Transcript 幻灯片 1 - Textile Science

PLLA-PEG-TCH-labeled bioactive molecule
nanofibers for tissue engineering
Haiyun Gao1,2,3, Jun Chen1,3, Beth Zhou1,2,3, Wen Zhong3 and
Malcolm Xing1,2,4
1.Mechanical Engineering, Faculty of Engineering, 2.Manitoba Institute of Child Health,
3.Textile Science, Faculty of Human Ecology and 4. Biochemistry and Medical Genetics,
Faculty of Medicine, University of Manitoba.
Nanofibers
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Fiber with nanodimensions
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an extraordinarily high surface area to volume ratio
tunable optical emission
super paramagnetic behavior
Methods to fabricate nanofibers
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Drawing
Template synthesis
Temperature-induced phase separation
Molecular self-assembly
Eletrospinning
S G Kumbar et al. Biomed. Mater. 3 (2008)
Electrospinning strategy
Advantages:
• Simple instrument
• Continuous process
• Cost effective compared to other
existing methods
• Scalable
• Ability to fabricate fiber diameters from
few nm to several microns
• High efficiency for biomedicine
application
S G Kumbar et al. Biomed. Mater. 3 (2008)
Drug Loading in Electrospun Nanofibers (ENs)
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Wide applications for ENs:
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Fltration, sensors, military protective clothing, photovoltaic devices, liquidcrystal display (LCD), ultra-light weight space craft materials, super-efficient
and functional catalysts
Variety of biomedical applications: carriers for drug/therapeutic agent delivery,
wound dressing materials and as porous three dimensional scaffolds for
engineering various tissues such as skin, blood vessels, nerve, tendon, bone and
cartilage
For my study:
Drug loaded in ENs: tetracycline hydrochloride [TCH]  a model antibiotic
TCH
PLLA/PLLA-PEG-NH2 Electrospinning Nanofibers
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Materials:
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Poly(L-lactide) (PLLA)
PLLA
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Poly(ethylene glycol) (PEG) with functional group
Preparation of solution:
1.
NaOH + tetrahydrofuran
2.
CH2Cl2 + trifluoroacetic
acid (TFA)
3.
BTAC (surfactant)
Blending electrospinning conditions:
1.
room temperature
2.
voltage of 22 kV
3.
flow rate of 7 mL/h
4.
distance of 12 cm between the
needle tip and the collector
PLLA/PLLA-PEG-NH2 electrospun nanofiabers
PEG
NH2
TCH-loaded Nanofibers
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HOW: emulsion electrospinning
3% w/w of TCH + 7.5% w/w PLLA/PLLA-PEG-NH2 + 5% w/w BTAC
Emulsification and electrospinning
Surface functionalization of electrospun nanofibers for the immobilization of proteins
Model proteins: Two fluorescently
tagged bovine serum albumins (BSAs)
Red: Rhodamin-BSA
Green: FITC-BSA
Validity of the Immobilization Method
NHS was coupled to the
carboxyl groups of surface
hydrolyzed ENS, resulting
in the formation of an NHS
ester, with the amide I band
at 1646 cm−1
EGS was conjugated to the
amino groups of water
vapor-treated ENS to form
an amide (1646 cm−1)
TCH-loaded Nanofibers
Table 1 Sample names and specifications
Morphology of the electrospun nanofibers (Scanning electron microscopy micrograph)
H0-1 (641nm)
Bar: 2 µm.
H0-3 (608nm)
H3-1 (740nm)
H3-3 (780nm)
PLLA/PLLA-PEG-NH2 nanofibers functionalized
with both FITC-BSA and rhodamine-BSA
Confocal images of PLLA/PLLA-PEG-NH2 nanofibers functionalized with
both FITC-BSA and rhodamine-BSA. (A) Image showing FITC-BSA, (B)
image showing rhodamine-BSA, and (C) merged A and B. Bar: 20 µm.
In Vitro Release of TCH and Antibiotic
Susceptibility Test
The encapsulation rate of TCH was 70% for ENSs without BSA
conjugation (H3-1) and 30% for ENSs with two conjugated BSAs (H3-3).
Antibiotic Susceptibility Test
Antibacterial tests of H3-1 and H3-3.
(A) Day 1 H3-3 (left) and H3-1 (right);
(B) day 2 H3-3 (left) and H3-1 (right);
(C) day 3 H3-3 (left) and H3-1 (right);
and (D) day 4 H3-1 (H3-3 was
discarded). Bar: 5 mm.
ENs in Tissue Engineering
Tissue engineering?
Bioresorbable
and biocompatible
materials
native tissues
Mimic /Replicate
In one approach to open system implants, three-dimensional highly
porous scaffolds composed of synthetic polymers serve as cell
transplant devices.
Langer, R. and J. P. Vacanti (1993). "Tissue Engineering." Science 260(5110):
920-926.
ENs in Tissue Engineering
ENs
Tunable porosity
maintain cellular functionality
cells exchange metabolites and
nutrients with environment
aid in the reconstruction of tissues
maintaining tailored mechanical
properties to protect the wound
bed from collapse
avoid mechanical mismatch
between scaffolds and host tissues
Cell adhesion and proliferation on
nanofibrous scaffold
PDGF-BB/RGDS(promote cell attachment)
conjugate
ENs
Immunofluorescence staining of human dermal fibroblasts on ENs of (A) PDGF and
RGDS conjugated and (B) blank. Images were recorded by a confocal microscope.
The same magnification was used for both pictures. Bar: 100 µm.
Conclusion
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Multifunctional ENSs were developed that incorporated the
antibacterial agent TCH and were successfully surface
functionalized with two different bioactive molecules.
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This novel material may have potential applications in wound
care and tissue engineering.
Acknowledgement comes to the Institute of
Textile Science, University of Manitoba, Manitoba
Institute of Child Health and all my colleagues.