Photoactive imaging and therapy for colorectal cancer using a CEA-Affimer conjugated Foslip nanoparticle

Theranostic nanoparticles hold a promising strategy for simultaneous imaging and therapy in colorectal cancer. Carcinoembryonic antigen can be used as a target for these nanoparticles because it is overexpressed in most colorectal cancers. Affimers reagents are synthetic proteins capable to binding specific targets, with additional advantages over antibodies for targeting. We fabricated silica coated Foslip nanoparticles and functionalised the surface with anti-CEA Affimers to facilitate fluorescent imaging and photodynamic therapy of colorectal cancer. CEA-specific fluorescent imaging and phototoxicity was quantified in colorectal cancer cell lines and a LS174T murine xenograft colorectal cancer model. Anti-CEA targeted nanoparticles exhibited CEA-specific fluorescence in LoVo, LS174T and HCT116 cell lines when compared to control particles (p<0.0001). No toxicity was observed in LS174T cancer mouse xenografts or other organs. Following photo-irradiation, anti-CEA targeted particles produced significant cell death in LoVo (60%), LS174T (90%) and HCT116 (70%) compared to controls (p<0.0001). Photodynamic therapy (PDT) at 24 h in vivo showed a 4-fold reduction in tumour volume compared to control mouse xenografts (p<0.0001). This study demonstrates the efficacy of targeted fluorescent imaging and PDT using Foslip nanoparticles conjugated to anti-CEA Affimer nanoparticles in in vitro and in vivo colorectal cancer models.