Simultaneous Gene Delivery and Tracking through Preparation of Photo-Luminescent Nanoparticles Based on Graphene Quantum Dots and Chimeric Peptides

Soroush Moasses Ghafary,Maryam Nikkhah,Saman Hosseinkhani,Shadie Hatamie

doi:10.1038/s41598-017-09890-y

Soroush Moasses Ghafary, Maryam Nikkhah + Show 2 more

Open Access

https://doi.org/10.1038/s41598-017-09890-y

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Abstract

Designing suitable nano-carriers for simultaneous gene delivery and tracking is in the research priorities of the molecular medicine. Non-toxic graphene quantum dots (GQDs) with two different (green and red) emission colors are synthesized by Hummer’s method and characterized by UV-Vis, Photoluminescence (PL), Fourier Transform Infrared (FTIR) and Raman spectroscopies, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The GQDs are conjugated with MPG-2H1 chimeric peptide and plasmid DNA (pDNA) by non-covalent interactions. Following conjugation, the average diameter of the prepared GQDs increased from 80 nm to 280 nm in complex structure, and the ζ-potential of the complex increased (from −36.87 to −2.56 mV). High transfection efficiency of the nano-carrier and results of confocal microscopy demonstrated that our construct can be considered as a nontoxic carrier with dual functions for gene delivery and nuclear targeting.

Highlights

Disruption of endosomal membrane and the acceleration of endosomal escape of the designed complexes into the cytosol and it’s protection against endosomal nucleases and peptidases
UV/Vis absorption spectroscopy of synthesized graphene quantum dots (GQDs) revealed an absorption shoulder in the visible region at 320 nm which is associated with n-π* transition and a strong absorbance at 230 nm attributed to π-π* transition (Fig. 2A), similar to previous reported studies for GQDs33, 34.The characteristic bands of surface functional groups on GQDs corresponding to epoxide, C=O, and O-H were detected by Fourier Transform Infrared (FTIR) spectroscopy (Fig. 2B)
We performed agarose-based gel retardation assay followed by ethidium bromide staining to confirm plasmid DNA (pDNA) attachment to the complexes (Figs 4C and S1) and the results showed that the mobility of pDNA decreased when conjugated to the peptide

Summary

Introduction

Disruption of endosomal membrane and the acceleration of endosomal escape of the designed complexes into the cytosol and it’s protection against endosomal nucleases and peptidases. Several studies shown wide applications of different fluorescent agents include organic fluorophores and fluorescence proteins for biological imaging and biomolecular tracking[14,15,16,17]. Quantum dots (QDs) as new fluorescence probes for biological imaging and tracking, have overcome the limitations of organic fluorophores and fluorescence proteins[18, 19]. Srinivasan et al have designed nanostructures of pDNA labeled with phospholipid coated CdSe/ZnS QDs for tracking of gene Their obtained complex has enabled gene transfection and cellular uptake monitoring[20]. One of the major barriers of semiconductor QDs is their cytotoxicity effects in biological systems, due to leakage of heavy metals Their applications in molecular and cellular tracking have been limited. The prepared nanocomplexes were successfully transfected into HEK 293 T cell lines as a model to assess, qualitatively and quantitatively the efficiency of gene transfection, DNA delivery into the nucleus and tracking

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Conclusion