Nanocrystalline apatites with different Ca/P ratios were synthesized using eggshell as a calcium source by microwave processing. The apatites were found to have a minor amount of Mg, Sr, Si and Na ions inherited from the eggshells. The presence of several foreign ions results in a perturbed lattice structure indicated by an increase in lattice constants and shift in vibrational frequencies of the functional groups. The apatites were heat treated to investigate the influence of foreign ions on thermal stability. The minor amounts of ions do not affect the thermal stability. The differences in thermal behaviour of these apatites were due to the presence of HPO2- 4 ions only and not due to other ions because of their low content. © 2009 IOP Publishing Ltd.

Sampath Kumar T S

Department of Metallurgical and Materials Engineering

A Siddharthan

Suresh Krishnamoorthy Seshadri

apatite

calcium

Functional groups

Lattice constants

Nanocrystalline materials

Phosphate minerals

Synthesis (chemical)

Thermodynamic stability

CA/P RATIO

FOREIGN IONS

MICROWAVE PROCESSING

NANOCRYSTALLINE APATITES

PERTURBED LATTICES

Synthesis and characterization

THERMAL BEHAVIOURS

thermal stability

Vibrational frequencies

Ions

Hydroxyapatite

magnesium ion

Nanocrystal

phosphate

Phosphorus

Silicon

sodium ion

strontium

article

Differential scanning calorimetry

EGG SHELL

infrared spectroscopy

microwave radiation

thermostability

Transmission electron microscopy

X ray diffraction

Animal

chemistry

chicken

heat

Animals

Apatites

Chickens

Hot Temperature

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Synthesis and characterization of nanocrystalline apatites from eggshells at different Ca/P ratios.

Biomedical Materials

Brushite cements are known for excellent osteoconductive and degradation properties, however, its widespread use is limited due to rapid setting time and poor mechanical properties. The eggshell derived calcium phosphates exhibits improved physical and biological properties due to the presence of biologically relevant ions. In this study, eggshell derived brushite cement (EB) was fabricated using β-tricalcium phosphate synthesized from eggshells. The presence of trace elements in EB prolonged its setting time. The size of brushite crystals in EB was found to be smaller than the pure brushite cement (PB) leading to increased initial compressive strength and higher in vitro degradation rate. The L6 and MG63 cell lines exhibited good biocompatibility with the cement at the end 72 h. In vivo studies of the cements were performed in rat calvarial defect model. Micro CT analysis showed faster degradation and accelerated bone formation in EB filled defect. Histological studies revealed infiltration of inflammatory cells into the implant site for both the cements till 6th week. However, inflammation was found to be significantly reduced at the 12th week in EB compared to PB leading to complete bone bridge formation. Multi-ion substituted EB seems to be a potential bone substitute material with a reasonable setting time for ease of handling, higher mechanical strength, minimal inflammatory response and higher bone regeneration. [Figure not available: see fulltext.]. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.

Journal of Materials Science: Materials in Medicine

Eggshell derived brushite bone cement with minimal inflammatory response and higher osteoconductive potential

Magnesium (Mg)-based biomaterials are widely investigated for degradable implant applications. Developing Mg-based composites is one of the strategies adopted to increase the bioactivity and to reduce the degradation rate ofMg. In the present study, hydroxyapatite (fHA) has been produced from fish bones and incorporated into pureMg sheets by friction stir processing (FSP). Microstructures of the composites clearly revealed the grain refinement in the stir zone up to 10 Μm from the starting size of 2000 Μm. Measurements of microhardness also indicated the effect of a smaller grain size and the presence of fHA on increasing the hardness in composites. Interestingly from the tensile tests, mechanical properties, such as yield strength and ultimate tensile strengths were measured as they decreased for the composite due to the presence of fHA particles. However, the observed % elongation of the composite was similar to that of a natural bone. From the electrochemical tests, the composite exhibited an enhanced corrosion performance. From the results, it can be concluded that the cost-effective Mg-fHA composites can be developed by FSP for degradable scaffold applications in biomedical fields. © Indian Academy of Sciences.

