Lecture 9 - Fibrous Scaffold Fabrication Flashcards
Applications of Polymer Nanofibers
- Wound dressing
- Medical prostheses
- Haemostatic devices
- Sensor devices
- Electrical conductors
- Optical applications
- Material reinforcement
- Protective clothing
- Filter media
- Cosmetics
- Drug delivery
- Tissue engineering scaffolds
Wound Dressing
- Prevents scar
- Bacterial shielding
Medical prostheses
- Lower stress concentration
- Higher fracture strength
Haemostatic devices
Higher efficiency in fluid absorption
Sensor devices
- High surface area
- Higher sensitivity
- For cells, arteries and veins
Electrical Conductors
- Au/Pt fibers
- Ultra small devices
Optical Applications
- Free volume
- Liquid crystal optical shutters
Material Reinforcement
- Large surface area
- Higher fracture toughness
- Higher delamination resistances
Protective Clothing
- Light
- Integrate additional functions
- Breathable fabric that blocks chemicals
Filter Media
- Light with specific wavelength
- Higher filter efficiency
Cosmetics
- Higher utilization
- Higher transfer rate
Drug Delivery
- Increased dissolution rate
- Drug-nanofiber interlace
Tissue Engineering Scaffolds
- Adjustable biodegradation rate
- Better cell attachment
- Controllable cell directional growth
Tissue Engineering
- ECM proteins (collagen and elastin) exist in nano-fibrous form in vivo
- Electrospinning fabricates nano-fibrous scaffolds having fiber sizes and morphologies closely resembling that of ECM proteins
- Electrospinning also allows the generation of anisotropic scaffolds mimicking the particular structural and mechanical anisotropy of ECM as dictated by its function within the body
Nanofibers Directing Neurite Outgrowth
- Neuron
- Cell consists of cell body and its extension neurite (axon + dendrite)
- Dendrites conduct impulses toward cell body and axons conduct impulses away from cell body
- Neurons are able to respond to stimuli, conduct impulses, and communicate with each other (and with other type of cells such as muscle cells)
Biodegradable Nanofiber Scaffold by Electrospinning for Bone Tissue Engineering
- Scaffold containing larger pores (via salt crystals or sacrificial fibers)
- PCL + Mesenchymal stem cells (larger - need bigger pores)
- After 4 weeks, continuous film —> successful population of cells on scaffold surface
Electrospun Nanofibers for In Vivo Would Healing of Diabetic Ulcers
- Functionalized with immobilized human epidermal growth factor (EGF)
- Start with block copolymer, want to integrate biomolecules
- Electrospin to create crosslinked network
- Introduce NH2
- Surface immobilization with growth factors (enhances biocompatibility)
- Advantage: simple, turn synthetic system into something more biocompatible
- Disadvantage: body attacks quickly, short term response
Drug Delivery
- Less expensive than growth factors
- Delivery of specific antibiotic through specific scaffold
Controlled Release of GF from Electrospun PCL Scaffold
- Angiogenesis critical for tissue construct survival in vivo
- When implanting engineering tissue in vivo, needs sufficient nutrients and oxygen to survive which can only be provided by blood vessels
- It is necessary to quickly induce blood vessel formation after implantation of engineered tissue (big challenge)
- Angiogenic growth factors are naturally occurring compounds that stimulate blood vessel growth
- Promoting endothelial cell migration crucial for accelerated angiogenesis in tissue constructs (force blood vessels to form
- Mimicking process of chemotaxis during formation of native blood vessels, creating angiogenic growth factor gradient in tissue constructs will stimulate endothelial cell migration and faster angiogenesis
Angiogenesis
- Physiological process involving growth of new blood vessels
- Delivers nutrition
FGF
Stimulator that promotes proliferation and differentiation of endothelial cells, smooth muscle cells, and fibroblasts
VEGF
Stimulator that promotes proliferation of endothelial cells
PDGF
Stimulator that recruits smooth muscle cells
PCL Scaffold Fabrication
- Syringe Pump A: bFGF solution (growth factors)
- Syringe Pump B: PLGA solution (shell for GF)
- Syringe Pump C: PCL solution (fibers)
- Use concentration gradient of bFGF to interact with cells, other side to attract
