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.

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Detection of chemical agents as poisons in water supplies not only requires microg/L sensitivity, but also requires the ability to distinguish their hydrolysis products. We have been investigating the ability of surface-enhanced Raman spectroscopy (SERS) to detect chemical agents at these concentrations. Here we expand these studies and present the SERS spectra of the nerve agent VX (ethyl S-2-diisopropylamino ethyl methylphosphonothioate) and its hydrolysis products, ethyl S-2-diisopropylamino methylphosphonothioate, 2(diisopropylamino) ethanethiol, ethyl methylphosphonic acid, and methylphosphonic acid. Vibrational mode assignments for the observed SERS peaks are also provided. Overall, each of these chemicals produces a series of peaks between 450 and 900 cm(-1) that are sufficiently unique to allow identification. SERS measurements were performed in silver-doped sol-gel-filled capillaries that are being developed as part of an extractive point sensor.

Rapid analysis of drugs in emergency room overdose patients is critical to selecting appropriate medical care. Saliva analysis has long been considered an attractive alternative to blood plasma analysis for this application. However, current clinical laboratory analysis methods involve extensive sample extraction followed by gas chromatography and mass spectrometry, and typically require as much as one hour to perform. In an effort to overcome this limitation we have been investigating metal-doped sol-gels to both separate drugs and their metabolites from saliva and generate surface-enhanced Raman spectra. We have incorporated the sol-gel in a disposable lab-on-a-chip format, and generally no more than a drop of sample is required. The detailed molecular vibrational information allows chemical identification, while the increase in Raman scattering by six orders of magnitude or more allows detection of microg/mL concentrations. Measurements of cocaine, its metabolite benzoylecgonine, and several barbiturates are presented.