50

nanotimes News in Brief Cancer Research //

The Synergistic Effect of Capture Agents and Nanostructures © Based on Material by RIKEN Advanced Science Institute

12-02 :: February/March 2012

R

esearch led by scientists at the RIKEN Advanced Science Institute in Wako, in collaboration with

colleagues at the University of California, Los An- geles, and the Institute of Chemistry at the Chinese Academy of Sciences, Beijing, has produced a po- lymer film that can capture specific circulating tumor cells (CTCs). With further development, the system could help doctors to diagnose an advancing cancer and assess the effectiveness of treatments.

The researchers used a small electrical voltage to help deposit a conducting polymer film of poly(3,4- ethylenedioxythiophene) (PEDOT) bearing carboxylic acid groups on to a 2-centimeter-square glass base (Fig. 1). The polymer formed nanodots, tiny bumps that measure 100 to 300nm across, depending on the voltage used (1–1.4 V).

Adding a chemical linker to the film allowed it to bind a protein called streptavidin; this protein then joined to an antibody. In turn, the antibody could latch on to an antigen called epithelial cell adhesion molecule (EpCAM), which is produced by most tu- mor cells. In this way, the film could grab tumor cells from just a few milliliters of a blood sample.

The team tested several types of tumor cells on films with various sizes and densities of nanodots,

The polymer film forms nanodots: tiny bumps that can be functionalized with antibodies to grab passing cancer cells. © WILEY-VHC

and used a microscope to observe how well they captured the cells. The most effective film, with nanodots measuring about 230nm across and contai- ning about 8 dots per square micrometer, captured roughly 240 breast-cancer cells per square millimeter of film. In contrast, it caught fewer than 30 cervical cancer cells that do not express EpCAM, proving that the antibody used on the film is highly selective. A smooth PEDOT-carboxylic acid film with the same antibody captured only 50 or so breast cancer cells.

The film’s efficiency depends on the size and spacing of the nanodots, and the presence of the capturing antibody. Since these can be easily modified, the same method could be used to make films that sense