Polyethylenimine-carbon nanotube nanohybrids for siRNA-mediated gene silencing at cellular level

Targeted delivery of LXR-agonists to atherosclerotic lesions mediated by polydiacetylene micelles

We report the development of compact and stabilized micelles incorporating a synthetic LXR agonist prodrug for the passive targeting of atherosclerotic lesions and therapeutic intervention. In vivo studies showed that the nanohybrid micelles exhibited favorable pharmacokinetics/biodistribution and were able to upregulate, to some extent, LXR target genes with no alteration of lipid metabolism.

Carbon-based nanostructures for cancer therapy and drug delivery applications

Synthesis, design, characterization, and application of carbon-based nanostructures (CBNSs) as drug carriers have attracted a great deal of interest over the past half of the century because of their promising chemical, thermal, physical, optical, mechanical, and electrical properties and their structural diversity. CBNSs are well-known in drug delivery applications due to their unique features such as easy cellular uptake, high drug loading ability, and thermal ablation. CBNSs, including carbon nanotubes, fullerenes, nanodiamond, graphene, and carbon quantum dots have been quite broadly examined for drug delivery systems. This review not only summarizes the most recent studies on developing carbon-based nanostructures for drug delivery (e.g. delivery carrier, cancer therapy and bioimaging), but also tries to deal with the challenges and opportunities resulting from the expansion in use of these materials in the realm of drug delivery. This class of nanomaterials requires advanced techniques for synthesis and surface modifications, yet a lot of critical questions such as their toxicity, biodistribution, pharmacokinetics, and fate of CBNSs in biological systems must be answered.

Carbon-based Nanomaterials for delivery of small RNA molecules: a focus on potential cancer treatment applications

BACKGROUND

Nucleic acid-mediated therapy holds immense potential in the treatment of recalcitrant human diseases such as cancer. This is underscored by advances in understanding the mechanisms of gene regulation. In particular, the endogenous protective mechanism of gene silencing known as RNA interference (RNAi) has been extensively exploited.

METHODS

We review here the developments from 2011 to 2021, in the use of nanographene oxide, carbon nanotubes, fullerenes, carbon nanohorns, carbon nanodots and nanodiamonds for the delivery of therapeutic small RNA molecules.

RESULTS

Appropriately designed effector molecules such as small interfering RNA (siRNA), can, in theory, silence the expression of any disease-causing gene. Alternatively, siRNA can be generated in vivo through the introduction of plasmid-based short hairpin RNA (shRNA) expression vectors. Other small RNAs such as micro RNA (miRNA) also function in post-transcriptional gene regulation and are aberrantly expressed under disease conditions. The miRNA-based therapy involves either restoration of miRNA function through the introduction of miRNA mimics; or the inhibition of miRNA function by delivering anti-miRNA oligomers. However, the large size, hydrophilicity, negative charge and nuclease-sensitivity of nucleic acids necessitate an appropriate carrier for their introduction as medicine into cells.

CONCLUSION

While numerous organic and inorganic materials have been investigated for this purpose, the perfect carrier agent remains elusive. In recent years, carbon-based nanomaterials have received widespread attention in biotechnology due to their tunable surface characteristics, mechanical, electrical, optical and chemical properties.

Cell-based high-throughput screening of cationic polymers for efficient DNA and siRNA delivery

Development of non-viral gene vectors which can efficiently and safely transfect plasmid DNA and siRNA into cells is of great importance for gene therapy. Despite lots of efforts spent, it is still imperative to develop suitable gene vectors with better transfection efficiency and low cytotoxicity. To this end, we successfully designed, synthesized and screened a library of 120 polymers (via nucleophilic substitution reaction between dihalides and amines). With cell-based transfection screening assays, 120 polymers were tested to evaluate their transfection efficiency of transporting DNA and siRNA into cells. Our results indicated that hydrophobic modification could greatly enhance cationic polymers' transfection efficiency, and polymers with long linkers usually showed better transfection performance, especially for polymers with the linker of 1, 12-dibromododecane (L3 linker). Besides, polyalkylamines exhibited better transfection efficiency with the polymer particle size around 200 nm and the zeta potential in the range of + 40 mV to +50 mV. Interestingly, polymer particles made from N15HL3 not only exhibited better DNA transfection efficiency in HEK 293T cells but also showed higher siRNA transfection efficiency in U87 Luc-GFP cells together with low cell toxicity than Lipofectamine 2000 (one of commercial transfection reagents). Therefore, it is hoped that our study here not only provides promising gene vector candidates for further evaluation in gene therapy, but also provides valuable insights for better understanding of the relationship between the chemical structures and gene transfection efficiency to rationally design better non-viral gene vectors for gene therapy in the future.

