Express cancer diagnosis: lure telomerase for gold
Gold for the diagnosis of tumor diseasesChemPort.Ru based on the materials of the Royal Society of Chemistry:
Cancer diagnosis goes for goldResearchers from China claim that gold nanoparticles can be useful in the diagnosis of a wide variety of tumor diseases by determining the intracellular activity of telomerase.
Telomerase is an enzyme that promotes the elongation of the terminal fragments of chromosomes – telomeres, due to the binding of short nucleotide chains to them. Telomeres The purpose of telomeres is to ensure the process of DNA replication during cell division, during this process telomeres are consumed. After the telomeres are consumed, the DNA of the cell loses its ability to replicate until telomerase promotes telomere expansion.
Usually, only a small number of cells in the human body are capable of expressing telomerase, so the vast majority of cells are unable to reproduce independently. However, the degeneration of a cell into a tumor leads to the fact that it begins to produce telomerase, as a result of which uncontrolled cell division begins.
The fact that telomerase is produced by cells of at least 85% of known types of malignant tumor diseases makes it possible to use telomerase as a general biomarker of tumors, however, currently existing methods for quantifying telomerase are characterized by low accuracy and sensitivity, require significant material and time costs.
Chemists from the Chinese Academy of Sciences, who worked under the leadership of Xiaogang Qu, decided to develop a new telomerase detection system based on the fact that gold nanoparticles are characterized by fluorescent properties, while the color of fluorescent radiation depends on the degree of their aggregation in solution.
The degree of aggregation depends on a number of factors – an increase in the concentration of salt in the solution stimulates the formation of aggregates, while molecules that bind to the surface of nanoparticles, in some cases, can interfere with aggregation.
Researchers from the Qu group applied a synthetic version of telomeres to the surface of nanoparticles, capable of lengthening as a result of the catalytic action of telomerase. Placing these gold nanoparticles in a saline solution led to the aggregation of particles and the transition from red to blue fluorescence. However, if modified gold nanoparticles come into contact with telomerase before being placed in a salt solution, an increase in the volume of telomeres prevents the aggregation of nanoparticles, and at the same time the red color of fluorescence remains.
Researchers have demonstrated that telomerase formed by only ten cancer cells causes changes in fluorescence that can be observed with the naked eye; using the spectrophotometry method, it is possible to detect telomerase expressed by a single tumor cell. This sensitivity significantly exceeds the sensitivity of existing methods for determining telomerase. Another advantage of the new system is its speed – the detection of telomerase by the new method is carried out in 10 minutes (it took several hours to determine telomerase by existing methods).
Article by Wang et al. Visualizing Human Telomerase Activity with Primer-Modified Au Nanoparticles is published in the journal Small.
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28.11.2011