The document discusses optimizing cell adhesion on magnesium-based implant materials through pre-incubation under cell culture conditions. It finds that pre-incubating Mg and Mg10Gd1Nd alloy samples in cell culture medium for just 6 hours is enough to form a natural protective surface layer suitable for cell culture by decreasing corrosion rates and increasing cell viability compared to untreated samples. Longer pre-incubation times further optimize cell adhesion and proliferation but do not significantly improve results enough to justify the increased contamination risk of longer experiments.
This document describes a study investigating bioceramic nanoparticles doped with magnesium and silver for use as implant materials. The nanoparticles were synthesized using a quick alkali-mediated sol gel method and had the composition xMgO-yAg2O-(40Àx)CaO-(20.5Ày)Na2O-35.5SiO2-4P2O5 with varying molar percentages of MgO and Ag2O. Characterization techniques were used to analyze the structure, morphology, degradation behavior, and antimicrobial properties of the samples. In vitro tests examined the samples' ability to support cell growth, deliver antibiotics in a controlled manner, and stimulate bone regeneration. The goal was to
SIMONA CAVALU_Microstructure and bioactivity of acrylic bone cementsSimona Cavalu
Polymer-ceramic composites based on polymethyl methacrylate are widely used in orthopaedics as suture materials and
fixation devices due to their biocompatibility and ability to support bony growth (osteoconductive) and also bone bioactive
(to form a calcium phosphate layer on its surface). In this study are compared the microstructure, bioactivity and
biocompatibility of two different types of biocomposites: BIOLOS3®and ANTIBIOTIC SIMPLEX®. They are investigated in
vitro in simulated body fluid using electrochemical measurements, SEM microscopy and ATR-FTIR spectroscopy in order to
evaluate the properties of the surface layer.
This document describes a method for fabricating porous poly(DL-lactic-co-glycolic acid) (PLGA) microspheres that fuse together at body temperature to form solid porous scaffolds, creating an injectable scaffold system. The microspheres were treated with ethanolic sodium hydroxide to increase surface porosity without disintegrating. When mixed with media and incubated at 37°C, the microspheres fused to form scaffolds with compressive strength of 0.9 MPa, porosity of 81.6%, and pore diameter of 54 μm, supporting NIH-3T3 cell attachment and proliferation in vitro. This study demonstrates a technique for producing an injectable and porous PLGA scaffold that solid
Effect of Relative Proportion of Pozzolana on Compressive Strength of Concret...CSCJournals
In this experimental and analytic research, the effect of curing regime on various combinations of silica fume and fly ash was investigated in terms of development of compressive strength. Over 24 mixes were prepared with the water-to-binder ratios of 0.45, 0.35 and 0.25 and with differing percentage of additives used as a combination of 2 or 3 binders. The specimens were subjected to five different curing regimes ranging from continuously water cured to continuously air cured. Results show that it is economical to use a combination of silica fume and fly ash rather than using only silica fume for attaining the same strength level. Poor curing condition adversely affect the strength characteristics of pozzolanic concrete than that of OPC concrete. For silica fume concrete, it is necessary to apply water curing for the initial 7 days to explore pozzolainc activity but it is imperative to cure the fly ash concrete for an extended period to utilize its full potential.
This document summarizes research on PMMA/Ag2O acrylic bone cement coated with collagen to improve biomineralization, biocompatibility, and antibacterial properties. Collagen was electrodeposited on cement samples containing 0.5%, 1%, and 2% silver oxide. FTIR analysis showed collagen deposition depended on silver content. In vitro tests in simulated body fluid revealed silver ion release and mineralization of hydroxyapatite on surfaces over 3 weeks. Antimicrobial tests showed inhibition of E. coli and S. aureus growth, with effectiveness depending on silver content.
Determination of Stability Constants and Gibbs Free Energies of Cefotaxime Zn...ijtsrd
Cefotaxime is a synthetic lactam antibiotic that is active against Gram negative and Gram positive bacteria. Cefotaxime is able to chelate metal ions due to the presence of C=O, NH2, COOH, COOR, NH and NO electron donating groups. The stability constants and Gibbs free energies of cefotaxime Zn II were determined colorimetrically at 25 and 40 oC using continuous variation and mole ratio methods. The formation of Zn II complex with cefotaxime was studied colorimetrically at an absorption maximum of 430 nm at different temperatures. The data showed that Zn II and cefotaxime combine in the molar ratio of 1 2 at pH 7.4 with ionic strength maintained using 0.1M KNO3. Calculated stability constants values were 1.96 x 105 and 1.28 x 105 using continuous variation method and 1.11 x 105 and 1.11 x 105 using mole ratio methods at 25 and 40 oC respectively. Calculated GO for the complex were 3.01 x 104 and 3.06 x 104 J using continuous variation method and 2.88 x 104 J and 3.02 x 104 J using mole ratio method at 25 and 40 oC respectively. The stability constant results suggested that cefotaxime used in the study is a good chelating agent and can be an efficient antidote in the therapy of Zn II overload or poisoning. O. V. Ikpeazu | I. E. Otuokere | K. K. Igwe "Determination of Stability Constants and Gibbs Free Energies of Cefotaxime-Zn(II) Complex at Different Temperatures" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-5 , August 2020, URL: https://www.ijtsrd.com/papers/ijtsrd31797.pdf Paper Url :https://www.ijtsrd.com/chemistry/other/31797/determination-of-stability-constants-and-gibbs-free-energies-of-cefotaximeznii-complex-at-different-temperatures/o-v-ikpeazu
Bioactive glass-ceramics used as a replacement material for bone tissues because
of its bioactivity, compatibility, and abilities to form a crystallized hydroxyapatite
(HA) bonding layer which has a similarity in composition and structure to the
inorganic component of bones mineral phase. The major objectives of this research is
estimating the effects of using MgO as an additive on the property of bioactive glass
ceramic in 45SiO2, 24.5 Na2O, 6 P2O5, (24.5-x)CaO, X MgO where X= 0,1,3 and 5
wt.%. Bioactive glass ceramic was made by traditional glasses melting techniques at
1200°C for 2hr. Compressed sample sintered at (850)°C, the X-ray diffraction test
confirmed the formations of (Na2CaSi3O8) and (Na2Ca2Si3O9) phases in the
structure of pure bioglass-ceramic and with (1wt.%) MgO, while (Na2CaSiO4) and
CaMg(SiO3)2 phases were present in the structure of bioglass-ceramic with
(3wt.%)MgO, and CaMg(SiO3)2 phase in the structure of bioglass-ceramic with
(5wt.%) MgO. Results of mechanical and physical studies showed that increasing
(MgO wt.%) in glass structure led to improving the bending strength, compressive
strength, microhardness, and density associating with decreasing in porosity. FTIR
confirmed the formations of the Si-O-Mg bond. The biological test was done by
immersion the sample in (SBF) simulated body fluid for (21 days). XRD, SEM and pH
tests revealed that appetite layers made on the samples surface, giving an evidence of
their bioactivity. As general the results of the present study demonstrate that partial
replacements of CaO by MgO in 45S5 glass ceramic improve the mechanical
properties without altering the bioactivity suggesting that glass ceramic was suitable
for the biomedical applications
The objective of the present investigation is to obtain the influence of facultative bacteria (Bacillus Cereus) on the strength of concrete made with and without bacteria. Three different cell concentrations (102,107, 1010 cells/ml) of bacteria are used in making the concrete mixes. In making concrete, one control specimen is prepared and three more mixes are also prepared by voluntarily replacing of 10, 20 and 30 litres of bacterial nutrient medium with water. Split Tensile strength test is performed at the age of 7, 14 and 28 days. Test results indicate that inclusion of Bacillus Cereus in concrete enhances the compressive strength. Maximum 25.64% increase in compressive strength is observed with 107 cells/ml of bacteria. The improvement in strength takes place due to microbiologically induced calcite precipitation (MICP). MICP is a layer of highly impermeable calcite deposition on the surface of already existing concrete layer. The effect of MICP is quantified by X-Ray Diffraction (XRD) analysis and visualized by Scanning Electron Microscopy (SEM).