Fulltext

Bulletin of Materials Science

Magnesium/fish bone derived hydroxyapatite composites by friction stir processing: Studies on mechanical behaviour and corrosion resistance

Hydroxyapatite (HA) nanoparticles were dispersed in AZ31 alloy by friction stir processing (FSP) to produce AZ31/HA metal matrix composites. The composite surface was acid treated using HNO3 and coated with polycaprolactone/HA (PCL/HA) mat by electrospinning. Coating parameters were optimized to obtain PCL/HA nanocomposite fibrous mat with an adhesion strength of 4B Grade (ASTM D3359-09 tape test) on AZ31/HA composite surface. Presence of HA on the substrate and in the coating helps in enhancing biomineralization and develop thick CaP layer on the surface which also facilitates controlled degradation in simulated body fluid at normal physiological conditions of pH 7.2 and 37 °C. Rat skeletal muscle cells culture study showed better adhesion and proliferation on coated samples compared to the uncoated samples. The combination of electrospun nanofibrous PCL/HA composite coating on acid pre-treated FSPed AZ31/HA composite surface seems to have the potential for biodegradable magnesium implant applications with enhanced bioactivity for tissue regeneration. © 2017 Elsevier B.V.

Journal of Materials Processing Technology

Electrospun PCL/HA coated friction stir processed AZ31/HA composites for degradable implant applications​

Abstract: Dental caries is an infection of the mineralized tooth structures that advances when acid secreted by bacterial action on dietary carbohydrates diffuses and dissolves the tooth mineral leading to demineralization. During treatment, clinicians often remove only the superficial infected tooth structures and retain a part of affected carious dentin to prevent excessive dentin loss and pulp exposure. Calcium hydroxide is used to treat the affected dentin because it is alkaline, induces pulp-dentin remineralization and decreases bacterial infection. Presence of strontium ions has also been reported to exhibit anticariogenic activity, and promote enamel and dentin remineralization. The objective of the present study was to develop novel hydroxyapatite cement from tetracalcium phosphate which gradually releases hydroxyl and strontium ions to exhibit antibacterial activity. Its potential to remineralize the dentin sections collected from extracted human molar tooth was studied in detail. The pH of all the experimental cements exhibited a gradual increase to ~10.5 in 10 days with 10% strontium substituted tetracalcium phosphate cement (10SC) showing the highest pH value which was sustained for 6 weeks. 10SC showed better antibacterial property against S. aureus and E. coli at the end of 1 week compared to other cements studied. It also exhibited the highest radiopacity equivalent to 4.8 mm of Al standard. 10SC treated dentin section showed better remineralization ability and highest elastic modulus. We can conclude that the hydroxyl and strontium ions releasing tetracalcium phosphate cement exhibits good antibacterial property, radiopacity and has the potential to encourage dentin remineralization. Graphical Abstract: [InlineMediaObject not available: see fulltext.]. © 2017, Springer Science+Business Media New York.

Dentin remineralizing ability and enhanced antibacterial activity of strontium and hydroxyl ion co-releasing radiopaque hydroxyapatite cement

The present work demonstrates a low cost route to produce hydroxyapatite (HA) from fish bones (natural source) by a simple heat treatment process. The produced HA was characterized by X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM). Elemental composition obtained from energy dispersive X-ray analysis confirmed the presence of Ca, P, O and Mg. XRD analysis has clearly shown that the produced phase as HA. The powders were heated from 600 to 1000 °C and from the TEM observations, large fused crystals (≈200 nm) were noticed. XRD analysis of the heat treated powders have also not shown new phases and which is an indication of the purity level of HA. © 2016 Elsevier B.V.

Materials Letters

Producing hydroxyapatite from fish bones by heat treatment

The eggshell waste has been value engineered to a nanocrystalline hydroxyapatite (HA) by microwave processing. To highlight the advantages of eggshell as calcium precursor in the synthesis of HA (OHA), synthetic calcium hydroxide was also used to form HA (SHA) following similar procedure and were compared with a commercially available pure HA (CHA). All the HAs were characterized by X-ray powder diffraction (XRD) method, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and specific surface area measurements. Nanocrystalline nature of OHA is revealed through characteristic broad peaks in XRD patterns, platelets of length 33-50 nm and width 8-14 nm in TEM micrograph and size calculations from specific surface area measurements. FT-IR spectra showed characteristic bands of HA and additionally peaks of carbonate ions. The cell parameter calculations suggest the formation of carbonated HA of B-type. The OHA exhibits superior sinterability in terms of hardness and density than both SHA and CHA may be due to larger surface area of its spherulite structure. The in vitro dissolution study shows longer stability in phosphate buffer and cell culture test using osteoblast cells establishes biocompatibility of OHA. © 2007 Springer Science+Business Media, LLC.

