In order to maximise the efficacy of the drug and avoid toxicity and adverse drug reaction, therapeutic drug monitoring (TDM) is an essential tool for measuring drug concentration at specific time intervals. TDM is essential when high-dose drug treatment is administered, or if the treatment needs to be personalized. Within a clinically-relevant pipeline, we showed that using surface-enhanced Raman spectroscopy (SERS) technique we can measure methotrexate (MTX) - an anticancer drug in PBS and serum in the linear range of 5 to 150 µM, and confirmed that MTX detection can be carried out even in the presence of the rescue drug Leucovorin. Moreover, we were able to achieve a detection limit of 0.7 µM for MTX in human serum samples. This disruptive improvement in TDM comes at significantly lower equipment cost (compared to chemical analysers) and at a much lower recurring cost for consumables (compared to immunoassays). In addition, the developed method enables fast (approx. 10 min) and quantitative detection of MTX from human serum samples at >90% accuracy.
