Optimising the self-assembly of siRNA loaded PEG-PCL-lPEI nano-carriers employing different preparation techniques

Tyrosine-modified linear PEIs for highly efficacious and biocompatible siRNA delivery in vitro and in vivo

Therapeutic gene silencing by RNA interference relies on the safe and efficient in vivo delivery of small interfering RNAs (siRNAs). Polyethylenimines are among the most studied cationic polymers for gene delivery. For several reasons including superior tolerability, small linear PEIs would be preferable over branched PEIs, but they show poor siRNA complexation. Their chemical modification for siRNA formulation has not been extensively explored so far. We generated a set of small linear PEIs bearing tyrosine modifications (LPxY), leading to substantially enhanced siRNA delivery and knockdown efficacy in vitro in various cell lines, including hard-to-transfect cells. The tyrosine-modified linear 10 kDa PEI (LP10Y) is particularly powerful, associated with favorable physicochemical properties and very high biocompatibility. Systemically administered LP10Y/siRNA complexes reveal antitumor effects in mouse xenograft and patient-derived xenograft (PDX) models, and their direct application into the brain achieves therapeutic inhibition of orthotopic glioma xenografts. LP10Y is particularly interesting for therapeutic siRNA delivery.

Advances in PEG-based ABC terpolymers and their applications

ABC terpolymers are a class of very important polymers because of their expansive molecular topologies and extensive architectures. As block A, poly(ethylene glycol) (PEG) is one of the most principal categories owing to good biocompatibility and wide commercial availability. More importantly, the synthetic approaches of ABC terpolymers using PEG as a macroinitiator are facile and varied. PEG-based ABC terpolymers from design and synthesis to applications are highlighted in this review. Linear, 3-miktoarm, and cyclic polymers as the architecture are separated. The synthetic approaches of PEG-based ABC terpolymers mainly include the sequential polymerization or coupling of polymers. PEG-based ABC terpolymers have wide applications in the fields of drug carriers, gene vectors, templates for the fabrication of inorganic hollow nanospheres, and stabilizers of metal nanoparticles.

Nanostructured Fibers Containing Natural or Synthetic Bioactive Compounds in Wound Dressing Applications

The interest in wound healing characteristics of bioactive constituents and therapeutic agents, especially natural compounds, is increasing because of their therapeutic properties, cost-effectiveness, and few adverse effects. Lately, nanocarriers as a drug delivery system have been actively investigated and applied in medical and therapeutic applications. In recent decades, researchers have investigated the incorporation of natural or synthetic substances into novel bioactive electrospun nanofibrous architectures produced by the electrospinning method for skin substitutes. Therefore, the development of nanotechnology in the area of dressings that could provide higher performance and a synergistic effect for wound healing is needed. Natural compounds with antimicrobial, antibacterial, and anti-inflammatory activity in combination with nanostructured fibers represent a future approach due to the increased wound healing process and regeneration of the lost tissue. This paper presents different approaches in producing electrospun nanofibers, highlighting the electrospinning process used in fabricating innovative wound dressings that are able to release natural and/or synthetic substances in a controlled way, thus enhancing the healing process.

Ionizing radiation attracts tumor targeting and apoptosis by radiotropic lysyl oxidase traceable nanoparticles

Lysyl oxidase (LOX) is a cell-secreted amine oxidase that crosslinks collagen and elastin in extracellular microenvironment. LOX-traceable nanoparticles (LOX_ab-NPs) consisting of LOX antibodies (LOX_ab) and paclitaxel, can accumulate at high concentrations at radiation-treated target sites, as a tumor-targeting drug carrier for chemotherapy. Tumor-targeting and anticancer effects of PLGA based LOX_ab-NPs in vitro and in vivo were evaluated at radiation-targeted site. In the in vivo A549 lung carcinoma xenograft model, we showed highly specific tumor targeting (above 7.0 times higher) of LOX_ab-NPs on irradiated tumors. Notably, systemically administered NPs delayed tumor growth, reducing tumor volumes by more than 2 times compared with non-irradiated groups (222% vs. >500%) over 2 weeks. Radiotropic LOX_ab-NPs can serve as chemotherapeutic vehicles for combined targeted chemo-radiotherapy in clinical oncology.

