The Comet Assay was first developed in the 1980’s by Ostling and Johanson and by Singh. Since then, over 14,000 publications include the comet assay.


The original comet assay involved a glass slide for each condition and individual imaging of each of 100 comets per condition, one by one.


To overcome the limitations of the standard comet assay, the CometChip® was created. 


The CometChip® overcomes a variety of technical challenges by creating a mammalian cell array in agarose. This is accomplished by creating tiny wells in agarose, roughly the diameter of a single cell, and then loading cells by gravity. Once in the array, the cells are treated using methods that are similar to the traditional assay, yielding results that are consistent with the traditional approach of gels on microscope slides.

Hands on process: The CometChip® is agarose bound to plastic that is attached to a glass slide. The agarose has thousands of microwells and encompasses the size of a 96 well plate. The CometChip® is handled using the CometChip® Device, which separates the area into 96 wells and allows for sample handling. The steps are:

  1. Place the CometChip® into the CometChip® Device. Use the key to slowly lower the lid onto the CometChip®.

  2. Add a solution of cells into each 96 well.

  3. Let cells load into the microwells by gravity. Remove the lid and remove off-grid cells by sheer force.

  4. Trap cells using low melting point agarose.

  5. Return the CometChip® to the device. Expose cells to varied conditions.

  6. Move the CometChip® to lysis buffer. Move to high pH buffer and perform electrophoresis. Stain with SyberGold and image using CometChip® software.

The Alkaline Comet Assay is best for detecting single strand breaks, and with modifications, can be used to detect damage bases and crosslinks. The Neutral Comet Assay is best for detecting double strand breaks.

Advantages of the CometChip® include: