Toward levofloxacin monitoring in human urine samples by employing the LoC-SERS technique

The pharmacokinetics of antibiotics like levofloxacin exhibits large inter-individual differences questioning the value of fix dose regimens and warranting individual dosing based on therapeutic drug monitoring. Here, in a proof of principal study, it is shown that levofloxacin can be detected in human urine samples by employing the lab-on-a chip surface enhanced Raman spectroscopy (LoC-SERS). First, artificial urine was chosen as matrix in order to get insights into the influence of different parameters such as matrix complexity, aggregation time of the Ag nanoparticles and matrix dilution on the overall SERS signal. Second, three anonymized individual and three pooled urine samples originating from patients undergoing either no or unknown medical treatments have been spiked with the target analyte. Measurements were performed with a benchtop and a portable Raman setup. In all six samples urinary levofloxacin concentrations between 0.45 mM (162.6 μg/ml) and 1.8 mM (650.5 μg/ml) have been successfully detected. According to the literature, the normal levofloxacin concentration in urine is 1.38 mM±0.68 mM with a minimum measured concentration of 0.45 mM after 4 hours from the administration of a 500 mg dose. The presented results therefore show that LoC-SERS is a promising bio-analytical tool forurine analysis.