Physical-chemical measurement method development for self-assembled, core-shell nanoparticles

Improvements in dimensional metrology and innovations in physical-chemical characterization of functionalized nanoparticles are critically important for the realization of enhanced performance and benefits of nanomaterials. Toward this goal, we propose a multi-technique measurement approach, in which correlated atomic force microscopy, dynamic light scattering, high performance liquid chromatography and mass spectroscopy measurements are used to assess molecular and structural properties of self-assembled polyplex nanoparticles with a core-shell structure. In this approach, measurement methods are first validated with a model system consisting of gold nanoparticles functionalized with synthetic polycationic branched polyethylenimine macromolecules. Shell thickness is measured by atomic force microscopy and dynamic light scattering, and the polyelectrolyte uptake determined by chromatographic separation and mass spectrometric analysis. Statistical correlation between size, structure and stability provide a basis for extending the methods to more complex self-assembly of nucleic acids and macromolecules via a condensation reaction. From these size and analytical chemical measurements, we obtain a comprehensive spatial description of these assemblies, obtain a detailed interpretation of the core-shell evolution, and identify regions of the parameter space where stable, discrete particle formation occurs.

Recent advances of controlled drug delivery using microfluidic platforms

Conventional systematically-administered drugs distribute evenly throughout the body, get degraded and excreted rapidly while crossing many biological barriers, leaving minimum amounts of the drugs at pathological sites. Controlled drug delivery aims to deliver drugs to the target sites at desired rates and time, thus enhancing the drug efficacy, pharmacokinetics, and bioavailability while maintaining minimal side effects. Due to a number of unique advantages of the recent microfluidic lab-on-a-chip technology, microfluidic lab-on-a-chip has provided unprecedented opportunities for controlled drug delivery. Drugs can be efficiently delivered to the target sites at desired rates in a well-controlled manner by microfluidic platforms via integration, implantation, localization, automation, and precise control of various microdevice parameters. These features accordingly make reproducible, on-demand, and tunable drug delivery become feasible. On-demand self-tuning dynamic drug delivery systems have shown great potential for personalized drug delivery. This review presents an overview of recent advances in controlled drug delivery using microfluidic platforms. The review first briefly introduces microfabrication techniques of microfluidic platforms, followed by detailed descriptions of numerous microfluidic drug delivery systems that have significantly advanced the field of controlled drug delivery. Those microfluidic systems can be separated into four major categories, namely drug carrier-free micro-reservoir-based drug delivery systems, highly integrated carrier-free microfluidic lab-on-a-chip systems, drug carrier-integrated microfluidic systems, and microneedles. Microneedles can be further categorized into five different types, i.e. solid, porous, hollow, coated, and biodegradable microneedles, for controlled transdermal drug delivery. At the end, we discuss current limitations and future prospects of microfluidic platforms for controlled drug delivery.

A multicomponent microemulsion using rational combination strategy improves lung cancer treatment through synergistic effects and deep tumor penetration

