Lecture 8 - Fibrous Scaffold Fabrication Flashcards
1
Q
Fabrication of Natural Polymer-Based Nanofibers
A
- Electrospun scaffolds usually crosslinked to improve stability (against water/enzymes) and to improve mechanical properties
- Solvents could denature polymer (lose bioactivity)
- Polymer goes through high voltage (20-25kV) which could change microstructure
2
Q
Fabrication of Synthetic Polymer-Based Nanofibers
A
Can electrospin almost any synthetic polymer based on solvent combine with
3
Q
Electrospinning Gelatin
A
- Gelatin dissolved at various concentrations in HFIP
- Control diameter by concentration
- Increase concentration, increase diameter
4
Q
Disadvantage of Electrospun Nanofibrous Scaffold
A
- Densely arranged architecture of fibers and accompanying small pores hinders efficient cellular infiltration and also prevents 3D cellular integration with host tissue in vivo after implantation
5
Q
Salt Leaching
A
- Use tube surrounding electrospinning needle to incorporate NaCl particles into electrospun nanofibers via gravity at specific intervals
- Layer-by-layer nanofiber constructs containing tiny salt particles were mechanically compressed and molded into desirable 3D shapes
- Required gentle ‘sintering’ to maintain strength upon aqueous exposure
- Pores not perfectly distributed
- Leach out salt with water, leaves sufficient pore size for cells to come in
6
Q
Cryogenic Electrospinning
A
- Uses ice crystals as part of electrospinning collection device
- Electrospun fibers collected onto ice crystals formed on surface of chilled ground drum within hollow cavity enabling loading/flowing of cooling material such as dry ice or liquid nitrogen
- After drying, ice particles removed and micron-sized pores or voids remain between fibers
7
Q
Sacrificial Fiber
A
- PCL and poly(ethylene oxide) were co-electrospun to form dual polymer composite fiber aligned scaffold
- PEO dissolved to obtain scaffold having larger pores
- Pore size controlled by PEO fiber diameter and density
8
Q
‘Wet’ Electrospinning
A
- Liquid reservoir collector such as coagulation bath
- Electrospun nanofibers spraying toward bath loop on top of liquid surface and then dispersed in bath and deposited onto metal electrode at bottom
- Makes foam like structure
- Highly porous sponge is formed following freeze drying
9
Q
Femtosecond Laser Irradiation
A
- Laser with high intensity and ultrafast irradiance pulsed onto target surface containing electrospun fibers
- Ultrafast heating, melting, and ablation of fibers induced by high laser energy can produce voids in fibers
- Desirable geometric patterns such as grooves or matrix pores fabricated by controlling process parameters such as laser power, pulse, scanning rate, and orientation
- Melting of remaining fibers eliminated
10
Q
UV Irradiation
A
- Use photolithography through one porous mask to fabricate a microporous patterned nanofiber structure
- Shallow holes etched into nanofibrous mesh beneath porous mask due to UV induced fiber degradation
11
Q
Combining Nanofiber and Microfibers
A
- Electrospun nanofibers have small pore size, hot melt extruded microfibers exhibit relatively larger pore size
- Combining into composites overcomes electrospun nanofiber shortcomings
- Electrospin nanofibers on top of existing microfiber layer
12
Q
Electric Field Controlled Deposition
A
- Varying electrode configurations to form specific electric field distribution can control deposition of electrospinning jet
- Auxiliary parallel electrodes applied to fabricate aligned electrospun nanofibers
13
Q
Overcoming Porosity Issues
A
Simultaneous electrospin fiber and electrospray cells