Keywords : Hydroxyapatite

Nanosecond Laser Surface Patterning of Ti6Al4V Bio-alloy for Improved Biological Performance

Sunita Kedia; Shazia Shaikh; Ananda G. Majumdar; Mahesh Subramanian; A. K. Sahu; Sucharita Sinha

Advanced Materials Letters, 2019, Volume 10, Issue 11, Pages 825-831
DOI: 10.5185/amlett.2019.0026

Biological performances such as osseointegration and biocompatibility of Ti6Al4V alloy primarily depends on topological and chemical properties of the surface of the bio-material. Here, a nanosecond pulsed Nd:YAG laser has been used to generate microstructures on Ti6Al4V surface by irradiating with 6000 number of laser shots per site. Formation of ripple structure and generation of sub-oxide phases on laser treated titanium surface supported uniform and dense growth of HAP on the sample. In contrast, discrete nucleation of HAP with comparable higher precipitation of calcium occurred on untreated Ti6Al4V sample when subjected to similar in vitro tests by exposing the sample to simulated body fluid. Initial interaction and growth of U2OS cells on untreated and laser treated Ti6Al4V substrates were quantified using MTT assay. More numbers of cell were attached to laser treated sample in comparison to untreated sample as observed in confocal microscope images. Our results suggested that surface patterning of Ti6Al4V alloy using nanosecond pulsed laser promoted bio-integration without compromising its biocompatibility. Copyright © VBRI Press.

Mechanical properties of hydroxyapatite scaffolds produced by gel-casting and combination gel-casting/polymer foams infiltration

Jazmín I. González; Diana M. Escobar; Claudia P. Ossa

Advanced Materials Letters, 2018, Volume 9, Issue 4, Pages 266-274
DOI: 10.5185/amlett.2018.1981

Hydroxyapatite is one of the appropriate materials for hard tissue engineering because it is the inorganic structural constituent of bones and teeth, and hydroxyapatite has been evaluated to compare the mechanical properties, processing as scaffolds to evaluate the influence of porosity, since the elastic modulus of material is influenced by the porosity, it is essential to establish a relationship between the two characteristics to obtain a material with optimum conditions for its implantation. The main objective of this research was to study the mechanical properties of hydroxyapatite scaffolds using compression and nanoindentation tests. The scaffolds were manufactured by gel-casting and gel-casting combined with foam polymer infiltration, in both cases 40 and 50% solids and three different monomers were used. The samples obtained by gel-casting exhibited a compressive strength between 0.93 and 6.15 MPa, an elastic modulus between 11.46 and 27.27 GPa; some of these scaffolds showed very similar values to human trabecular bone reported. In addition, samples produced by gel-casting combined with foam polymer infiltration, it was found that compressive strength was between 0.05 and 0.12 MPa, the elastic modulus between 1.61 and 6.24 GPa, concluding that the gel-casting produces scaffolds with closest to trabecular bone.

Porous hydroxyapatite scaffolds fabricated from nano-sized powder via honeycomb extrusion

Mohammed Elbadawi; James Meredith; Mosalagae Mosalagae; Ian M. Reaney

Advanced Materials Letters, 2017, Volume 8, Issue 4, Pages 377-385
DOI: 10.5185/amlett.2017.7063

In this study, we have developed hydroxyapatite (HA) scaffolds for synthetic bone graft from nano-sized HA particles using ceramic extrusion. We also demonstrate that these HA scaffolds show enhanced compressive strength (29.4 MPa), whilst possessing large pore sizes (> 600 µm) that are suitable for bone grafting. The extrusion process involved forming a ceramic paste by mixing the HA powder with a binder and distilled water. The ceramic paste was then fabricated using a ram extruder that was fitted with a honeycomb die to impart large, structured pores. Several green bodies were extruded and then subjected to the same drying and thermal debinding treatment. The samples underwent three different sintering temperatures and two varied dwell times, in order to determine the optimum sintering parameters. The scaffolds were then analysed for their chemical, physical, mechanical and biological properties to elucidate the effects of the sintering parameters on extruded HA scaffolds. The results revealed that the nano-sized particles exhibited a high sinterability, and XRD analysis showed phase purity until 1300 o C. At 1300 o C, trace amounts of phase impurities were detected, however, scaffolds sintered at this temperature exhibited the highest mean compressive strength. The findings demonstrated that traces of phase impurities were not detrimental to the scaffold’s compressive strength. In addition, scanning electron microscopy and density measurements revealed a highly densified solid phase was attained.

