Screening of usage of OCT drugs by means of SERS spectroscopy

Abstract

The misuse or abuse of over-the-counter (OTC) drugs has a significant impact on patient health and if used without caution can lead to serious health issues. The prevalence of OTC drugs due to a well-developed market and the lack of patient knowledge about the drug safety has led to the increase in the number of hospitalizations related to the drug missuses. In order to choose a correct treatment procedure a fast and precise identification of the misused drug is necessary. Various accurate drug-screening methods are clinically available, however, they are rather slow or too complicated and more efficient method would be beneficial. In this work we present the first results of application of SERS spectroscopy for a fast screening of salicylic acid (metabolite of aspirin) and paracetamol directly in human blood. Conventional Raman spectroscopy is known to be a sensitive technique for identification and quantification of molecular substances in various molecular mixtures without the need of a large amount of the sample. However, when dealing with low concentrations of molecules under study in some biological fluids (like drugs or their metabolites in blood) unconventional sensitive spectral methods like surface enhanced Raman scattering (SERS) spectroscopy must be used. The extremely high sensitivity of the SERS allows identification of the blood metabolites in micromole or even in lower concentrations by analyzing the spectra of thin films of dried blood samples formed on the metal colloidal film. Additionally, the possibility to tailor the metal nanoparticles applied in colloidal SERS can be utilized to increase selectivity and sensitivity of the method. The SERS methodology proposed in this work allows fast and accurate identification of the aspirin with the detection limit – standard 500 mg one and half pills, while usage of up to 2 pills of paracetamol at once cannot be detected due to extremely low concentration of this drug in the blood.