This document describes a study investigating bioceramic nanoparticles doped with magnesium and silver for use as implant materials. The nanoparticles were synthesized using a quick alkali-mediated sol gel method and had the composition xMgO-yAg2O-(40Àx)CaO-(20.5Ày)Na2O-35.5SiO2-4P2O5 with varying molar percentages of MgO and Ag2O. Characterization techniques were used to analyze the structure, morphology, degradation behavior, and antimicrobial properties of the samples. In vitro tests examined the samples' ability to support cell growth, deliver antibiotics in a controlled manner, and stimulate bone regeneration. The goal was to
SIMONA CAVALU_Microstructure and bioactivity of acrylic bone cementsSimona Cavalu
Polymer-ceramic composites based on polymethyl methacrylate are widely used in orthopaedics as suture materials and
fixation devices due to their biocompatibility and ability to support bony growth (osteoconductive) and also bone bioactive
(to form a calcium phosphate layer on its surface). In this study are compared the microstructure, bioactivity and
biocompatibility of two different types of biocomposites: BIOLOS3®and ANTIBIOTIC SIMPLEX®. They are investigated in
vitro in simulated body fluid using electrochemical measurements, SEM microscopy and ATR-FTIR spectroscopy in order to
evaluate the properties of the surface layer.
This document describes a method for fabricating porous poly(DL-lactic-co-glycolic acid) (PLGA) microspheres that fuse together at body temperature to form solid porous scaffolds, creating an injectable scaffold system. The microspheres were treated with ethanolic sodium hydroxide to increase surface porosity without disintegrating. When mixed with media and incubated at 37°C, the microspheres fused to form scaffolds with compressive strength of 0.9 MPa, porosity of 81.6%, and pore diameter of 54 μm, supporting NIH-3T3 cell attachment and proliferation in vitro. This study demonstrates a technique for producing an injectable and porous PLGA scaffold that solid
Effect of Relative Proportion of Pozzolana on Compressive Strength of Concret...CSCJournals
In this experimental and analytic research, the effect of curing regime on various combinations of silica fume and fly ash was investigated in terms of development of compressive strength. Over 24 mixes were prepared with the water-to-binder ratios of 0.45, 0.35 and 0.25 and with differing percentage of additives used as a combination of 2 or 3 binders. The specimens were subjected to five different curing regimes ranging from continuously water cured to continuously air cured. Results show that it is economical to use a combination of silica fume and fly ash rather than using only silica fume for attaining the same strength level. Poor curing condition adversely affect the strength characteristics of pozzolanic concrete than that of OPC concrete. For silica fume concrete, it is necessary to apply water curing for the initial 7 days to explore pozzolainc activity but it is imperative to cure the fly ash concrete for an extended period to utilize its full potential.
This document summarizes research on PMMA/Ag2O acrylic bone cement coated with collagen to improve biomineralization, biocompatibility, and antibacterial properties. Collagen was electrodeposited on cement samples containing 0.5%, 1%, and 2% silver oxide. FTIR analysis showed collagen deposition depended on silver content. In vitro tests in simulated body fluid revealed silver ion release and mineralization of hydroxyapatite on surfaces over 3 weeks. Antimicrobial tests showed inhibition of E. coli and S. aureus growth, with effectiveness depending on silver content.
