Figure 1.
Schematic representation of rolling up protocol for NGC preparartion.
1) Porous SF/SWNT substrates prepared by freeze-drying. 2) Aligned FN containing nanofibers prepared by electrospinning on freeze-dried substrate. 3) Rolling up the complex together by manually manipulation of a flat-tweezer. 4) A tubular NGC with internal aligned nanofibers coated by porous Silk/SWNT substrate.
Figure 2.
Scanning electron micrographs of: a) porous structure of freeze-died SF/SWNT conduits, b) Aligned fibronectin nanofibers produced through electrospining process.
Figure 3.
a) PSD curve of electrospun FN nanofibers, b) Diameter distribution histogram of FN nanofibers.
Figure 4.
FTIR spectra of: a) Methanol treated pure SF. Three characteristic peaks in 1630 cm−1 (amide I), 1530 cm−1 (amide II), and 1230 cm−1 (amide III) are revealed due to β-sheet formation, b) SF/SWNT.
The bands corresponding to amide I, II, and III are intensified to 1639−1; 1537 cm−1, and 1235 cm−1, c) SF/SWNT/FN. FN has also enhanced the typical peaks in comparison to SF/SWNT conduits.
Figure 5.
Raman spectra of: a) pure SF: the amide I band around 1665 cm−1, 1616 cm−1 for Trp, Phe and Tyr, 1240 cm−1 for amide III were observed, b) SF/SWNT: the peak correspondence to skeletal ν (C-C) associated in pure SF is removed, c) SF/SWNT/FN: the β-sheet structure in FN was identified by the characteristically amide I band around 1669 cm−1 and a higher intense band at 1245 cm−1 in the amide III region.
Table 1.
Main Raman band wavenumbers and assignments.
Figure 6.
DSC thermogram of: a) pure SF, b) Pure SF after methanol treatment, c) SF/SWN substrates.
Incorporating SWNT to the structure of methanol treated SF has a cumulative effect on growing the thermal stability to 288.4°C. A melting point absorption peak in the DSC trace of SF/SWNT in 77.7°C would also indicate the existence of SWNT.
Figure 7.
Solution stability curve of SWNT dispersion in SF solution.
It seems that SF as an amphiphilic structure could act as a surfactant agent for dispersing carboxylated-SWNT in stabilized manner.
Figure 8.
Fibronectin bioactivity after 14 days in vitro study.
FN exhibited high bioactivity (about 85%).
Figure 9.
Viability of U373 cells (MTT assay).
Less proliferation was observed for cells grown on SWNT containing conduits but not significantly.
Figure 10.
Attachment of the cells (NR assay).
On day/SWNT/FN conduits was significant in comparison to all samples after 7th and 14th days. * P<0.05(compared with the pure SF and TPS).
Figure 11.
Scanning electron micrographs of U373 cells seeded on SF/SWNT/FN conduits.
The cells were found to have attached and were distributed on aligned FN nanofibers with a spread out morphology.
Figure 12.
Nerve conduction velocities (NCVs) of normal sciatic nerve, negative control, SF/SWNT and SF/SWNT/FN after 5 weeks implantation in rats compared with each other (n = 3).
*P<0.05 in comparison to negative control group. **P<0.05 in comparison to negative control and SF/SWNT groups.
Figure 13.
a) Defected sciatic nerve without NGC (control group), b) Implanted SF/SWNT conduit, c) Implanted SF/SWNT/FN conduit.
Figure 14.
Histological assessment of NGCs after 5
a) Normal nerve, b) negative control (Defected sciatic nerve without NGC), c) Defects filled by SF/SWNT conduits, d) Defects filled by SF/SWNT/FN conduits. Wide arrows: myelinated axon. Narrow arrows: Schwann cells.
Figure 15.
Cross sections of regenerated nerves taken from types of nerve conduits implanted in rats for 5
a) Normal nerve, b) negative control (Defected sciatic nerve without NGC), c) Defects filled by SF/SWNT conduits, d) Defects filled by SF/SWNT/FN conduits. Wide arrows: myelinated axon. Narrow arrows: Schwann cells.
Table 2.
Statistical analysis of histological assessment after 5
Figure 16.
Cross sections of regenerated nerves taken from types of nerve conduits implanted in rats for 5-100.
a) Normal nerve, b) Defected sciatic nerve without NGC (control group), c) Defects filled by SF/SWNT conduits, d) Defects filled by SF/SWNT/FN conduits. Wide arrows: myelinated axon. Narrow arrows: Schwann cells.