during bone repair. The GelMA/SFMA bioink showed significant advantages due to their tunable rheology, rapid thermal crosslinking, and improved shape fidelity following bioprinting. The in vitro experiments demonstrated that high cell viability of cells-laden constructs, while FTY-720-containing scaffolds significantly promoted migration and induced tube-like structure formation of human umbilical vein endothelial cells (HUVECs) as well as expressed high osteogenic-related genes expression of BMSCs. The implantation in a critical-size rat cranial defect model further revealed that FTY-720-loaded scaffolds significantly promoted vascularization and bone regeneration. Furthermore, scaffolds carrying BMSCs and FTY-720 were more osteogenic in vivo than scaffolds carrying BMSCs alone. Therefore, the constructed BMSCs-laden and FTY-720-loaded GelMA/SFMA scaffolds would be an ideal candidate with required structure and desired function for vascularization of bone regeneration.

Zinc (Zn) is a new generation of biodegradable metal as temporary biomedical implants with a promising degradation rate. However, its clinical applications have been limited because of the insufficient mechanical properties. Considering the degradation property and biocompatibility, we proposed Zn–Sr alloys after extrusion treatments to simultaneously improve the mechanical strength and ductility. The in vitro and in vivo degradation and biocompatibility were also evaluated using electrochemical and immersion corrosion tests, various cell and bacterial models, together with subcutaneous and femoral implantations in rats. Results showed that the extruded Zn-0.7Sr alloys exhibited two times higher mechanical strengths (∼120 ​MPa) and better ductility (∼10%) than the pure Zn counterparts. The Zn–Sr alloys provided enhanced in vitro and in vivo biocompatibility along with promising antibacterial properties.

Magnesium (Mg) alloy has received thorough attention in the biomedical field due to its excellent mechanical properties, good biocompatibility, and biodegradability. However, Mg alloy usually shows excessive degradation rate in the physiological environment owning to its active chemical nature. At the same time, the hydrogen generated by the degradation of Mg will increase the pH of local tissues, which will harm the growth of surrounding tissues. Given the above problems, it has become a research hotspot to obtain various properties of Mg alloy for clinical application by surface modification. In this paper, the surface coatings of Mg alloy are reviewed according to different types, including metals (metal oxides, metal hydroxides), inorganic non-metals, polymers (synthetic polymers and natural polymers), and composite coatings. The preparation methods, corrosion resistance, and biocompatibility of different types of coatings are discussed, and the development prospect of biomedical Mg alloy surface coatings is also predicted.

Cells are naturally surrounded by an electroactive extracellular matrix in vivo, which is composed of a diverse array of charged molecules such as glycosaminoglycans and proteoglycans, together with piezoelectric collagen fibers capable of generating electrical signals in response to mechanical stimuli. In recent years, electroactive scaffold materials have attracted much attention in tissue engineering and regenerative medicine applications, as a biomimetic strategy to recapitulate the natural physiological electrical microenvironment in vivo, which could enhance the differentiation of stem/progenitor cells into specific lineages, thus facilitating tissue repair and regeneration. The key to improving the functional design of electroactive scaffold biomaterials would be to understand the various intracellular signaling pathways that are activated by electrical stimuli. Therefore, this review critically examines the effects of electrical stimuli and/or scaffolds with electroactive properties on directing stem/progenitor cells towards the osteogenic, neurogenic and other lineages, with particular focus on the molecular signaling pathways involved.

Benefiting from fusion element (peptides or proteins) anchoring, several biological membrane vesicles or synthetic liposomes have great potency to fuse with the target cell membrane via virus-mimetic behavior. When this process happens, the encapsulated cargos can be released directly into the cytoplasm together with membrane component (protein receptor, channel proteins, chemical receptors, antibodies) transfer, a process that facilitates cellular/molecular diagnosis and therapy.

Biomedical magnesium (Mg) alloys have been widely studied as important structural materials and biodegradable materials in cardiovascular stents system. However, excessively rapid degradation and delayed endothelialization are still the bottlenecks limiting the further application of Mg alloy stents. The core scientific problem lies in how Mg alloys and their degradation products direct the fate of cardiovascular cells to develop in favor of endothelialization, which is still unclear. The aggregation of macrophages (MA) is the earliest cellular response after stent implantation for atherosclerotic lesions, and our previous research proved that MA behaviors played crucial roles on endothelialization in vitro. Thus, the present study chooses a Mg alloy, Mg–Zn–Y-Nd, to investigate its degradation behavior on directing the fates of MA and endothelial cells (EC). Our data shows that the increased ratio of Mg²⁺/Ca²⁺ in medium during the degradation of the Mg–Zn–Y-Nd alloy may regulate the MA to switch to their M2 phenotype, and the MA conditioned medium further promote the proliferation and CD31 expression of EC in vitro. Co-culture of MA and EC indicates that M2-type MA also contribute to proliferation and CD31 expression of EC. All these results suggest controlling the degradation behavior of Mg alloys will direct the fates of MA and EC, further improving endothelialization in vitro.

Wearable electronic devices are important in recording signals related to human activities. Because the performance of wearable electronic devices depends heavily on power sources, batteries, especially fiber batteries have been attracting numerous attention in the past decades. Here, we present a perspective of fiber lithium-ion battery (FLIB) equipped with excellent energy supply, deformability, and feasibility to be woven into textile electronics. The scalable production and sustainable application of these FLIBs in health monitoring could be realized benefitting from the decreased internal resistance with length. This kind of fiber battery is anticipated to show its potentials in not only next-generation flexible devices but also regenerative medicine and tissue engineering.

Controlling biomolecular interactions with light has gained traction among biomedical researchers due to its high spatiotemporal precision. Although a variety of photoresponsive chemical moieties are readily available thanks to the efforts made by chemists, genetically encoded photoswitches, also known as optogenetic tools, that are compatible with complex biological systems remain highly desirable. Recently, detailed mechanistic studies of the B₁₂-dependent bacterial photoreceptor CarH have provided researchers with some new approaches to materials synthetic biology. Further development of this emerging molecular tool will continue to benefit future materials science and optogenetics.

Cells in the body reside within the extracellular matrix (ECM), a three-dimensional environment that not only provides structural support for the cells, but also influences cellular processes, like migration and differentiation. The ECM and the cells continuously engage in a complex and highly dynamic interplay, shaping both the matrix as well as the cellular outcome. To study these dynamic, bidirectional interactions in a systematic manner, the ability to dynamically control cellular environments is highly desirable. Stimuli-responsive materials are a class of materials that have been engineered to respond to external cues, e.g., light, electricity, or magnetic field, and therefore hold fascinating potentials as an ideal experimental platform to introduce changing spatiotemporal signals to cells. Here, we review the state of the art in stimuli-responsive materials and their design strategies, with an emphasis on the dynamic introduction of physical and mechanical cues. The effects of such dynamic stimuli on the responses of living cells are examined on three different levels: cellular phenotypes, intracellular and cytoskeletal changes, and nuclear and epigenetic effects. Finally, we discuss the current challenges and limitations as well as the potential outlooks in exploiting stimuli-responsive biomaterials.