Previously, we have developed a multicomponent-based microemulsion composed of etoposide, coix seed oil, and ginsenoside Rh2 (ECG-MEs). In this study, our goal was to validate the feasibility of ECG-MEs in lung cancer treatment and explore the mechanism underling the enhanced antitumor efficacy. The optimal weight ratio of ginsenoside Rh2 (G-Rh2) in ECG-MEs was determined as 3% (wt%), that was capable of forming the microemulsion readily with small particle size and high drug encapsulation efficiency. In cellular studies, the intracellular fluorescence of human non-small cell lung cancer (A549) cells treated with fluorescein isothiocyanate-labeled ECG-MEs (FITC/ECG-MEs) was significantly higher than that of various controls, leading to the obviously synergistic anticancer activities in cytotoxicity and in vitro cell apoptosis induction. The anticancer efficacy in vivo results showed that ECG-MEs markedly inhibited the growth of A549 tumor xenografts, potently induced tumor cells apoptosis, and obviously prolonged the survival time of mice. Of note, the mechanisms of enhanced anticancer efficiency were connected with the small size-mediated deep tumor penetration and increase in serum concentration of T helper 1 (Th1) cytokines. In summary, ECG-MEs exerting the rational drug combination strategy offers a solid evidence for lung cancer treatment, and has a promising potential for clinical application.

Inhalable siRNA-loaded nano-embedded microparticles engineered using microfluidics and spray drying

Medicines based on small interfering RNA (siRNA) are promising for the treatment of a number of lung diseases. However, efficient delivery systems and design of stable dosage forms are required for inhalation therapy, as well as cost-effective methods for manufacturing of the final product. In this study, a 3D-printed micromixer was used for preparation of siRNA-dendrimer nanocomplexes, which were subsequently processed into microparticle-based dry powders for inhalation using spray drying. By applying the disposable micromixer, nanocomplexes were prepared of an average hydrodynamic diameter comparable to that of nanocomplexes prepared by manual mixing, but with narrower size distribution and low batch-to-batch variation. The nanocomplexes were processed into nanoembedded microparticles using different saccharide excipients. Data showed that siRNA integrity and bioactivity are retained after processing, and nanocomplexes could be reconstituted from the dry powders. The amorphous saccharide excipients trehalose and inulin provided better stabilization than crystalline mannitol, and they enabled full reconstitution of the nanocomplexes. In particular, a binary mixture of trehalose and inulin showed optimal stabilization, and enhanced cellular uptake and gene silencing efficiency. This study demonstrates that inexpensive and scalable micromixers can be used to optimize the production of siRNA-dendrimer nanocomplexes, and they can be applied in combination with spray drying for the engineering of dry powder formulations suitable for delivery of siRNA to the therapeutic target site.

The impact of microfluidic mixing of triblock micelleplexes on in vitro / in vivo gene silencing and intracellular trafficking

The triblock copolymer polyethylenimine-polycaprolactone-polyethylene glycol (PEI-PCL-PEG) has been shown to spontaneously assemble into nano-sized particulate carriers capable of complexing with nucleic acids for gene delivery. The objective of this study was to investigate micelleplex characteristics, their in vitro and in vivo fate following microfluidic preparation of siRNA nanoparticles compared to the routinely used batch reactor mixing technique. Herein, PEI-PCL-PEG nanoparticles were prepared with batch reactor or microfluidic mixing techniques and characterized by various biochemical assays and in cell culture. Microfluidic nanoparticles showed a reduction of overall particle size as well as a more uniform size distribution when compared to batch reactor pipette mixing. Confocal microscopy, flow cytometry and qRT-PCR displayed the subcellular delivery of the microfluidic formulation and confirmed the ability to achieve mRNA knockdown. Intratracheal instillation of microfluidic formulation resulted in a significantly more efficient (p < 0.05) knockdown of GAPDH compared to treatment with the batch reactor formulation. The use of microfluidic mixing techniques yields an overall smaller and more uniform PEG-PCL-PEI nanoparticle that is able to more efficiently deliver siRNA in vivo. This preparation method may prove to be useful when a scaled up production of well-defined polyplexes is required.