Determination of Stability Constants and Gibbs Free Energies of Cefotaxime Zn...ijtsrd
Cefotaxime is a synthetic lactam antibiotic that is active against Gram negative and Gram positive bacteria. Cefotaxime is able to chelate metal ions due to the presence of C=O, NH2, COOH, COOR, NH and NO electron donating groups. The stability constants and Gibbs free energies of cefotaxime Zn II were determined colorimetrically at 25 and 40 oC using continuous variation and mole ratio methods. The formation of Zn II complex with cefotaxime was studied colorimetrically at an absorption maximum of 430 nm at different temperatures. The data showed that Zn II and cefotaxime combine in the molar ratio of 1 2 at pH 7.4 with ionic strength maintained using 0.1M KNO3. Calculated stability constants values were 1.96 x 105 and 1.28 x 105 using continuous variation method and 1.11 x 105 and 1.11 x 105 using mole ratio methods at 25 and 40 oC respectively. Calculated GO for the complex were 3.01 x 104 and 3.06 x 104 J using continuous variation method and 2.88 x 104 J and 3.02 x 104 J using mole ratio method at 25 and 40 oC respectively. The stability constant results suggested that cefotaxime used in the study is a good chelating agent and can be an efficient antidote in the therapy of Zn II overload or poisoning. O. V. Ikpeazu | I. E. Otuokere | K. K. Igwe "Determination of Stability Constants and Gibbs Free Energies of Cefotaxime-Zn(II) Complex at Different Temperatures" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-5 , August 2020, URL: https://www.ijtsrd.com/papers/ijtsrd31797.pdf Paper Url :https://www.ijtsrd.com/chemistry/other/31797/determination-of-stability-constants-and-gibbs-free-energies-of-cefotaximeznii-complex-at-different-temperatures/o-v-ikpeazu
Bioactive glass-ceramics used as a replacement material for bone tissues because
of its bioactivity, compatibility, and abilities to form a crystallized hydroxyapatite
(HA) bonding layer which has a similarity in composition and structure to the
inorganic component of bones mineral phase. The major objectives of this research is
estimating the effects of using MgO as an additive on the property of bioactive glass
ceramic in 45SiO2, 24.5 Na2O, 6 P2O5, (24.5-x)CaO, X MgO where X= 0,1,3 and 5
wt.%. Bioactive glass ceramic was made by traditional glasses melting techniques at
1200°C for 2hr. Compressed sample sintered at (850)°C, the X-ray diffraction test
confirmed the formations of (Na2CaSi3O8) and (Na2Ca2Si3O9) phases in the
structure of pure bioglass-ceramic and with (1wt.%) MgO, while (Na2CaSiO4) and
CaMg(SiO3)2 phases were present in the structure of bioglass-ceramic with
(3wt.%)MgO, and CaMg(SiO3)2 phase in the structure of bioglass-ceramic with
(5wt.%) MgO. Results of mechanical and physical studies showed that increasing
(MgO wt.%) in glass structure led to improving the bending strength, compressive
strength, microhardness, and density associating with decreasing in porosity. FTIR
confirmed the formations of the Si-O-Mg bond. The biological test was done by
immersion the sample in (SBF) simulated body fluid for (21 days). XRD, SEM and pH
tests revealed that appetite layers made on the samples surface, giving an evidence of
their bioactivity. As general the results of the present study demonstrate that partial
replacements of CaO by MgO in 45S5 glass ceramic improve the mechanical
properties without altering the bioactivity suggesting that glass ceramic was suitable
for the biomedical applications
The objective of the present investigation is to obtain the influence of facultative bacteria (Bacillus Cereus) on the strength of concrete made with and without bacteria. Three different cell concentrations (102,107, 1010 cells/ml) of bacteria are used in making the concrete mixes. In making concrete, one control specimen is prepared and three more mixes are also prepared by voluntarily replacing of 10, 20 and 30 litres of bacterial nutrient medium with water. Split Tensile strength test is performed at the age of 7, 14 and 28 days. Test results indicate that inclusion of Bacillus Cereus in concrete enhances the compressive strength. Maximum 25.64% increase in compressive strength is observed with 107 cells/ml of bacteria. The improvement in strength takes place due to microbiologically induced calcite precipitation (MICP). MICP is a layer of highly impermeable calcite deposition on the surface of already existing concrete layer. The effect of MICP is quantified by X-Ray Diffraction (XRD) analysis and visualized by Scanning Electron Microscopy (SEM).
Durability of standard concrete incorporatingiaemedu
The document discusses the durability of standard concrete incorporating supplementary cementing materials (SCMs) using the rapid chloride permeability test. It presents test results that show incorporating SCMs like fly ash, silica fume, and metakaolin as partial replacements for cement in an M40 grade concrete mix can improve durability as measured by lower chloride ion permeability compared to conventional concrete without SCMs. The rapid chloride permeability test was performed on concrete specimens according to ASTM standards after 90 days of curing and the total charge passed through in coulombs was measured and used to determine the chloride permeability rating. Concrete mixes containing SCMs showed lower charge values, and therefore better durability ratings, than normal concrete without SCMs.
This document summarizes research on developing bacterial cellulose/chondroitin sulfate scaffolds for dental materials. Bacterial cellulose was produced with the addition of 1% chondroitin sulfate to the culture medium. Characterization with SEM, FTIR and XRD showed the chondroitin sulfate was incorporated and did not significantly alter the bacterial cellulose structure. The bacterial cellulose nanocomposites were also able to incorporate calcium phosphate when soaked in simulated body fluid, as seen with SEM, FTIR and XRD analysis. Future work will investigate cell adhesion and viability on the scaffolds.
STUDY OF THE EFFECT OF NANO SILICA ON THE SELF HEALING ABILITY OF HIGH STRENG...IAEME Publication
The aim of this study is analyzing the self-healing capability of high strength concrete (M70) with nano silica and crystalline admixture in three types of environmental exposures i.e. water immersion, wet/dry cycles and water contact. The percentage replacements of cement with nano silica were 1%, 2%, 3% with addition of 1.1% crystalline admixture. The specimens were pre-cracked at 28 days in the range of 0.10-0.40mm and the time set for healing was 42 days. The result shows that all the mixes have considerable amount of closing ability and strength regaining capacity for all exposure conditions. The concrete with 2% nano silica and 1.1% crystalline admixture (CA) has complete crack closing ability and strength regaining capacity for water immersion and wet/dry cycle conditions.
Curcumin extract nanoparticles: preparation, characterization and antimicrobi...Innspub Net
In recent years, synthesized zinc oxide nanoparticles have been increasingly investigated for different medicinal uses. In the present study, we aimed at the biosynthesis of zinc oxide using a curcumin extract. Although, toxic effects of curcumin derivative and zinc oxide nanoparticles in different concentration have been studied specifically on animal models besides the antibacterial activity of synthesized curcumin extract and zinc oxide nanoparticles. The aim of the study was to synthesize extract combined zinc oxide nanoparticles. Methods: The synthesized nanoparticles and extract were characterized for the particle size distribution, morphology, optical properties and surface charge by using UVvisible spectroscopy, dynamic light scattering (DLS), (TEM) and (SEM). Elemental composition and structural properties were studied by energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction spectroscopy (XRD). Results: The synthesized nanoparticles and curcumin were irregular shape and had a size distribution in the range of 50–100 nm. The in vitro toxicity effects of zinc oxide and extract showed no toxic effect with different concentration with antibacterial effect.
Effect of Nano-Tio2addition on Mechanical Properties of Concrete and Corrosio...IJERA Editor
Concrete science is a multidisciplinary area of research where nanotechnology potentially offers the opportunity to enhance the understanding of concrete behavior, to engineer its properties and to lower production and ecological cost of construction materials. The main objective of this research was to evaluate the effect of nanoTiO2on compressive strength,bond strength and corrosion behavior of reinforcement bars. It has been found that the compressive strength, bond strength and corrosion resistance was increased with increasing nano-TiO2to 1.5wt. % as replacement of cement. Beyond this value, these properties decrease.
