Title: In vitro Evaluation of Biocompatibility of Spherical-shaped Calcined Hydroxyapatite Nanoparticles Synthesized via Calcium Sucrets Method

Biography:

Synthetic hydroxyapatite (HA) nanoparticles that mimic natural HA are widely used as coatings on prostheses to repair, reconstruct and substitute human bones. However, for developing countries as Sri Lanka, the accessibility of most of these materials is limited due to the high cost of both raw materials and processing. Therefore, Wijesinghe et al. (2014) have prepared Sri Lankan origin HA nano-particles through atomized spray pyrolysis technique and have successfully prepared Ti surfaces with a binder TiO₂ layer and HA layer on the TiO₂ surfaces, which would be a simple material with high economic value for orthopaedic applications. In order to evaluate the appropriateness to utilize in the production of bone implants, this material was evaluated for cytotoxicity and biocompatibility (i.e.: morphology, proliferation and differentiation) in-vitro using osteoblast-like cells (HOS). The results of this study demonstrate that the surfaces of Ti with TiO₂ thin layer, coated with HA did not elicit any toxic substance which would bring deleterious effects to HOS cells and have supported cell adhesion once the cells are in contact with the material surfaces (Image 1).  Moreover, cells attached to the surfaces retained their typical polygonal morphology and osteoblast phenotype, while undergoing the developmental stages of HOS cells (proliferation and differentiation) successfully, confirming the biocompatibility of the material.

In conclusion, this material will be a promising alternative for the production of synthetic bone substitutes with high potential for future developments in load bearing as well as non-load bearing orthopaedic applications.

Abstract

M.G.G.S.N. Thilakarathna has completed her BSc. Special degree in Molecular biology and Biotechnology from University of Peradeniya and currently reading for her PhD. in biomaterials at Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, Sri Lanka. At present, she is mainly involved in evaluating the biocompatibility of different nano-structured materials which can be used as synthetic bone substitutes.

Title: In vitro evaluation of biocompatibility of spherical-shaped calcined hydroxyapatite nanoparticles synthesized via calcium sucrets method

Biography:

Gayan Sasanka Nirodha Thilakarathna holds a B. Sc. Degree in Chemistry and Biology stream from University of Peradeniya, Sri Lanka, and currently he is reading for his M.Phil. Degree attached to the Postgraduate Institute of Science, University of Peradeniya. His research focuses on Novel method of porous Hydroxyapatite nanoparticles for Biocompatibility applications and is carried out under the supervision of the co-authors of this abstract. He has a few Communications at International Conferences to his credit and he won the Best Presenter Award of the 4^th International Conference in Nanotechnology held in Colombo, Sri Lanka and also a similar Award with a Cash Prize from the Mineral Symposium held in Colombo, Sri Lank, both in 2017.

Abstract

There are numerous bio-materials, such as metals, metal alloys, carbon-based materials, polymers, ceramics, and composites of the above materials used in biomedical applications as bone cements, bone fillers and implants, though all of them have advantages and drawbacks. These materials that are used to fill and reconstruct bone defects have many limitations, due to unfavorable corrosion properties, improper stress distribution and adverse tissue reactions.

Recently, throughout the world, biocompatible hydroxyapatite (HA) nanomaterials have been widely used in a broad range of biomedical applications. However, current synthesis techniques of biocompatible HA nanomaterials are very expensive. Therefore, we have developed a simple and cost-effective method to synthesize HA having spherical porous structures with chemical compositions closely related to the mineral phase of the human bone so as to impart osteo-conductive properties. These products may be used in biomedical applications at low-cost.

These nanoparticles were prepared by precipitating from a precursor solution containing calcium sucrate and ammonium dihydrogen orthophosphate, at a Ca:P mole ratio of 1.67:1, at room temperature. The obtained product was analyzed for it’s crystallinity, crystallite size, morphology, and composition, by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FT-IR) spectroscopic techniques. Analyses were also done after calcining the respective products, soon after their synthesis, for 3 h, at 700 °C. The calcined samples always produced spherical nanoparticles of essentially the same diameter, between 90 nm and 100 nm, which does not change due to aging or by changing preparative-temperature in the range from 20-90 °C.

Biocompatibility, cytotoxicity and bio-functionality of these materials are currently being under investigation to make sure their suitability for biomedical application. HA nanoparticles are nontoxic according to the cytotoxicity results which confirm their potential usage in biomedical applications.  MTT (3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay, Alamarblue assay for cell proliferation, Alkaline phosphatase (ALP) activity assay for cell differentiation and SEM analysis for the cell morphology studies confirmed that the synthesized HA nanoparticles are nontoxic.