Fluorescence-Raman Nanoprobes Synthesis for Fluorescence-Raman Endoscopic System and Its Application on Colorectal Cancer Model

Abstract

In recent years, endoscopic imaging techniques with the spectroscopic assistance have been actively developed due to both the increase in demand and necessity for early diagnosis of cancer and the development of optical technology. These devices are classified into using intrinsic analysis methods that analyze signals based on living organs and using a labeling method that uses spectroscopic probes that specifically bind to specific biomarkers. Such techniques can be breakthrough for diagnosis of a lesion that has not been detected through white light endoscopic imaging technology. However, there are limits to the fluorescence-based markers currently being used. It have a wide bandwidth and possibility to overlap with auto-fluorescence emitted by tissue. To overcome these problems, recent studies suggest surface-enhanced Raman scattering (SERS) nanoparticles as alternative probes in molecular diagnosis. Raman signal have narrow bandwidth and high sensitivity that allows multiplexed diagnosis in endoscopic methods. In this study, we synthesized optically stable fluorescence-SERS nanoprobes (F-SERS dot) that have separated fluorescence from Raman signal without interference. In order to utilize the F-SERS dots as nanoprobes for cancer-specific biomarkers, the antibodies were immobilized on the particle surface by EDC/NHS coupling method. To confirm the specificity of the synthesized F-SERS dots, epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) were selected as tumor cell biomarkers in colorectal cancer mouse model. We conjugated antibodies which specifically binding with each antigen type with different Raman molecule labeled F-SERS dot, then we confirmed the feasibility of F-SERS dots at in vitro and in vivo diagnosis of colorectal cancer model.