COLORECTAL CANCER CELL DETECTION BY FOLIC ACID-CONJUGATED CHITOSAN NANOPARTICLES

The endoscopy is a common diagnosis method for the detection of colorectal cancer and there are two methods to improve the diagnostic sensitivity. One is chromoendoscopy, and the other is magnifying endoscopy. Color contrast dye, such as indigo carmine, usually is sprayed on the surface of the intestine and can accumulate in the pits and crevices of the mucosa to enhance the identification of the lesion. However, this color contrast dye does not have target-specific and local-retention properties. For these reasons we encapsulated indigo carmine into chitosan nanoparticles (CNIC) by the ionic gelation to increase the retention time on intestine surface, and conjugated folic acid with chitosan nanoparticles (fCNIC) to target specifically adenomatous polyps. The size and zeta potential of CNIC and fCNIC measured by transmission electron microscope and zetasizer were both at the range of 120-140 nm and 20mV respectively. The loading efficiency of indigo carmine in fCNIC was in the range of 60-70% and depended on the concentration of acetic acid solution used to dissolve chitosan and folic acid-chitosan conjugates and folic acid conjugation percentage. Bioassy results of fCNIC targeting to HT-29 colon cancer cells revealed that the prepared particle with high folic acid conjugation had a better adhesion effect. These results implied that fCNIC with high folic acid conjugation could serve as an ideal vector for a colon-specific targeting system. According to this concept, we designed a novel detection system to enhance the accuracy of endoscopic diagnosis for colorectal cancer.