PEG-PCL-based nanomedicines: A biodegradable drug delivery system and its application

The lack of efficient therapeutic options for many severe disorders including cancer spurs demand for improved drug delivery technologies. Nanoscale drug delivery systems based on poly(ethylene glycol)-poly(ε-caprolactone) copolymers (PEG-PCL) represent a strategy to implement therapies with enhanced drug accumulation at the site of action and decreased off-target effects. In this review, we discuss state-of-the-art nanomedicines based on PEG-PCL that have been investigated in a preclinical setting. We summarize the various synthesis routes and different preparation methods used for the production of PEG-PCL nanoparticles. Additionally, we review physico-chemical properties including biodegradability, biocompatibility, and drug loading. Finally, we highlight recent therapeutic applications investigated in vitro and in vivo using advanced systems such as triggered release, multi-component therapies, theranostics, or gene delivery systems.

Continuous microfluidic assembly of biodegradable poly(beta-amino ester)/DNA nanoparticles for enhanced gene delivery

Translation of biomaterial-based nanoparticle formulations to the clinic faces significant challenges including efficacy, safety, consistency and scale-up of manufacturing, and stability during long-term storage. Continuous microfluidic fabrication of polymeric nanoparticles has the potential to alleviate the challenges associated with manufacture, while offering a scalable solution for clinical level production. Poly(beta-amino esters) (PBAE)s are a class of biodegradable cationic polymers that self-assemble with anionic plasmid DNA to form polyplex nanoparticles that have been shown to be effective for transfecting cancer cells specifically in vitro and in vivo. Here, we demonstrate the use of a microfluidic device for the continuous and scalable production of PBAE/DNA nanoparticles followed by lyophilization and long term storage that results in improved in vitro efficacy in multiple cancer cell lines compared to nanoparticles produced by bulk mixing as well as in comparison to widely used commercially available transfection reagents polyethylenimine and Lipofectamine® 2000. We further characterized the nanoparticles using nanoparticle tracking analysis (NTA) to show that microfluidic mixing resulted in fewer DNA-free polymeric nanoparticles compared to those produced by bulk mixing. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1813-1825, 2017.

Powering up the molecular therapy of RNA interference by novel nanoparticles

With more suitable for disease treatment due to reduced cellular toxicity, higher loading capacity, and better biocompatibility, nanoparticle-based siRNA delivery systems have proved to be more potent, higher specific and less toxic than the traditional drug therapy.

One-pot Synthesis of Functional Poly(amino ester sulfide)s and Utility in Delivering pDNA and siRNA

The development of efficacious carriers is an important long-standing challenge in gene therapy. In the past few decades, tremendous progress has been made toward non-viral vectors for gene delivery including cationic lipids and polymers. However, there continues to be a need for clinically translatable polymer-based delivery carriers because they offer tunable degradation profiles and functional groups, diverse structures/morphologies, and scalability in preparation. Herein, we developed a library of 144 degradable polymers with varying amine and hydrophobic content via a facile method that involves thiobutyrolactone aminolysis and consequent thiol-(meth)acrylate or acrylamide addition in one-pot. The polymer platform was evaluated for pDNA and siRNA delivery to HeLa cells in vitro. Hydrophobically modified 5S, 2E1, 6CY1, 5CY2, and 2M1 grafted HEMATL polymers are capable of delivering pDNA depending on the chemical composition and the size of the polyplexes. Hydrophobically modified 5S and 2B grafted HEMATL and 5S grafted ATL polymers exhibit capability for siRNA delivery that approaches the efficacy of commercially available transfection reagents. Due to tunable functionality and scalable preparation, this synthetic approach may have broad applicability in the design of delivery materials for gene therapy.

Smart Dressings Based on Nanostructured Fibers Containing Natural Origin Antimicrobial, Anti-Inflammatory, and Regenerative Compounds

