Delivery of Bioactive Gene Particles via Gelatin-Collagen-PEG-Based Electrospun Matrices

The fabrication of fiber mats via electrospinning has been adopted in the last decades to produce high quality scaffolds for tissue engineering. However, an effective combination of electrospinning methods with gene delivery therapies remains a challenge. In this study, we describe how the delivery of gene complexes via electrospun mats that contain different volumes of gelatin (Gel), collagen (Col), and polyethylene glycol (PEG) can affect gene expression by transfected cells. Non-viral complexes were formulated by using lipid modified polyethylenimine (PEI) polymer and plasmid DNAs (pDNA) like the reporter Green Fluorescent Protein (GFP) and the therapeutically relevant Bone Morphogenetic Protein-2 (BMP-2) and electrospuned after being mixed with different volumes of Gel-Col-PEG mats and delivered to human myoblast (C2C12) and mouse osteoblast cells (MC3T3). The entrapment of GFP complexes via different homogeneous electrospun fiber mats revealed that a high fraction of collagen in the mats affected the quality of the fibers and led to reduced transfection efficiency on target cells. On the other hand, the fabrication of double-layered mats that contained collagen without complexes as a first layer and gelatin-collagen-PEG with complexes as a second layer successfully induced GFP expression and ALP activity in C2C12 cells. We conclude that this study has established the advantage of formulating multilayered bioactive collagen-based mats for gene delivery applications

Two-dimensional fast evanescent wave algorithm

A new fast evanescent wave algorithm (FEWA) is introduced in the two-dimensional (2-D) case. It expands the Green's function into propagating waves and directional evanescent waves. Applying the evanescent wave correction technique, a procedure similar to the traditional MLFMA can be expedited. No buffer region is necessary anymore, and fewer translators are needed. Numerical examples are given to show the features of this method.link_to_subscribed_fulltex

Hydrophobe-substituted bPEI derivatives: boosting transfection on primary vascular cells

Gene therapy targeted to vascular cells represents a promising approach for prevention and treatment of pathological conditions such as intimal hyperplasia, in-stent and post-angioplasty restenosis. In this context, polymeric non-viral gene delivery systems are a safe alternative to viral vectors but a further improvement in efficiency and cytocompatibility is needed to improve their clinical success. Herein, a library of 24 branched polyethylenimine (bPEI) derivatives modified with hydrophobic moieties was synthesised, characterised and tested in vitro on primary vascular cells, aiming to identify delivery agents with superior transfection efficiency and low cytotoxicity. Low molecular weight PEIs (0.6, 1.2 and 2 kDa) were grafted with long (C18) and short (C3) aliphatic chains, featuring different unsaturation degrees and degrees of substitution. 0.6 kDa bPEI-based derivatives were generally ineffective in transfection on vascular smooth muscle cells (VSMCs), while among the other derivatives some promising vectors were identified. Forcing polyplexes on the cell surface by means of centrifugation invariably boosted transfection levels but increased cytotoxicity as well. Of note, a propionyl-substituted derivative (PEI2-PrA1, C3: 0) was the most effective on both VSMCs and endothelial cells (ECs), with higher and more sustained gene expression in combination with markedly lower cytotoxicity with respect to the gold standard 25 kDa bPEI. In addition, a linoleoyl-substituted derivative (PEI1.2-LA6, C18:2) owing to its high efficiency in VSMCs and relative inefficacy in ECs, combined with tolerable cytotoxicity was proposed as a vector for specific VSMCs targeting

Evolution of the Composition and Suspension Performance of Nitrogen-Doped Graphene

Nitrogen functionalization of graphene enables it to be used for catalysis and targeted adsorption of biomolecules in both the solid state and in suspension. Thus, we sought to characterize the functional groups and suspension charge behavior of nitrogen-doped graphene (NDG) prepared in the absence of hydrazine, a highly toxic reagent. The hydrothermal reaction of graphite oxide (GO) with ammonia was shown to effectively remove oxygen and to restore the graphitic framework within the resulting NDG sheets. The enhanced graphitic character of the NDG materials was verified using X-ray photoelectron spectroscopy, thermogravimetic analysis, and electrical conductivity measurements. With six hours of reaction time (sample NDG-6), up to 9.6 wt % (7.1 atomic %) of nitrogen could be introduced into the graphene. All the NDG materials exhibited excellent dispersibility in water allowing their surface charge to be probed by measuring zeta potential (ζ) as a function of suspension pH. The NDG-6 material could hold surface charge ranging from ζ = −50 mV to ζ = +20 mV, which is, to the best of our knowledge, the widest range of surface charges measured on a colloidal graphene material