Tuning the cationic interface of simple polydiacetylene micelles to improve siRNA delivery at the cellular level

Polydiacetylene micelles were assembled from four different cationic amphiphiles and photopolymerized to reinforce their architecture. The produced micelles were systematically investigated, in interaction with siRNAs, for intracellular delivery of the silencing nucleic acids. The performances of the carrier systems were rationalized based on the cell penetrating properties of the micelles and the nature of their cationic complexing group, responsible for efficient siRNA binding and further endosomal escape.

Gene Delivery to Tobacco Root Cells with Single-Walled Carbon Nanotubes and Cell-Penetrating Fusogenic Peptides

Development of efficient, easy, and safe gene delivery methods is of great interest in the field of plant biotechnology. Considering the limitations of the usual transfection methods (such as transgene size and plant type), several new techniques have been tested for replacement. The success of some biological and synthetic nanostructures such as cell-penetrating peptides and carbon nanotubes in transferring macromolecules (proteins and nucleic acids) into mammalian cells provoked us to assess the ability of an engineered chimeric peptide and also arginine functionalized single-walled carbon nanotube in gene delivery to intact tobacco (Nicotiana tabacum var. Virginia) root cells. It was suggested that the engineered peptide with its special cationic and hydrophobic domains and the arginine functionalized single-walled carbon nanotube due to its nano-cylindrical shape can pass plant cell barriers while plasmid DNA (which codes green fluorescent protein) has been condensed on them. The success of gene delivery to tobacco root cells was confirmed by fluorescence microscopy and western blotting analysis.

The Yin and Yang of carbon nanomaterials in atherosclerosis

With unique characteristics such as high surface area, capacity of various functionalization, low weight, high conductivity, thermal and chemical stability, and free radical scavenging, carbon nanomaterials (CNMs) such as carbon nanotubes (CNTs), fullerene, graphene (oxide), carbon nanohorns (CNHs), and their derivatives have increasingly been utilized in nanomedicine and biomedicine. On the one hand, owing to ever-increasing applications of CNMs in technological and industrial fields as well as presence of combustion-derived CNMs in the ambient air, the skepticism has risen over the adverse effects of CNMs on human being. The influences of CNMs on cardiovascular system and cardiovascular diseases (CVDs) such as atherosclerosis, of which consequences are ischemic heart disease and ischemic stroke, as the main causes of death, is of paramount importance. In this regard, several studies have been devoted to specify the biomedical applications and cardiovascular toxicity of CNMs. Therefore, the aim of this review is to specify the roles and applications of various CNMs in atherosclerosis, and also identify the key role playing parameters in cardiovascular toxicity of CNMs so as to be a clue for prospective deployment of CNMs.

Biomedical applications of carbon nanomaterials: Drug and gene delivery potentials

One of the major components in the development of nanomedicines is the choice of the right biomaterial, which notably determines the subsequent biological responses. The popularity of carbon nanomaterials (CNMs) has been on the rise due to their numerous applications in the fields of drug delivery, bioimaging, tissue engineering, and biosensing. Owing to their considerably high surface area, multifunctional surface chemistry, and excellent optical activity, novel functionalized CNMs possess efficient drug-loading capacity, biocompatibility, and lack of immunogenicity. Over the past few decades, several advances have been made on the functionalization of CNMs to minimize their health concerns and enhance their biosafety. Recent evidence has also implied that CNMs can be functionalized with bioactive peptides, proteins, nucleic acids, and drugs to achieve composites with remarkably low toxicity and high pharmaceutical efficiency. This review focuses on the three main classes of CNMs, including fullerenes, graphenes, and carbon nanotubes, and their recent biomedical applications.

Creative use of analytical techniques and high-throughput technology to facilitate safety assessment of engineered nanomaterials

With the rapid development and numerous applications of engineered nanomaterials (ENMs) in science and technology, their impact on environmental health and safety should be considered carefully. This requires an effective platform to investigate the potential adverse effects and hazardous biological outcomes of numerous nanomaterials and their formulations. We consider predictive toxicology a rational approach for this effort, which utilizes mechanism-based in vitro high-throughput screening (HTS) to make predictions on ENMs' adverse outcomes in vivo. Moreover, this approach is able to link the physicochemical properties of ENMs to toxicity that allows the development of structure-activity relationships (SARs). To build this predictive platform, extensive analytical and bioanalytical techniques and tools are required. In this review, we described the predictive toxicology approach and the accompanying analytical and bioanalytical techniques. In addition, we elaborated several successful examples as a result of using the predictive approach.

