Abstract

Low-molecular-weight (LMW) compounds, including both endogenous and exogenous molecules, are critical in characterizing diverse life processes, such as cancer. Specifically, the comprehensive characterization of LMW compounds aids in understanding the pharmacological effects of traditional Chinese medicine (TCM), enabling the identification of active ingredients and assessment of therapeutic efficacy against tumor cells. However, challenges arise in laser desorption/ionization mass spectrometry (LDI MS) due to the limited availability of existing matrices and the detection preference for specific molecules. Here, ZnS/Au (ZA) composites are developed as matrices for LDI MS, achieving a 100% detection coverage of 78 standard analytes in dual-ion modes. The composites are optimized with a loose ZnS substrate densely anchored with large Au nanoparticles, forming a Schottky heterostructure at the interface. This design results in the generation of stable hotspot layers and long-lifetime electron-hole pairs. Consequently, a wide coverage of phytochemicals (12 categories, 50 types) is identified from 11 TCMs. Further, the growth-inhibitory of TCMs on A549 lung cancer cells are validated based on metabolic profiles of endogenous molecules. This study provides an efficient tool to elucidate the active components and action mechanisms of the complex TCM system at the molecular level, thereby advancing the modernization and standardization of TCM.

SCHEME 1 Schematic illustration for (a) the synthesis workflow of ZA composites, (b) the comparison of morphology between ZA-20, ZA-50,and ZA-100, highlighting the unique Schottky heterojunction of ZA composites, (c) the mechanisms promoting the LDI processes in both positive- and negative-ion modes, and (d) the applications of ZA-50-assisted dual-ion mode LDI MS for the comprehensive analysis of biofunctional ingredients in TCMs and their potential pharmacological effects on cancer cell metabolism.

Figure 1. The pharmaceutical analysis of TCMs using ZA-50-assisted LDI MS in dual-ion mode. (a) Schematic of experimental workflow for comprehensive profiling of the bioactive ingredients of TCMs and their pharmacological interactions with cancer cells. (b) Heatmap of TCM fingerprints from 11 kinds of TCMs, using 169 and 205 m/z features through data processing. The color scale was processed by logarithmic treatment. (c) Typical mass spectra of Rheum palmatum L. (Da Huang, DH) in positive-ion mode and negative-ion mode. (d) Heatmap of the detection of 50 bifunctional compounds identified from the fingerprints of 11 TCMs (30 in positive ion mode and 21 in negative ion mode). (e) Cell viability assay after treatment of cells with different TCMs. (f) The t-distributed stochastic neighbor embedding (t-SNE) analysis for the positive and negative metabolic feature pattern of six TCM-treated and control groups. (g) The linear calibration curves collected by plotting the Euclidean distance between cluster centroids of each TCM-treated group and the blank control group in unsupervised clustering as a function of the corresponding CCK-8 viabilities of A549 cells.

https://doi.org/10.1002/adfm.202525256