Electrohydrodynamic (EHD) direct-writing has recently gained attention as a highly promising additive manufacturing strategy for fabricating intricate micro/nanoscale architectures. This technique is particularly well-suited for mimicking the extracellular matrix (ECM) present in biological tissue, which serves a vital function in facilitating cell colonization, migration, and growth. The integration of EHD direct-writing with other techniques has been employed to enhance the biological performance of scaffolds, and significant advancements have been made in the development of tailored scaffold architectures and constituents to meet the specific requirements of various biomedical applications. Here, a comprehensive overview of EHD direct-writing is provided, including its underlying principles, demonstrated materials systems, and biomedical applications. A brief chronology of EHD direct-writing is provided, along with an examination of the observed phenomena that occur during the printing process. The impact of biomaterial selection and architectural topographic cues on biological performance is also highlighted. Finally, the major limitations associated with EHD direct-writing are discussed.EHD direct-writing has notable advantages for the controlled fabrication of micro/nanoscale architectures and particularly suitable for mimicking the extracellular matrix (ECM) present in biological tissue. Herein, a comprehensive overview of EHD direct-writing, including its evolution, principles, materials, and biomedical applications, is summarized. Meanwhile, the most relevant and recent advances related to biomedical applications impacted by biomaterial selection and architectural topographic cues are highlighted. Finally, perspectives on the challenges of EHD direct-writing and its prospects for future development are discussed. image

Titanium and its alloys are often used as substrates for dental implants due to their excellent mechanical properties and good biocompatibility. However, their ability to bind to neighboring bone is limited due to the lack of biological activity. At the same time, they show poor antibacterial ability which can easily cause bacterial infection and chronic inflammation, eventually resulting in implant failure. The preparation of composite hydroxyapatite coatings with antibacterial ability can effectively figure out these concerns. In this review, the research status and development trends of antibacterial hydroxyapatite coatings constructed on titanium and its alloys are analyzed and reviewed. This review may provide valuable reference for the preparation and application of high-performance and multi-functional dental implant coatings in the future.

Effective clinical methods for large bone defects are not yet available on account of the complex intrinsic structure and mechanical characteristics of natural bone tissue. It remains a challenge to restore bone damage to its original form by tissue engineering. With the continuous development of three-dimensional (3D) printing in recent years, the emergence of new technical supports and material innovations has established the foundation for bone tissue engineering (BTE). 3D printing has significant advantages for personalized treatment, as it allows for the specific fabrication of scaffolds with appropriate size, shape and intrinsic structural characteristics via patients' computerized axial tomography scan or magnetic resonance imaging. In this review, we first systematically reviewed the development of 3D printing, printing methods and the selection of printing inks, then focused on the application of high-strength hydrogels in 3D printing for BTE. A brief anticipation of the future development of 3D printing was presented.[GRAPHICS].

Conventional stem cell delivery typically utilize administration of directly injection of allogenic cells or domesticated autogenic cells. It may lead to immune clearance of these cells by the host immune systems. Alginate microgels have been demonstrated to improve the survival of encapsulated cells and overcome rapid immune clearance after transplantation. Moreover, alginate microgels can serve as three-dimensional extracellular matrix to support cell growth and protect allogenic cells from rapid immune clearance, with functions as delivery vehicles to achieve sustained release of therapeutic proteins and growth factors from the encapsulated cells. Besides, cell-loaded alginate microgels can potentially be applied in regenerative medicine by serving as injectable engineered scaffolds to support tissue regrowth. In this review, the properties of alginate and different methods to produce alginate microgels are introduced firstly. Then, we focus on diverse applications of alginate microgels for cell delivery in tissue engineering and regenerative medicine.

Antimicrobial hydrogels have been proposed to be interesting materials used for wound healing due to their unique properties. Therefore, numerous scientists have made efforts to design and synthesize antibacterial hydrogels. At present, there are two commonly used methods for preparing antibacterial hydrogels. One is combining antibacterial agents with hydrogels. Antibacterial drugs include antibiotics, some biological extracts, natural polymers and some metal nanoparticles. In this review, physical combination (directly incorporating, swelling diffusion method, encapsulated in carriers) and chemical combination (hydrogels with inherent antibacterial activity, forming chemical bonds) are introduced depending on the methods and types of antibacterial agents incorporated with hydrogels. The other one is light-assisted antibacterial hydrogels, which involve photothermal antibacterial hydrogels and photo-dynamic antibacterial hydrogels. The common methods to prepare light-assisted antibacterial hydrogels are also described in this work. With the rapid improvements in antibacterial technology, many novel antibacterial hydrogels are constantly emerging. The most relevant studies and the latest status of research in this area were evaluated in this review.

