Nanotech News

September 6, 2005

Gold Nanoparticles Help Study Cancer Drug Resistance Pump

Multiple drug resistance (MDR) is a major factor limiting the effectiveness of chemotherapy. Indeed, research has shown that tumor cells can develop the ability to produce a membrane-bound protein, known as P-glycoprotein, that can quickly pump chemotherapy drugs out of a tumor cell. Now, a team of investigators at Nanjing University in China and the University of South Florida has used gold nanoparticles to develop a quick and sensitive method for identifying P-glycoprotein on the surfaces of cancer cells. Having a quick and easy assay to determine if tumor cells have P-glycoprotein on their surfaces could provide clinicians with crucial information to help refine how they treat cancer patients.

Writing in the journal Biochemistry, Hongyuan Chen, Ph.D., and his colleagues in China and Florida describe how they constructed a nanoparticle-based electrochemical detector that can quantify how many cells with P-glycoprotein bind to the electrode. A standard glass electrode is first coated with chitosan, a complex sugar obtained from crab and shrimp shells, and then with gold nanoparticles. The gold nanoparticles provide a electrically conductive surface upon which cancer cells can stick without damaging the cells. The cancer cells can be taken from a patient and suspended in a suitable growth solution.

After cells are allowed to bind to the electrode, two monoclonal antibodies are added to the assay solution. The first antibody binds to P-glycoprotein, while the second causes an electrochemical reaction to occur only if the first antibody has bound to any P-glycoprotein. The electrochemical reaction triggers an electrical signal that the gold nanoparticles are able to detect and amplify. The intensity of the signal is proportional to the number of cells with P-glycoprotein present on their surfaces.

This work is detailed in a paper titled, “Electrochemical Immunoassay of Membrane P-glycoprotein by Immobilization of Cells on Gold Nanoparticles Modified on a Methoxysilyl-Terminated Butyrylchitosan Matrix.” This paper was posted online in advance of print publication. An abstract is available at the journal’s website.
View abstract.