Difference between Radioactive and Nonradioactive Probes

Hybridisation probes are strands of DNA or RNA (15-10000 bp long) that are used to analyse nucleotide sequences complementary to them in a pool of sequences. These probes are helpful in a number of techniques such as blotting, microarray and other hybridisation methods.

The probes are labelled for easy detection. On the basis of labels, there are two types of probes: Radioactive probes and Nonradioactive probes.

Radioactive probes are labelled with the radioactive isotopes of sulphur, phosphorus or nitrogen for detection. Nonradioactive probes are the ones that are labelled with chemical tags or fluorescent molecules such as biotin, fluorescein and digoxigenin.

The labelled probes are hybridised with the target nucleic acid sequences, and the transcript with the most similarity is detected by autoradiography and other imaging techniques.

Radioactive Probes

Non-radioactive Probes


Radioactive probes are DNA or RNA sequences that are labelled with radioactive isotopes.

Nonradioactive isotopes are DNA or RNA sequences that are labelled with chemicals or fluorescent tags.

Hazardous Material

The radioactive isotopes used are hazardous to humans as well as the environment.

It does not use any hazardous material.

Half Life

The radioactive isotopes have a shorter half life, and therefore the experiment has to be conducted rapidly.

No hassle of half life in these probes.


No such advantages.

  • It is safer.
  • The detection time is less.
  • The probe is more stable.


  • It is not safe.
  • It is costly.
  • Their disposal is tedious.

No such disadvantage.

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Also Read:

Frequently Asked Questions on Difference between Radioactive and Nonradioactive Probes


What kind of probe is used in Southern blotting?

DNA probes labelled with radioactive or chemical tags are used in Southern blotting.


How are radioactive probes useful in DNA fingerprinting?

The radioactive probes bind to specific DNA fragments that have been separated by gel electrophoresis.


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