Delineating effect of headgroup and preparation method on transfection versus toxicity of DNA-loaded lipid nanocarriers - supplementary materials

Aim: To perform a parallel comparison of key parameters affecting the safety and efficiency of lipidbased nanovectors (i.e., complexing headgroups, composition and preparation method). Materials & methods: Various cationic and ionizable headgroups were screened for formulating lipoplexes with GFP– plasmid DNA. Ethanol injection and microfluidics were used to prepare nanoparticles with GFP–plasmid DNA complexed on the surface or within the interior of lipid bilayers. Results: Lipoplexes composed of sphingomyelin 102 exhibited the highest transfection efficiency given their higher cellular uptake in BRAF inhibitor-resistant melanoma cells. Lipid nanoparticles demonstrated acceptable transfection efficiency and high spheroid penetration while protecting plasmid DNA under simulated physiological conditions. Conclusion: Selecting the right complexing lipid and preparation method is critical for developing lipid nanocarriers to treat intractable diseases.Plain language summary: Certain genetic diseases or cancers can be treated with gene therapy. This involves the delivery of working genes to cells with a faulty copy. These genes are often contained in a circular piece of DNA called a plasmid. Plasmids can be delivered by a variety of structures called vectors. These vectors include altered viruses as well as lipid-based nanovectors, which are nanoscale spheres of phospholipids, a type of fat. Plasmids can either be internalized inside these spheres in lipid nanoparticles (LNPs) or attached to the surface in nanocomplexes. A section of the phospholipid called the headgroup faces outward in lipid-based nanovectors. The chemical makeup of these headgroups determines the function of the lipid-based nanovector. This study aimed to determine an optimal lipid-based nanovector in gene delivery by testing a variety and identifying which was most effective at delivering a gene that makes cells fluoresce green when successfully delivered. The more intense the fluorescence, the greater the degree of successful gene delivery. This study found that LNPs were more effective at delivering plasmid DNA than nanocomplexes and were safer and protected plasmid DNA better. The best performing LNP contained the lipid sphingomyelin 102, which is biodegradable. Therefore, the optimized LNP formulation employing sphingomyelin 102 as a biodegradable lipid could be an efficient nonviral gene-delivery system and will be further investigated to target drug-resistant melanoma, a type of skin cancer.</p