A fast and effective wound healing process would substantially decrease medical costs, wound care supplies, and hospitalization significantly improving the patients' quality of life. The search for effective therapeutic approaches seems to be imperative in order to avoid the aggravation of chronic wounds. In spite of all the efforts that have been made during the recent years towards the development of artificial wound dressings, none of the currently available options combine all the requirements necessary for quick and optimal cutaneous regeneration. Therefore, technological advances in the area of temporary and permanent smart dressings for wound care are required. The development of nanoscience and nanotechnology can improve the materials and designs used in topical wound care in order to efficiently release antimicrobial, anti-inflammatory and regenerative compounds speeding up the endogenous healing process. Nanostructured dressings can overcome the limitations of the current coverings and, separately, natural origin components can also overcome the drawbacks of current antibiotics and antiseptics (mainly cytotoxicity, antibiotic resistance, and allergies). The combination of natural origin components with demonstrated antibiotic, regenerative, or anti-inflammatory properties together with nanostructured materials is a promising approach to fulfil all the requirements needed for the next generation of bioactive wound dressings. Microbially compromised wounds have been treated with different essential oils, honey, cationic peptides, aloe vera, plant extracts, and other natural origin occurring antimicrobial, anti-inflammatory, and regenerative components but the available evidence is limited and insufficient to be able to draw reliable conclusions and to extrapolate those findings to the clinical practice. The evidence and some promising preliminary results indicate that future comparative studies are justified but instead of talking about the beneficial or inert effects of those natural origin occurring materials, the scientific community leads towards the identification of the main active components involved and their mechanism of action during the corresponding healing, antimicrobial, or regenerative processes and in carrying out systematic and comparative controlled tests. Once those natural origin components have been identified and their efficacy validated through solid clinical trials, their combination within nanostructured dressings can open up new avenues in the fabrication of bioactive dressings with outstanding characteristics for wound care. The motivation of this work is to analyze the state of the art in the use of different essential oils, honey, cationic peptides, aloe vera, plant extracts, and other natural origin occurring materials as antimicrobial, anti-inflammatory and regenerative components with the aim of clarifying their potential clinical use in bioactive dressings. We conclude that, for those natural occurring materials, more clinical trials are needed to reach a sufficient level of evidence as therapeutic agents for wound healing management.

Biomaterials-based nanofiber scaffold: targeted and controlled carrier for cell and drug delivery

Nanofiber scaffold formulations (diameter less than 1000 nm) were successfully used to deliver the drug/cell/gene into the body organs through different routes for an effective treatment of various diseases. Various fabrication methods like drawing, template synthesis, fiber-mesh, phase separation, fiber-bonding, self-assembly, melt-blown, and electrospinning are successfully used for fabrication of nanofibers. These formulations are widely used in various fields such as tissue engineering, drug delivery, cosmetics, as filter media, protective clothing, wound dressing, homeostatic, sensor devices, etc. The present review gives a detailed account on the need of the nanofiber scaffold formulation development along with the biomaterials and techniques implemented for fabrication of the same against innumerable diseases. At present, there is a huge extent of research being performed worldwide on all aspects of biomolecules delivery. The unique characteristics of nanofibers such as higher loading efficiency, superior mechanical performance (stiffness and tensile strength), controlled release behavior, and excellent stability helps in the delivery of plasmid DNA, large protein drugs, genetic materials, and autologous stem-cell to the target site in the future.

Transferrin- and folate-modified, double-targeted nanocarriers for gene delivery

CONTEXT

Surface modification of nanocarriers with specific ligands defines a new biological identity, which assist in targeting and internalization of the nanocarriers to specific cell populations, such as cancers and disease organs.

OBJECTIVE

This study aimed to develop systemically administrable dual ligands modified nanocarriers, which could target the cells through receptor-mediated pathways to increase the nuclear uptake of genetic materials.

MATERIALS AND METHODS

In the present work, transferrin (Tf) and folate (Fa) were linked onto polyethylene glycol-phosphatidylethanolamine (PEG-PE) separately to get transferrin-PEG-PE (T-PEG-PE) and folate-PEG-PE (F-PEG-PE) ligands for the surface modification of carriers. The in vivo transfection efficiency of the novel dual ligands modified (D-modified) vectors were evaluated in tumor-bearing animal models.

