•The incorporation of GO and f-MWCNTs on HAP exhibits more corrosion resistive in SBF.•The hardness of the coatings with GO and f-MWCNTs revealed enhanced strength.•Hydrophilicity of the coated ...implant surface allows the formation of apatite layer.•The attachment of HAP on chemically modified f-MWCNTs and GO are proved by HR-TEM.
Bioceramic composite coatings were deposited on surgical grade 316L stainless steel substrate via in-situ electrolytic method by supplying the voltage of −1.5 V for 30 mins using three electrode arrangements. Formations of pure HAP/GO and HAP/f-MWCNTs composite films were developed and the structure of hydroxyapatite was retained even with incorporation of secondary materials into its matrix. Homogeneously dispersed dense coating was observed for the electrochemically derived HAP composite films on 316L SS. The attachment of GO and f-MWCNTs with hydroxyapatite particles were observed using high resolution transmission electron microscopic (HR-TEM). In-vitro corrosion studies of the fabricated bioceramic composite coatings showed better corrosion protection against the simulated body fluid. Apatite mineralization formed at faster rate for the prepared bioceramic composite films; further which it enhance their bone bonding ability. These results concluded that the electrochemical deposition of bioceramic coatings on implant may be treated as an effective method for orthopedic repair and replacements.
The study reports on the use of sol-gel technique to yield zircon type Zr
GdxTi
(SiO
)
(PO
)
solid solution. Titanium has been used as a mineralizer to trigger zircon formation while equimolar ...concentrations of Gd
and PO
were added to determine their accommodation limits in the zircon structure. The crystallization of t-ZrO
as a dominant phase alongside the crystallization of m-ZrO
and zircon were detected at 1200°C while their further annealing revealed the formation of zircon as a major phase at 1300°C. Heat treatment at 1400°C revealed the formation of zircon-type solid solution Zr
Gd
Ti
(SiO
)
(PO
)
comprising the accommodation of 10 mol.% of Gd
/PO
at the zircon lattice. Beyond 10 mol.% of Gd
/PO
, the crystallization of GdPO
as a secondary phase is noticed. Structural analysis revealed the expansion of zircon lattice due to the simultaneous occupancy of Gd
/PO
for the corresponding Zr
/SiO
sites. The mechanical strength of single-phase zircon solid solution was higher in comparison to that of multiphase materials, namely in the presence of GdPO
formed as a secondary phase in samples with added equimolar Gd
/PO
contents beyond 10 mol.%. Nevertheless, the paramagnetic behavior of the samples demonstrated a steady surge as a function of enhanced Gd
content.
Hydroxyapatite HAP and tricalcium phosphate ß-TCP are a class of calcium phosphate related ceramic materials that are widely used in tissue regeneration and biomedical applications owing to their ...excellent bioactivity and biocompatibility. In this investigation, nanocrystalline pure HAP was prepared via sol-gel method by incorporating snail shell as calcium precursor with different phosphorus sources such as triethyl phosphate/phosphite (without using any additives like pH maintaining solutions or gelling agents). Nanocrystalline HAP and biphasic calcium phosphate (HAP + ß TCP) were prepared from triethyl phosphate and triethyl phosphite precursors, respectively. The prepared material was further characterized by powder XRD, IR, Raman spectroscopy, and thermo-gravimetrical analysis to confirm the phase purity, functional groups, and thermal stability. SEM coupled with EDAX was also used to examine the size, shape of particles, and elemental composition of Ca to P ratio in the material. Different phosphorus based HAP has shown rod and spherical shaped surface morphology which was further confirmed by TEM analysis. MTT assay was performed using NIH-3T3 fibroblast cell lines which indicated that the viability was not affected in various concentrations of pure nanocrystalline HAP (12.5-100 µg/ml). This study confirms the improved biocompatibility of biowaste converted HAP which would have implications in biomedical applications.