Functionalization of Halloysite Nanotubes via Grafting of Dendrimer for Efficient Intracellular Delivery of siRNA

Here, polyamidoamine grafted halloysite nanotubes (PAMAM- g-HNTs) were synthesized for loading of siRNA in order to intracellular delivery of siRNA and treat of breast cancer via gene therapy. The successful grafting of PAMAM on HNTs was confirmed by various analytical methods. The size, zeta potential, and grafting ratio of PAMAM- g-HNTs is ∼206.2 nm, +19.8 mV, and 3.04%, respectively. PAMAM- g-HNTs showed good cytocompatibility toward HUVECs (84.7%) and MCF-7 cells (82.3%) even at high concentration of 100 μg/mL. PAMAM- g-HNTs/siRNA exhibited enhanced cellular uptake efficiency of 94.3% compared with Lipofectamine 2000 (Lipo2000)/siRNA (83.6%). PAMAM- g-HNTs/small interfering RNA-vascular endothelial growth factor (siVEGF) led to 78.0% knockdown of cellular VEGF mRNA and induced 33.6% apoptosis in the MCF-7 cells, which is also much higher than that of Lipo2000/siVEGF. In vivo anti-cancer results demonstrated that PAMAM- g-HNTs/siVEGF treated 4T1-bearing mice showed enhanced anti-cancer efficacy than Lipo2000/siVEGF group. Also, the nanocarrier system showed negligible toxic effects toward the major organs of mice. In vivo fluorescence imaging studies showed that there is a slight decrease in the fluorescence signal of PAMAM- g-HNTs/cy5-siVEGF after 72 h post-injection. Therefore, PAMAM- g-HNTs show promising application as novel nanovectors for siRNA delivery and gene therapy of cancer.

Ultrasonic synthesis and characterization of poly(acrylamide)-co-poly(vinylimidazole)@MWCNTs composite for use as an electrochemical material

Applying a nanocomposite to increase the conductivity of an electrode can facilitate electrochemical analysis. In this regard, multi-walled carbon nanotubes (MWCNTs) evenly dispersed in hydrophilic solution can play an important role in electrochemical bio-sensing due to their unique properties, such as their high electrical conductivity and ability to conjugate with hydrophilic enzymes. Herein, we report the simple ultrasonic synthesis of a highly dispersible, enzyme-binding nanocomposite, poly(acrylamide)-co-poly(vinyl imidazole) (7:1 mol ratio)-MWCNTs (PAA-PVI@MWCNTs). This material, having a zeta potential of 36.6 ± 0.53 mV, was applied as a film to an electrode surface and stably bound with glucose oxidase to transfer an electron between the enzyme and electrode in the presence of glucose. The PAA-PVI@MWCNTs composite, which was readily dispersed in deionized water, can be used as a biocompatible material for applications such as bio-sensing, point-of-care testing (POCT), and other health care functions.

A precision-guided MWNT mediated reawakening the sunk synergy in RAS for anti-angiogenesis lung cancer therapy

Multi-walled carbon nanotube (MWNT) with its versatility has exhibited tremendous superiority in drug delivery. Despite plenty of researches on MWNT based delivery systems, precision-guided assistances to maximize their profitable properties are still lacking in substantive progress. We developed here a dual-targeting and co-delivery system based on MWNT for antiangiogenesis therapy in lung cancer which aimed at renin-angiotensin system (RAS) dysregulation by synergistically conducting angiotensin II type 1 receptor (AT₁R) and type 2 receptor (AT₂R) pathway. In this work, iRGD peptide connected to polyethyleneimine (PEI) was linked to MWNT skeleton, accompanying with candesartan (CD) conjugated to MWNT mediated by cystamine (SS). The functionalized MWNT is assembled with plasmid AT₂ (pAT₂) to form iRGD-PEI-MWNT-SS-CD/pAT₂ complexes. iRGD and CD act as pilots for complexes to dually target symbolic ανβ3-integrin and AT₁R both overexpressed on tumor angiogenic endothelium and lung cancer cell. CD as chemotherapy showed synergistic downregulation of VEGF when combining of pAT₂ and efficiently inhibited angiogenesis. iRGD-PEI-MWNT-SS-CD/pAT₂ complexes greatly appreciated drug activities by changing drug distribution and exhibited remarkable tumor growth suppression in A549 xenograft nude mice. Our work presents that such dual-targeting strategy highly improves the delivery performance of MWNT and open a new avenue for RAS related lung cancer therapy.