RESULTS

D-Modified solid lipid nanoparticles/enhanced green fluorescence protein plasmid (D-SLN/pEGFP) has a particle size of 226 nm and a gene-loading quantity of 90%. D-SLN/pEGFP displayed over 30% higher transfection efficiency than unmodified SLN/pEGFP and single ligand modified particles in HepG2 cells.

CONCLUSION

It could be concluded that Tf and Fa could function as excellent active targeting ligands to improve the cell-targeting ability of the carriers and the resulting dual ligands modified vectors could be applied as a promising active targeting gene delivery system.

Amphiphilic biodegradable PEG-PCL-PEI triblock copolymers for FRET-capable in vitro and in vivo delivery of siRNA and quantum dots

Amphiphilic triblock copolymers represent a versatile delivery platform capable of co-delivery of nucleic acids, drugs, and/or dyes. Multifunctional cationic triblock copolymers based on poly(ethylene glycol), poly-ε-caprolactone, and polyethylene imine, designed for the delivery of siRNA, were evaluated in vitro and in vivo. Moreover, a nucleic acid-unpacking-sensitive imaging technique based on quantum dot-mediated fluorescence resonance energy transfer (QD-FRET) was established. Cell uptake in vitro was measured by flow cytometry, whereas transfection efficiencies of nanocarriers with different hydrophilic block lengths were determined in vitro and in vivo by quantitative real-time PCR. Furthermore, after the proof of concept was demonstrated by fluorescence spectroscopy/microscopy, a prototype FRET pair was established by co-loading QDs and fluorescently labeled siRNA. The hydrophobic copolymer mediated a 5-fold higher cellular uptake and good knockdown efficiency (61 ± 5% in vitro, 55 ± 18% in vivo) compared to its hydrophilic counterpart (13 ± 6% in vitro, 30 ± 17% in vivo), which exhibited poor performance. FRET was demonstrated by UV-induced emission of the acceptor dye. Upon complex dissociation, which was simulated by the addition of heparin, a dose-dependent decrease in FRET efficiency was observed. We believe that in vitro/in vivo correlation of the structure and function of polymeric nanocarriers as well as sensitive imaging functionality for mechanistic investigations are prerequisites for a more rational design of amphiphilic gene carriers.

Microfluidics-assisted in vitro drug screening and carrier production

Microfluidic platforms provide several unique advantages for drug development. In the production of drug carriers, physical properties such as size and shape, and chemical properties such as drug composition and pharmacokinetic parameters, can be modified simply and effectively by tuning the flow rate and geometries. Large numbers of carriers can then be fabricated with minimal effort and with little to no batch-to-batch variation. Additionally, cell or tissue culture models in microfluidic systems can be used as in vitro drug screening tools. Compared to in vivo animal models, microfluidic drug screening platforms allow for high-throughput and reproducible screening at a significantly lower cost, and when combined with current advances in tissue engineering, are also capable of mimicking native tissues. In this review, various microfluidic platforms for drug and gene carrier fabrication are reviewed to provide guidelines for designing appropriate carriers. In vitro microfluidic drug screening platforms designed for high-throughput analysis and replication of in vivo conditions are also reviewed to highlight future directions for drug research and development.

Design of polyethylene glycol-polyethylenimine nanocomplexes as non-viral carriers: mir-150 delivery to chronic myeloid leukemia cells

