Rapid Detection and Identification of Overdose Drugs in Saliva by Surface-Enhanced Raman Scattering Using Fused Gold Colloids

Abstract

The number of drug-related emergency room visits in the United States doubled from 2004 to 2009 to 4.6 million. Consequently there is a critical need to rapidly identify the offending drug(s), so that the appropriate medical care can be administered. In an effort to meet this need we have been investigating the ability of surface-enhanced Raman spectroscopy (SERS) to detect and identify numerous drugs in saliva at ng/mL concentrations within 10 minutes. Identification is provided by matching measured spectra to a SERS library comprised of over 150 different drugs, each of which possess a unique spectrum. Trace detection is provided by fused gold colloids trapped within a porous glass matrix that generate SERS. Speed is provided by a syringe-driven sample system that uses a solid-phase extraction capillary combined with a SERS-active capillary in series. Spectral collection is provided by a portable Raman analyzer. Here we describe successful measurement of representative illicit, prescribed, and over-the-counter drugs by SERS, and 50 ng/mL cocaine in saliva as part of a focused study.

Utility of surface enhanced Raman spectroscopy (SERS) for elucidation and simultaneous determination of some penicillins and penicilloic acid using hydroxylamine silver nanoparticles

“…With the combination of non-destructive data recording, high sensitivity and unique spectroscopic fingerprints, surface-enhanced Raman spectroscopy (SERS); has become one of the most widely utilized spectroscopic tools for the identifications and detection of chemical species [14][15][16][17]. Silver substrates are more accessible to obtain SERS signals at the excitation of the entire visible region.…”

Methodologies for assessment of limit of detection and limit of identification using surface-enhanced Raman spectroscopy

“…), 1603 cm −1 (C C stretch of the benzoic acid moiety), and, unlike the other compounds, the (C O stretch) is here observed at 1722 cm −1 . The vibrations between 800 and 900 cm −1 are tentatively assigned to C C stretches [17,38,39].…”

“…As the number of analytes increases, it is appropriate to introduce selectivity in the SERS methodology, which commonly is supported by powerful algorithms and chemometric based analyses. A remaining challenge is to introduce sufficient selectivity to resolve signals from an interfering matrix, as for example for drugs in saliva [16][17][18] or antibiotic substances [19] and nicotine [20] in urine. The first step towards this goal is to obtain SERS substrates that are giving rise to reliable, reproducible and satisfying detection limits in the analytical set-up.…”

Detecting Drugs in Saliva

“…Saliva is easily collected from subjects, and is conveniently in aqueous form for application to a substrate. Researchers have previously demonstrated the effectiveness of SERS for testing saliva for drugs, but their method required a two-step procedure combined with a solid phase extraction step to extract the drug concentrate from the saliva [4].…”