The study investigated the cytocompatibility of various magnesium alloys with human urothelial cells (HUCs) in vitro. HUCs were cultured with magnesium alloy substrates for 24 and 48 hours. Cell density, substrate morphology, pH, magnesium ion concentration, and substrate mass were analyzed. The results showed that Mg_Y_O and Mg_Y_P alloys had the lowest cell densities, highest ion concentrations, and lowest mass ratios, indicating poorer cytocompatibility compared to other alloys. In contrast, AZ31_O, AZ31_P, Mg_O, and Mg_P maintained stable cell densities and masses, suggesting better cytocompatibility. The study provides initial
This document summarizes a study on the influence of curing regime on the strength development of grade C60 concrete. Concrete cubes were cured in water or ambient air and tested at various ages to determine compressive strength. Additional cubes were water cured for limited durations and then stored in air, and tested at 28 and 90 days. The results showed that cubes water cured for only 3 days reached the highest 28-day strength of 74.15N/mm2, while cubes water cured for 28 days reached the highest 90-day strength of 77.58N/mm2. Sorptivity and water absorption tests also indicated improved pore structure and reduced permeability with increased water curing duration.
SIMONA CAVALU_Bioactivity evaluation of new silver doped bone cementSimona Cavalu
This document summarizes a study that evaluated the bioactivity and antimicrobial properties of two types of silver-doped bone cement composites. Electrochemical measurements and SEM/FTIR analysis were used to analyze the composites after incubation in simulated body fluid for up to 14 days. The results showed that both composites released silver and calcium ions into the fluid over time. One composite released silver ions more rapidly initially but both developed a hydroxyapatite-like surface layer indicating bioactivity. The layer formed more intensely on the surface of the composite also containing antibiotics. The study demonstrates the antimicrobial activity and bone bonding properties of the silver-doped composites.
This document summarizes a study on the effect of cationization on the adsorption of silver nanoparticles on cotton surfaces and its antibacterial activity. The key findings are:
1) Cotton was cationized using CHPTAC to introduce quaternary ammonium groups, which increased the surface roughness and decreased crystallinity.
2) Cationized cotton adsorbed more silver nanoparticles from colloidal solutions compared to normal cotton when exposed using an exhaustion method.
3) Testing showed the cationized cotton with higher levels of adsorbed silver nanoparticles had greater antibacterial activity against E. coli bacteria.
Aligned and random nanofibrous nanocomposite scaffolds for bone tissue engine...Nanomedicine Journal (NMJ)
Abstract
Aligned and random nanocomposite nanofibrous scaffolds were electrospun from polycaprolactone (PCL), poly (vinyl alcohol) (PVA) and hydroxyapatite nanoparticles (nHA). The morphology and mechanical characteristics of the nanofibers were evaluated using scanning electron microscopy and tensile testing, respectively. Scanning electron microscopy revealed fibers with an average diameter of 123 ± 32 nm and 339 ± 107 nm for aligned and random nanofibers, respectively. The mechanical data indicated the higher tensile strength and elastic modulus of aligned nanofibers. The in vitro biocompatibility of aligned and random nanofibrous scaffolds was also assessed by growing mesenchymal stem cells (MSCs), and investigating the proliferation and alkaline phosphatase activity (ALP) on different nanofibrous scaffolds. Our findings showed that the alignment orientation of nanofibers enhanced the osteogenic differentiation of stem cells. The in vitro results showed that the aligned biocomposite nanofibrous scaffolds of PCL/nHA/PVA could be a potential substrate for tissue engineering applications, especially in the field of artificial bone implant.
This study investigated the effects of adding nano silica to fly ash concrete. Fly ash was partially replaced with cement at various percentages from 0-80%. Nano silica was then added at 2.5% of the cement weight. Corrosion resistance and flexural strength were evaluated. Test results showed that nano silica fly ash concrete had lower mass loss, smaller cracks, and higher strength compared to plain fly ash concrete. This indicates nano silica improves corrosion resistance and strength even when fly ash replaces cement. The optimal fly ash replacement was found to be 30-40% to maintain strength while nano silica helped compensate for strength loss from fly ash addition.
1. The study assessed the durability of coconut shell ash concrete in different conditions through various tests on mortar samples.
2. The tests included exposure to NaCl and MgSO4 solutions, wet-dry cycling, and submersion in saline water.
3. The results showed that the compressive strength and weight of the mortar samples generally decreased with higher percentages of coconut shell ash replacement and exposure to deteriorating environments, with more reduction observed with MgSO4 exposure.
4. However, up to 10% coconut shell ash replacement, the samples demonstrated good resistance in the different durability tests. Ultrasonic pulse velocity testing also indicated the concrete was homogeneous and compact up to 10% replacement
4 2010-fouling behavior of electroacidifed soy protein extracts during cross-...Bảo Dung Phan
This document discusses a study that used computational fluid dynamics (CFD) modeling and experimentation to examine membrane fouling during cross-flow ultrafiltration of soy protein extracts subjected to electroacidification. The study measured transient reversible (water removal) and irreversible (chemical removal) fouling resistances, permeate flux, protein concentration, and viscosity experimentally. A fouling resistance model describing the reversible and irreversible resistances was developed and used as a boundary condition when solving momentum and concentration equations with CFD. The CFD model estimates agreed well with experimental measurements and accurately predicted transient fouling resistances. The model showed significant axial variation of reversible fouling resistance and protein concentration at the membrane surface.
This document summarizes a research article that developed orally disintegrating tablets (ODTs) using microwave-assisted direct compression. Key points:
1) Placebo ODTs were prepared by direct compression followed by exposure to humidity and microwave irradiation. This simple process produced ODTs with hardness over 5 kg/cm2 and disintegration time under 60 seconds.
2) Lamotrigine (LMG) ODTs were then optimized using a 2^3 factorial design to achieve hardness over 5 kg/cm2, disintegration time under 30 seconds, and rapid drug dissolution. Beta-cyclodextrin was used to improve drug solubility.
3) Electronic tongue testing confirmed the optimized
1. The document studies the effect of chemical solutions on the mechanical and thermal properties of an epoxy resin composite reinforced with 1% and 3% nano aluminum oxide powder.
2. Test results showed that reinforcing the epoxy increased its flexural strength, Young's modulus, surface hardness, and thermal conductivity.
3. Immersing the composites in acid and base solutions for 9 weeks decreased the mechanical properties over time due to material degradation, while increasing the thermal conductivity. The acid solution had a greater impact than the base.
Critical Literature Review on Improvement of Concrete Properties by Bacterial...IRJET Journal
This document provides a literature review of research on improving concrete properties using bacterial solutions. It summarizes 15 previous studies that investigated how adding various bacteria like Bacillus pasteurii and Bacillus subtilis to concrete affects mechanical properties and durability. The studies found that bacterial concrete has higher compressive strength, flexural strength, elastic modulus, and lower water absorption and permeability compared to normal concrete. The bacteria are able to precipitate calcium carbonate in concrete cracks, potentially providing a self-healing effect. Bacterial solutions from 105-107 cells/ml were found to be most effective. Using fly ash or slag cement along with bacterial solutions can further enhance concrete properties. Overall, the literature demonstrates that bacterial solutions have potential to
This document discusses various social media platforms and how they are used to share different types of media content. It describes how Facebook, Instagram, Snapchat, and YouTube are primarily used to share photos and videos, with each having their own editing and sharing features. It also explains that YouTube, Soundcloud, and Myspace are commonly used to share music content like videos, audio recordings, and songs.
