Detecting proteins

By Biplab Das
Published: Thursday 30 April 2009

Linked to diseases like Alzheimer's made easy

diagnosing diseases requires cumbersome biochemical processes which are very time-consuming. A research team has employed a class of semiconducting nanocrystals called quantum dots (containing microscopic amounts of the semiconductor material) to detect the concentration of proteins in blood samples. Levels of certain proteins increase during diseases like Alzheimer's and Huntington's. A quick detection of these proteins is what this research promises.

The team had earlier studied how amino acids and dna bases interact with semiconducting nanoparticles. For the present study, they took quantum dots of cadmium telluride and the enzyme glucose oxidase (gox) which plays a major role in glucose metabolism. The nanocrystals were capped with the amino acid cysteine to make them biocompatible.

The researchers prepared solutions of gox and the nanocrystals and studied their interaction under ultraviolet light. Every protein has the amino acid tryptophan that absorb and emit light or, in other words, fluoresce. The nanocrystals were found to bind with tryptophan in gox and reduce its intensity. This reduction in fluorescence is protein-specific and can be measured to reveal the proteins' identity and, in turn, the diseases associated with them. For the test, samples of blood or cerebrospinal fluid can be used.

"This method paves the way for developing nanoparticle-based sensors for detection of enzymatic activity," said lead researcher Abhijit Saha who led a team from ugc-dae Consortium for Scientific Research, Kolkata and department of chemistry, Jadavpur University. The findings were published in the March issue of Photochemical and Photobiological Sciences (Vol 8, No 3).

Subscribe to Daily Newsletter :

Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.