INTRODUCTION TO PROCESSING OF BIOMATERIALS - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 249

Although the aforementioned steps of processing are commonly applicable
to most polymeric biomaterials, there can be special applications wherein the pro-
cessing of polymers can be relatively unique. One such example is that of process-
ing polymers for the fabrication of scaffolds to be used in tissue engineering
applications. Scaffolds are usually made from biodegradable polymers and act as
a transient ECM that provides support and guidance for the growth of seeded
cells that eventually leads to the formation of new tissue. Hence the polymers
used for the fabrication of scaffolds are necessarily biocompatible and biodegrad-
able while providing mechanical strength (especially important in the case of
hard tissue regeneration) and being intrinsically transient in nature. In addition to
these properties, more recent scaffolding systems are associated with proteins
such as growth factors that govern tissue growth. The association of proteins with
scaffolds limits the processing conditions in terms of temperature and usage of
solvents, thereby making the processing more challenging. Various techniques
that have been previously reported for the fabrication of scaffold are: fi ber
bonding, solvent casting and salt leaching, phase separation, freeze drying, mem-
brane lamination, melt molding, and in situ polymerization [46, 47] .

8.3.3.2.2 SURFACE TREATMENT [48] . Polymeric materials also undergo
various surface fi nishing processes (Figure 8.4) with the aim of improvement of
appearance, biocompatibility and biointegration.
Polymers, being chemically and physically versatile, have been used in a
variety of biomedical applications. Due to the versatility of polymers and the
growth in the biomedical device industry, the processing of polymeric biomate-
rials has experienced an exponential growth in the past few decades. Future
development should involve machinery design, process analysis and optimization
to enable the fabrication of polymeric products with improved properties.

Oxidation by
air

Interpenetrating grafts

Cross-linked grafts

Grafting

Brush grafting

Stimuli-responsive
grafts

Embossing

Polymer surface
modifications

Plasma modification

High energy
treatment

Fused deposition
modeling process

Gamma irradiation

Ink jet printing

Contact printing

Microcontact
printing
Proton
micromachining

Surface
printing

Laser etching

E-beam etching

Rapid prototyping

Figure 8.4. Schematic representation of techniques used for polymer surface modifi cations.