This document contains the resume of Peter Penklis applying for a role with the Queensland Department of Community Safety. It summarizes his extensive experience over nearly 30 years working in public, private, and community sectors, including roles in law, transportation management, and social services. It outlines his qualifications in law, case management experience, and skills in team leadership, conflict resolution, and customer service.
This document appears to be the portfolio of Kyle Malone, a branding and design professional. It includes examples of projects he worked on for various clients across different mediums including branding, print ads, radio, social media, and photography. The portfolio provides details on each project such as the client, dates, and collaborators. It aims to showcase Kyle Malone's work and experience in visual communication and branding.
This document discusses the debate around using crops for fuel versus food. It provides overviews of various biofuel crops like corn, soybeans, sugarcane, and algae. Corn ethanol production has increased significantly in the US, with over 30% of the corn crop now used for ethanol. The document also discusses myths around biofuels, noting that oil prices rather than corn prices are the main driver of increased food costs globally. Alternative crops and sources like switchgrass, palm oil, and seaweed are presented as more sustainable biofuel options.
Durability of standard concrete incorporatingiaemedu
The document discusses the durability of standard concrete incorporating supplementary cementing materials (SCMs) using the rapid chloride permeability test. It presents test results that show incorporating SCMs like fly ash, silica fume, and metakaolin as partial replacements for cement in an M40 grade concrete mix can improve durability as measured by lower chloride ion permeability compared to conventional concrete without SCMs. The rapid chloride permeability test was performed on concrete specimens according to ASTM standards after 90 days of curing and the total charge passed through in coulombs was measured and used to determine the chloride permeability rating. Concrete mixes containing SCMs showed lower charge values, and therefore better durability ratings, than normal concrete without SCMs.
This document summarizes research on developing bacterial cellulose/chondroitin sulfate scaffolds for dental materials. Bacterial cellulose was produced with the addition of 1% chondroitin sulfate to the culture medium. Characterization with SEM, FTIR and XRD showed the chondroitin sulfate was incorporated and did not significantly alter the bacterial cellulose structure. The bacterial cellulose nanocomposites were also able to incorporate calcium phosphate when soaked in simulated body fluid, as seen with SEM, FTIR and XRD analysis. Future work will investigate cell adhesion and viability on the scaffolds.
STUDY OF THE EFFECT OF NANO SILICA ON THE SELF HEALING ABILITY OF HIGH STRENG...IAEME Publication
The aim of this study is analyzing the self-healing capability of high strength concrete (M70) with nano silica and crystalline admixture in three types of environmental exposures i.e. water immersion, wet/dry cycles and water contact. The percentage replacements of cement with nano silica were 1%, 2%, 3% with addition of 1.1% crystalline admixture. The specimens were pre-cracked at 28 days in the range of 0.10-0.40mm and the time set for healing was 42 days. The result shows that all the mixes have considerable amount of closing ability and strength regaining capacity for all exposure conditions. The concrete with 2% nano silica and 1.1% crystalline admixture (CA) has complete crack closing ability and strength regaining capacity for water immersion and wet/dry cycle conditions.
Curcumin extract nanoparticles: preparation, characterization and antimicrobi...Innspub Net
In recent years, synthesized zinc oxide nanoparticles have been increasingly investigated for different medicinal uses. In the present study, we aimed at the biosynthesis of zinc oxide using a curcumin extract. Although, toxic effects of curcumin derivative and zinc oxide nanoparticles in different concentration have been studied specifically on animal models besides the antibacterial activity of synthesized curcumin extract and zinc oxide nanoparticles. The aim of the study was to synthesize extract combined zinc oxide nanoparticles. Methods: The synthesized nanoparticles and extract were characterized for the particle size distribution, morphology, optical properties and surface charge by using UVvisible spectroscopy, dynamic light scattering (DLS), (TEM) and (SEM). Elemental composition and structural properties were studied by energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction spectroscopy (XRD). Results: The synthesized nanoparticles and curcumin were irregular shape and had a size distribution in the range of 50–100 nm. The in vitro toxicity effects of zinc oxide and extract showed no toxic effect with different concentration with antibacterial effect.
Effect of Nano-Tio2addition on Mechanical Properties of Concrete and Corrosio...IJERA Editor
Concrete science is a multidisciplinary area of research where nanotechnology potentially offers the opportunity to enhance the understanding of concrete behavior, to engineer its properties and to lower production and ecological cost of construction materials. The main objective of this research was to evaluate the effect of nanoTiO2on compressive strength,bond strength and corrosion behavior of reinforcement bars. It has been found that the compressive strength, bond strength and corrosion resistance was increased with increasing nano-TiO2to 1.5wt. % as replacement of cement. Beyond this value, these properties decrease.
The study investigated the cytocompatibility of various magnesium alloys with human urothelial cells (HUCs) in vitro. HUCs were cultured with magnesium alloy substrates for 24 and 48 hours. Cell density, substrate morphology, pH, magnesium ion concentration, and substrate mass were analyzed. The results showed that Mg_Y_O and Mg_Y_P alloys had the lowest cell densities, highest ion concentrations, and lowest mass ratios, indicating poorer cytocompatibility compared to other alloys. In contrast, AZ31_O, AZ31_P, Mg_O, and Mg_P maintained stable cell densities and masses, suggesting better cytocompatibility. The study provides initial
This document summarizes a study on the influence of curing regime on the strength development of grade C60 concrete. Concrete cubes were cured in water or ambient air and tested at various ages to determine compressive strength. Additional cubes were water cured for limited durations and then stored in air, and tested at 28 and 90 days. The results showed that cubes water cured for only 3 days reached the highest 28-day strength of 74.15N/mm2, while cubes water cured for 28 days reached the highest 90-day strength of 77.58N/mm2. Sorptivity and water absorption tests also indicated improved pore structure and reduced permeability with increased water curing duration.
SIMONA CAVALU_Bioactivity evaluation of new silver doped bone cementSimona Cavalu
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Ijms 15-07639 solucion-celulascancer
1. Int. J. Mol. Sci. 2014, 15, 7639-7650; doi:10.3390/ijms15057639
OPEN ACCESS
International Journal of
Molecular Sciences
ISSN 1422-0067
www.mdpi.com/journal/ijms
Article
Optimization of Cell Adhesion on Mg Based Implant Materials
by Pre-Incubation under Cell Culture Conditions
Regine Willumeit *, Anneke Möhring and Frank Feyerabend
Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Str. 1, Geesthacht 21502,
Germany; E-Mails: anmo@tf.uni-kiel.de (A.M.); frank.feyerabend@hzg.de (F.F.)