The research on extracellular matrix (ECM) is new and developing area that covers cell proliferation and differentiation and ensures improved cell viability for different biomedical applications. ...Extracellular matrix not only maintains biological functions but also exhibits properties such as tuned or natural material degradation within a given time period, active cell binding and cellular uptake for tissue engineering applications. The principal objective of this study is classified into two categories. The first phase is optimization of various electrospinning parameters with different concentrations of HAP-HPC/PLA(hydroxyapatite-hydroxypropylcellulose/poly lactic acid). The second phase is in vitro biological evaluation of the optimized mat using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay for bone regeneration applications. Conductivity and dielectric constant were optimized for the production of thin fiber and bead free nanofibrous mat. With this optimization, the mechanical strength of all compositions was found to be enhanced, of which the ratio of 70:30 hit a maximum of 9.53 MPa (megapascal). Cytotoxicity analysis was completed for all the compositions on MG63 cell lines for various durations and showed maximum cell viability on 70:30 composition for more than 48 hrs. Hence, this investigation concludes that the optimized nanofibrous mat can be deployed as an ideal material for bone regenerative applications. In vivo study confirms the HAP-HPC-PLA sample shows more cells and bone formation at 8 weeks than 4 weeks.
Hydroxyapatite Ca
10
(PO
4
)
6
(OH)
2
has attracted widespread interest from both orthopedic and dental fields due to its excellent biocompatibility and tissue bioactivity properties. Since nanophase ...materials can mimic the dimensions of constituent components of natural tissues, the implants developed from nanophase material could serve as a successful alternative. However, the defects of hydroxyapatite ceramics, mainly brittleness and low fracture toughness, have been overcome by the use of nanophase hydroxyapatite coatings on the implant surfaces that integrate the good mechanical properties of metals and the bioactivity of hydroxyapatite. In the present investigation, Sol–gel hydroxyapatite was prepared from two different phosphorus precursors such as triethyl phosphate and phosphorus pentoxide respectively with calcium nitrate tetrahydrate as a calcium precursor. The effects of pH and liquid P
31
Nuclear Magnetic Resonance spectroscopy for the solution aged at different periods were investigated and the synthesized hydroxyapatite powder was characterized by Transmission electron microscopy, X-ray Powder Diffraction, Fourier transform infrared spectroscopy and thermal analysis respectively. In order to fully understand the bioactivity of the synthesized materials, they were coated on 316L Stainless Steel implant surface by spin coating method at the spin speed of 2,000 Revolutions per minute. The effect of nanoparticles on the surface of 316L Stainless Steel implant was studied by adhesive strength measurements. The corrosion resistance property of the hydroxyapatite coatings was evaluated by electrochemical impedance analysis. From the results, it was observed that the hydroxyapatite coatings obtained from different precursors have very high resistance to corrosion with higher adhesive strength.
Electrospinning is one of the promising techniques to fabricate the nanofiber based scaffold for bone regeneration applications. In this study, firstly sol–gel method was employed to synthesize 5 % ...of Ag doped hydroxyapatite and also 10 wt% of polyvinyl alcohol solution was prepared for the electrospun process. For the first time, we have successfully fabricated the composite nanofibers in the combination of various concentration of Ag doped hydroxyapatite such as 1, 2, 3, and 5 wt% with polyvinyl alcohol solution. The developed Ag doped hydroxyapatite-polyvinyl alcohol composites were further characterized by Fourier transform infrared spectroscopy and powder-X-ray diffraction analysis to examine the characteristic functional groups and phase composition of Ag doped hydroxyapatite embedded into polyvinyl alcohol matrix. The uniform distribution of Ag doped hydroxyapatite in polyvinyl alcohol polymer with nanofiber diameter of 188–242 nm range was confirmed by high resolution transmission electron microscope and dynamic light scattering analysis, also the chemical/elemental composition was observed by scanning electron microscopy-energy dispersive spectroscopy analysis. The antibacterial activity was evaluated for the fabricated Ag doped hydroxyapatite polyvinyl alcohol composite nanofibers by using
Staphylococcus aureus
(
S. aureus
) and
Escherichia coli
(
E. coli
) pathogens and the results demonstrated that
E. coli
exhibits excellent zone of inhibition than
S. aureus
due to its lesser cell wall thickness. The hemocompatibility study proves that the developed composite nanofibers are blood compatible and showed the hemolytic ratio of less than 5 %. In addition to this, in vitro bioactivity assessment was carried out for 7 days by immersing in simulated body fluid solution to generate the dense apatite layer on their surfaces which was further examined by X-ray diffraction and scanning electron microscopy-energy dispersive spectroscopy analysis. Hence, these electrospun fabricated Ag doped hydroxyapatite-polyvinyl alcohol composite nanofibers will acts as a potential scaffold material for tissue engineering applications.
