Colorectal cancer cell detection by chitosan nanoparticles conjugated with folic acid

Endoscopy is a common diagnosis device 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 intestine and can accumulate in the pits and crevices of the mucosa to enhance the identification of the lesion. But this color contrast dye does not have target-specific property. Due to the reason we modified chitosan conjugated with target-specific ligand, such as folic acid, and used this polymer to prepare chitosan nanoparticles (fCN) by ionic gelation method. Then fCN loaded with indigo carmine (fCNIC) by the same method. The size and zeta potential of fCN and fCNIC were measured by transmission electron microscope and zetasizer, respectively. fCN and fCNIC were both at the range of 120-140 nm in size, 20 mV in zeta potential. The loading efficiency of indigo carmine in fCNIC was in the range of 60%-70% depending on the concentration of acetic acid and conjugated ratio of folic acid. Bioassy results of fCNIC adhesion on HT-29 colon cancer cell revealed that the quantity of particles, which adhered onto cells increased with incubation time, and the higher conjugated ratio of folic acid particles had better adhesion effect. These results implied that fCNIC could serves as an ideal vector of colon-specific targeting system. According to this concept, we designed a novel detection system to enhance the accuracy of endoscopic diagnosis for colorectal cancer.