* Author to whom correspondence should be addressed; E-Mail: regine.willumeit@hzg.de;
Tel.: +49-4152-87-1291; Fax: +49-4152-87-2666.
Received: 27 February 2014; in revised form: 20 March 2014 / Accepted: 16 April 2014 /
Published: 5 May 2014
Abstract: Magnesium based implants could revolutionize applications where orthopedic
implants such as nails, screws or bone plates are used because they are load bearing and
degrade over time. This prevents a second surgery to remove conventional implants.
To improve the biocompatibility we studied here if and for how long a pre-incubation of
the material under cell culture conditions is favorable for cell attachment and proliferation.
For two materials, Mg and Mg10Gd1Nd, we could show that 6 h pre-incubation are
already enough to form a natural protective layer suitable for cell culture.
Keywords: magnesium implants; natural corrosion protection; pre-incubation;
biocompatibility
1. Introduction
To make use of magnesium alloys as orthopedic biomaterial is an idea which has developed already
in the first half of the 20th century [1]. Mg is an essential element in life and about half of the 30 g
which can be found in the body is stored in bones [2]. The material is load bearing and the mechanical
properties tensile yield strength, fracture toughness or Young’s modulus [3] are more similar to those
of natural bone than polymers, ceramics implant materials or titanium (Ti) which remains the most
common and preferred implant material. Last but not least the metal is degrading which should have
several advantages over permanent implant materials [4,5]. However, due to their high degradation
rates accompanied by hydrogen (H2) release up to now only few implant prototypes are about to come
2. Int. J. Mol. Sci. 2014, 15 7640
for orthopedic [6] or cardiovascular [7,8] applications. The major problem remains the decrease of the
degradation rate to keep the stability of the implant and to reduce the ion release and H2 production to
a value the body can deal with [9].
There are several approaches to tailor the degradation rate. The first step is the use of alloying
elements (e.g., rare earth elements (REE [10,11], Ca, Y, Ag etc. [12])) accompanied by heat
treatments [13] or for example extrusion processes which change the microstructure and thus the
mechanical and corrosive properties. If this is still not enough coatings come into play. The principle
idea is to reduce the immediate corrosion to a level the body can cope with directly after implantation.
Over time also the coating should degrade offering the possibility for the underlying Mg material to
have access to the surrounding liquid which will then start the degradation process of the metal.
In the literature several approaches can be found (for an overview see [9,14–16]). The most often
used coating is based on calcium phosphates (for review see [17]). This is relative straight forward
because a material which is also found in the anorganic matrix of the bone is used as coating.
In addition under certain circumstances it is already a corrosion product of the degrading Mg
material [18–20]. The application of CaP coatings not only changes the surface chemistry and can be
influenced by the presence of chloride salts and proteins [21]. In addition, the micro- [22,23] or
nanostructure of the HA crystallites deposited on the surface can improve cell adhesion and reduce the
corrosion rate [24]. To improve the performance of the CaP coatings also composites with degradable
polymers were prepared [25,26].
Degradable (bio) polymers as such are also a useful approach to increase the resistance of the Mg
material against corrosion. They do not only hinder the immediate corrosion but can also influence
the long term behavior of the specimens [27]. In addition these layers can be chemically modified to
introduce specific properties or can be used as drug delivery systems [28].
A promising alternative to relatively thick polymer coatings can be the covalent binding of
proteins [29,30] or for example 3-amino-propyltrimethoxysilane [31] and the lipid head group
phosphatidylcholine (PC) [32] to activated Mg-alloy surfaces.
Protection layers can also be formed by a fluoride coating [33,34] or micro-arc oxidation
(MAO) [35,36]. Doping the surface with Nd by diffusion coating [37] or treating it with NaOH [38,39]
also reduces the corrosion rate.
The most straight forward approach however is to make use of the naturally formed protective layer
which is found after some immersion time (for example [40]) and also in vivo [41,42]. The formation
of this biomimetic coating was studied in several experiments. Mg specimens were either soaked at
37 °C in SBF for 5 days [43], in growth medium DMEM (without and with FBS) or pure FBS for 24 h
under cell culture conditions [44]. The results showed that in all cases the cell attachment and
proliferation rate was improved with respect to the untreated and thus faster degrading specimens.
The best results were obtained for the incubation in DMEM.
In this study, we systematically investigated which pre-incubation time gives the optimal results
with respect to cell adhesion, proliferation, corrosion rate and composition of the corrosion layer.
We used extruded material and elucidated pure Mg and the alloy Mg10Gd1Nd which have different
corrosion rates. All pre-incubation tests were performed in DMEM and under cell culture conditions
varying the exposure time between 30 min and three days.
3. Int. J. Mol. Sci. 2014, 15 7641
2. Results and Discussion
The aim of this study was to elucidate if a time dependent improvement of cell interaction
depending on varying pre-incubation times can be observed. Therefore specimens were pre-incubated
to form a natural corrosion and probably protective layer. Then the samples were washed, dried and
stored until the cell experiments were started. All specimens were incubated with Saos-2 cells for
30 min to achieve cell adhesion. Subsequently all specimens were then incubated for three further days
to be examined for the parameters corrosion rate, pH, osmolality, cell viability and shape as well as
element distribution on the surface. Thus the total immersion time varied from 72.5 h for untreated
specimen (non pre-incubation, only cell adhesion time + cell culture incubation) to 144.5 h after 3 days
of pre-incubation.
2.1. Determination of the Corrosion Rate, pH and Ssmolality
The corrosion rate of the two materials without pre-incubation and cells was determined to
0.81 ± 0.04 mm/year for Mg. For the alloy Mg10Gd1Nd this value is two third = 0.53 ± 0.08 mm/year.
This was decreased upon pre-incubation to values of 0.33 ± 0.02 and 0.35 ± 0.03 mm/year for Mg and
Mg10Gd1Nd (Figure 1A).
Figure 1. (A) Corrosion rate; (B) pH values and (C) osmolality determined after the
indicated pre-incubation time.