Evaluation of chemical modification effects on DNA plasmid transfection efficiency of single-walled carbon nanotube-succinate- polyethylenimine conjugates as non-viral gene carriers

Polyethylenimine (PEI) is a widely used non-viral vector for DNA delivery. One major obstacle of higher molecular weight PEIs is the increased cytotoxicity despite the improved transfection efficiency and numerous chemical modifications that have been reported to overcome this problem. Carbon nanotubes (CNT) are carbon nanomaterials capable of penetrating into cell membranes with no cytotoxic effects. Covalent and noncovalent functionalization methods have been used to improve their solubility in aqueous media. The idea of conjugating PEIs and CNT through different chemical bonds and linkers seems promising as it may result in highly effective carriers due to combination of the transfection ability of PEI with cell internalization of CNT. In this study, six different water-soluble PEI conjugates of single-walled carbon nanotubes (SWNTs) were prepared by grafting PEI with one of three molecular weights (1.8, 10 and 25 kDa) through succinate as a linker which refers to "an organic moiety through which a SWNT is conjugated to PEI." The succinate linker was introduced to the surface of SWNTs through two different chemical strategies: a) ester and b) acyl linkages. The resulting SWNT-PEI vectors were characterized by IR spectroscopy, thermogravimetric analysis (TGA) and SEM imaging. All synthesized carriers were evaluated and compared for their cytotoxicity and transfection efficiency in murine neuroblastoma cells as polyplexes with plasmid DNA for luciferase and green fluorescent protein (GFP). The most efficient carriers were prepared by attaching PEI with the lowest molecular weight (1.8 kDa) through acyl linkage, which gave a transfection efficiency 190-fold greater than that of the corresponding free PEI. Transfection efficiency was the highest in polyplexes prepared with acyl-linked conjugates in all the plasmid/vector ratios studied.

Cationic DOPC-Detergent Conjugates for Safe and Efficient in Vitro and in Vivo Nucleic Acid Delivery

The ability of a nonviral nucleic acid carrier to deliver its cargo to cells with low associated toxicity is a critical issue for clinical applications of gene therapy. We describe biodegradable cationic DOPC-C12 E4 conjugates in which transfection efficiency is based on a Trojan horse strategy. In situ production of the detergent compound C12 E4 through conjugate hydrolysis within the acidic endosome compartment was expected to promote endosome membrane destabilization and subsequent release of the lipoplexes into cytosol. The transfection efficiency of the conjugates has been assessed in vitro, and associated cytotoxicity was determined. Cellular uptake and intracellular distribution of the lipoplexes have been investigated. The results show that direct conjugation of DOPC with C12 E4 produces a versatile carrier that can deliver both DNA and siRNA to cells in vitro with high efficiency and low cytotoxicity. SAR studies suggest that this compound might represent a reasonable compromise between the membrane activity of the released detergent and susceptibility of the conjugate to degradation enzymes in vitro. Although biodegradability of the conjugates had low impact on carrier efficiency in vitro, it proved critical in vivo. Significant improvement of transgene expression was obtained in the mouse lung tuning biodegradability of the carrier. Importantly, this also allowed reduction of the inflammatory response that invariably characterizes cationic-lipid-mediated gene transfer in animals.

Polymeric Nanohybrids as a New Class of Therapeutic Biotransporters

A possible solution to enhance existing drug and gene therapies is to develop hybrid nanocarriers capable of delivering therapeutic agents in a controlled and targeted manner. This goal can be achieved by designing nanohybrid systems, which combine organic or inorganic nanomaterials with biomacromolecules into a single composite. The unique combination of properties along with their facile fabrication enables the design of smart carriers for both drug and gene delivery. These hybrids can be further modified with cell targeting motifs to enhance their biological interactivity. In this Talents and Trends article, an overview of emerging nanohybrid-based technologies will be provided to highlight their potential use as innovative platforms for improved cancer therapies and new strategies in regenerative medicine. The clinical relevance of these systems will be reviewed to define the current challenges which still need to be addressed to allow these therapies to move from bench to bedside.

