Neurotoxin-directed synthesis and in vitro evaluation of Au nanoclusters

Abstract

Multifunctional theranostic materials with good biocompatibility are desirable for cancer imaging and therapy. In this paper, a glioma-specific theranostic agent is prepared using Chlorotoxin fusion protein GST-CTX (gCTX) as a template to direct the synthesis of Au nanoclusters (NCs). By trapping the Au NCs in the gCTX, the prepared Au@gCTX NCs show ultrasmall size with hydrodynamic diameter of ∼2.2 nm and exhibit red-emitting fluorescence with a quantum yield of approximately 6.5%. The investigation from confocal fluorescent microscopy reveals the bright fluorescence and high specificity of the Au@gCTX NCs to label glioma cells through binding to membrane-bound matrix metalloproteinase 2 (MMP-2). Gelatin Zymography, MTT cell viability assay and flow cytometry studies further demonstrate that the Au@gCTX NCs can inhibit the enzymatic activity of MMP-2 and cancer proliferation by elevating intracellular ROS levels, and without harming normal cells. Our results suggest an efficient method for the synthesis of multifunctional theranostic agents for the treatment of cancer.