Sintering And Characterization Of A Hydroxya-patite Matrix And Hydroxyapatite Matrix Nano-composites

Nelson H. A. Camargo; Eliakim E. G. de Borba; Priscila F. Franczak; Enori Gemelli

Advanced Materials Letters, 2017, Volume 8, Issue 1, Pages 19-23
DOI: 10.5185/amlett.2017.6032

Microporous calcium phosphate biomaterials are known for their physical and biological applications. Among the best known are the stoichiometric hydroxyapatite (HA) and tricalcium phosphate (TCP). This is because these biomaterials exhibit chemical and crystallographic compositions which are similar to that found in bones and teeth. The use of nanotechnology enables obtaining calcium phosphate nanostructured powders and calcium phosphate nanocomposite matrix formed by a second nano phase of type SiO2, TiO2, Al2O3-a, ZrO2, Mg. Different methods and techniques for the synthesis and preparation of nanostructured powders and biomaterials are noted in the literature, but it is known that not all lead to the same results. Calcium phosphates nanostructured biomaterials are a new class of biomaterials which provide new physical, morphological, nanostructural and microstructural features with interconnected microporosity which are promising to wettability, capillary action, cell adhesion and proliferation on the surface of grains and micropores. Based on research of these biomaterials, it has been found that they show potential applications in traumatology, orthopedic and dental applications in reconstruction, defects and bone tissue repairing, implants attachment and dental remineralization treatment. This study was aimed at the sintering and characterization of an HA matrix and three nanocomposite biomaterials with 5% by volume of the respective second phases: SiO2, ZrO2 and Al2O3-a in the HA matrix. The HA powder and nanocomposite HA/SiO2 were sintered at 1100 °C/2h. HA/ZrO2 nanocomposite powder followed two sintering conditions: a temperature of 1100 °C/2h and the other, at 1300 ºC/2h. HA/Al2O3-a nanocomposite powder was only sintered at 1300 ºC/2h. The biomaterials were characterized by scanning electron microscopy, X-ray diffraction and open porosity and hydrostatic density were also determined by applying the Arthur method. The results are encouraging and show for HA, HA/SiO2, HA/ZrO2 biomaterials (obtained by sintering at 1100 °C) interconnected microporous microstructures, formed by fine grains which are favorable for the expected wettability and capillarity characteristics.

A Prototype Synthesis And Characterization Of Hydroxyapatite Bioceramics Nanocrystallites

Pramod N. Jagadale; Pramod P. Jagtap; Meghnad G. Joshi; Sambhaji R. Bamane

Advanced Materials Letters, 2016, Volume 7, Issue 4, Pages 325-329
DOI: 10.5185/amlett.2016.5837

Novel porous bioactive hydroxyapatite (HAP) nanocrystallites were synthesized by auto-combustion technique. The texture properties of the HAP nanopowder were determined through series of characterization techniques. The thermal decomposition behaviour and required sintering temperature of citrate precursor to phase formation of the sample was checked by thermogravimetric analysis (TG-DTA). The hexagonal structure and porous nature of the material were estimated by using X-ray diffraction (XRD) and electron microscopy scanned with different magnifications. Phase formation of HAP was determined by FTIR technique. Transmission electron microscopic (TEM) study indicated the nanostructure of the ceramics, particle size was found to be 30 - 35 nm. These nanoparticles were evaluated for the qualitative and quantitative determination of different elements by energy-dispersive X-ray spectroscopy. In vitro MTT assays showed HAP nanopowder have good biocompatibility and promotes cell proliferation. This nanostructured HAP powder with enhanced biocompatibility can be potentially used as a material for bone tissue engineering.

Effect Of The Granulation Of Starting Powder On Superplastic Deformation Of Hydroxyapatite

Ryo Yamazaki; Yoshio Sakka;Kiyoshi Itatani; Koji Morita

Advanced Materials Letters, 2016, Volume 7, Issue 2, Pages 130-135
DOI: 10.5185/amlett.2016.6135

The effect of the granulation of starting powder on the superplasticity of hydroxyapatite (Ca10(PO4)6(OH)2, HAp) specimen was examined; the tensile elongation of specimen at high temperature was measured in order to evaluate the superplastic deformation. The translucent ceramics were fabricated using HAp powders with and without granulate (HAp and g-HAp) through the pulse current pressure sintering at 1000 ºC for 10 min: the mean grain sizes in both cases were approximately 0.2 mm. The tensile elongation of g-HAp specimen at 1000 ºC was 289 % (strain rate: 1.2 × 10 -3 s -1 ). The tensile stress was always lower than 30 MPa with maximum stress of 28.3 MPa, in contrast to the case of HAp specimen showing the maximum stress of 75.3 MPa (tensile elongation: 344 %). The lower stress of g-HAp specimen, compared to the case of HAp specimen, indicated the weak bonding of grains, but the failure being occurred by the concentrated stress at the strong bonding sites.  

