A simulated body fluid (SBF) is a solution with an ion concentration close to that of human

blood plasma Blood plasma is a light amber-colored liquid component of blood in which blood cells are absent, but contains proteins and other constituents of whole blood in suspension. It makes up about 55% of the body's total blood volume. It is the intra ...

, kept under mild conditions of pH and identical physiological temperature. SBF was first introduced by Kokubo et al. in order to evaluate the changes on a surface of a bioactive glass ceramic. Later, cell culture media (such as DMEM, MEM, α-MEM, etc.), in combination with some methodologies adopted in

cell culture Cell culture or tissue culture is the process by which cells are grown under controlled conditions, generally outside of their natural environment. The term "tissue culture" was coined by American pathologist Montrose Thomas Burrows. This te ...

, were proposed as an alternative to conventional SBF in assessing the bioactivity of materials.

Applications

Surface modification of metallic implants

For an artificial material to bond to living bone, the formation of bonelike

apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH−, F− and Cl− ions, respectively, in the crystal. The formula of the admixture of the three most common e ...

layer on the surface of an implant is of significant importance. The SBF can be used as an

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...

testing method to study the formation of apatite layer on the surface of implants so as to predict their

in vivo Studies that are ''in vivo'' (Latin for "within the living"; often not italicized in English) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and ...

bone bioactivity. The consumption of calcium and phosphate ions, present in the SBF solution, results in the spontaneous growth of bone-like apatite nuclei on the surface of biomaterials in vitro. Therefore, the apatite formation on the surface of biomaterials, soaked in the SBF solution, is considered a successful development of novel bioactive materials. The SBF technique for surface modification of metallic implants is usually a time-consuming process, and obtaining uniform apatite layers on substrates takes at least 7 days, with daily refreshing of the SBF solution. Another approach for decreasing the coating time is to concentrate the calcium and phosphate ions in the SBF solution. Enhanced concentration of calcium and phosphate ions in SBF solution accelerates the coating process and, in the meantime, eliminates the need for regular replenishment of the SBF solution.

Gene delivery

An attempt was made to investigate the application of SBF in gene delivery.

Calcium phosphate The term calcium phosphate refers to a family of materials and minerals containing calcium ions (Ca2+) together with inorganic phosphate anions. Some so-called calcium phosphates contain oxide and hydroxide as well. Calcium phosphates are white ...

nanoparticles, required for the delivery of

plasmid A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; how ...

DNA (pDNA) into the nucleus of the cells, were synthesized in a SBF solution and mixed with pDNA. The ''in vitro'' studies showed higher gene delivery efficiency for the calcium-phosphate/DNA complexes made of SBF solution than for the complexes prepared in pure water (as control).

Formulation

References

{{reflist Body fluids Gene delivery