A Fluorescent Self-Reporting Vector with GSH Reduction Responsiveness for Nucleic Acid Delivery

Nonviral gene vectors with stimulus responsiveness and self-reporting properties have broad application prospects in gene therapy. Herein, we developed a nanosized reduction-responsive cationic liposomal vector formed from DNS(Zn), in which a naphthalimide-sulfonamide group was used as the glutathione (GSH)-responsive group to generate a blue fluorescence signal at 458 nm. Macrocyclic polyamine (cyclen) was used as a cationic headgroup to facilitate Zn(II) coordination, which may reduce the cytotoxicity and improve transfection efficiency. The Zn-free and nonresponsive analogues were used for comparison. Fluorescent assays revealed that the GSH response of DNS(Zn) could increase the blue fluorescence signal and improve the DNA release in cells. The title material also showed higher positive ζ-potential than its nonresponsive analogue, resulting in stronger DNA binding ability and better cellular uptake. These advantages made DNS(Zn) a good candidate for nonviral gene delivery, and the transfection efficiency in HeLa cells was distinctly higher than that of its analogue and the commercially available transfection reagent. Besides plasmid DNA, DNS(Zn) could also deliver small interfering RNA (siRNA) with good gene silencing efficiency, extending the application of the liposomes. These results suggest that DNS(Zn) can serve as a highly efficient nucleic acid delivery vector with reduction-responsive fluorescence self-reporting ability in tumor cells.

Zn-Promoted gene transfection efficiency for non-viral vectors: a mechanism study

Mechanism studies revealed that a Zn coordination to cyclen-based cationic polymer may effectively improve the buffering capacity and endosomal escape ability.

Supramolecularly cross-linked amphiphilic block copolymer assembly by the dipolar interaction of a merocyanine dye

Dipolar interaction driven dimerization of a merocyanine (MC) dye has been exploited to achieve non-covalently crosslinked stable micelles in water and reverse micelles in toluene with emissive properties from a MC-pendant amphiphilic block copolymer.

Self-associating cellulose-graft-poly(ε-caprolactone) to design nanoparticles for drug release

The growing interest in the use of polysaccharides nanoparticles for biomedical applications is related to the recent progresses on the synthesis of cellulose-based polymers with the specific functionalities. In particular, cellulose graft copolymers are emerging as amphiphilic materials suitable to fabricate smart nanoparticles for drug delivery applications. In this work, a cellulose-graft-poly(ε-caprolactone) (cell-g-PCL) was synthetized and characterized by FTIR, TGA and DSC in order to validate the synthesis process. We demonstrated that fast evaporation processes promoted cell-g-PCL self-assembly to form nanomicellar structures with hydrodynamic radius ranged from 30 to 60 nm as confirmed by TEM analysis. Moreover, the application of controlled electrostatic forces on solvent evaporation - namely electrospraying - allowed generating round-like nanoscaled particles, as confirmed by SEM supported via image analysis. We demonstrated also that sodium diclofenac (DS) drastically influenced the mechanism of particle formation, favoring the deposition of erythrocyte-like particles with highly concave surfaces, not penalizing the encapsulation efficiency of nanoparticles (>80%). The release profile showed a fast delivery of DS - about 60% during the first 24 h - followed by a sustained release - about 20% during the next 6 days - strictly related to the peculiar weak interactions among amphiphilic polymer segments and water molecules, thus suggesting a successful use of electrosprayed cell-g-PCL nanoparticles for therapeutic treatments in nanomedicine.

Polymeric siRNA gene delivery - transfection efficiency versus cytotoxicity

Within the field of gene therapy, there is a considerable need for the development of non-viral vectors that are able to compete with the efficiency obtained by viral vectors, while maintaining a good toxicity profile and not inducing an immune response within the body. While there have been many reports of possible polymeric delivery systems, few of these systems have been successful in the clinical setting due to toxicity, systemic instability or gene regulation inefficiency, predominantly due to poor endosomal escape and cytoplasmic release. The objective of this review is to provide an overview of previously published polymeric non-coding RNA and, to a lesser degree, oligo-DNA delivery systems with emphasis on their positive and negative attributes, in order to provide insight in the numerous hurdles that still limit the success of gene therapy.

