Despite the growing relevance of 3D cell culture as a research model, imaging techniques used to characterize these models are highly limited. Due to the thickness and opacity of 3D cellular structures, most current imaging technologies cannot penetrate to the center of the tissues, resulting in only the outer 2 to 3 layers of cells being detected. This causes the dark centers often seen in images of 3D cell culture models, which proves highly problematic for accurate analysis as these outer cells are most exposed to compounds, nutrients and oxygen and thus do not reflect the entire cell population.

Growth Promotion and Cytotoxicity Corning classical media products undergo a variety of tests to determine functionality and toxicity using growth-promotion analysis. Product performance is measured by harvest-to-plant ratios or fold increase according to predetermined specifications.

Physiochemical Properties Liquid and powder classical media products are tested to determine pH and osmolality. Classical media powders are also tested for residual moisture. The pH and osmolality tests are performed according to specific procedures in which all equipment is calibrated using standards traceable to the National Institute of Standards and Technology.

Biological Tests Quality release testing of Corning liquid classical media products assures low levels of endotoxin, mycoplasma, and an absence of contamination.

Endotoxin Classical media products are tested for bacterial endotoxin using the Limulus Amoebocyte Lysate (LAL) chromogenic assay. For release, each lot of standard liquid classical media must have an endotoxin level of <0.25 EU/mL. Classical media powder products must have an endotoxin level of <0.25 EU/mL when reconstituted to formula weight with low endotoxin water.

Sterility All Corning liquid classical media products are tested for sterility.

Mycoplasma Liquid classical media products are tested for mycoplasma using a large-volume method.