Question

For a compound, Agar diffusion test is used to evaluate:

• A. Mechanical strength
• B. Thermal conductivity
• C. Corrosion resistance
• D. Cytotoxicity

Hint:

Cytotoxicity = Cell Toxicity. The Agar diffusion test uses a gel barrier to see if escaping chemicals from an implant compound will kill or harm living cells underneath. It has nothing to do with mechanical or thermal testing.

Answer 1

The Correct Option is D

Concept: Before any newly engineered material or chemical compound can be introduced into clinical medical devices, it must undergo rigorous biocompatibility testing to evaluate potential toxicity at a cellular level.

Step 1: Understanding the design of the Agar Diffusion Test.
The agar diffusion assay is a well-established in vitro biocompatibility screening method. In this testing methodology:
• A monolayer of mammalian target cells (such as fibroblasts) is cultured evenly on a nutritive medium substrate.
• The cell layer is overlaid with a thin barrier layer of nutrient-rich agar gel gelled solid.
• The test sample compound or material is placed directly on top of the agar layer.

Step 2: Evaluating the outcome variable.
Leachable chemical elements or toxic compounds inside the test sample dissolve and diffuse downwards through the agar gel matrix toward the cell monolayer. If the diffusing substance is toxic to cells, it leaves a clear zone of dead or malformed cells directly underneath the sample site. By measuring the physical diameter of this cellular destruction zone (lysis zone), researchers evaluate the level of cytotoxicity (cellular toxicity) of the compound. This directly aligns with Option (D).