Bioceramics are an important subclass of inorganic, non-metallic biomaterials. Attributing to their bioactivity and the ability to form bonds with native bone, bioceramics are increasingly used in medical implants, especially for bone repair and regeneration. With chemical composition similar to that of native bone, hydroxyapatite (HAp), a type of bioceramics, may impart to biomaterial implants biocompatibility, osteoconductivity, as well as surface properties that are germane to osteointegration at the bone-implant interface. However, porous bioceramics are very brittle and have low fracture toughness and compressive strength, which limits their uses as bulk materials for orthopedic implants. Increasing their mechanical strength by reducing the porosity may prevent tissue infiltration, therefore, bone regeneration. In comparison, polymers may mimic the mechanical properties of native bone, however, may lack the appropriate surface properties to seamlessly integrate with natural bone. There is a critical need to combine the bulk properties of polymers with the surface properties of bioceramics in the design of functional scaffolds for bone tissue engineering. There are several ways to incorporate bioceramics on scaffold surfaces, including plasma spraying, sputter coating, physical adsorption, laser deposition, and biomineralization. Biomineralization, which allows easy fabrication of bioceramics under physiological conditions, provides an effective means to produce bonelike minerals, e.g., HAp, on scaffold surfaces. By following the cascade of biological mineralization in vivo, biomineralization in vitro on polymers may be achieved using several different methods, including immersion in simulated body fluid (SBF), alternative soaking in calcium and phosphate solutions, urea-mediated solution mineralization, enzymatic method, and direct incorporation of HAp nanoparticles into polymers. The uniformity, structure, and composition of the bioceramic coatings can be fine-tuned by governing bimineralization parameters such as composition and concentration of the immersion solution, immersion time, temperature, and agitation. A variety of surface modification techniques can be chosen to functionalize/activate polymer surfaces to facilitate biomineralization. In this review, the mechanism for biomineralization in vivo, different mechanisms and methods for biomineralization in vitro, surface modifications for enhanced biomineralization, polymers for biomineralization, and biomineralization for drug delivery will be discussed in details.
Polymer nanofibers are favorable for tissue engineering scaffolds because of their high surface-to-volume ratio and biomimicry of the extracellular matrix. Random and uniaxially oriented polymer nanofibers are easily fabricated by conventional electrospinning techniques; however, control over fiber organization within nanofiber structures is limited when they are collected directly from an electrospinning jet. The regenerative medicine applications of electrospun scaffolds could be expanded by developing assembly methods that allow better control of fiber organization. Here, a novel technique is presented that utilizes parallel automated tracks to orient and collect nanofibers from an electrospinning jet. The stabilized fibers are then subsequently assembled into desirable structures. It is difficult to assemble complex structures directly from an electrospinning jet because of high electrical charge and velocities, so this technology adds an intermediate step where nanofibers are immobilized on automated tracks. The result is a continuous steady-state delivery of static stabilized nanofibers that provides a unique and promising platform for automated post processing into useful nanofiber structures. This technique also allows for an indefinite amount of time, as determined by design parameters, for fibers to dry or cool before they contact other nanofibers in the collection site, thus eliminating potential for fiber-to-fiber adhesions even with slow evaporating solvents or high-temperature melts. To demonstrate potential in regenerative medicine applications, several nanofiber structures were fabricated, including: 2D structures with well-controlled fiber density; 3D loosely assembled aligned nanofiber structures with good cell penetration properties; and, complex layer-by-layer 3D aligned fiber structures assembled by integration with post-processing techniques.
Scientific interest in the self-assembly of collagen composite films has been increasing for their potential application in constructing bioactive materials. Here we report a highly stable and cytocompatible collagen/alginate (COL/ALG) ultrathin film, which was linearly fabricated via a layer-by-layer self-assembled technique. The variation in morphology and thickness of the films in air and in solutions with different pH and ion values were tested by atomic force microscopy. Results showed that the solutions with high pH values or solutions that contained electrolytes would disintegrate the film, while films with that were cross-linked for a long time prevented the dissolution and contributed to stability maintenance of the films. Interestingly, the COL/ALG coating not only improved the adhesion and proliferation of the human periodontal ligament cells, but also modified the morphology and migration of cells on the surface of glass and poly-L-lactic acid (PLA) electrospun scaffolds. In conclusion, the COL/ALG ultrathin films were highly stable and cytocompatible and could be easily fabricated by the cost-effective self-assembled technique presented. The findings of this study have the potential to play an important role in the surface modification of biomaterials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.