Effects of hydroxyapatite particle size on PAH-GMA hydrogel

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Effects of hydroxyapatite particle size on
PAH-GMA hydrogel

• Venkata Damaraju
• Mentor Dr. Sidney Sit

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What is a hydrogel?

• Biocompatible jello-like substance
• A matrix of polymers
• Poly(allylamine hydrochloride) (PAH)
• Glycidyl methacrylate (GMA)
• Poly (ethylene glycol) diacrylate (PEG-DA)

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Uses of hydrogel

• Cell and tissue repair/regeneration
• Drug delivery systems
• Wound dressing
• ? Cornea implants ?

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Problem?

• Cells dont stick to the hydrogel!

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Solution?

• Add adhesive peptides
• Add particles ?
• Particles create pores
• Allow cells to filter in and self adhere

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Which particles?

• Hydroxyapatite
• Micro size (100-300 µm)
• Nano size (100 nm)
• Found in bones

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My experiment setup
Negative control
Experimental Group 1 Sonicated for 20 min. Both
nano and micro particles
Experimental Group 2 Sonicated for 40 min. Both
nano and micro particles
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Electrochemical Impedance Spectroscopy

• Non-destructive way of characterizing the
  physical properties
• Measures the impedance (Resistance) over a
  frequency range
• Constant AC current of 0.1 mA

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Experimental Group 1
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Experimental Group 2
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SEM Imaging
Control hydrogel without particles
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SEM Images
Hydrogel with hydroxyapatite particles
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Conclusion

• Addition of particles decreased the overall
  impedance
• Lower impedance means more pores
• Sonication for 40 min gave better dispersion of
  particles
• SEM shows particles settled in the hydrogel, but
  as very small fragments

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Future work

• Perform cell culture on the hydrogel with
  particles
• Add other particles to achieve larger pores

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Acknowledgement

• Dr. Sidney Sit
• Stephanie Tully
• Dillip
• Praveen
• Syeda
• Karen Xu
• Nicolas McHughes