Quantifying folic acid-functionalized multi-walled carbon nanotubes bound to colorectal cancer cells for improved photothermal ablation
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Peritoneal metastases of colorectal cancer are a significant challenge in the field of medicine today due to poor results of systemic chemotherapy caused by the poor diffusion of drugs across the blood–peritoneal barrier. Multi-walled carbon nanotubes (MWNTs) are a biocompatible nanomaterial that strongly absorb near-infrared light to locally heat the surrounding area. Colorectal cancer is known to overexpress folate receptor; therefore, folic acid (FA) was covalently attached to MWNTs to target colorectal cancer cells. Results from real-time polymerase chain reaction found differing expression of folate receptor-α in two colorectal cancer cell lines, RKO and HCT116, as well as a healthy epithelial cell line, HEPM. A spectrophotometric method was developed to quantify the mass of MWNTs bound to cells, and it was determined that FA-targeted MWNTs resulted in a 400–500 % greater affinity for colorectal cancer cells than untargeted MWNTs. The non-cancerous cell line, HEPM, had higher non-specific MWNT interaction and similar MWNT–FA affinity. Stimulated by 1,064 nm light, FA-functionalized MWNTs caused a 50–60 % decrease in colorectal cancer cell viability compared to a 4–10 % decrease caused by untargeted MWNTs. Our results indicate that FA-targeted MWNTs may increase the therapeutic index of MWNT-induced photothermal therapy.
KeywordsColorectal cancer Carbon nanotube Folic acid Polymerase chain reaction (PCR) Near-infrared photothermal ablation
We thank the Department of Plastic and Reconstructive Surgery at Wake Forest University Baptist Medical Center for funding and the Department of Chemistry at Wake Forest University for the use of the Raman, ESI–MS, NMR, and FTIR.
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