Properties Of Novel Bone Hemostat By Random Co-polymer Of Ethylene Oxide And Propylene Oxide With sugar-containing Hydroxyapatite

Eri Shima; Yoshiro Musha;Kiyoshi Itatani; Tomohiro Umeda

Advanced Materials Letters, 2016, Volume 7, Issue 2, Pages 90-94
DOI: 10.5185/amlett.2016.6132

Novel hemostatic agents were prepared using (i) phosphoryl oligosaccharides of calcium (POs-Ca ® 45 and POs-Ca ® 50 with calcium contents being 4.5 and 5.0 mass %, respectively), (ii) sugar-containing hydroxyapatites (s-Ca10(PO4)6(OH)2; s-HAp) obtained by the hydrolyses of POs-Ca ® 45 and POs-Ca ® 50, respectively (s-HAp(45); Ca/P ratio = 1.56, 61.2 mass % HAp and 38.8 mass % organic materials and s-HAp(50); Ca/P ratio = 1.61, 79.3 mass % HAp and 20.7 mass % organic materials), and (iii) thermoplastic resin (random copolymer of ethylene oxide (EO) and propylene oxide (PO)) (EPO). The gels formed by mixing the EPO with water (EPO/water (mass ratio): 0.20) were freeze-dried at -50 ËšC for 15 h, and then blended with POs-Ca or s-HAp ((POs-Ca or s-HAp)/EPO-EO (mass ratio): 0.2). The noted findings due to the addition of POs-Ca or s-HAp to the composite gels were: (a) the stanching time of more than 80 min due to the addition of POs-Ca ® 50 to the composite gel with EPO : EO : water = 25 : 15 : 60 (mass ratio) (25EPO-15EO) and (b) formation of osteoid at the drilled hole within the tibia and femur of Japanese white rabbits due to the addition of s-HAp(45). The combined addition of POs-Ca and s-HAp to the EPO-EO were expected to enhance the hemostasis and bone regeneration. 

A Facile Strategy To Elute Amoxicillin In A Controlled Way From Hydroxyapatite-gelatin Composite

K. Sangeetha; Y. Yokogawa; E.K. Girija

Advanced Materials Letters, 2015, Volume 6, Issue 12, Pages 1031-1036
DOI: 10.5185/amlett.2015.5905

In recent decades bone infection is one of the most challenging issues encountered in biomedical field and local antibiotic delivery is a key strategy to overcome this issue. Hence developing bioactive materials in combination with antibiotics is much focused recently for bone substitutes. Here we report the fabrication of pristine and natural polymer (gelatin) composite matrices of hydroxyapatite (HA) by a facile wet precipitation method and their drug release behavior from directly loaded and in situ loaded matrices using amoxicillin as the model drug. The products thus obtained were analyzed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry (TG) and scanning electron microscopy (SEM) which confirmed the formation of HA and nanocomposite of HA with gelatin. It was observed that under physiological conditions, for sustained and prolonged release of the drug in situ loading in composite matrix is a favorable approach.

Biomimetic Ion Substituted Hydroxyapatite Coating On Surgical Grade 316L SS For Implant Applications

K. Prem Ananth; Sujin P. Jose; A. Joseph Nathanael; Tae Hwan Oh; D. Mangalaraj; A. M. Ballamurugan

Advanced Materials Letters, 2015, Volume 6, Issue 11, Pages 984-989
DOI: 10.5185/amlett.2015.5913

In this paper, we have reported a successful synthesis of ionic substituted (Si, Sr and Zn) hydroxyapatite (HAp) using chemical precipitation method and the coating of the synthesized materials on surgical grade 316 L SS using electrophoretic deposition technique. The structural, compositional, functional group and morphological characterization of the developed coatings were carried out using XRD, EDX, FT-IR, and FE-SEM. Electrochemical studies such as potentiodynamic polarization, electrochemical impedance studies were performed to evaluate the corrosion resistance imparted by the coatings and was found that considerable resistance was exhibited by the coated samples. Furthermore the coated samples were tested for in-vitro biomineralization ability in simulate body fluid (SBF) solution at different immersion time periods and was found that the thickness of the apatite film was increased with the increase in the immersion time and the surface became entirely covered with apatite. Thus it is opined that the developed Si, Sr, and Zn substituted Hydroxyapatite (I-HAp) coating on 316 L SS substrate would be ideal candidates for bio implant applications.

