Application of label-free SERS and EC-SERS for detection of traces of drugs in biological fluids.

Abstract

Nowadays, with various available choices of non-prescription medication it is quite easy when under illness instead advising with the specialist to self-medicate and try different types of pharmaceuticals at once in order to save time or money. Such unguided or incorrect self-diagnosis of one’s health often results in overdose and other serious health risks. In these cases when such life threatening events occur it is of the most importance to apply early medical treatment. However, specific treatment can be only chosen when the species of pharmaceutical is known. Thus, in order to prevent serious outcomes it is necessary to have a tool which would allow to diagnose the type of drug that was used as soon as possible. The fastest way to gather the required information is to analyze chemically biofluids like blood, saliva or etc. since the pharmaceuticals or their metabolites are contained and transported via biofluids. But the concentration of the molecules to detect is often very low thus the technique not only should be fast but also very sensitive. Of course, there are several clinically available drug screening methods which have already been used for decades and can identify chemical constituents with high sensitivity. Even though such conventional clinically used drug screening methods like liquid chromatography and mass spectroscopy, are sensitive enough, the sample preparation procedure and analysis is not easy and take time. Faster methods would be beneficial and could help avoid serious complications of unguided selfmedication. Vibrational spectroscopy is known to be a reliable tool for chemical composition and structure analysis. Be that as it may, the sensitivity of the conventional vibrational spectroscopy techniques is not sufficient for the detection of trace amounts of molecules. Surface enhanced Raman scattering (SERS) spectroscopy - one of the unconventional methods of vibrational spectroscopy is known to be very sensitive and chemically specific thus suitable for detection of low concentration substances in bodily fluids. This work presents the possible approach of label-free SERS and EC-SERS spectroscopies for application as a faster method for drug screening from biological fluids.