Methods In Simulated Body Fluid Research Articles

Developing micro-lamellar composites of magnesium-calcium deficient nanohydroxyapatite by powder metallurgy route: in vitro degradation studies

ABSTRACT In the present work, magnesium-calcium deficient nano hydroxyapatite (Mg-CDHA) lamellar composites with 5, 10 and 15 wt. % CDHA of crystallite size 32 nm were produced by ball milling and sintering. The Mg laminas were uniformly covered with CDHA crystals after 20 h of milling as confirmed by transmission electron microscopy. Enhanced biomineralisation was confirmed from X-ray diffraction method for the composites after 72 h of immersion in simulated body fluid (SBF). Degradation studies carried out by weight loss method and electrochemical tests in SBF clearly indicated the increased corrosion resistance for the composites with 10%HA compared to other combinations. The corrosion current values were observed as decreased (1.98 × 10−5 µA/cm2) for Mg-10%HA compared with other composites and pure Mg. Micro-lamellar structure and the deposited mineral phases from the simulated body fluids made the composite with 10% HA as optimum for biodegradable medical scaffold applications.

Electrochemical Corrosion and In vitro Biocompatibility Performance of AZ31Mg/Al2O3 Nanocomposite in Simulated Body Fluid

In this present investigation, AZ31 alloy nanocomposite was prepared with the inclusion of Al2O3 nanoparticles using innovative disintegrated melt deposition (DMD) process followed by hot extrusion to improve the corrosion resistance and in vitro biocompatibility in simulated body fluid (SBF). This investigation systematically inspected the degradation performances of AZ31 alloy with Al2O3 nanoparticles through hydrogen evolution, weight loss and electrochemical methods in SBF. Further, the surface microstructure with the in vitro mineralization of the alloys in SBF was characterized by XRD, XPS, and SEM/EDS analysis. It was seen that the addition of Al2O3 nanoparticles significantly decreased the weight loss of AZ31 alloy substrates after 336 h of exposure in SBF. The corrosion resistance of the monolithic and nanocomposite samples was evaluated using potentiodynamic polarization tests, electrochemical impedance spectroscopy measurements in short- and long-term periods. Accordingly, the electrochemical analysis in SBF showed that the corrosion resistance performance of the AZ31 alloy enhanced considerably due to the incorporation of Al2O3 nanoparticles as reinforcement. Moreover, the rapid formation of bone-like apatite layer on the surface of the nanocomposite substrate demonstrated a good bioactivity of the nanocomposite samples in SBF.

Calcium phosphate deposition rate, structure and osteoconductivity on electrospun poly(l-lactic acid) matrix using electrodeposition or simulated body fluid incubation

Mineralized nanofibrous scaffolds have been proposed as promising scaffolds for bone regeneration due to their ability to mimic both nanoscale architecture and chemical composition of natural bone extracellular matrix. In this study, a novel electrodeposition method was compared with an extensively explored simulated body fluid (SBF) incubation method in terms of the deposition rate, chemical composition and morphology of calcium phosphate formed on electrospun fibrous thin matrices with a fiber diameter in the range ∼200–1400nm prepared using 6, 8, 10 and 12wt.% poly(l-lactic acid) (PLLA) solutions in a mixture of dichloromethane and acetone (2:1 in volume). The effects of the surface modification using the two mineralization techniques on osteoblastic cell (MC3T3-E1) proliferation and differentiation were also examined. It was found that electrodeposition was two to three orders of magnitude faster than the SBF method in mineralizing the fibrous matrices, reducing the mineralization time from ∼2weeks to 1h to achieve the same amounts of mineralization. The mineralization rate also varied with the fiber diameter but in opposite directions between the two mineralization methods. As a general trend, the increase of fiber diameter resulted in a faster mineralization rate for the electrodeposition method but a slower mineralization rate for the SBF incubation method. Using the electrodeposition method, one can control the chemical composition and morphology of the calcium phosphate by varying the electric deposition potential and electrolyte temperature to tune the mixture of dicalcium phosphate dihydrate and hydroxyapatite (HAp). Using the SBF method, one can only obtain a low crystallinity HAp. The mineralized electrospun PLLA fibrous matrices from either method similarly facilitate the proliferation and osteogenic differentiation of preosteoblastic MC3T3-E1 cells as compared to neat PLLA matrices. Therefore, the electrodeposition method can be utilized as a fast and versatile technique to fabricate mineralized nanofibrous scaffolds for bone tissue engineering.

Determination of rat and mice arylesterase activity using serum mimetics

The paraoxonase (PON1) enzyme exhibits several enzymatic activities, including an arylesterase activity, and it is thought to inhibit lipoprotein peroxidation and facilitate reverse cholesterol transport. Reduced arylesterase activity has been associated with several chronic diseases including hypercholesterolemia. An accurate and reproducible determination of arylesterase activity may be useful for predicting the risk of cardiovascular disease. We present a new method to measure serum arylesterase activities in rat and mouse serum activity using a simulated body fluid (SBF). To validate the SBF method in rodents, arylesterase activity was measured in 20 mice (age 6–18 months) and 20 rats, 10 of which were hypercholesterolemic. When compared with the reference Tris/HCl method, the linearity range of arylesterase activity was higher using SBF indicating its potential use in a larger concentration interval. Furthermore, the measurements differed markedly in samples with very low arylesterase activity due to the tendency of the Tris/HCl method to overestimate arylesterase activity in the low range. The ionic environment in SBF, which is physiologically related to serum, is likely to contribute to the improved measurement of arylesterase activity.

Modifying the properties of titanium surface with the aim of improving its bioactivity and corrosion resistance

The paper presents the results of examinations of how the oxidation of titanium in a solution containing calcium and phosphorus ions affects the corrosion resistance and bioactivity of titanium. Prior to examination, the samples were exposed in the simulated body fluid (SBF) at the temperature of 37 °C for 13 and 1000 h. Then the corrosion resistance was examined by electrochemical methods in SBF at a temperature of 37 °C. The chemical composition of the surface layers was determined by photoelectron spectroscopy (XPS). The examinations have shown that after the oxidation the corrosion resistance increases. After long-term exposures, calcium phosphates were found on the sample surface, and their amount was bigger on the oxidised surfaces.