A SERS‐Based Microfluidic Biosensor With Integrated Pretreatment for Therapeutic Drug Monitoring of Imatinib

ABSTRACT Therapeutic drug monitoring (TDM) of imatinib (IMT) is critical for the effective treatment of chronic myeloid leukemia (CML) and gastrointestinal stromal tumors (GIST). Herein, a surface‐enhanced Raman scattering (SERS)‐based microfluidic biosensor integrated with a pretreatment function was developed for the highly sensitive TDM of IMT. Experimentally, a three‐dimensional carbon framework decorated with silver nanoparticles (Ag NPs) was first synthesized as the SERS substrate to ensure high uniformity and sensitivity. Specifically, a gelatin/AgNO 3 mixed solution was spin‐coated onto a silicon substrate, followed by high‐temperature annealing to form a carbon skeleton lightly decorated with Ag NPs. Subsequently, the density of Ag NPs was further optimized via additional silver sputtering, and optimal SERS performance with the detect limit of 10 −10 M (R6G) was achieved. Meanwhile, a triple‐channel microfluidic system was fabricated using a mold casting method, with a serpentine mixing channel section designed for on‐chip deproteinization pretreatment. Thereafter, the aforementioned SERS substrate was cascaded with the prepared microfluidic system to serve as the sensing module. By leveraging the system's on‐chip pretreatment capability and high sensitivity, the novel biosensor achieves a broad detection range of 10 2 –10 6 ng/mL, which covers the IMT entire therapeutic window (1000–3200 ng/mL) and paves the way for its future application in point‐of‐care testing (POCT).