To determine the pH values the samples were first pre-incubated in cell culture medium for the
indicated duration. Then the specimens were washed, dried and then incubated with cells for 3 days
and the pH value at the end of this period was determined (Figure 1B). As it can be seen the pH is
increased above the physiological level to 8.6 and nearly the same for both materials when the
specimens were not pre-incubated. However, for pre-incubated specimens clear differences can be
seen for the materials. In the case of pure extruded Mg the pre-incubation has nearly no influence on
the pH observed. It is in all cases around 8.6 which is significantly higher than the pH-value of fresh,
pure Mc Coy’s medium which is between 6.9 and 7.1. For the Mg10Gd1Nd alloy a clear decrease in
pH depending on the pre-incubation time can be seen. This indicates the formation of a protective layer
which does not completely hinder the corrosion process.
The osmolality was measured in the supernatant which was also used for pH determination.
The results of this measurement are shown in Figure 1C. The measured osmolality of the supernatants
4. Int. J. Mol. Sci. 2014, 15 7642
is equal or lower than the cell culture medium which equals to 0.283 (±0.001, n = 6). Two trends can
be observed: the osmolality of the medium from the extruded Mg10Gd1Nd decreases with longer
pre-incubation time while the osmolality of the medium from pure magnesium increases with longer
pre-incubation times. During degradation of the material in the absence of cells normally an increase
of osmolality can be observed [45]. A drop in osmolality could indicates that the ion release from
the degrading material is lower than the consumption of ions by metabolically active cells and could be
used as an indirect measure of cell viability.
2.2. Determination of Cell Viability
The cells were cultivated for three days on the pre-incubated specimens. It can clearly be seen that
the cell viability is zero for specimens which did not experience a pre-incubation (Figure 2). However,
after only 2 h one can see the first positive effect. In general a pre-incubation of 6 h is enough to form
a surface which is favorable for cell adhesion and proliferation. Longer pre-incubation times optimize
this behavior but not in a way that would justify an increased experiment period, as the contamination
risk is increasing with time.
Figure 2. Life Dead Staining of Saos-2 cells incubated on two materials with varying
pre-incubation times.
2.3. Imaging with Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy
(EDX) Analysis
While in Figure 2 the viability of cells was imaged, with SEM the cell morphology can be seen in
detail (Figure 3). Comparable to the findings in Figure 2 well attached cells are found already after 6 h
of pre-incubation time.
The analysis of the corrosion layer surface by EDX (Figure 4) exhibits the increase of cell
attachment (carbon-mapping; C) after 72 h of pre-incubation time. In the case of the alloy the
pre-incubation leads to an exposure of the alloying elements. In addition the deposition of Ca and Na
coming from the incubation medium is visualized for a longer pre-incubation time. Interestingly P is
found already after the short pre-incubation time of 0.5 h. The co-precipitation of Ca and P indicates
the formation of calcium-phosphates. A further interesting observation is that there is a similar
distribution of Na and Nd, which could indicate that during the corrosion process new complex phases
could be formed. This could be e.g., the formation of Na7Mg13Nd(PO4)12, which was recently
5. Int. J. Mol. Sci. 2014, 15 7643
crystallized from a solution containing Na2CO3, MgCO3, Nd2O3, NH4H2PO4, [46] which are all
ingredients of cell culture medium (except for Nd, which is derived from the alloy).
Figure 3. SEM images of Saos-2 cells incubated on two materials with varying pre-incubation times.
2.4. Discussion of Results
In this study, we evaluated the optimal pre-incubation time in cell culture medium for pure Mg and
the alloy Mg10Gd1Nd. Both materials exhibit a corrosion rate below 1 mm/year which is in our
opinion the maximum corrosion rate suitable for proper in vivo application. However, even this low
corrosion rate might pose problems in in vitro experiments because already then gas formation and
increase of pH might prevent cell adhesion and proliferation. Therefore pre-incubation was applied to
create a natural corrosion protection layer. Our results show that already 6 h under cell culture
conditions are sufficient to form a protective layer suitable for cell experiments. Though the corrosion
rate is reduced by this layer formation it does not necessarily change the pH and osmolality values.
6. Int. J. Mol. Sci. 2014, 15 7644
This indicates that not the mere decrease in corrosion rate facilitates cell adhesion but that probably the
combination of reduced gas formation plus a change in surface chemistry and morphology supports
cell growth on the material. The results—in terms of cell adhesion and proliferation—are comparable
for both materials. This indicates that influence of alloying elements on the cells can be neglected at
least in the first few days of experiments.
A detailed study of the composition of the corrosion layer could shed light on the mechanisms of
corrosion in this very complex environment and might bridge the gap toward in vivo corrosion studies.
Figure 4. EDX element mapping of specimens with Saos-2 cells incubated on two
materials with varying pre-incubation times.
3. Experimental Section
3.1. Materials
Pure magnesium and Mg10Gd1Nd were cast in the Magnesium Innovation Center (MagIC) of the
Helmholtz-Zentrum Geesthacht by direct-chill casting. High-purity magnesium (99.94%) was obtained
from Magnesium Elektron (Manchester, UK). Pure Gd and Nd (99.5%) were obtained from Grirem
7. Int. J. Mol. Sci. 2014, 15 7645
(Beijing, China). The nominal amounts were added to the melt (750 °C) under a protective atmosphere
(Ar + 2% SF6, Linde, Hamburg, Germany), which was stirred at 200 rpm and then poured in
a preheated mold (550 °C). The cleanliness of the ingots was assured by using a filter (Foseco SIVEX
FC, Foseco, London, UK). Cylindrical ingots with a diameter of 12 cm and a length of 20 cm were
obtained. The materials were afterwards extruded in the Strangpresszentrum Berlin to rods with 12 mm
diameter and machined to round discs with dimensions of 10 × 1.5 mm. The average weight of the
specimens was approximately 0.2 g. They were used without further surface treatment.
Samples were disinfected in 70% ethanol (VWR International, Darmstadt, Germany) in an ultrasonic
bath for 20 min. Afterwards they were processed in parallel using standard 24 well plates (Cellstar,
Greiner Bio-one GmbH, Frickenhausen, Germany), with one sample per well. Pure Mg and
Mg10Gd1Nd discs were directly used (0 h) or immersed in 2 mL Mc Coy’s cell culture medium
(Mc Coy’s 5A Medium, Life Technologies, Darmstadt, Germany) supplemented with 10% FBS
(FBS Gold, PAA Laboratories, Linz, Austria) for 0.5, 2, 6, 16, 24, 48 h and under cell culture
conditions (37 °C, 21% O2, 5% CO2, 95% relative humidity). In each case n = 4 was chosen per alloy
and per pre-incubation time.
