**2.3 Nutrient (solutions and LB agar)**

The microorganisms used to carry out the experiments were grown in an aqueous culture medium Luria Broth (LB). Recommendation of the culture medium LB was NaCl 0.5% w/v, tryptone 1% w/v, and yeast extract 0.5% w/v. In a Petri dish, nutrient material is placed in which the cells of the microorganisms of the experiments grow. The composition of the nutrient is agar (gel agent) 1.5 g, NaCl (electrolyte) 0.5 g, tryptone (source of proteins and nitrogen) 0.5 g, fungal extract (source of metals and carbohydrates) 0.3 g and distilled water 100 ml. Each dish is partially filled with warm LB agar containing a mixture of substances described in the table above. The investigation of cell vitality is a characteristic indicator and a necessary condition in cases of cytotoxic action of polymer microspheres where they will be used in materials that will come into direct contact with humans. It is performed by identifying vital cell functions. Cell vitality refers to the percentage of healthy cells in a culture. This indicator, by definition unclear, is usually determined by controlling vital functions such as cell metabolic activity (MTT).
