Facile synthesis of plasmonic BP@Au nanomatrix for sensitive detection of irinotecan and its active SN-38 metabolite via laser desorption/ionization mass spectrometry

A new methodology is presented for the rapid, specific, and sensitive detection of irinotecan (CPT-11), a chemotherapeutic agent utilized in the treatment of cancer, along with its metabolically active derivative, SN-38, via laser desorption/ionization mass spectrometry (LDI MS). The method includes the detection of camptothecin (CPT), which can be utilized as an internal standard for the quantitative assessment of both CPT-11 and SN-38 in mouse serum. The approach utilizes a plasmonic two-dimensional (2D) black phosphorus nanosheet (BPN)-gold nanomatrix (BP@Au) in LDI MS. The experimental results demonstrated that the BP@Au nanomatrix outperformed the standard organic matrices (SA, CHCA, and DHB) in detecting irinotecan and its active metabolite with improved specificity and sensitivity, crucial factors for applications in personalized medicine. Mass spectra obtained using organic matrices revealed interference from matrix peaks overlapping with analyte peaks. The coefficient of determination (R²) was 0.9806 for CPT-11 and 0.9932 for SN-38, indicating strong linearity suitable for quantification. Moreover, the method achieved a lower limit of detection (LOD) of 62.76 ng/mL for CPT-11 and 189.87 ng/mL for SN-38, significantly enhancing the detection sensitivity by approximately 2-8 times compared with previous matrix-assisted laser desorption/ionization (MALDI) methodologies. This method was subsequently applied to the quantitative determination of analytes in mouse serum. The analyte recoveries for CPT-11 and SN-38 were 95.40% and 92.95%, respectively. Overall, this study offers potential insights and opens avenues for developing new nanomaterials as a MALDI nanomatrix, demonstrating enhanced capabilities for the rapid, specific, and sensitive detection of small biomolecules within the realms of analytical chemistry and personalized medicine.