Fig. 8

AuNP and AuNR light scattering immunoassay with detection by SERS. Using the 785nm custom Raman microscope, the Raman spectra of the AuNP and AuNR SERS probes bound to the polystyrene plate were recorded. Fig. 8a shows the Raman spectrum of DTTC iodide labeled AuNP SERS probes. The spectrum shows characteristic peaks corresponding to DTTC iodide at 493 cm⁻¹ and 508 cm⁻¹ and to polystyrene at 1002 cm⁻¹ and 1032 cm⁻¹. By solving for the area under each reporter peak, an AuNP SERS probe standard curve was developed (Fig. 8b). The curve was fit using a five-parameter logistic equation and the LLOD was calculated as 76.1 pM. The Raman spectra of AuNR SERS probes were also acquired (Fig. 8c). A standard curve and sensitivity plot shows that the LLOD for the AuNR SERS probe assay was 44.7 pM (Fig. 8d)