Graphical Abstract
Graphical abstract of electrospun fabrication of Ag@HAP-PVA composite nanofibers and its in vitro biological evaluations.
In this study, Inconel 625 superalloy was laser peened without protective coating to advance its electrochemical characteristics. For this purpose, a water penetrable laser source (wavelength ~532nm) ...was operated at two power densities (6 and 9GWcm−2). Substantial residual compressive stresses developed at 9GWcm−2 whilst they were preponderantly tensile and anisotropic at 6GWcm−2. Hardness was unchanged after peening due to higher strength of the alloy. Peening increased the roughness but it is merely ≤1μm. Corrosion rate exceedingly lowered about ~104 times at 6GWcm−2 compared to other conditions with a belittled current density fluctuation over certain applied potential range due to increased roughness. No pitting resulted in untreated and peened specimens. Threefold increase in charge transfer resistance noticed at 6GWcm−2 owing to enhanced defect density (measured with X-ray peak broadening).
Display omitted
•Residual stresses of ~−800MPa developed in laser peened Inconel 625 superalloy.•Average roughness at laser peened surface was found to be smaller (≤1μm).•Corrosion rate decreased about 104 fold at laser peened surface.•Charge transfer resistance increased about 3 times at laser peened surface.
Graphene oxide incorporated hydroxyapatite hybrid films were coated on 316L stainless steel substrate with the aid of electrochemical studies at the voltage of −1.5 V for 30 min using three electrode ...arrangements. Purity and crystallinity of the formed HAP/GO composite coatings were examined using X-ray diffraction and Fourier transform infrared spectroscopic studies. Phase of the hydroxyapatite was not affected with incorporation of graphene oxide into its matrix. Well-ordered and compact coating morphology was observed for the electrochemically deposited HAP/GO on 316L substrate using the scanning electron microscopy. High-resolution transmission electron microscopic studies reveal the tight bonding and growth of HAP particles on to the sidewalls of GO sheets. Electrochemical studies for the HAP/GO composite coating against the physiological solution showed improved corrosion efficiency. Addition of GO into HAP enhances the apatite precipitation and bone-bonding ability. These results concluded that the electrochemical deposition of bioceramic coatings on implant may be treated as an effective method for orthopedic repair and replacements.
Human bone is composed of nano-sized organic and mineral phases. Hydroxyapatite (HAP) is the main mineral component of bone (70% of bone composition) and it is effectively used in all biomedical ...applications. This component has been extensively studied as a material for bone implantation, and its excellent bioactivity and osteoconductivity has been clearly established. A key component in tissue engineering for bone regeneration is the scaffold that acts as a template for cell interactions and the formation of bone-extracellular matrix that provides mechanical support to the newly formed tissue. In the present investigation, hydroxyapatite has been prepared by wet chemical method and the polymers such as PVA, PVP are to be used to prepare the scaffolds. The genipin used as cross linker to control the pore size which can enhance the cell proliferation for tissue engineering. The formations of synthetic scaffolds are characterized by FT-IR, XRD, and SEM-EDAX analysis. Invitro study of the scaffolds are analysed by SBF immersion, Hemolytic assay, biodegradation study, MTT Assay. From the study we inferred that the polymer based cross linked scaffolds demonstrated stimulatory effects to control the pore and also showing good hemolysis, control biodegradation and enhancing the cell proliferation for bone tissue engineering application.
