Self-supporting liquid film as reproducible SERS platform for therapeutic drug monitoring of berberine hydrochloride in human urine.

• A self-supporting liquid film SERS method was proposed for the sensitive detection of berberine. • Berberine in urine was successfully analyzed and showed great consistency with HPLC. • The average excretion rates of berberine after oral administration in patients were monitored. Though surface-enhanced Raman scattering (SERS) has been widely used in the biomedical field, pharmacokinetic monitoring remains a challenge due to its inherent poor reproducibility. Here in this work, a novel and reproducible SERS platform based on the self-supporting liquid film (SLF) was proposed for the pharmacokinetic monitoring of berberine hydrochloride (BB) in human urine. Briefly, the KBr-modified silver nanoparticles (Ag NPs) suspension was mixed with the analyte. Then the mixture was placed in a customized template to form the SLF platform. In the optimized condition, the results showed that the limit of detection (LOD) of BB was 0.55 ppb. The relative standard deviation (RSD) of the SERS measurements was stable below 10%, and a wide linear range from 1 to 100 ppb (R2 = 0.997) and 100 to 500 ppb (R2 = 0.994). The averaged recovery was determined from 94% to 104% for spiked urine samples. Side-by-side comparison for urine sample analysis was performed between the proposed SLF method and high-performance liquid chromatography (HPLC), where good agreement was achieved. Moreover, the average excretion rates of BB after oral administration in six patients were satisfactorily monitored. The SLF SERS platform can realize rapid and reliable quantitative drug analysis and has potential applications in point-of-care testing. [ABSTRACT FROM AUTHOR]