A Novel Detection of Early Colorectal Cancer by Chitosan Nanoparticles Conjugated with Folic Acid

Photodynamic medicine is a novel approach for cancer detection and treatment via different photosensitizers and suitable light source. The 5-Aminolevulinic acid (5-ALA) can be converted into protoporphyrin IX (PpIX), and in cancer cells which serves as a fluorescent probe for tumor detection. In this study, folic acid was conjugated onto chitosan molecules via covalent bond for specific target, then 5-ALA was encapsulated in chitosan nanoparticles to prevent the uptake by E. coli. Chitosan nanoparticles (CN) and folic acid conjugated chitosan nanoparticles (fCN) were prepared by ionic gelation. Then the nanoparticles loaded with 5-ALA (CNA and fCNA) were prepared by the same method. The size and zeta potential of nanoparticles were measured by transmission electron microscope and zetasizer, respectively. The particle size was at the range of 90-110 nm and the loading efficiency of 5-ALA was at the range of 80%-90% depending on the concentration of 5-ALA prepared and the percentage of amino groups left in chitosan. Bioassy results of CNA and fCNA for HT-29 colon cancer cell uptake revealed that HT-29 colon cancer cells could uptake CNA and fCNA, and the content of PpIX converted from 5-ALA depended on the modified percentage. This result implied that fCNA could exclude the influence of normal flora inside the gut and serves as an ideal vector of colon-specific drug delivery system. According to this concept, we designed a novel photodynamic detection system to enhance the accuracy of endoscopic diagnosis for early colorectal cancer.