Multiwalled Carbon Nanotubes Inhibit Tumor Progression in a Mouse Model

Understanding the molecular mechanisms underlying the biosynthetic interactions between particular nanomaterials with specific cells or proteins opens new alternatives in nanomedicine and nanotoxicology. Multiwalled carbon nanotubes (MWCNTs) have long been explored as drug delivery systems and nanomedicines against cancer. There are high expectations for their use in therapy and diagnosis. These filaments can translocate inside cultured cells and intermingle with the protein nanofilaments of the cytoskeleton, interfering with the biomechanics of cell division mimicking the effect of traditional microtubule-binding anti-cancer drugs such as paclitaxel. Here, it is shown how MWCNTs can trigger significant anti-tumoral effects in vivo, in solid malignant melanomas produced by allograft transplantation. Interestingly, the MWCNT anti-tumoral effects are maintained even in solid melanomas generated from paclitaxel-resistant cells. These findings provide great expectation in the development of groundbreaking adjuvant synthetic microtubule-stabilizing chemotherapies to overcome drug resistance in cancer.

Carbon nanotube-mediated delivery of budesonide to macrophages

A carbon nanotube-based carrier was developed for the delivery of anti-inflammatory budesonide to intracellular compartments of macrophages.

Sulfhydrylated graphene-encapsulated iron nanoparticles directly aminated with polyethylenimine: a novel magnetic nanoplatform for bioconjugation of gamma globulins and polyclonal antibodies

A graphene layer was directly aminated with polyethylenimine and a novel magnetic nanoplatform for bioconjugation of biologically active compounds was obtained.

Non-Covalently Functionalized of Single-Walled Carbon Nanotubes by DSPE-PEG-PEI for SiRNA Delivery

The expression of a gene can be specifically downregulated by small interfering RNA (SiRNA). Modified carbon nanotubes (CNT) can be used to protect SiRNA and facilitate its entry into cells. Regardless of that, simple and efficient functionalization of CNT is lacking. Effective SiRNA delivery can be carried out using non-covalently functionalized CNT, where non-covalent (versus covalent) functionalization is simpler and more expeditious. Non-covalently functionalized single walled carbon nanotubes (SWCNT) that include a lipopolymer are described here. Polyethylenimine (PEI) conjugated to 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE-PEG) was generated and the products used to disperse CNT to form DSPE-PEG-PEI/CNT (DGI/C), an agent capable of facilitating SiRNA delivery to cells in vitro and organs and cells in vivo.

Efficient in vitro and in vivo pulmonary delivery of nucleic acid by carbon dot-based nanocarriers

Cationic carbon dots were fabricated by pyrolysis of citric acid and bPEI25k under microwave radiation. Various nanoparticles were produced in a 20-30% yield through straightforward modifications of the reaction parameters (stoichiometry of the reactants and energy supply regime). Particular attention was paid to the purification of the reaction products to ensure satisfactory elimination of the residual starting polyamine. Intrinsic properties of the particles (size, surface charge, photoluminescence and quantum yield) were measured and their ability to form stable complexes with nucleic acid was determined. Their potential to deliver plasmid DNA or small interfering RNA to various cell lines was investigated and compared to that of bPEI25k. The pDNA in vitro transfection efficiency of these carbon dots was similar to that of the parent PEI, as was their cytotoxicity. The higher cytotoxicity of bPEI25k/siRNA complexes when compared to that of the CD/siRNA complexes however had marked consequences on the gene silencing efficiency of the two carriers. These results are not fully consistent with those in some earlier reports on similar nanoparticles, revealing that toxicity of the carbon dots strongly depends on their protocol of fabrication. Finally, these carriers were evaluated for in vivo gene delivery through the non-invasive pulmonary route in mice. High transgene expression was obtained in the lung that was similar to that obtained with the golden standard formulation GL67A, but was associated with significantly lower toxicity. Post-functionalization of these carbon dots with PEG or targeting moieties should significantly broaden their scope and practical implications in improving their in vivo transfection efficiency and biocompatibility.

Conjugation of polyethylenimine and its derivatives to carbon-encapsulated iron nanoparticles

Polyethylenimine and its pre-synthesized derivatives were conjugated to carbon-encapsulated iron nanoparticles.

