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Surface-enhanced Raman Spectral Measurements of 5-Fluorouracil in Saliva
Real-Time Analyzers, Inc., Middletown, CT 06457, USA
Yale University, New Haven CT 06520, USA
* Author to whom correspondence should be addressed.
Received: 8 August 2008; in revised form: 16 October 2008 / Accepted: 20 October 2008 / Published: 22 October 2008
Abstract: The ability of surface-enhanced Raman spectroscopy (SERS) to measure 5-fluorouracil (5-FU) in saliva is presented. The approach is based on the capacity of Raman spectroscopy to provide a unique spectral signature for virtually every chemical, and the ability of SERS to provide μg/mL sensitivity. A simple sampling method, that employed 1-mm glass capillaries filled with silver-doped sol-gels, was developed to isolate 5-FU from potential interfering chemical components of saliva and simultaneously provide SERSactivity. The method involved treating a 1 mL saliva sample with 1 mL of acetic acid, drawing 10 μL of sample into a SERS-active capillary by syringe, and then measuring the SER spectrum. Quality SER spectra were obtained for samples containing as little as 2 μg of 5-FU in 1 mL saliva. The entire process, the acid pretreatment, extraction and spectral measurement, took less than 5 minutes. The SERS of 5-fluorouridine and 5-fluoro-2’-deoxyuridine, two major metabolites of 5-FU, were also measured and shown to have unique spectral peaks. These measurements suggest that disposable SERS-active capillaries could be used to measure 5-FU and metabolite concentrations in chemotherapy patient saliva, thereby providing metabolic data that would allow regulating dosage. Tentative vibrational mode assignments for 5-FU and its metabolites are also given.
Keywords: 5-FU; Chemotherapy; Drug analysis; Saliva analysis; Raman; SERS
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Farquharson, S.; Gift, A.; Shende, C.; Inscore, F.; Ordway, B.; Farquharson, C.; Murren, J. Surface-enhanced Raman Spectral Measurements of 5-Fluorouracil in Saliva. Molecules 2008, 13, 2608-2627.
Farquharson S, Gift A, Shende C, Inscore F, Ordway B, Farquharson C, Murren J. Surface-enhanced Raman Spectral Measurements of 5-Fluorouracil in Saliva. Molecules. 2008; 13(10):2608-2627.
Farquharson, Stuart; Gift, Alan; Shende, Chetan; Inscore, Frank; Ordway, Beth; Farquharson, Carl; Murren, John. 2008. "Surface-enhanced Raman Spectral Measurements of 5-Fluorouracil in Saliva." Molecules 13, no. 10: 2608-2627.