Gas Sensing and Dielectric Studies on Cobalt Doped Hydroxyapatite thick films

Megha P. Mahabole; Ravindra U. Mene;Rajendra S. Khairnar

Advanced Materials Letters, 2013, Volume 4, Issue 1, Pages 46-52
DOI: 10.5185/amlett.2013.icnano.146

This present paper deals with the investigation on effective utilization of cobalt doped hydroxyapatite (Co-HAp) thick films for improvement in gas sensing and dielectric properties. Chemical precipitation route is used for synthesis of nanocrystalline hydroxyapatite (HAp) bioceramic and ion exchange process is carried out for the partial substitution of cobalt ions in HAp matrix. Hydroxyapatite thick films, prepared using screen printing technique, are used as samples for gas sensing and dielectric measurements. The structural identification of HAp thick films is carried out using X-ray diffraction and the presence of functional groups in pure and doped HAp is confirmed by means FTIR spectroscopy. The surface morphology of these films is visualized by means of SEM and AFM analysis. Detailed study on CO2 gas sensing performance of pure and Co-HAp thick films is carried out wherein operating temperature, response/recovery times and gas uptake capacity are determined. It is remarkable to note that Co-HAp film with 0.01M cobalt concentration shows maximum sensitivity to CO2 gas at relatively lower operating temperature of 135 o C in comparison with pure HAp as well as other concentrations of cobalt doped HAp films. The frequency dependent variation of dielectric constant (K) and dielectric loss (tan δ) of HAp thick films are also studied in the range of 10 Hz-1MHz at room temperature. The result shows that increase of cobalt concentration in HAp matrix leads to increase in dielectric constant. The study reveals clear influence of cobalt substitution on dielectric properties and gas sensing properties HAp matrix.

A Facile Fabrication Of Hydroxyapatite In Vitro Using Polymer Fasciculus As Biotemplate Carrier

Tao Yan; Dong Wei; Xianpeng Zheng; Xiaodong Xin; Nuo Zhang; Dan Wu; Liangguo Yan; He Li; Bin Du; Qin Wei

Advanced Materials Letters, 2010, Volume 1, Issue 2, Pages 106-113
DOI: 10.5185/amlett.2010.4111

For biomimetic synthesis of hydroxyapatite by simulating biomineralization, the polyamide 66 (PA 66) was used as biotemplate carrier, and the biotemplate was prepared by the adsorption of AOT surfactants at interfaces of polymer fasciculus. Simulating biomineralization was carried out at physiological condition (pH = 7.4, T = 37 o C). The phase components, morphologies and possible growth mechanism of calcium phosphate were studied by fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results indicated that the course of crystal growth, as well as the morphology and composition of product was markedly dependent on biotemplate; the crystals size were within nanometer scope, with a sphere and short rod-like shape extraordinary close to natural bone. The possible mechanism of crystal growth was discussed.

Studies On The Interaction Of DNA With Vitamin B12 Based On The Immobilization Of DsDNA On Nano-scale Hydroxyapatite Coating

Nuo Zhang; Caixia Xu; Qin Wei; Bin Du; Ru Li; Tianguo Zhang; Dan Wu; Yuxue Dai

Advanced Materials Letters, 2010, Volume 1, Issue 1, Pages 34-39
DOI: 10.5185/amlett.2010.3104

Nano-scale hydroxyapatite (HAp) was prepared by combining co-precipitation with microemulsion method, which exhibited strong adsorption for DNA due to its excellent biocompatibility and particular adsorbability. DNA and HAp could be modified onto glassy carbon electrode (GCE) by the simple and convenient “tip-coating” method. Cyclic voltammetry was used to investigate the interaction of DNA immobilized on the HAp film with vitamin B12 (VB12). The existence of DNA led to the decrease of reduction current of VB12. Both the electron transfer coefficient (α) and the standard rate constant (ks) were different obtained on GCE and dsDNA/HAp/GCE, which indicated the formation of an electrochemical inactive super molecular complex DNA-nVB 12 . The equilibrium constant of this complex was calculated to be 5.35 × 10 5 mol·L -1 and the binding number between DNA and VB12 of the complex were determined to be one.