Biomedical Engineering Reference
In-Depth Information
to concentrate the DNA as a result of dissimilar charges attract intensify
permeability by surface modification and biodegrade into low-toxic product
(Hwang and Davis 2001; Ratner and Bryant 2004). Meanwhile, its fast degra-
dation and weak mechanical strength impose restrictions on its application
especially for load bearing (Di Martino et al. 2005). Following the research
progresses, inorganic materials have shown comparable and, in some
instances, better gene delivery efficiencies than organic systems (Sokolova
and Epple 2008). Calcium phosphates (CaPs), gold nanoparticles (GNPs),
silica, magnesium phosphates, and iron oxides have been introduced for
study and exhibited excellent characteristics lying in antibacterial activity,
biocompatibility, and bioactivity (Kim et al. 1998; Chowdhury and Akaike
2005; Kawano et al. 2006).
However, weak interactions between the inorganic
vector and the ribonucleic acid molecules are usually established in the case
of gene delivery system (Vallet-Regi et al. 2011).
In recent years, research into bioactive organic-inorganic hybrid materials
has captured the scientific and public interest with the promise to gene deliv-
ery. Bioactive organic-inorganic hybrid materials can be generally defined as
materials with organic and inorganic components that are not only closely
mixed in phases but also coexist intimately through size domain effects and
nature of the interfaces (Gómez-Romero and Sanchez 2004; Vallet-Regi et
a l. 2011).
Bioactive organic-inorganic hybrid materials offer unique biologi-
cal, electrical, and mechanical properties for the design of an excellent gene
delivery system (Yang et al. 2009).
For the sake of organization, this chapter has been divided into two parts
of bone regeneration and gene delivery. Each part presents three classi-
fications that are the combination of CaP inorganic materials including
phosphate (hydroxyapatite [HAp], tricalcium phosphate [TCP], or biphasic
calcium phosphate [BCP]) composite materials, the bioactive glass composite
materials, and the silicate bioceramic composite materials. We will discuss
the microstructure and mechanical properties of these materials, then evalu-
ate the feasibility in the field of biomedical materials. Furthermore, three sec-
tions were organized to introduce the gene delivery of composites materials,
including CaP-based hybrid materials, hybrid materials integrated with gold
nanoparticles (GNPs), silicate-based hybrid materials, quantum-dots-based
hybrid materials, and iron-based hybrid materials for gene delivery.
7.2 Bioactive Inorganic-Organic Composite
Materials for Bone Regeneration
Tissue engineering composites are potential bone substitutes. The brittle-
ness of inorganic materials is their main disadvantage as scaffold materials.
Polymers are easily fabricated to form complex shapes and structures, but
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