MicroRNAs (miRNAs) are acknowledged as indispensable regulators relevant in many biological processes, and they have been pioneered as therapeutic targets for curing disease. miRNAs are single-stranded, small (19-22 nt) regulatory non-coding RNAs whose deregulation of expression triggers human cancers, including leukemias, mainly through dysregulation of expression of leukemia genes. miRNAs can function as tumour suppressors (suppressing malignant potential) or oncogenes (activating malignant potential) like actors of complex diseases. To address the issue of overcoming instability and low transfection efficiency in vitro, the polyethylene glycol-polyethyleneimine (PEG-PEI) nanoparticle was used as non-viral vector carrier for miR-150 transfection, which is downregulated in chronic myeloid leukemia. PEG-PEI [PEG(550)3 -g-PEI(1800) ]/miRNA nanocomplexes were synthesised and characterised by particle size distribution (PSD), polydispersity index (PDI) and zeta potential, surface charge, their cytotoxicity, and transfection efficiency. Interaction with human leukemia cells (K-562 and KU812) and control cells NCI-BL2347 with them has been investigated. The transfection efficiency of PEG-PEI/miRNA at N/P 26 rose 6.7-fold above the control by qRT-PCR. The size of homogenous nanocomplexes (PBI < 0.5) was 160.8 ± 11 nm. The data indicate that PEG-PEI may be an encouraging non-viral carrier for altering miRNA expression in the treatment of chronic myeloid leukemia, with many advantages such as relatively high miRNA transfection efficiency and low cytotoxicity.

Dual ligands modified double targeted nano-system for liver targeted gene delivery

CONTEXT

It is now well established that the surface of nanocarriers with specific ligands defines a new biological identity, which assist in targeting and internalization of the nanocarriers to specific cell populations, such as cancers and disease organs.

OBJECTIVE

The aim of this study is to develop systemically administrable dual ligands modified nano-system which could both target cancer cells and macrophages in the liver.

METHODS

Transferrin (Tf) and mannan (M) were linked onto polyethylene glycol-phosphatidylethanolamine (PEG-PE) and PE separately to get transferrin-PEG-PE (T-PEG-PE) and mannan-PE (M-PE) ligands for the surface modification of carriers. The in vivo transfection efficiency of the novel dual ligands modified (D-modified) vectors were evaluated in tumor bearing animal models.

RESULTS

D-modified solid lipid nanoparticles/enhanced green fluorescence protein plasmid (D-SLN/pEGFP) has a particle size of 198 nm and a gene loading quantity of 89%. D-SLN/pEGFP displayed over 25% higher transfection efficiency than M-PE modified SLN/pEGFP (M-SLN/pEGFP) in HepG2 cells and T-PEG-PE modified SLN/pEGFP (T-SLN/pEGFP) in Kupffer cells (KCs) isolated from mice.

CONCLUSION

It could be concluded that T-PEG-PE and M-PE could function as excellent active targeting ligands to improve the cell targeting ability of the carriers and the dual ligands modified vectors could be applied as a promising active targeting gene delivery system.

Degradable cationic shell cross-linked knedel-like nanoparticles: synthesis, degradation, nucleic acid binding, and in vitro evaluation

In this work, degradable cationic shell cross-linked knedel-like (deg-cSCK) nanoparticles were developed as an alternative platform to replace similar nondegradable cSCK nanoparticles that have been utilized for nucleic acids delivery. An amphiphilic diblock copolymer poly(acrylamidoethylamine)(90)-block-poly(DL-lactide)(40) (PAEA(90)-b-PDLLA(40)) was synthesized, self-assembled in aqueous solution, and shell cross-linked using a hydrolyzable cross-linker to afford deg-cSCKs with an average core diameter of 45 ± 7 nm. These nanoparticles were fluorescently labeled for in vitro tracking. The enzymatic- and hydrolytic-degradability, siRNA binding affinity, cell uptake and cytotoxicity of the deg-cSCKs were evaluated. Esterase-catalyzed hydrolysis of the nanoparticles resulted in the degradation of ca. 24% of the PDLLA core into lactic acid within 5 d, as opposed to only ca. 9% degradation from aqueous solutions of the deg-cSCK nanoparticles in the absence of enzyme. Cellular uptake of deg-cSCKs was efficient, while exhibiting low cytotoxicity with LD50 values of ca. 90 and 30 μg/mL in RAW 264.7 mouse macrophages and MLE 12 cell lines, respectively, ca. 5- to 6-fold lower than the cytotoxicity observed for nondegradable cSCK analogs. Additionally, deg-cSCKs were able to complex siRNA at an N/P ratio as low as 2, and were efficiently able to facilitate cellular uptake of the complexed nucleic acids.

