Jun 5, 2014
Enhanced gene silencing using dual-ligand modification
Nanoparticle-based gene carriers do not have the selectivity and transfection efficiency required for their much-needed role. Researchers are increasingly looking for alternatives and a group from Wuhan National Laboratory for Optoelectriconics, Huazhong University of Science and Technology, may have found one. Reporting in Nanotechnology, they have designed a dual receptor targeted gene-delivery carrier, based on semiconductor quantum dots, that has enhanced gene silencing efficiency.
Incorporating more than one ligand with nanoparticle-based carriers for specific delivery of therapeutic nucleic acids – such as antisense oligonucleotides (AS-ODNs) and siRNA – to tumour sites is a promising approach in anti-cancer strategies. However, as they possess a negative charge they cannot permeate across biological membranes freely.
Visibility and tracking
As an alternative, quantum dots (QDs) can be used as gene carriers in tumour gene regulation. They provide an entirely visible means to investigate gene intracellular transport and the targeted uptake of nucleic acids. In this gene-delivery system, QDs can not only be used as a gene vehicle but also as a fluorescent probe, allowing for localization and tracking during the delivery process.
The gene carrier
Here, biotinylated peptide GE11, c(RGDfK) and AS-ODN are conjugated with QDs by the interaction of streptavidin (SA) and biotin. This forms their gene carrier: QD-(AS-ODN+GE11+c(RGDfK)). The absorbance and fluorescence spectra, capillary electrophoresis, agarose electrophoresis and transmission electron microscopy (TEM) are used to characterize the conjugation.
The researchers demonstrate the synergistic effect between epidermal growth factor receptors (EGFR) and integrin ανβ3 by quantitative flow cytometry and inductively coupled plasma mass spectrometry (ICP/MS). They then confirm that the endocytosis pathway of the QD-(AS-ODN+GE11+c(RGDfK)) probe is mainly mediated by clathrin using special endocytosis inhibitors. Western blot further confirms that QD-(AS-ODN+GE11+c(RGDfK)) can enhance gene silencing efficiency compared with QD-(AS-ODN+GE11) and QD-(AS-ODN +c(RGDfK)). This suggests that this dual receptor targeted gene carrier achieves the desired transfection efficiency for its application.
More information can be found in the journal Nanotechnology 25 255102.
About the author
Ming-Zhen Zhang is a PhD candidate in the research group of Yuan-Di Zhao at Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, China. During his PhD study, his research focuses on the synthesis, characterization and application of functional nanoparticles, such as quantum dots and mesoporous silica, in targeted fluorescence imaging, targeted gene delivery and controlled gene/drug release.