Quantitative detection of 6-thioguanine in body fluids based on a free-standing liquid membrane SERS substrate

The adverse reactions caused by 6-thioguanine (6-TG) in anti-cancer treatment are closely related to the dose, leading to the urgent need for clinical monitoring of its concentration. In this work, a highly reproducible free-standing liquid membrane (FLM) surface-enhanced Raman spectroscopy (SERS) substrate was developed to detect 6-TG in human urine and serum quantitatively. Briefly, a prepared sample was adjusted to pH 2 and mixed with concentrated core-shell bimetallic nanoparticle (AgcoreAushell NP) suspension. The Au/Ag ratio of the AgcoreAushell NPs was optimized. Then the mixture was formed into an FLM using a custom mold. The relative standard deviation (RSD) of the experimental results can be stabilized below 10% (n >= 10). The R-2 of the calibration curve in the range of 10 similar to 100 mu g kg(-1) was 0.988. In addition, the limit of detection (LOD) (3 sigma/k) of 6-TG was 5 mu g kg(-1). The FLM SERS platform has been successfully applied to the rapid and reliable analysis of 6-TG spiked in body fluids.

Automated summary

A highly reproducible FLM SERS substrate was developed for quantitative detection of 6-TG in human urine and serum, with an optimized Au/Ag ratio of AgcoreAushell NPs. The platform showed stable experimental results with RSD below 10% and a calibration curve with an R-2 value of 0.988 in the range of 10-100 μg kg-1. The LOD of 6-TG was determined to be 5 μg kg-1, making it suitable for rapid and reliable analysis in body fluids.