A comprehensive review of theoretical approaches to simulate plasmonic-active metallic nano-arrangements is given. Further, various fabrication methods based on bottom-up, self-organization and top-down techniques are introduced. Here, analytical approaches are discussed to investigate the optical properties of isotropic and non-magnetic spherical or spheroidal particles. Furthermore, numerical methods are introduced to research complex shaped structures. A huge variety of fabrication methods are reviewed, e.g. bottom-up preparation strategies for plasmonic nanostructures to generate metal colloids and core-shell particles as well as complex-shaped structures, self-organization as well as template-based methods and finally, top-down processes, e.g. electron beam lithography and its variants as well as nanoimprinting. The review article is aimed at beginners in the field of surface enhanced spectroscopy (SES) techniques and readers who have a general interest in theoretical modelling of plasmonic substrates for SES applications as well as in the fabrication of the desired structures based on methods of the current state of the art.

The pharmacokinetics of antibiotics such as levofloxacin exhibits large interindividual differences, questioning the value of fixed 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 lab-on-a-chip surface enhanced Raman spectroscopy (LoC-SERS). First, artificial urine is used as a matrix in order to get insights into the influence of different parameters such as matrix complexity, aggregation time, 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 h from the administration of a 500 mg dose. The presented results therefore show that LoC-SERS is a promising bioanalytical tool for urine analysis.