Advances in the biomedical application of polymer-functionalized carbon nanotubes

Water soluble carbon nanotubes as multivalent nanomaterials for biomedical applications have been discussed.

Comparative assessment of the in vitro toxicity of some functionalized carbon nanotubes and fullerenes

Carbon nanotubes and fullerenes with different surface coatings are evaluated for their potential cytotoxicity on a panel of cell lines.

Tumor-targeting multifunctional nanoparticles for siRNA delivery: recent advances in cancer therapy

RNA interference (RNAi) is a naturally occurring regulatory process that controls posttranscriptional gene expression. Small interfering RNA (siRNA), a common form of RNAi-based therapeutics, offers new opportunities for cancer therapy via silencing specific genes, which are associated to cancer progress. However, clinical applications of RNAi-based therapy are still limited due to the easy degradation of siRNA during body circulation and the difficulty in the delivery of siRNA to desired tissues and cells. Thus, there have been many efforts to develop efficient siRNA delivery systems, which protect siRNA from serum nucleases and deliver siRNA to the intracellular region of target cells. Here, the recent advances in siRNA nanocarriers, which possess tumor-targeting ability are reviewed; various nanoparticle systems and their antitumor effects are summarized. The development of multifunctional nanocarriers for theranostics or combinatorial therapy is also discussed.

Enhancing endosomal escape for nanoparticle mediated siRNA delivery

Gene therapy with siRNA is a promising biotechnology to treat cancer and other diseases. To realize siRNA-based gene therapy, a safe and efficient delivery method is essential. Nanoparticle mediated siRNA delivery is of great importance to overcome biological barriers for systemic delivery in vivo. Based on recent discoveries, endosomal escape is a critical biological barrier to be overcome for siRNA delivery. This feature article focuses on endosomal escape strategies used for nanoparticle mediated siRNA delivery, including cationic polymers, pH sensitive polymers, calcium phosphate, and cell penetrating peptides. Work has been done to develop different endosomal escape strategies based on nanoparticle types, administration routes, and target organ/cell types. Also, enhancement of endosomal escape has been considered along with other aspects of siRNA delivery to ensure target specific accumulation, high cell uptake, and low toxicity. By enhancing endosomal escape and overcoming other biological barriers, great progress has been achieved in nanoparticle mediated siRNA delivery.

Role of pH controlled DNA secondary structures in the reversible dispersion/precipitation and separation of metallic and semiconducting single-walled carbon nanotubes

Single-stranded DNA (ss-DNA) oligomers (dA20, d[(C3TA2)3C3] or dT20) are able to disperse single-walled carbon nanotubes (SWNTs) in water at pH 7 through non-covalent wrapping on the nanotube surface. At lower pH, an alteration of the DNA secondary structure leads to precipitation of the SWNTs from the dispersion. The structural change of dA20 takes place from the single-stranded to the A-motif form at pH 3.5 while in case of d[(C3TA2)3C3] the change occurs from the single-stranded to the i-motif form at pH 5. Due to this structural change, the DNA is no longer able to bind the nanotube and hence the SWNT precipitates from its well-dispersed state. However, this could be reversed on restoring the pH to 7, where the DNA again relaxes in the single-stranded form. In this way the dispersion and precipitation process could be repeated over and over again. Variable temperature UV-Vis-NIR and CD spectroscopy studies showed that the DNA-SWNT complexes were thermally stable even at ∼90 °C at pH 7. Broadband NIR laser (1064 nm) irradiation also demonstrated the stability of the DNA-SWNT complex against local heating introduced through excitation of the carbon nanotubes. Electrophoretic mobility shift assay confirmed the formation of a stable DNA-SWNT complex at pH 7 and also the generation of DNA secondary structures (A/i-motif) upon acidification. The interactions of ss-DNA with SWNTs cause debundling of the nanotubes from its assembly. Selective affinity of the semiconducting SWNTs towards DNA than the metallic ones enables separation of the two as evident from spectroscopic as well as electrical conductivity studies.

