A surface-enhanced Raman spectroscopy (SERS) approach was utilized for urine biochemical analysis with the aim to develop a label-free and non-invasive optical diagnostic method for esophagus cancer detection. SERS spectrums were acquired from 31 normal urine samples and 47 malignant esophagus cancer (EC) urine samples. Tentative assignments of urine SERS bands demonstrated esophagus cancer specific changes, including an increase in the relative amounts of urea and a decrease in the percentage of uric acid in the urine of normal compared with EC. The empirical algorithm integrated with linear discriminant analysis (LDA) were employed to identify some important urine SERS bands for differentiation between healthy subjects and EC urine. The empirical diagnostic approach based on the ratio of the SERS peak intensity at 527 to 1002 cm<sup>-1</sup> and 725 to 1002 cm<sup>-1</sup> coupled with LDA yielded a diagnostic sensitivity of 72.3% and specificity of 96.8%, respectively. The area under the receive operating characteristic (ROC) curve was 0.954, which further evaluate the performance of the diagnostic algorithm based on the ratio of the SERS peak intensity combined with LDA analysis. This work demonstrated that the urine SERS spectra associated with empirical algorithm has potential for noninvasive diagnosis of esophagus cancer.
A novel method for rapidly synthesized Au colloidal under microwave irradiation was present in this paper. Size of the
Au nanoparticles varied from 10 nm to 60 nm along with varying mol fractions by chloroauric acid solution reduced with
sodium citrate. The prepared Au nanoparticles were characterized by transmission electron microscope (TEM) and
ultraviolet-visible (UV-Vis) spectrophotometer. It is found that the nanoparticle size and shape are highly dependent on
the reaction time and the molar ratios of the reducing agent. By the SERS measurements of R6G, 4-MBA and Crystal
violet, this Au colloid is shown to be an excellent SERS substrate with good stability. As the fabrication process of this
SERS substrate is simple and inexpensive, this method may be used in large-scale preparation of substrates that can serve
as an ideal SERS substrate in biomedical application.