Cationic polymer-derived carbon dots for enhanced gene delivery and cell imaging

Carbon dots have attracted rapidly growing interest in recent years. In this report, we prepared two cationic polymer-derived carbon dots (Taea-CD and Cyclen-CD, collectively called C-dots) via a hydrothermal method. Transmission electron microscopy (TEM) results show that the C-dots were sphere-like and the size distribution was 1.8 ± 0.4 nm for Taea-CD and 5.4 ± 2 nm for Cyclen-CD. The C-dots emitted bright blue fluorescence under UV light (365 nm). Confocal laser scanning microscopy (CLSM) assay indicates that the C-dots-mediated transfection process could be detected in real time, and their tunable fluorescence emission under different wavelengths could satisfy varying requirements. Luciferase assay indicates that the transformation from the polymer to CD is an effective strategy to improve the transfection efficiency (TE) of the materials. Moreover, the C-dots also exhibit higher serum tolerance and cell viability than commercially available polyethyleneimine (PEI). These results demonstrate that the preparation of carbon dots from polymers is a promising method for developing multifunctional gene vectors with high TE and biocompatibility.

A one-pot modular assembly strategy for triple-play enhanced cytosolic siRNA delivery

Robust efficiency for cytosolic small interfering RNA (siRNA) delivery is of great importance for effective gene therapy. To significantly improve the cytosolic siRNA delivery, a "one-pot modular assembly" strategy is developed to assemble a triple-play enhanced cytosolic siRNA delivery system via a facile and innocuous copper-free click reaction. Specifically, three modules are prepared including octreotide for receptor-mediated endocytosis, a cell-penetrating peptide (CPP) for cell penetration, and glutamic acid for the charge-reversal property. All three modules with distinct facilitating endocytosis effects are expediently assembled on the surface of the siRNA/liposome complex to fabricate a multifunctional integrated siRNA delivery system (OCA-CC). OCA-CC has been demonstrated to have enhanced cytosolic delivery and superior gene-silencing efficiency in multiple tumor cells due to the combined effects of all the three modules. High levels of survivin-silencing are also achieved by OCA-CC on orthotopic human breast cancer (MCF-7)-bearing mice accompanied by significant tumor inhibition. This research provides a facile strategy to produce safe and tunable siRNA delivery systems for effective gene therapy and to facilitate the development of multifunctional siRNA vectors.

Enzyme/pH-sensitive polyHPMA-DOX conjugate as a biocompatible and efficient anticancer agent

In this study, to enhance the therapeutic function and reduce the side-effects of doxorubicin (DOX), a biodegradable N-(2-hydroxypropyl) methacrylamide (HPMA) polymer-DOX conjugate has been prepared through reversible addition fragmentation chain transfer (RAFT) polymerization and conjugation chemistry, and the anticancer agent DOX was covalently linked to the polymeric vehicle through a pH-responsive hydrazone bond. The cellular mechanisms of the conjugate were explored, and the therapeutic indexes were studied as well. The high molecular weight (MW) polymeric conjugate (94 kDa) was degraded into products with low MW (45 kDa) in the presence of lysosomal cathepsin B and also showed pH-responsive drug release behavior. In vitro cellular mechanism studies revealed that the polymeric conjugate was uptaken by the 4T1 cells, leading to cell apoptosis and cytotoxicity to cancer cells, while the polymeric conjugate demonstrated excellent in vivo biosafety even at a high dose. Compared to free DOX, the conjugate has a much longer half-life in pharmacokinetics and accumulates in tumors with a much higher amount. The conjugate therefore has a much greater in vivo anticancer efficacy against 4T1 xenograft tumors and shows subtle side-effects, which were confirmed via tumor size and weight, immunohistochemistry and histological studies. Overall, this polymeric conjugate may be used as an enzyme/pH-sensitive anticancer agent.

Controlling CO2 -Responsive Behaviors of Polymersomes Self-Assembled by Coumarin-Containing Star Polymer via Regulating Its Crosslinking Pattern

An oligo(ethylene glycol)-based star polymer of N₂ -(OEG-C)₃ with fluorescent coumarin as hydrophobic end groups and dual tertiary amines as the star center is designed and synthesized. Owing to its amphiphilic nature of N₂ -(OEG-C)₃ , it will self-assemble into hollow vesicles with coumarin groups dispersed in the hydrophobic membrane and exhibits CO₂ -responsive behavior due to the protonation of amine centers with CO₂ . More importantly, coumarin moieties can either form non-crosslinking with γ-cyclodextrin via the 2/1 host-guest inclusion, or covalently photodimerized by 365 nm light, offering a tunable crosslinking pattern in the hydrophobic membrane and thus adjusting its CO₂ -stimulated reorganization and disassembly behaviors of these vesicles in aqueous solution.