Non-covalently functionalized single-walled carbon nanotube for topical siRNA delivery into melanoma

RNAi can specifically regulate gene expression, but efficient delivery of siRNA in vivo is difficult while it has been shown that modified carbon nanotubes (CNT) protect siRNA, facilitate entry into cells and enhance transdermal drugs delivery. Single-walled carbon nanotubes (SWCNT) were functionalized non-covalently with succinated polyethyleimine (PEI-SA). In this study, the water soluble CNT, PEI-SA/CNT (IS/C) were isolated and characterized, the gene silencing induced by IS/C/siRNA complexes was achieved in vitro in B16-F10 cells. In vivo delivery was topically applied to shaved mouse skin, as well as topically to a C57BL/6 mice melanoma model. We found significant uptake of Cy3-labeled siRNA specific to Braf (siBraf) and gene silencing in the tumor tissue. Treatment with IS/C/siBraf resulted in attenuation of tumor growth over a 25-day period. This new delivery method has provided a new possibility for future siRNA delivery and therapy, which providing insight for the potential application and development of CNT-based siRNA delivery.

Delivery of small interfering RNAs in human cervical cancer cells by polyethylenimine-functionalized carbon nanotubes

Carbon nanotubes are capable of penetrating the cell membrane and are widely considered as potential carriers for gene or drug delivery. Because the C-C and C=C bonds in carbon nanotubes are nonpolar, functionalization is required for carbon nanotubes to interact with genes or drugs as well as to improve their biocompatibility. In this study, polyethylenimine (PEI)-functionalized single-wall (PEI-NH-SWNTs) and multiwall carbon nanotubes (PEI-NH-MWNTs) were produced by direct amination method. PEI functionalization increased the positive charge on the surface of SWNTs and MWNTs, allowing carbon nanotubes to interact electrostatically with the negatively charged small interfering RNAs (siRNAs) and to serve as nonviral gene delivery reagents. PEI-NH-MWNTs and PEI-NH-SWNTs had a better solubility in water than pristine carbon nanotubes, and further removal of large aggregates by centrifugation produced a stable suspension of reduced particle size and improved homogeneity and dispersity. The amount of grafted PEI estimated by thermogravimetric analysis was 5.08% (w/w) and 5.28% (w/w) for PEI-NH-SWNTs and PEI-NH-MWNTs, respectively. For the assessment of cytotoxicity, various concentrations of PEI-NH-SWNTs and PEI-NH-MWNTs were incubated with human cervical cancer cells, HeLa-S3, for 48 h. PEI-NH-SWNTs and PEI-NH-MWNTs induced cell deaths in a dose-dependent manner but were less cytotoxic compared to pure PEI. As determined by electrophoretic mobility shift assay, siRNAs directed against glyceraldehyde-3-phosphate dehydrogenase (siGAPDH) were completely associated with PEI-NH-SWNTs or PEI-NH-MWNTs at a PEI-NH-SWNT/siGAPDH or PEI-NH-MWNT/siGAPDH mass ratio of 80:1 or 160:1, respectively. Furthermore, PEI-NH-SWNTs and PEI-NH-MWNTs successfully delivered siGAPDH into HeLa-S3 cells at PEI-NH-SWNT/siGAPDH and PEI-NH-MWNT/siGAPDH mass ratios of 1:1 to 20:1, resulting in suppression of the mRNA level of GAPDH to an extent similar to that of DharmaFECT, a common transfection reagent for siRNAs. Our results indicate that the PEI-NH-SWNTs and PEI-NH-MWNTs produced in this study are capable of delivering siRNAs into HeLa-S3 cells to suppress gene expression and may therefore be considered as novel nonviral gene delivery reagents.

Surface charge and cellular processing of covalently functionalized multiwall carbon nanotubes determine pulmonary toxicity

Functionalized carbon nanotubes (f-CNTs) are being produced in increased volume because of the ease of dispersion and maintenance of the pristine material physicochemical properties when used in composite materials as well as for other commercial applications. However, the potential adverse effects of f-CNTs have not been quantitatively or systematically explored. In this study, we used a library of covalently functionalized multiwall carbon nanotubes (f-MWCNTs), established from the same starting material, to assess the impact of surface charge in a predictive toxicological model that relates the tubes' pro-inflammatory and pro-fibrogenic effects at cellular level to the development of pulmonary fibrosis. Carboxylate (COOH), polyethylene glycol (PEG), amine (NH2), sidewall amine (sw-NH2), and polyetherimide (PEI)-modified MWCNTs were successfully established from raw or as-prepared (AP-) MWCNTs and comprehensively characterized by TEM, XPS, FTIR, and DLS to obtain information about morphology, length, degree of functionalization, hydrodynamic size, and surface charge. Cellular screening in BEAS-2B and THP-1 cells showed that, compared to AP-MWCNTs, anionic functionalization (COOH and PEG) decreased the production of pro-fibrogenic cytokines and growth factors (including IL-1β, TGF-β1, and PDGF-AA), while neutral and weak cationic functionalization (NH2 and sw-NH2) showed intermediary effects. In contrast, the strongly cationic PEI-functionalized tubes induced robust biological effects. These differences could be attributed to differences in cellular uptake and NLRP3 inflammasome activation, which depends on the propensity toward lysosomal damage and cathepsin B release in macrophages. Moreover, the in vitro hazard ranking was validated by the pro-fibrogenic potential of the tubes in vivo. Compared to pristine MWCNTs, strong cationic PEI-MWCNTs induced significant lung fibrosis, while carboxylation significantly decreased the extent of pulmonary fibrosis. These results demonstrate that surface charge plays an important role in the structure-activity relationships that determine the pro-fibrogenic potential of f-CNTs in the lung.