A novel route for synthesis of nanocrystalline hydroxyapatite from eggshell waste

Rapid synthesis of calcium deficient hydroxyapatite (CDHA, Ca 10-x(HPO4)x(PO4)6-x(OH) 2-x) with Ca/P ratio 1.5 was done by precipitation using calcium nitrate tetra-hydrate and phosphoric acid and subsequently subjecting to microwave irradiation in a domestic microwave oven for 15 min. Transmission electron microscopy analysis shows needle like morphology of CDHA having length 16-39 nm and width 7-16 nm. The synthesized CDHA has the characteristic HPO 2- 4 vibration band at 875 cm-1 in Fourier transform infrared (FT-IR) spectra. The X-ray powder diffraction (XRD) analysis shows a pattern corresponding to stoichiometric hydroxyapatite (HA) with broad peaks suggesting that CDHA particles were nanosized. Fourier transform Raman spectroscopy (FT-Raman) do not indicate any fluorescence band that is characteristic of non-stoichiometric HA. The thermal decomposition of CDHA to beta tricalcium phosphate (β-TCP) was also studied for the additional confirmation. The nanosized CDHA was found to be stable up to 600°C. © 2004 Kluwer Academic Publishers.

Microwave accelerated synthesis of nanosized calcium deficient hydroxyapatite

Chemically and thermally treated bovine bone has been proposed as an alternative to bone grafts and synthetic bone substitutes. Fluorinated bovine hydroxyapatite (FBHA) was prepared by two different methods at low and high temperatures. The effect of reaction temperature and fluorine concentration on the crystal morphology, phase purity and functional groups were observed by X-ray diffraction (XRD) method and FT-IR spectroscopy. The XRD results indicted that [3 0 0] reflection peak was shifted towards higher angle due to fluorination. The a-axis dimensions of both the FBHA samples were found to be decreased with the fluorination. The FT-IR spectra of FBHA samples confirm partial fluorination into the hydroxyl group of bovine hydroxyapatite. The in vitro physiological stability study was performed in phosphate buffered saline (PBS) of pH 7.4 at 37 °C and the samples were found to be quite stable for about a month. These results suggest the tremendous potential of fluorinated bovine hydroxyapatite as a bone substitute due to their bioactive nature. © 2002 Elsevier Science B.V. All rights reserved.

Fluorinated bovine hydroxyapatite: Preparation and characterization

Carbonated hydroxyapatites (CHA) were synthesized by the substitution of calcium carbonate for calcium hydroxide during the reaction with diammonium phosphate under microwave irradiation. The X-ray powder diffraction analysis indicates the decrease of a-axis up to 20mol% of carbonate substitution confirming the formation of the B-type CHA. Further increase of carbonate content shows the presence of tricalcium phosphate (TCP) in addition to CHA. Reaction of substituted magnesium carbonate instead of calcium carbonate in the above process results in the formation of biphasic calcium phosphate (BCP) ceramics consisting of both CHA and TCP phases. Fourier transform infrared spectroscopic study also confirmed the carbonate substitution in HA and BCP formation. The in vitro solubility study in phosphate buffer of pH 7.2 at 37°C showed the resorbable nature of the BCP samples. The present study thus indicates the feasibility of in situ formation of BCP ceramics using microwave irradiation. (C) 2000 Elsevier Science Ltd.Carbonated hydroxyapatites (CHA) were synthesized by the substitution of calcium carbonate for calcium hydroxide during the reaction with diammonium phosphate under microwave irradiation. The X-ray powder diffraction analysis indicates the decrease of a-axis up to 20 mol% of carbonate substitution confirming the formation of the B-type CHA. Further increase of carbonate content shows the presence of tricalcium phosphate (TCP) in addition to CHA. Reaction of substituted magnesium carbonate instead of calcium carbonate in the above process results in the formation of biphasic calcium phosphate (BCP) ceramics consisting of both CHA and TCP phases. Fourier transform infrared spectroscopic study also confirmed the carbonate substitution in HA and BCP formation. The in vitro solubility study in phosphate buffer of pH 7.2 at 37°C showed the resorbable nature of the BCP samples. The present study thus indicates the feasibility of in situ formation of BCP ceramics using microwave irradiation.

Biomaterials

Synthesis of carbonated calcium phosphate ceramics using microwave irradiation

Journal of Biomedical Materials Research Part A

The influence of Sr doses on thein vitrobiocompatibility andin vivodegradability of single-phase Sr-incorporated HAP cement

Synthesis and characterization of nanocrystalline apatites from eggshells at different Ca/P ratios

Journal	Biomedical Materials
Publisher	Institute of Physics Publishing
ISSN	17486041
Open Access	No