NANOFIBROUS SCAFFOLDING FOR BONE TISSUE ENGINEERING - Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine - page 278

beads. Compared with pure PCL, wherein cell growth was limited,
theblendednanofibershowedbetterpenetration ofcellswithinthe
nanofiber matrix. 15 PLA was mixed with gelatin at various ratios
(1:3, 1:1, and 3:1) and electrospun into nanofibers. 16 The blended
nanofiber improved the water a nity of the matrix with respect
to the PLA nanofiber. Osteoblastic cells (MC3T3-E1) were shown to
have better proliferation behavior and expression of genes related
with bone on the PLA-gelatin than on pure PLA. Along with bio-
logical functions, mechanical improvement was also noticed in the
blending of collagen with PCL. 17 The collagen-added PCL presented
ahigherelongationratethanPCL,whilepreservingtensilestrength,
suggesting the role of collagen in the mechanical function. When
implanted in a subcutaneous region, tissue cells penetrated actively
into the pores of the collagen-PCL nanofiber, whilst only limited
progress was noticedin the PCL nanofiber. 17
Alongwithsyntheticpolymers,naturalpolymers,includingcolla-
gen,gelatin,chitosan,andsilk,havebeensourcesfortheboneregen-
erative nanofiber matrix. Among these, collagen is the one that has
gained the most considerable attention. 18 - 20 Collagen (type I), as
the major organic component of tissue, constitutes the main bone
ECM with a nanofibrillar structure and performs mechanical and
biological functions. Collagen nanofibers have been electospun with
various diameters, which were well in the regime of native colla-
gen fibrils. Electrospun collagen (type I) has shown to provide an
active substrate condition for BMSCs to adhere and migrate. 19 How-
ever, organic solvents such as fluoroalcohols are generally used to
dissolve collagen for electrospinning. In this course, the biological
activity of collagen can be degraded. As demonstrated by Jeugolis
et al. , 20 the use of fluoroalcohols as a solvent is detrimental to pre-
servingnativecollagencharacteristics,duetothedegradationofthe
structure and possible biological functionality. Furthermore, cross-
linking is generally needed after electrospinning in order to provide
thenanofibermatrixwithappropriatestructuralstabilityandchem-
ical integrity to prevent premature degradation in a fluid. Using a
water-basedsolvent,gelatinwassuccessfullyproducedbyintroduc-
ingethylacetateasaco-dissolvingsolvent.Ethylacetatesignificantly
reduced the surface tension of water and, consequently, favored the
jet spinning into the nanofiberform. 21