Determination of methotrexate in spiked human urine using SERS-active sorbent

Abstract

This report is dedicated to determination of anticancer drug methotrexate (MTX) in human urine using surface-enhanced Raman spectroscopy (SERS). Aluminum oxide loaded with silver nanoparticles (AO-Ag) was proposed as SERS-active sorbent and used for solid-phase extraction (SPE) of the analyte and its SERS-based determination (SPE-SERS protocol). MTX has strong SERS signal only in alkaline media that challenges its determination in urine due to strong background signal caused by creatinine. The application of SPE step enables to purify and concentrate the analyte making MTX determination possible. Also, the application of the same material for SPE pretreatment and SERS analysis enables to simplify and speed-up the protocol. The protocol was developed and tested using artificially spiked samples of human urine collected during different time of day to account deviating composition of the urine matrix. The use of dilution step of the analyte-containing urine was proposed prior SPE-SERS protocol to reduce the difference between morning-time-and daytime-collected urine achieving maximal reliability of the analysis. Additional physicochemical study was performed to estimate an influence of the primary intrinsic urine components (salts, urea, creatinine) and their mixtures on the analytical signal. Final protocol enables MTX determination in human urine within 20-300 μg mL −1 range of concentrations with satisfactory precision (11-19% RSD), accuracy (97-104% apparent recovery), and limit of detection (4.2 μg mL −1). Accounting that the analysis requires less than 15 min and portable Raman spectrometer, the protocol seems to be promising for therapeutic drug monitoring in hospitals to identify poor MTX clearance in a timely manner and minimize adverse effects of therapy.

Quantification of Methotrexate in Human Serum Using Surface-Enhanced Raman Scattering—Toward Therapeutic Drug Monitoring

“…57 Additionally, Markina et al were able to detect MTX in spiked human urine using the SERS-active sorbent for solid-phase extraction. 58 Furthermore, Subaihi et al demonstrated that by combining HPLC with SERS-based sensing, it is possible to detect MTX and its metabolite in patient urine samples. 59 Even when combining detection with simple sample preparation, MTX detection with Raman spectroscopy or SERS is challenging, especially when aiming to reach the 0.2 μM detection limit in biological matrices.…”

“…Recently, Parachalil et al showed the possibility of using a robust size-exclusion filtration technique called centrifugal filtration to process human serum samples for MTX detection in human serum with Raman spectroscopy . Additionally, Markina et al were able to detect MTX in spiked human urine using the SERS-active sorbent for solid-phase extraction . Furthermore, Subaihi et al demonstrated that by combining HPLC with SERS-based sensing, it is possible to detect MTX and its metabolite in patient urine samples .…”

How Surface-Enhanced Raman Spectroscopy Could Contribute to Medical Diagnoses

“…Markina et al developed a method to detect the anticancer drug MTX [74]. Their tests were performed on human urine samples that had been artificially enriched.…”

Cyclodextrin-assisted surface-enhanced Raman spectroscopy: a critical review

“…The simplest one is the adjustment of pH, ionic strength, and/or dielectric constant of the analyzed solution to maximize interaction of analyte molecules with SERS substrate and minimize such interaction for admixtures [3][4][5]. The next approach implies preliminary separation of the analyte by chromatographic separation or by solid-phase/ liquid-liquid extraction [6][7][8]. The last approach is based on modification of SERS substrates by various recognition elements, e.g., by antibodies, aptamers, and molecularly imprinted polymers.…”