A linear polyethylenimine mediated siRNA-based therapy targeting human epidermal growth factor receptor in SPC-A1 xenograft mice

Background

Linear polyethylenimine (LPEI) is considered as a desirable gene in vivo delivery system, but whether it could deliver the specific siRNA targeted EGFR to the tumor site to inhibit the growth of NSCLC xenograft in nude mice still needs to be examined.

Methods

In this study, LPEI/siRNA was made into a complex and SPC-A1-xenografted mice model was established. Then, stable LPEI/siRNA-EGFR complexes were intraperitoneally administrated. Afterwards, tumor growth was measured every 3 days. At the end of the experiment, tumor volume was calculated, and tumors were weighed, and examined for EGFR expression, proliferation, and apoptosis evaluations. By using blood samples, toxicity tests including aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea and creatinine (Cr) were measured for liver and renal function evaluation. Serum concentrations of TNF-α and IFN-γ were also examined.

Results

Our results demonstrated that LPEI/siRNA-EGFR complexes could downregulate EGFR expression in SPC-A1 xenografted tumor upon single i.p. injection. LPEI/siRNA-EGFR complexes inhibited tumor growth and did not induce organ toxicity in SPC-A1-xenografted mice. At the end of the experiment no significant IFN-α increase was detected in LPEI/siRNA complexes or glucose-treated groups.

Conclusions

The novel modality of siRNA-based therapy targeting EGFR may be of great potential in NSCLC treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/2213-0802-1-2) contains supplementary material, which is available to authorized users.

Advanced materials and processing for drug delivery: the past and the future

Design and synthesis of efficient drug delivery systems are of vital importance for medicine and healthcare. Materials innovation and nanotechnology have synergistically fueled the advancement of drug delivery. Innovation in material chemistry allows the generation of biodegradable, biocompatible, environment-responsive, and targeted delivery systems. Nanotechnology enables control over size, shape and multi-functionality of particulate drug delivery systems. In this review, we focus on the materials innovation and processing of drug delivery systems and how these advances have shaped the past and may influence the future of drug delivery.

Enhancing in vivo circulation and siRNA delivery with biodegradable polyethylenimine-graft-polycaprolactone-block-poly(ethylene glycol) copolymers

The purpose of this study was to enhance the in vivo blood circulation time and siRNA delivery efficiency of biodegradable copolymers polyethylenimine-graft-polycaprolactone-block-poly(ethylene glycol) (hy-PEI-g-PCL-b-PEG) by introducing high graft densities of PCL-PEG chains. SYBR(®) Gold and heparin assays indicated improved stability of siRNA/copolymer-complexes with a graft density of 5. At N/P 1, only 40% siRNA condensation was achieved with non-grafted polymer, but 95% siRNA was condensed with copolymer PEI25k-(PCL570-PEG5k)(5). Intracellular uptake studies with confocal laser scanning microscopy and flow cytometry showed that the cellular uptake was increased with graft density, and copolymer PEI25k-(PCL570-PEG5k)(5) was able to deliver siRNA much more efficiently into the cytosol than into the nucleus. The in vitro knockdown effect of siRNA/hyPEI-g-PCL-b-PEG was also significantly improved with increasing graft density, and the most potent copolymer PEI25k-(PCL570-PEG5k)(5) knocked down 84.43% of the GAPDH expression. Complexes of both the copolymers with graft density 3 and 5 circulated much longer than unmodified PEI25 kDa and free siRNA, leading to a longer elimination half-life, a slower clearance and a three- or fourfold increase of the AUC compared to free siRNA, respectively. We demonstrated that the graft density of the amphiphilic chains can enhance the siRNA delivery efficiency and blood circulation, which highlights the development of safe and efficient non-viral polymeric siRNA nanocarriers that are especially stable and provide longer circulation in vivo.