**2.5 Cell cultures**

The type of cells that covered the needs of this work are THE-293. They're human cells of fetal tissue. For their maintenance they contain adenovirus and therefore their management must be very careful. They are used for efficacy tests, host contamination tests and iodide tests [2]. Their development conditions depend on the specific characteristics of the cells. Cell culture materials consist of a nutrient cell growth solution DMEM (Dulbecco's Modified Eagle Medium) enriched with 2 mM glutamine, 0.85 g/L NaHCO3, 25 mM HEPES, 10% FBS (Fetal Bovine Serum), 6.8 < pH < 7.2. 0.2% w/v streptomycin, 2 × 103 U/mL penicillin, in PBS (1×) and cell separation solution (0.02% EDTA-thrypsin). Cell culture is suspended with fresh nutrient solution, at a final concentration of 2–4 × 105 cells/mL, and maintained at 37°C, removal of nutrients from cultivation, addition of cell separation solution (4 mL/bottle 75 mL) and incubation at 37°C for 4 min, removal of the solution, re-addition of 0.4 mL of cell separation solution and incubation at 37 <sup>ο</sup> C for 15–20 min, in order to detach the liver and separate the cells and add a DMEM nutrient solution and cell growth at 37 <sup>ο</sup> C. Cell lines can undergo uncontrolled changes related to their morphology, growth, vitality, and karyotype due to prolonged recultures or any unfortunate infections. This risk is avoided by creating a renewable cell bank, after cooling the cells and keeping them in liquid nitrogen for long periods of time (years). Cooling is led to cells that are in a logarithmic phase of growth or are close to filling a single carpet. The methodology followed is (a) cell implantation at a concentration of 4 × 105 cells/mL, (b) at 48 h, where the cells are at the completion of the logarithmic growth phase; detachment and centrifugation at 1000 rpm for 5 min, (c) re-dissolution of cells in DMEM in the presence of 10% DMSO in FBS (cryoprotective substance), at a final concentration of 4 × 106–10 × 106 cells/ mL (depending on the cell line), (d) transfer to ampoules which are then gradually placed in a freezer; so as to avoid the creation of crystals inside the cells and therefore cellular solution, and (e) finally is placed in a cell retention device (−196 °C, liquid nitrogen) for several years. The restoration of cells stored in liquid nitrogen into current culture (36.5–37°C) is carried out by quickly defrosting the ampoule sample at 37°C (avoid denaturing the protein content of the cell). Centrifuge to remove cold protective material (DMSO) from cultivation. Rapid removal of DMSO is particularly important because it acts as an inhibitor in the development of cell proliferation and in some cases triggers differentiation, apoptosis, or even necrosis; depending on the cell type, redialysis of cells in nutrient solution and growth of crops at 37°C, frequent cell recultures at the beginning are necessary, to fully restore the normal growth rate of the crop. Infectious environmental factors, the most common of which are fungi and bacteria, are often an obstacle to maintaining an in vitro cell culture. For this reason, all cell cultures are handled within a nematically flow chamber in order to achieve sterile conditions for the cells. Sterilization of the cell area is achieved on a daily basis by exposure to ultraviolet radiation for at least 15 minutes, while ethanol solution (70% v/v) is used for local sterilization of the site. The materials used are sterilized in a special liquid sterilization furnace (automatically) at 120°C and pressure 1 kp/cm2 for 20 minutes.

*Self-Healing of Concrete through Ceramic Nanocontainers Loaded with Corrosion Inhibitors… DOI: http://dx.doi.org/10.5772/intechopen.93514*
