Fig. 1From: Label-free blood serum detection by using surface-enhanced Raman spectroscopy and support vector machine for the preoperative diagnosis of parotid gland tumorsa The UV/visible absorption spectra of the Au NPs, serum and the mixture of Au NPs and serum. b SERS spectrum of serum, normal Raman spectrum of serum and background Raman spectrum of the Au NPs colloid. c The SEM images of Au NPs. d The SEM images of the mixture of Au NPs and serumBack to article page