Fabrication and Characterization of Bioactive Bone Cement

The knowledge regarding bone cement is of top importance to all Orthopedic surgeons. Although the bone cement had been the gold standard in the field of joint replacement surgery, its use has somewhat decreased because of the advent of the press-fit implants which encourage bone ingrowth. The shortc

Project Title

Fabrication and Characterization of Bioactive Bone Cement

Project Area of Specialization

Biomedical Engineering

Project Summary

The knowledge regarding bone cement is of top importance to all Orthopedic surgeons. Although the bone cement had been the gold standard in the field of joint replacement surgery, its use has somewhat decreased because of the advent of the press-fit implants which encourage bone ingrowth. The shortcomings, side effects, and toxicity of the bone cement are common. To address these limitations, we have chosen our project on PMMA based bone cement. PMMA, along with the presence of various additives, gives the mixture, a set of physical and chemical properties. 
In this project, we intend to develop a bone cement consisting of bioactive glass, ZnO nanoparticles and PMMA. PMMA is an acrylic polymer that is formed by mixing two sterile components. a liquid MMA monomer and a powdered MMA-styrene co-polymer. When these two components are mixed, the liquid monomer polymerizes around the pre polymerized powder particles to form hardened PMMA.  
PMMA-based bone cements have been used due to their cost effectiveness, biocompatibility, good mechanical strength and easy processing. However, these materials lack in suitable biodegradation rate, bioactivity and connectivity with host bone tissues. We hypothesize that bioactivity of bio glass and cell proliferation property of ZnO nanoparticles will improve the biological properties of PMMA-based bone cement along with the physical and mechanical properties.  
To the best of our knowledge, the effect of 45S5 bio-glass composition variation has not been studied with ZnO in PMMA-based cement, which is the novelty of our project. In our research work, we proposed to solve these limitations by incorporation of bio-glass with variations in its composition. For this purpose, we will prepare different samples of PMMA-based bone cement containing ZnO with varying composition of bio-glass and will characterize to study the effects on biological, mechanical, physical and thermal properties.Material's testing will include the application of XRD, FTIR, Raman Spectroscopy, SEM, and TGA. For mechanical evaluation; we will perform Hardness and Compressive Strength tests. For biological evaluation; we will do Biodegradability, Bioactivity, Contact Angle Measurement. 

Project Objectives

1. To fabricate and characterize bone cement for its mechanical/physical, thermal and biological properties.
2. To study the behaviour of bone calcium formation due to change in bio glass composition. 

Characterization of Mechanical/Physical Properties:

For mechanical evaluation; we will perform Hardness and Compressive Strength tests. This test will tells us about the strength of bone cement.

Characterization of Thermal Properties:
For Thermal evaluation; we will do Thermo Gravimetri Analysis (TGA). This test will tell us about the Thermal Stability of PMMA which we will improve by addition of ZnO.

Characterization of Biological Properties:

For Biological evaluation; we will perform Biodegradability test, Bioactivity test and Contact Angle Measurement.

To Study behaviour of bone calcium formation:

For this we will check bioactivity of bone cement having different composition of bioglass by imersion of scaffold into SBF solution.

Project Implementation Method

Fabrication method of modified Silicate (45S5) Bio-glass:

The 45S5 BG composition consists of 45% SiO2, 24.5% CaO, 24.5% Na2O and 6% (for BG-1) and 3% (for BG-2 and 3) of P2O5 (in mole percentages, mol.%). Further addition of 1% and 2% of MgO and B2O3, in above mentioned compositions, was done by sol-gel technique. Initially, tetraethyl-orthosilicate (TEOS) was added into a mixture of nitric acid, deionized water and (H3BO3) at different compositions (1 and 2 mol.%), followed by stirring for 1hr to allow TEOS 
25 
 
hydrolysis. Then triethyl-phosphate (TEP) was added in the solution, followed by the addition of calcium nitrate and sodium nitrite at 15 minutes interval. Then Mg (NO)3.6H2O at different compositions (1 and 2 mol.%) was added in the glass mixture using the similar procedure at 15 minutes interval. After gelation, the solution was left for aging (70?C), drying (120?C) and sintering (700?C) according to the requirement.

Fabrication method of Bioactive PMMA-based Bone Cement.

For fabricating the bioactive bone cement, we will use prepared bio-glass, ZnO powder, PMMA powder & MMA monomer. Initially ZnO and bio-glass will incorporate into PMMA powder. Then liquid MMA monomer will be added into PMMA powder. Solid/hard PMMA will obtain by the addition polymerization of MMA monomer.  
We will use 3 different types of composition of prepared bio-glass in PMMA based Bone Cement. And compare the results by performing different biological and mechanical test. 

Benefits of the Project

This research will facilitate the health care sectors in following ways:

Every day several individuals fall victim to accidents leading to severe bone injuries and trauma mainly caused by bicycles/motor vehicle accidents and they may lose fragments of bone which obligate immediate bone implantation. The unavailability of donors and cadaveric tissues suffice for synthetic bone cement. Therefore, need of synthetic bone cement is increasing day by day. We intend to resolve this need by our research work. This research will provide synthetic bioactive bone cement which can address such problems by its excellent biocompatibility, strength, rapid bone formation and its antibacterial as well as bioactive nature.

Technical Details of Final Deliverable

As we are using PMMA as a base of our bone cement scaffold which has low thermal stability and cell proliferation therefore, we are incorporating ZnO nanoparticles into PMMA matrix. ZnO shows excellent cell proliferation and was considered to improve low thermal stability of pure PMMA matrix.  
Furthermore, we intend to fabricate “Bioactive Bone Cement” by inclusion of “Silicate based bioglass (45S5)” into PMMA matrix to address the slow bone regeneration, as bioactive bone cement is capable of fast osteoconduction, osteointegration as well as osteoinduction which eventually decreases the time of bone growth and repair. 
Among different bio-glass types (such as; silicate, borate, phosphate and metallic) we have chosen silicate based bio-glass (45S5) because it is considered as the best candidate for forming apatite layer which increases bioactivity rate and ultimately enhance osteogenesis.  Moreover, it was found that silicone which releases upon degradation of 45S5 bio-glass, is harmlessly expel out in soluble form via urine which shows its excellent biocompatibility.  
Besides the advantages of 45S5 bio-glass there is one drawback of the silicate based bio-glass such as slow degradation and conversion into a hydroxyapatite layer thus to encounter this limitation we incorporated Boric Acid (H3BO3) as a precursor in 45S5 bio-glass to get B2O3 which promotes new bone formation more rapidly in comparison to B2O3 less bio-glass. Moreover, we also incorporated Magnesium Nitrate Hexahydrate (MgNO3.6H2O) as a precursor to get MgO which plays a vital role in bone remodelling and skeleton development. In addition, inclusion of MgO enhances the biocompatibility of bio-glass by showing its antibacterial activity. Furthermore, it also plays a positive role in influencing bone strength by improving the early stages of mineralization which contribute to an intimate contact with living tissues thus improving bone healing by increasing the attachment and differentiation of osteoblastic cells which ultimately overcomes the insufficient strength of PMMA polymer matrix upon inclusion. 

Thus this bioactive bone cement not only overcome severe bone injuries and trauma but also able to provide improved mechanical strength that is required for bone defects mainly caused by bicycles/motor vehicle accidents, falling from height and by different bone disorders such as osteoporosis, osteomyelitis etc.

Final Deliverable of the Project

Hardware System

Core Industry

Health

Other Industries

Medical

Core Technology

Others

Other Technologies

Sustainable Development Goals

Good Health and Well-Being for People, Industry, Innovation and Infrastructure

Required Resources

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