A simple chemical conversion coating was adopted to deposit zinc calcium phosphate (ZCP) coating and strontium doped ZCP (SZCP) coating on AZ31 magnesium alloy to induce biocompatibility and reduce the degradation rate. The surface morphology, chemical composition and functional groups of the coating were characterized by Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy (SEM-EDS), X-Ray Diffraction (XRD) studies and Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy respectively. SZCP coating formed at 20 min deposition time produced crack free surface with a high degree of crystallinity with barrier property, which ultimately retards the dissolution of magnesium in Simulated Body Fluid (SBF). The corrosion resistance of AZ31 magnesium alloy was improved by SZCP coating as evident from hydrogen evolution test (HET). Cytotoxicity evaluation with L969 cells showed that Sr doped ZCP coatings showed less toxicity on resorbable magnesium alloy. © 2017 Trans Tech Publications, Switzerland.

Sampath Kumar T S

Department of Metallurgical and Materials Engineering

P. Amaravathy

biocompatibility

Body fluids

calcium

Calcium phosphate

Coatings

corrosion

Corrosion resistance

Corrosion resistant alloys

Cytotoxicity

Degradation

Energy dispersive spectroscopy

Fourier transform infrared spectroscopy

Magnesium

Magnesium alloys

Medical applications

Metal implants

Scanning electron microscopy

strontium

X ray diffraction

X ray spectroscopy

Zinc

ATTENUATED TOTAL REFLECTANCE FOURIER TRANSFORM INFRARED

Biomedical applications

Chemical compositions

CHEMICAL CONVERSION COATINGS

Degree of crystallinity

energy dispersive X ray spectroscopy

PHOSPHATE CONVERSION COATINGS

Simulated body fluids

ZINC COATINGS

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

Journal of Biomimetics, Biomaterials and Biomedical Engineering

AZ31 magnesium alloy was coated with polycaprolactone (PCL) nano-fibrous layer using electrospinning technique so as to control degradation in physiological environment. Before coating, the alloy was treated with HNO3 to have good adhesion between the coating and substrate. To elucidate the role of pre-treatment and coating, samples only with PCL coating as well as HNO3 treatment only were prepared for comparison. Best coating adhesion of 4B grade by ASTM D3359-09 tape test was observed for pre-treated samples. The effect of coating on in vitro degradation and biomineralization was studied using supersaturated simulated body fluid (SBF 5 ×). The weight loss and corrosion results obtained by immersion test showed that the combination of HNO3 pre-treatment and PCL coating is very effective in controlling the degradation rate and improving bioactivity. Cytotoxicity studies using L6 cells showed that PCL coated sample has better cell adhesion and proliferation compared to uncoated samples. Nano-fibrous PCL coating combined with prior acid treatment seems to be a promising method to tailor degradation rate with enhanced bioactivity of Mg alloys. © 2016 Elsevier B.V. All rights reserved.

Materials Science and Engineering C

Tailoring degradation of AZ31 alloy by surface pre-treatment and electrospun PCL fibrous coating

Strontium-substituted apatites have provoked increased interest in recent years for their beneficial effects on osteoporotic bone treatment and replacement. In this study, rod- and acicular-shaped, strontium-substituted calcium deficient hydroxyapatite (CDHA) nanoparticles with (Ca + Sr)/P ratio of 1.61 were synthesized via accelerated microwave processing. The X-ray powder diffraction analysis indicates the synthesized nanoparticles as apatite phase with diffraction patterns similar to those of hydroxyapatite. The hydrodynamic diameter of the particles were observed to be ∼200-500 nm and found to increase with strontium substitution along with an increase in the negative zeta potential by dynamic light scattering method, suggesting the particles to be agglomerates in water. The morphology of the nanoparticles was studied using transmission electron microscopy (TEM), where, pure CDHA showed globular and strontium substituted CDHAs showed rod and acicular shape for 5% and 10% Sr substitution, respectively. The average size of the particles in TEM was measured to be 33 nm × 5 nm, 40 nm × 6 nm, and 55 nm × 8 nm (L × W) for pure and strontium-substituted CDHAs, respectively. Inductively coupled plasma spectroscopy, energy dispersive X-ray analysis, and Fourier transform infrared spectroscopy further confirm the substitution of strontium and deficiency of calcium in the synthesized nanoparticles. Thermal stability and in vitro solubility of CDHA nanoparticles were observed to increase with strontium substitution. The MTT [3-(4, 5-Dimethylthiazole-2-yl)-2, 5-diphenyl tetrazolium bromide] assay indicate that the substituted nanoparticles are non-toxic to human periodontal ligament fibroblast (HPDLF) cells. Cell uptake study by fluorescence microscopy using rhodamine-123 and actin/DAPI stained HPDLF cells show cellular localization of the nCDHA, nSr5CDHA, nSr10CDHA nanoparticles without any adverse effects. The strontium-substituted CDHAs showed significant antimicrobial activity against Escherichia coli and Staphylococcus aureus bacteria by colony count method. The 10% Sr substituted CDHA show the maximum microbial reduction of around 56% for E. coli and 35% for S. aureus with 1 × 10 5 cells/mL of respective bacterial culture. © 2012 The American Ceramic Society.

Journal of the American Ceramic Society

Strontium-substituted calcium deficient hydroxyapatite nanoparticles: Synthesis, characterization, and antibacterial properties

Interventional Medicine and Applied Science

Magnesium-based biodegradable alloys: Degradation, application, and alloying elements

Dentistry

The Impact of Strontium Ranelate on Implant Osseointegration of Osteoporosis in Vivo Experiment

Science and Technology of Advanced Materials

Surface treatments for controlling corrosion rate of biodegradable Mg and Mg-based alloy implants

Novel strontium doped zinc calcium phosphate conversion coating on az31 magnesium alloy for biomedical applications

Journal	Journal of Biomimetics, Biomaterials and Biomedical Engineering
Publisher	Trans Tech Publications Ltd
ISSN	22969837
Open Access	No