Octahedral silver oxide nanoparticles enabling remarkable SERS activity for detecting circulating tumor cells

摘要

The detection of circulating tumor cells(CTCs)is a crucial tool for early cancer diagnosis,prognosis,and postoperative evaluation.However,detection sensitivity remains a major challenge because CTCs are extremely rare in peripheral blood.To effectively detect CTCs,octahedral Ag_(2)O nanoparticles(NPs)with high dispersibility,good biocompatibility,remarkable surface-enhanced Raman scattering(SERS)enhancement,and obvious enhancement selectivity are designed as an SERS platform.Ag_(2)O NPs with many oxygen vacancy defects are successfully synthesized,which exhibit an ultra-high SERS enhancement factor(1.98×10^(6))for 4-mercaptopyridine molecules.The remarkable SERS activity of octahedral Ag_(2)O NPs is derived from the synergistic effect of the surface defect-promoted photo-induced charge transfer(PICT)process and strong vibration coupling resonance in the Ag_(2)O-molecule SERS complex,greatly amplifying the molecular Raman scattering crosssection.The promoted PICT process is confirmed using ultraviolet-visible(UV-Vis)absorption spectroscopy,demonstrating that obvious PICT resonance occurs in Ag_(2)O SERS system under visible light.An additional growth step of SERS bioprobe is proposed by modifying the Raman signal molecules and functional biological molecules on Ag_(2)O NPs for CTC detection.The Ag_(2)O-based SERS bioprobe exhibits excellent detection specificity for different cancer cells in rabbit blood.Importantly,the high-sensitivity Ag_(2)O-based SERS bioprobe satisfies the requirement for rare CTC detection in the peripheral blood of cancer patients,and the detection limit can reach 1 cell per m L.To our knowledge,this study is the first time that a semiconductor SERS substrate has been successfully utilized in CTC detection.This work provides new insights into CTC detection and the development of novel semiconductor-based SERS platforms for cancer diagnosis.