3.2. Determination of Corrosion Rate, pH and Osmolality
The corrosion rate was determined by weight loss. Each sample was weighed (Scaltec SBA52,
Scaltec Instruments GmbH, Göttingen, Germany), numbered and sterilized (again 20 min in ultrasonic
bath with ethanol) before pre-incubation (n = 3 per alloy and pre-incubation time). After pre-incubation
the samples were placed into a new agarose coated 12-well-plate and treated as described below with
cells. After three days of incubation under cell culture conditions the samples were taken from the
corrosion medium. To remove all corrosion residues from the samples they were immersed in chromic
acid (180 g/L in distilled water, VWR International, Darmstadt, Germany) for 10 min, turned and left
for another 10 min. Afterwards the samples were cleaned with distilled water and then with 100%
ethanol. When the samples were dried their weight was measured again and the corrosion rate (CR)
was calculated as follows [47]:
CR
8.76 104
W A t
A = surface area [cm2], t = time [h], ρ = density (Mg = 1.74; Mg10Gd1Nd = 1.90 [g/cm3]),
ΔW = mass loss [g].
After the final three days of incubation with cells on the pre-incubated specimens the cell culture
medium was removed from the wells and used for analysis of the pH-value and osmolality.
For measuring the pH-value the electrode was calibrated each time before using. Then the electrode was
dipped into the solution and left there until the value on the display of the measurement device was stable.
The osmolality of the supernatants was analyzed by cryoscopic osmometer (Osmomat 030-D,
Gonotec GmbH, Berlin, Germany). 60 μL of the supernatant were pipetted into a small cup (1 mL) and
put into the osmometer. The device is a freezing point osmometer which determines the osmolality by
measuring the freezing point. This goes down by 1.86 °C when 1 mole of a non ionic solute is added to
one kilogram of solvent [48].
8. Int. J. Mol. Sci. 2014, 15 7646
3.3. Determination of Cell Viability
The human osteosarcoma cell line Saos-2 was purchased from the European Collection of Cell
Cultures (ECACC, Salisbury, UK) and cultured under cell culture conditions.
After pre-incubation, the Mg samples were transferred into agarose pre-coated 12-well-plate
(one sample per well). The agarose-coating was applied by heating pre-sterilized agarose (1% w/v in a dest;
VWR International, Darmstadt, Germany) to about 80 °C and rapid filling and decanting of the wells.
This leads to a thin film of agarose throughout the well. For cell adhesion, Saos-2 cells were
trypsinized, centrifuged and afterwards resuspended in Mc Coy’s medium + 10% FBS to a concentration
of 1 × 106 cells per mL. Then 50 μL of the cell suspension were homogeneously applied onto each
sample. Samples were incubated for 30 min to allow the study of initial and fast adhesion. Then 2 mL
Mc Coy’s medium + 10% FBS was added in each well of the 12-well-plate followed by a further
incubation for three days under cell culture conditions.
Cell viability was assessed via a two-color fluorescence assay (Live/Dead Viability/Cytotoxicity
Kit, Life Technologies, Darmstadt, Germany). One sample per pre-incubation time was used for
live/dead staining. After removing the cell culture medium the sample was washed with phosphate
buffer solution (PBS, 137 mM NaCl, 2.7 mM KCl, 4.3 mM Na2HPO4, 1.4 mM KH2PO4, all chemicals
from VWR), then transferred to a new 12-well-plate and covered with the staining solution (2 μL
Calcein AM and 5 μL ethidiumhomidimer-1 in 5 mL PBS) and incubated for 20 min. Afterwards the
staining solution was replaced by PBS and samples were directly examined with a fluorescent
microscope (Eclipse Ti-S, Nikon, Düsseldorf, Germany). Living cells can be detected by using the
FITC-filter (Ex: 465–495 nm, Em: 515–555 nm, Mirror at 505 nm) as green areas, dead cells can be
observed by using the Texas Red-filter (Ex: 540–580 nm, Em: 600–660 nm, Mirror at 595 nm) as red
areas. The overlaying image was merged by the microscope software.
3.4. Imaging with Low-Voltage Scanning Electron Microscope (LVSEM) and Energy Dispersive X-ray
Spectroscopy (EDX) Analysis
To visualize magnesium samples covered with cells without the application of additional coatings
a special sample preparation was needed. After removing the cell culture medium the samples were
washed with PBS and put on a new 12-well-plate (one sample per well). All chemicals were supplied
by VWR International. 2.5% glutaraldehyde solution was loaded in each well and the plate was stored
overnight under the fume hood. On the next day samples were placed in a new plate and the
glutaraldehyde was replaced by 1% osmiumtetroxide for 30 min for lipid counterstaining [49].
Samples were again put into a new well to start the alcoholic row. At first 20% isopropanol was added
in each well so that the samples were completely covered. After one to two hours it was replaced by
40% isopropanol for another one to two hours. The same procedure was repeated with 60%, 80%, and
finally with 100% isopropanol followed by critical point drying (EM CPD030, Leica Mikrosysteme
Vertrieb GmbH, Wetzlar, Germany). During the procedure of critical point drying the isopropanol
contained in the cells was slowly and totally replaced by CO2 at 8 °C. Afterwards, temperature and
pressure were raised to the critical point of CO2, leading to water-free preparations. After drying
samples were transferred into a new 12-well-plate and stored in a drying cabinet. Cells on carriers were
9. Int. J. Mol. Sci. 2014, 15 7647
then visualised by low voltage mode in charge contrast at 1 keV, using the SEM in lens detector
(SEM Auriga, Carl Zeiss, Jena, Germany).
Additionally to the SEM an analysis with energy dispersive X-ray spectroscopy (EDX) was
performed (EDS; Apollo XP, EDAX, Ametek GmbH, Wiesbaden, Germany). The preparation of the
samples was done in the same way as for SEM. EDX-mapping of various elements (C, Na, Mg, Nd, Gd,
Ca, P) was done at an accelerating voltage of 8 keV with 120 μm aperture size at 200-fold magnification.
4. Conclusions
The natural protection layer which is formed already after 6 h of pre-incubation under cell culture
conditions is enough to improve cell adhesion and viability. This is—at least for Mg and Mg10Gd1Nd
studied here—independent of the material and its corrosion rate.
Acknowledgments
We wish to thank the colleagues from the MagIC, especially Norbert Hort and Karl-Ulrich Kainer,
for the provision of the materials and Bernhard Eltzschig for the preparation of the samples. We deeply
acknowledge the help of Bérengère Luthringer, Daniela Lange and Gabriele Salamon in the cell
experiments. Finally we are very grateful to Daniel Laipple who technically supported the SEM/EDX
analysis and Christine Selhuber-Unkel from the CAU Kiel for the intense discussion.
Author Contributions
A. M. performed the experiments as part of her BSc thesis, F. F. supervised her work in the
laboratory and gave advice for the experiments. R. W. was the main supervisor of the BSc thesis and
wrote the manuscript.
Conflicts of Interest
The authors declare no conflict of interest.
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