UCL- SERS dual-mode sensing of NaYF4: Yb3+ ,Er3+/ NaYF4: Yb3+@ Au composite nanoparticles

Upconversion luminescence-Surface enhanced Raman spectroscopy (UCL-SERS) dual-mode composite materials have great potential application in disease detection. To obtain a dual-mode composite materials, NaYF4: Yb3+,Er3+/NaYF4: 10 %Yb3+@Au composite nanoparticles (NPs) were designed. The designed NPs consists of two parts: UCL material and SERS material. Under the excitation of 980 nm continuous light, the UCL intensity of the composite NPs was enhanced by 8.86 times (522 nm), 7.82 times (541 nm) and 7.40 times (654 nm) compared to that of NaYF4: Yb3+,Er3+ core upconversion nanoparticles (UCNPs), respectively. Through cytotoxicity experiments, the composite NPs has been proven to be non-cytotoxic and can be applied in cell imaging. The composite NPs can also be used as SERS substrate due to surface modified Au NPs. Under the excitation of 785 nm continuous light, using 4-MPy as ligand molecule, the low limit of detection at 8.13 x 10(-6) M was successfully attained on the NaYF4: Yb3+,Er3+/NaYF4: 10 %Yb3+@Au composite NPs substrate. The SERS immune structure composed of the composite NPs immune probe and immune substrate was constructed, achieving the detection of prostate-specific antigen (PSA). This indicates that the composite has applications in tumor biomarker detection.