Analysis of 5-fluorouracil in saliva using surface-enhanced Raman spectroscopy

Abstract

The ability of surface-enhanced Raman spectroscopy (SERS) to measure the chemotherapy drug 5-fluorouracil in saliva is presented. A silver-doped sol-gel provided SERS and also some chemical selectivity. 5-Fluorouracil and physiological thiocyanate produced SERS, whereas large biochemicals, such as enzymes and proteins, did not, supporting the expectation that the larger molecules do not diffuse through the sol-gel to any appreciable extent. In addition, 5-fluorouracil samples of 2 µg ml −1 were easily measured, and an estimated limit of detection of 150 ng ml −1 in 5 min should provide sufficient sensitivity to perform pharmacokinetic studies and to monitor and regulate patient dosage. This would fill a critical need for this highly used drug, since genetic-based variations in its metabolism can range by as much as five-fold from one patient to another.

FTIR and Raman Spectra Compared with Ab Initio Calculated Frequency Modes for 5-Aminouracil

“…In the present case, the IR band at 1,100 cm −1 is associated with this mode. For 2-thiocytosine, the ω (NH 2 ) and τ (NH 2 ) modes have been assigned at 540 and 527 cm −1 , respectively, by Beetz and Ascarelli [17]. In fact, the ω (NH 2 ) and τ (NH 2 ) modes arise due to the out-of-phase and the in-phase coupling of the two NH out-of-plane bending motions of the NH 2 group.…”

“…In fact, the ω (NH 2 ) and τ (NH 2 ) modes arise due to the out-of-phase and the in-phase coupling of the two NH out-of-plane bending motions of the NH 2 group. In the assignment of substituted uracil [54], the ω (NH 2 ) and τ (NH 2 ) modes have been assigned at 650 and 315 cm −1 and also, in the assignment of benzene derivatives [55,56], assigned near 750 and 400 cm −1 , respectively. But 2-thiocytosine [4] has been assigned the ω (NH 2 ) and τ (NH 2 ) modes at 804 and 527 cm −1 , respectively.…”

“…But 2-thiocytosine [4] has been assigned the ω (NH 2 ) and τ (NH 2 ) modes at 804 and 527 cm −1 , respectively. Due to its complexity, removal of the ω (NH 2 ) and τ (NH 2 ) modes have been performed in parallel studies of substituted uracil [5-X-uracil, X = F, Cl, Br I, NH 2 and CH 3 ] with a comparison of ω (NH 2 ) and τ (NH 2 ) modes clearly expected at 485 and 430 cm −1 compared with the results described in [37].…”

“…The photochemistry of thymine is significant; UV-induced photoproducts of thymine in DNA lead to skin cancer and other diseases [1]. 5-Fluorouracil is a derivative of uracil and one of the most often used drugs to treat solid tumours and colorectal carcinoma [2].…”

Raman characterization and chemical imaging of biocolloidal self-assemblies, drug delivery systems, and pulmonary inhalation aerosols: A review

“…70 Disadvantages of classical Raman spectroscopy, in the context of pharmaceutical applications, are fluorescence in the sample interfering with Raman scatter detectability and the inherently weak Raman scattering process, resulting in low sensitivity and the need for sensitive detectors and intense laser excitation sources. 23 SERS 16,23,71 overcomes these limitations by providing high sensitivity and hence is a powerful analytical technique for biocolloidal systems, antibiotic drug adsorption, 72 precise drug detection and quantification in bodily fluids, 73 and antiretroviral 74,75 and antitubercle bacillus drug 76 molecular conformational investigations. Using a combination of micro-Raman and SERS, the recognition process of drugs with large biomolecules (eg, albumin) through the use of colloidal nanoparticles was reported through investigation of the binding properties of the drugs with albumin.…”