Determination of Salivary Sialic Acid Through Nanotechnology: A Useful Biomarker for the Screening of Breast Cancer.

PURPOSE: To demonstrate the usefulness of sialic acid (SA) in saliva as a biomarker for breast cancer (BC) and develop a new tool for early detection. METHODS: Considering that the amount of SA in human saliva is limited, the levels of SA were measured using surface-enhanced Raman spectroscopy (SERS) with tailored citrate-reduced silver nanoparticles. We calibrated the spectrum using analytical reagent SA. The 164 patients included in this study were undergoing screening mammography and/or ultrasound testing. The SA test was performed in the absence of previous information regarding the health of the subjects. Biopsies were performed to determine the diagnosis of cancer condition. The biopsy studies determined that 35 patients are BC affected and 129 gave negative results. RESULTS: SERS showed a sensitivity and specificity of 80 and 93%, respectively. The cut-off value for SA (12.5 mg/dL) was established through a receiver operating characteristic (ROC) curve analysis. The area under the curve of the ROC analysis resulted in 95% with this SA level cut-off. Our results suggest that SA may be a useful biomarker for the screening of breast cancer in women. CONCLUSIONS: Our results suggest that the SA levels measured from saliva may be highly sensitive and specific markers for the presence of breast cancer.

Determination of sialic acid levels by using surface-enhanced Raman spectroscopy in periodontitis and gingivitis.

OBJECTIVES: To compare the sialic acid (SA) levels in saliva among periodontitis-affected, gingivitis and control patients. METHODS: The study involved 93 subjects. The participants were divided into three groups: (1) 30 subjects without periodontal disease (control group); (2) 30 subjects with gingivitis; and (3) 33 subjects with periodontitis. The oral parameters examined were as follows: (a) Simplified Oral Hygiene Index; (b) Calculus Index; (c) Gingival Index; (d) probing pocket depth; and (e) level of epithelial attachment. SA levels in saliva were measured by means of surface-enhanced Raman spectroscopy (SERS). This method has demonstrated the capacity to detect extremely low concentrations of molecules. The spectrum was calibrated using analytical reagent SA. RESULTS: The obtained median values for SA concentrations were 5.98, 7.32, and 17.12 mg/dl for control, gingivitis, and periodontitis patients, respectively. CONCLUSIONS: Our measurements by SERS corroborate that in periodontitis-affected patients, the SA concentration is larger than their concentrations in either control or gingivitis patients. This confirms previous reports and opens the possibility of using SERS as a diagnostic tool.

Determination of sialic acid in saliva by means of surface-enhanced Raman spectroscopy as a marker in adnexal mass patients: ovarian cancer vs benign cases.

BACKGROUND: To demonstrate the use of surface-enhanced Raman spectroscopy (SERS) to determine sialic acid (SA) levels in saliva using silver nanoparticles as substrates, in adnexal mass patients scheduled for surgical intervention to remove invasive masses, with the aim to compare SA levels in benign tumor vs ovarian cancer patients. METHODS: Quantification of SA levels was accomplished by measuring their SERS and calibrating with analytical reagent SA. The mean SA concentration in saliva from 37 benign adnexal mass resulted smaller (5.1 mg/dL) than the mean concentration in 15 Ovarium cancer patients (23 mg/dL). The cancer condition was determined by biopsy of the removed adnexal mass. The CA-125 biomarker was also measured. The predictive potential of both biomarkers is discussed, together with the malignity risk index (MRI). RESULTS: Our results showed a sensitivity/specificity of 80%/100% with a cutoff to distinguish between benign/cancer cases of SA 15.5 mg/dL, as established from a ROC analysis. Our results suggest that SA may be a more useful biomarker than CA-125 to detect ovarian cancer. CONCLUSIONS: Our results suggest that the SA levels measured from saliva may be as good predictors as the MRI index for the presence of ovarian cancer in sensitivity/negative predictive value and outperforms it in specificity/positive predictive value.