LoC-SERS technique toward drug quantification in complex materials

LoC-SERS Technique Toward Drug Quantification in Complex Matrices Kumulative Dissertation Zur Erlangung des akademischen Grades doctor rerum naturalium (Dr. rer. nat.) vorgelegt dem Rat der Chemisch-Geowissenschaftlichen Fakultät der Friedrich-Schiller-Universität Jena M. Sc. Izabella Jolán Hidi geboren am 27. Februar 1987 in Deva, Rumänien Abstract Detection and quantification of drugs in complex matrices challenged each analytical method at its moment of development and implementation. On one side, clinical samples, i.e. blood and urine, are routinely analyzed for diagnosis and treatment follow-up purposes. On the other side, monitoring the successful removal of pharmaceutically active compounds in waste and surface water is of high interest to overcome the occurrence of antibacterial resistance in the ecosystem. Among the newly developed analytical techniques, surface enhanced Raman spectroscopy (SERS) has high potential to be considered as an alternative analytical technique for the detection of clinically and environmentally relevant molecules in complex matrices. The biggest barrier for its application is the low reproducibility of measurements and automation. A solution that requires low-cost SERS substrates and offers reproducible and automated measurement conditions at the same time is represented by the droplet based lab-on-a-chip SERS (LoC-SERS) technique. This platform offers the advantage of highly precise controlled manipulation of nanoparticle and sample solution via computer controlled systems and a direct, on chip detection. The aim of the present thesis was to assess the potential and limitations of the LoC-SERS technique to detect and quantify drugs in various complex matrices. As SERS active substrates, easy-to-prepare silver nanoparticles in a colloidal solution were employed and as sample clean-up procedure filtration and dilution with water was carried out. Urine samples originating from healthy volunteers and patients with urinary tract infection, as well as river water sample were included in the present study. Analytical performances, such as lower limit of detection (LOD), linear and dynamic range and measurement reproducibility, were tested for methotrexate, levofloxacin, nitroxoline and ciprofloxacin. Furthermore, the potential of the LoC-SERS platform for on-site applications is also demonstrated by replacing the bench-top Raman microscope by a portable one.