Plasmid DNA delivery: nanotopography matters

By altering the nanotopography of engineered plasmid DNA vectors, researchers from The University of Queensland have significantly improved transfection efficacy and reduced transfection decay.

An illustration of nanotopography design for plas-mid DNA delivery. (a) A 3D model (top) and an AFM image (bottom) of pDNA-EGFP on a mica surface. (b-g) 3D model images displaying silica nanoparti-cles featured with rambutan- (b), raspberry- (c) and flower-like (d) morphologies and spike (e), hemi-sphere (f) and bowl (g) type subunit nanotopogra-phies conjugated with plasmid DNA at the interface. (h) Schematic representation of pDNA-EGFP DNase I protection, cellular delivery and transfection pro-cess by Rambutan SNPs. Credit to: Chengzhong (Michael) Yu.

The development of safe and effective nonviral vectors for gene-delivery applications is an area of ongoing development. Various types of delivery vehicles have been fabricated, including silica-based nanovectors which allow delicate nanostructure tailoring with versatile surface chemistry and good biocompatibility.

In their paper Plasmid DNA Delivery: Nanotopography Mattersthe team led by Prof Michael Yu have shown that understanding the impact of the delicate nanotopography of silica nanoparticles can improve the rational design of nonviral vectors for more efficient gene delivery.

By using ANFF-Q’s Cypher AFM to identify the plasmid DNA topography and analysing the clearly visualised numerous loops of the DNA’s rope-like structures, the team were able to further identify the DNA-particle interactions at the nanoscale interface. The confocal images taken by ANFF-Q’s Zeiss LSM 710 provided important information of the DNA and nanoparticle intracellular trafficking pathway, which also benefited their delivery system design.

Their research has shown that the rambutan-like nanoparticles engineered with spiky surfaces demonstrate the highest plasmid DNA binding capability and transfection efficacy of 88%, higher than those reported for silica-based nanovectors. Additionally, the surface spikes of rambutan-like nanoparticles protect the gene molecules against nuclease degradation, resulting in no significant transfection decay. This unique protection feature is in great contrast to the ‘gold standard’ of Lipofecatmine-2000, a benchmark commercial transfection agent with similar transfection performance but poor protection capability. The team’s nanotopography design provides a new strategy in the development of nonviral vectors with improved performance.

“Successful translation of this technology would result in an advanced nano-delivery system for gene therapy and DNA vaccines to combat with disease such as cancers and other genetic disorders,” explained Michael. “This research will lead to novel nanoparticle-based anticancer formulations or vaccine products in the future.”

“The next project may focus on the development of effective vaccination formulations based on this technology. The advanced manufacturing facilities as well as the characterisation support from ANFF would greatly strengthen our future studies,” Michael added.