Date of Defense
31-10-2024 4:00 PM
Location
Yanah Theatre
Document Type
Dissertation Defense
Degree Name
Doctor of Philosophy in Biomedical Sciences
College
College of Medicine and Health Sciences
Department
Anatomy
First Advisor
Dr. Sahar Mohsin
Keywords
Bone tissue engineering, nano-hydroxyapatite, Zn, Sr, PLGA, scaffolds.
Abstract
Bones have an inherent ability to remodel, but critical-size defects can hinder regeneration, leading to delayed healing or non-union fractures. Traditional bone grafts have limitations, such as donor site morbidity and immune rejection, driving the need for synthetic bone substitutes. Bone tissue engineering (BTE) addresses this by developing biomimetic scaffolds that replicate bone properties. This research aimed to fabricate composite scaffolds from strontium (Sr) and zinc (Zn) doped nano-hydroxyapatite (nHAp), collagen, and poly(lactide-co-glycolide) (PLGA) polymer. Different doping percentages of Sr/Zn (1%, 2.5%, 4%) were used to fabricate the scaffolds using supercritical CO2 (ScCO2) and electrospinning techniques. Scaffolds were then analyzed for their spectral properties, structure, porosity, mechanical strength, bioactivity, biodegradation, biocompatibility, and antibacterial efficacy. Results showed that scaffolds fabricated with both techniques exhibited low crystallinity at higher Sr/Zn doping levels, which improved the scaffold's bioactivity. The Sr/Zn-nHAp-PLGA scaffolds fabricated using ScCO2 exhibited favorable biodegradability in simulated body fluid (SBF) and adequate pore size of 189-406 μm. Notably, the 2.5% Sr/Zn-nHAp-PLGA scaffolds demonstrated improved ultimate compressive strength of 15.06 ± 3.05 MPa and Young’s modulus of 0.196 ± 0.007 GPa, while the 4% Sr/Zn-nHAp-PLGA scaffolds exhibited the highest antibacterial activity and promoted osteoblastic proliferation, though they lacked homogeneity and displayed lower ultimate strength. In comparison, electrospun Sr/Zn-nHAp-collagen-PLGA scaffolds were confirmed as composites by spectral analysis. The 4% Sr/Zn scaffolds had a fiber diameter of 331.6 ± 96.11 nm and a pore size of 233.5 ± 18.8 μm, they demonstrated bioactivity by forming needle-like calcium phosphate crystals after immersion in SBF. Additionally, their good homogeneity contributed to excellent mechanical strength, with Young's modulus of 9.91 ± 1.7 GPa, which is comparable to that of cancellous bone. In summary, the electrospun scaffolds demonstrated better stability, bioactivity, and mechanical properties, highlighting the superiority of electrospinning and the promising potential of these scaffolds for BTE.
Included in
FABRICATION AND EVALUATION OF MULTICOMPONENT BIOMIMETIC SCAFFOLDS FOR BONE TISSUE ENGINEERING
Yanah Theatre
Bones have an inherent ability to remodel, but critical-size defects can hinder regeneration, leading to delayed healing or non-union fractures. Traditional bone grafts have limitations, such as donor site morbidity and immune rejection, driving the need for synthetic bone substitutes. Bone tissue engineering (BTE) addresses this by developing biomimetic scaffolds that replicate bone properties. This research aimed to fabricate composite scaffolds from strontium (Sr) and zinc (Zn) doped nano-hydroxyapatite (nHAp), collagen, and poly(lactide-co-glycolide) (PLGA) polymer. Different doping percentages of Sr/Zn (1%, 2.5%, 4%) were used to fabricate the scaffolds using supercritical CO2 (ScCO2) and electrospinning techniques. Scaffolds were then analyzed for their spectral properties, structure, porosity, mechanical strength, bioactivity, biodegradation, biocompatibility, and antibacterial efficacy. Results showed that scaffolds fabricated with both techniques exhibited low crystallinity at higher Sr/Zn doping levels, which improved the scaffold's bioactivity. The Sr/Zn-nHAp-PLGA scaffolds fabricated using ScCO2 exhibited favorable biodegradability in simulated body fluid (SBF) and adequate pore size of 189-406 μm. Notably, the 2.5% Sr/Zn-nHAp-PLGA scaffolds demonstrated improved ultimate compressive strength of 15.06 ± 3.05 MPa and Young’s modulus of 0.196 ± 0.007 GPa, while the 4% Sr/Zn-nHAp-PLGA scaffolds exhibited the highest antibacterial activity and promoted osteoblastic proliferation, though they lacked homogeneity and displayed lower ultimate strength. In comparison, electrospun Sr/Zn-nHAp-collagen-PLGA scaffolds were confirmed as composites by spectral analysis. The 4% Sr/Zn scaffolds had a fiber diameter of 331.6 ± 96.11 nm and a pore size of 233.5 ± 18.8 μm, they demonstrated bioactivity by forming needle-like calcium phosphate crystals after immersion in SBF. Additionally, their good homogeneity contributed to excellent mechanical strength, with Young's modulus of 9.91 ± 1.7 GPa, which is comparable to that of cancellous bone. In summary, the electrospun scaffolds demonstrated better stability, bioactivity, and mechanical properties, highlighting the superiority of electrospinning and the promising potential of these scaffolds for BTE.