Screening and identification of ligand-protein interactions using functionalized heat shock protein 90-fluorescent mesoporous silica-indium phosphide/zinc sulfide quantum dot nanocomposites

Currently, nanosphere-based ligand fishing cannot be accomplished with imaging processing, although this step is important for real-time identification. Herein, a ligand fishing technique combined with real-time imaging is presented for the identification of ligands for heat shock protein 90α (Hsp 90α) from a complex matrix, Alisma plantago-aquatica Linn. crude extract, using Hsp 90α-functionalized mesoporous silica nanoparticle (MSN)-InP/ZnS quantum dot (QD) nanocomposites as a support material. Twenty ligands for Hsp 90α were screened, and their structures were identified by mass spectrometry. The activities of the ligands were verified by real-time imaging of cells apoptotic morphological changes. Quantitative analysis showed that Alisma plantago-aquatica Linn contained 8.19 μg/g Alisol F, which regarded as one typical component of Alisma plantago-aquatica Linn, and the extraction ratio of Alisol F was 76.2%. The precision for five replicate measurements was 7.0% (RSD). The prepared nanocomposites were also used to screen proteins from a mixture of cellular extracts, and five proteins from HeLa cells were identified as potential client proteins of Hsp 90α.