Synergistic anticancer effect of RNAi and photothermal therapy mediated by functionalized single-walled carbon nanotubes

Single-walled carbon nanotubes (SWNTs) are special nano-materials which exhibit interesting physical and chemical properties, presenting new opportunities for biomedical research and applications. In this study, we have successfully adopted a novel strategy to chemically functionalize SWNTs with polyethylenimine (PEI) through purification, oxidation, amination and polymerization, which were then bound by DSPE-PEG2000-Maleimide for further conjugation with the tumor targeting NGR (Cys-Asn-Gly-Arg-Cys-) peptide via the maleimide group and sulfhydryl group of cysteine, and finally hTERT siRNA was loaded to obtain a novel tumor targeting siRNA delivery system, designated as SWNT-PEI/siRNA/NGR. The results showed that SWNT-PEI/siRNA/NGR could efficiently cross cell membrane, induced more severe apoptosis and stronger suppression in proliferation of PC-3 cells in vitro. Furthermore, in tumor-bearing mice model the delivery system exhibited higher antitumor activity due to more accumulation in tumor without obvious toxicity in main organs. The combination of RNAi and near-infrared (NIR) photothermal therapy significantly enhanced the therapeutic efficacy. In conclusion, SWNT-PEI/siRNA/NGR is a novel and promising anticancer system by combining gene therapy and photothermal therapy.

Current status of gene delivery: spotlight on nanomaterial-polymer hybrids

Gene therapy aims to treat human disorders by introducing genetic materials into specific target cells or tissues. Despite the curability for the origIn of diseases by restoring missing functionalities, no technical feasibility of gene therapy has been established due to the lack of safe and efficient gene delivery systems. The emergence of nanotechnology has provided an opportunity to create nanomaterials that are suitable for the biomedical applications. Nanomaterials integrated with cationic polymers offer novel platforms that allow not only easy incorporation of genetic materials through electrostatic interactions but also further modifications to be upgraded to theranostics. In this article, current status of gene delivery utilizing hybrid nanomaterials that are composed of novel nanoplatforms and cationic polymers are highlighted. In particular, different strategies employed for the construction of nanomaterial-polymer hybrids are described.

Gene therapy for C-26 colon cancer using heparin-polyethyleneimine nanoparticle-mediated survivin T34A

BACKGROUND

Gene therapy provides a novel method for the prevention and treatment of cancer, but the clinical application of gene therapy is restricted, mainly because of the absence of an efficient and safe gene delivery system. Recently, we developed a novel nonviral gene carrier, ie, heparin-polyethyleneimine (HPEI) nanoparticles for this purpose.

METHODS AND RESULTS

HPEI nanoparticles were used to deliver plasmid-expressing mouse survivin-T34A (ms-T34A) to treat C-26 carcinoma in vitro and in vivo. According to the in vitro studies, HPEI nanoparticles could efficiently transfect the pGFP report gene into C-26 cells, with a transfection efficiency of 30.5% ± 2%. Moreover, HPEI nanoparticle-mediated ms-T34A could efficiently inhibit the proliferation of C-26 cells by induction of apoptosis in vitro. Based on the in vivo studies, HPEI nanoparticles could transfect the Lac-Z report gene into C-26 cells in vivo. Intratumoral injection of HPEI nanoparticle-mediated ms-T34A significantly inhibited growth of subcutaneous C-26 carcinoma in vivo by induction of apoptosis and inhibition of angiogenesis.

CONCLUSION

This research suggests that HPEI nanoparticle-mediated ms-T34A may have a promising role in C-26 colon carcinoma therapy.