Antimicrobial hydrogels have been proposed to be interesting materials used for wound healing due to their unique properties. Therefore, numerous scientists have made efforts to design and synthesize antibacterial hydrogels. At present, there are two commonly used methods for preparing antibacterial hydrogels. One is combining antibacterial agents with hydrogels. Antibacterial drugs include antibiotics, some biological extracts, natural polymers and some metal nanoparticles. In this review, physical combination (directly incorporating, swelling diffusion method, encapsulated in carriers) and chemical combination (hydrogels with inherent antibacterial activity, forming chemical bonds) are introduced depending on the methods and types of antibacterial agents incorporated with hydrogels. The other one is light-assisted antibacterial hydrogels, which involve photothermal antibacterial hydrogels and photo-dynamic antibacterial hydrogels. The common methods to prepare light-assisted antibacterial hydrogels are also described in this work. With the rapid improvements in antibacterial technology, many novel antibacterial hydrogels are constantly emerging. The most relevant studies and the latest status of research in this area were evaluated in this review.

Conventional stem cell delivery typically utilize administration of directly injection of allogenic cells or domesticated autogenic cells. It may lead to immune clearance of these cells by the host immune systems. Alginate microgels have been demonstrated to improve the survival of encapsulated cells and overcome rapid immune clearance after transplantation. Moreover, alginate microgels can serve as three-dimensional extracellular matrix to support cell growth and protect allogenic cells from rapid immune clearance, with functions as delivery vehicles to achieve sustained release of therapeutic proteins and growth factors from the encapsulated cells. Besides, cell-loaded alginate microgels can potentially be applied in regenerative medicine by serving as injectable engineered scaffolds to support tissue regrowth. In this review, the properties of alginate and different methods to produce alginate microgels are introduced firstly. Then, we focus on diverse applications of alginate microgels for cell delivery in tissue engineering and regenerative medicine.

The application of Gd-based contrast agent is widely broad for magnetic resonance imaging in clinic diagnosis. However, the toxicity of Gd-based contrast agent still cannot be ignored. Therefore, most researchers have made a great effort to find low toxic contrast agent. lion oxide nanoparticles (IONP) have a great dark contrast effects in magnetic resonance imaging (MRI) due to their superparamagnetic properties , and they also have good biocompatibility. With the rapid development of biomaterials and molecular image technology, the application of IONP in MRI has become more and more broad. In recent years , IONP has made great progress in dual-modal imaging. What' s more, IONP is not only used to clinical diagnosis, but also in treatment. It offers some new strategies for the treatment of disease. Based on the magnetic resonance imaging mechanism and preparation, surface modification of IONP, this review elaborates the research progress of IONP in magnetic resonance imaging in recent years.

Titanium (Ti) and Ti alloys have been the main clinical application materials for bone and dental implants due to their excellent mechanical properties and good biocompatibility. However, it is not easy to achieve rapid osseointegration with surrounding bone tissues because of the biological inertia of titanium materials. Therefore, the biological activity of implant surface is further required. Hydroxyapatite (HA) is the main inorganic component of human bones and teeth, which has good bioactivity and biocompatibility. But restricted by its own brittleness, HA is often used as a coating material to cover the surface of Ti substrates to improve the biological activity of implants. However, the problems of weak bonding strength between coating and substrate and poor mechanical stability of coating have been the main factors limiting the wide clinical applications of HA coated titanium implants. From the aspects of coating structure, composition and preparation method, the research status and development trend of improving the interface bonding strength between Ti substrate and HA coating at home and abroad are summarized, which could provide a reference for the preparation and application of high-performance titanium implants.

Titanium (Ti) and Ti alloys have been the main clinical application materials for bone and dental implants due to their excellent mechanical properties and good biocompatibility. However, it is not easy to achieve rapid osseointegration with surrounding bone tissues because of the biological inertia of titanium materials. Therefore, the biological activity of implant surface is further required. Hydroxyapatite (HA) is the main inorganic component of human bones and teeth, which has good bioactivity and biocompatibility. But restricted by its own brittleness, HA is often used as a coating material to cover the surface of Ti substrates to improve the biological activity of implants. However, the problems of weak bonding strength between coating and substrate and poor mechanical stability of coating have been the main factors limiting the wide clinical applications of HA coated titanium implants. From the aspects of coating structure, composition and preparation method, the research status and development trend of improving the interface bonding strength between Ti substrate and HA coating at home and abroad are summarized, which could provide a reference for the preparation and application of high-performance titanium implants.