Key Engineering Materials Vol. 441

Abstract: Bone problems affect millions of people across the world. In fact, musculoskeletal conditions such as joint pathologies, fractures related to osteoporosis, back pain, serious injuries and different sorts of bone diseases and disabilities are among the most common causes for hundreds of millions of people worldwide suffering acute and severe long-term pain and becoming physically handicapped. It has been reported that over 100 million Europeans are affected by different bone related problems and suffer chronic musculoskeletal pain, while in the US musculoskeletal problems affect over 40 million people aged 45 years and older. It is expected that the percentage of population affected by musculoskeletal conditions will double by the year 2020. Although morbidity is low, they have a major effect on disability, medical costs and patient quality of life [1,2]. Thus, bone defect treatments represent a significant medical and socioeconomic challenge.

Abstract: Dendrimers are a relatively new class of molecules that display a variety of potentially useful architecture-induced properties. In this chapter, we firstly present a general description of this interesting class of macromolecules, making special emphasis in their current biomedical applications. The combination of dendrimers with ceramics, traditionally used in the biomedical field, provides synergistic features and functions to the resulting hybrid materials. After the dendrimers introduction, an overall description of mesoporous silicas, iron oxide nanoparticles and carbon nanotubes bioceramics, is presented. Finally, recent research examples of dendrimer-functionalized ceramics, both from the synthetic and biomedical applicative points of view, are reviewed.

Abstract: 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.

Abstract: Calcium phosphate is a natural biomineral and therefore possesses an excellent biocompatibility due to its chemical similarity to human hard tissue (bone and teeth). Calcium phosphate nanoparticles can be precipitated under controlled conditions and used as carrier in biological systems, e.g. to transfer nucleic acids or drugs. Such nanoparticles can also be suitably functionalized with fluorescing dyes, polymeric agents, pro-drugs or activators. The small monodisperse nanoparticles only mildly influence the intracellular calcium level and therefore are not toxic for cells.

Abstract: Although governments invest billions of dollars in cancer research, cancer remains one of the major causes of death worldwide (Liu et al., 2007). During the last decades, outstanding results have been attained in fundamental cancer biology but, unfortunately, they have not been translated in even distantly comparable progressions in the clinic. The main reason for this gap being the inability to administer therapeutic agents so that they can reach target cells without or with minimal side-effects (Ferrari, 2005). Today, scientists are faced with the recognition that very few molecules reach the desired locations and thus fail to selectively reach the target cells. Consequently, patients experience a very poor quality of life (Ferrari, 2004; Ferrari, 2005; Chan, 2006).

Abstract: . Aqueous suspensions containing small magnetic particles have been increasingly used in biosciences and biotechnology. Magnetic particles develop magnetic polarization and magnetophoretic mobility, and because of such unique properties, these carriers may be eligible candidates for delivering drugs to specific sites within the body. Their special properties also allow other uses, such as those in embolization, radioisotope delivery, magnetic cell tracking for monitoring cell therapy, magnetofection, and hyperthermia. This review focuses on a discussion about magnetic particles, the properties and fate of magnetic carriers, the methods used to produce and characterize them, and their other uses in biotechnology.