Fabrication of Nanostructured Scaffolds …
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8 Scaffold Requirements
For tissue engineering scaffold fabrication, the selection of materials with functional
requirements for the preferred application is essential. The ideal tissue engineering
scaffold should be a biocompatible, biodegradable, non-toxic, non-immunogenic,
higher porous structure with interconnected pores, reproducible, higher surface to
volume ratio, suitable for surface modification, acceptable mechanical strength,
promote ECM development and able to deliver biomolecule signals [6, 29–33].
The ultimate aim of any tissue engineering scaffold should satisfy by providing a
three-dimensional environment for cell attachment and better tissue ingrowth on it.
The first biodegradable tissue scaffold fabricated and reported by Hutmacher et al.
in 2002 using fused deposition modeling (FDM). The ideal qualities of the tissue
regeneration scaffold are following; (i) micro (<20 μm) and macro (>100 μm) pore
size respectively, (ii) high porosity with interconnected open pores for in vivo tissue
in-growth; (iii) should provide adequate mechanical strength and well-controlled
degradation rate (iv) easy and harmless to handle for sterilization, packaging, transportation to surgery and (v) should be sterile for seeding the cells [34]. Moreover,
the difference among the required qualities for tissue regeneration and bone graft
substitutes is still imprecise. However, in general agreement, the bone tissue regeneration scaffolds should have more open pores (>40–60%) to allow the easy diffusion dissolved gases and nutrients which permit more cell migration [35]. The pore
sizes should be in the range of 50–1000 μm to attain the required porous structure needed for tissue regeneration [36, 37]. However, the ideal tissue engineering
scaffold requires diverse configurations for suitable tissue healing or regeneration
applications.
8.1 Polymers
Polymers are widely used materials in tissue engineering and drug delivery applications. As mentioned earlier, polymers can be either naturally derived or synthetic
origin or both the natural polymers such as polysaccharides, including alginate,
chitin/chitosan, hyaluronic acid and its derivatives similarly, proteins such as
collagen, elastin, gelatin, fibrin gels, and silk. The natural polymers are beneficial due
to their high biocompatibility [28]. Since the 1960s, synthetic biodegradable polymers play a significant role in tissue regeneration scaffold fabrication. They have
many advantages compared to natural polymers by which they can easily custommade to offer a wide range of functional properties and the significant benefit of
being devoid of immunogenicity. In addition to that, they can be easy for processing,
surface modification, and sterilized by different techniques. A limited number of
synthetic biodegradable polymers are only used for tissue engineering applications and approved by the United States Food and Drug Authority (USFDA) for
use in specific biomedical applications. The synthetic polymers such as poly(lactic
323
8 Scaffold Requirements
For tissue engineering scaffold fabrication, the selection of materials with functional
requirements for the preferred application is essential. The ideal tissue engineering
scaffold should be a biocompatible, biodegradable, non-toxic, non-immunogenic,
higher porous structure with interconnected pores, reproducible, higher surface to
volume ratio, suitable for surface modification, acceptable mechanical strength,
promote ECM development and able to deliver biomolecule signals [6, 29–33].
The ultimate aim of any tissue engineering scaffold should satisfy by providing a
three-dimensional environment for cell attachment and better tissue ingrowth on it.
The first biodegradable tissue scaffold fabricated and reported by Hutmacher et al.
in 2002 using fused deposition modeling (FDM). The ideal qualities of the tissue
regeneration scaffold are following; (i) micro (<20 μm) and macro (>100 μm) pore
size respectively, (ii) high porosity with interconnected open pores for in vivo tissue
in-growth; (iii) should provide adequate mechanical strength and well-controlled
degradation rate (iv) easy and harmless to handle for sterilization, packaging, transportation to surgery and (v) should be sterile for seeding the cells [34]. Moreover,
the difference among the required qualities for tissue regeneration and bone graft
substitutes is still imprecise. However, in general agreement, the bone tissue regeneration scaffolds should have more open pores (>40–60%) to allow the easy diffusion dissolved gases and nutrients which permit more cell migration [35]. The pore
sizes should be in the range of 50–1000 μm to attain the required porous structure needed for tissue regeneration [36, 37]. However, the ideal tissue engineering
scaffold requires diverse configurations for suitable tissue healing or regeneration
applications.
8.1 Polymers
Polymers are widely used materials in tissue engineering and drug delivery applications. As mentioned earlier, polymers can be either naturally derived or synthetic
origin or both the natural polymers such as polysaccharides, including alginate,
chitin/chitosan, hyaluronic acid and its derivatives similarly, proteins such as
collagen, elastin, gelatin, fibrin gels, and silk. The natural polymers are beneficial due
to their high biocompatibility [28]. Since the 1960s, synthetic biodegradable polymers play a significant role in tissue regeneration scaffold fabrication. They have
many advantages compared to natural polymers by which they can easily custommade to offer a wide range of functional properties and the significant benefit of
being devoid of immunogenicity. In addition to that, they can be easy for processing,
surface modification, and sterilized by different techniques. A limited number of
synthetic biodegradable polymers are only used for tissue engineering applications and approved by the United States Food and Drug Authority (USFDA) for
use in specific biomedical applications. The synthetic polymers such as poly(lactic