Highly efficient molecular delivery into mammalian cells using carbon nanotube spearing

Translocation of Bioactive Molecules through Carbon Nanotubes Embedded in the Lipid Membrane

One of the major challenges of nanomedicine and gene therapy is the effective translocation of drugs and genes across cell membranes. In this study, we describe a systematic procedure that could be useful for efficient drug and gene delivery into the cell. Using fully atomistic molecular dynamics (MD) simulations, we show that molecules of various shapes, sizes, and chemistries can be spontaneously encapsulated in a single-walled carbon nanotube (SWCNT) embedded in a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid bilayer, as we have exemplified with dendrimers, asiRNA, ssDNA, and ubiquitin protein. We compute the free energy gain by the molecules upon their entry inside the SWCNT channel to quantify the stability of these molecules inside the channel as well as to understand the spontaneity of the process. The free energy profiles suggest that all molecules can enter the channel without facing any energy barrier but experience a strong energy barrier (≫k_BT) to translocate across the channel. We propose a theoretical model for the estimation of encapsulation and translocation times of the molecules. Whereas the model predicts the encapsulation time to be of the order of few nanoseconds, which match reasonably well with those obtained from the simulations, it predicts the translocation time to be astronomically large for each molecule considered in this study. This eliminates the possibility of passive diffusion of the molecules through the CNT-nanopore spanning across the membrane. To counter this, we put forward a mechanical method of ejecting the encapsulated molecules by pushing them with other free-floating SWCNTs of diameter smaller than the pore diameter. The feasibility of the proposed method is also demonstrated by performing MD simulations. The generic strategy described here should work for other molecules as well and hence could be potentially useful for drug- and gene-delivery applications.

Tubular Micro/Nanomotors: Propulsion Mechanisms, Fabrication Techniques and Applications

Micro/nanomotors are self-propelled machines that can convert various energy sources into autonomous movement. With the great advances of nanotechnology, Micro/Nanomotors of various geometries have been designed and fabricated over the past few decades. Among them, the tubular Micro/Nanomotors have a unique morphology of hollow structures, which enable them to possess a strong driving force and easy surface functionalization. They are promising for environmental and biomedical applications, ranging from water remediation, sensing to active drug delivery and precise surgery. This article gives a comprehensive and clear review of tubular Micro/Nanomotors, including propulsion mechanisms, fabrication techniques and applications. In the end, we also put forward some realistic problems and speculate about corresponding methods to improve existing tubular Micro/Nanomotors.

Non-viral Gene Delivery

Although viral vectors comprise the majority of gene delivery vectors, their various safety, production, and other practical concerns have left a research gap to be addressed. The non-viral vector space encompasses a growing variety of physical and chemical methods capable of gene delivery into the nuclei of target cells. Major physical methods described in this chapter are microinjection, electroporation, and ballistic injection, magnetofection, sonoporation, optical transfection, and localized hyperthermia. Major chemical methods described in this chapter are lipofection, polyfection, gold complexation, and carbon-based methods. Combination approaches to improve transfection efficiency or reduce immunological response have shown great promise in expanding the scope of non-viral gene delivery.

Therapeutic targeting of non-coding RNAs in cancer

The majority of the human genome encodes RNAs that do not code for proteins. These non-coding RNAs (ncRNAs) affect normal expression of the genes, including oncogenes and tumour suppressive genes, which make them a new class of targets for drug development in cancer. Although microRNAs (miRNAs) are the most studied regulatory ncRNAs to date, and miRNA-targeted therapeutics have already reached clinical development, including the mimics of the tumour suppressive miRNAs miR-34 and miR-16, which reached phase I clinical trials for the treatment of liver cancer and mesothelioma, the importance of long non-coding RNAs (lncRNAs) is increasingly being recognised. Here, we describe obstacles and advances in the development of ncRNA therapeutics and provide the comprehensive overview of the ncRNA chemistry and delivery technologies. Furthermore, we summarise recent knowledge on the biological functions of miRNAs and their involvement in carcinogenesis, and discuss the strategies of their therapeutic manipulation in cancer. We review also the emerging insights into the role of lncRNAs and their potential as targets for novel treatment paradigms. Finally, we provide the up-to-date summary of clinical trials involving miRNAs and future directions in the development of ncRNA therapeutics.

On the impact of nanotube diameter on biomembrane indentation - Computer simulations study

The influence of the single-walled carbon nanotubes on the phospholipid bilayer has been studied using steered molecular dynamics (SMD) simulations. The impact of different nanotubes on the phospholipid bilayer structure is discussed as well as the speed of indentation. Additionally, a series of simulations with pulling out of the nanotubes from the membrane were performed. The deflection of the membrane in both nanoindenation and extraction processes is also discussed. The self-sealing ability of membrane during this process is examined. Complete degradation of the bilayer was not observed even for the most invasive nanoindentation process studied. The obtained results show that carbon nanotubes can be regarded as potential drug carriers for targeted therapy.

Nanoengineered strategies for siRNA delivery: from target assessment to cancer therapeutic efficacy

The promise of RNA interference (RNAi) technology in cancer therapeutics aims to deliver small interfering RNA (siRNA) for silencing of gene expression in cell type-specific pathway. However, the challenge for the delivery of stable siRNA is hindered by an immune-hostile tumor microenvironment and physiological barriers of the circulatory system. Therefore, the development and validation of safe, stable, and efficient nanoengineered delivery systems are highly essential for effective delivery of siRNA into cancer cells. This review focuses on gene-silencing mechanisms, challenges to siRNA delivery, design and delivery of nanocarrier systems, ongoing clinical trials, and translational prospects for siRNA-mediated cancer therapeutics.

New bio-nanocomposites based on iron oxides and polysaccharides applied to oxidation and alkylation reactions

Polysaccharides from natural sources and iron precursors were applied to develop new bio-nanocomposites by mechanochemical milling processes. The proposed methodology was demonstrated to be advantageous in comparison with other protocols for the synthesis of iron oxide based nanostructures. Additionally, mechanochemistry has enormous potential from an environmental point-of-view since it is able to reduce solvent issues in chemical syntheses. The catalytic activity of the obtained nanocatalysts was investigated in both the oxidation of benzyl alcohol to benzaldehyde and in the alkylation of toluene with benzyl chloride. The microwave-assisted oxidation of benzyl alcohol reached 45% conversion after 10 min. The conversion of the alkylation of toluene in both microwave-assisted and conventional heating methods was higher than 99% after 3 min and 30 min, respectively. The transformation of benzyl alcohol and toluene into valuable product in both the oxidation and alkylation reaction reveals a potential method for the valorization of lignocellulosic biomass.

Influence of CNTRENE® C100LM carbon nanotube material on the growth and regulation of Escherichia coli

The growing use of carbon nanotubes (CNTs) in industrial and consumer products raises important questions about their environmental fate and impact on prokaryotes. In the environment, CNTs are exposed to a variety of conditions (e.g., UV light) that could lead to decomposition and changes in their chemical properties. Therefore, the potential cytotoxic effect of both pristine and artificially aged carboxyl functionalized CNTRENE^® C100LM CNTmaterial at neutral and acidic conditions on Escherichia coli K12 was analyzed using a minimal inhibitory concentration (MIC) assay, which also allowed monitoring of non-lethal growth effects. However, there were no observable MIC or significant changes in growth behavior in E. coli K12 when exposed to pristine or aged CNTs. Exposure to pristine CNTRENE^® C100LM CNT material did not appear to influence cell morphology or damage the cells when examined by electron microscopy. In addition, RNA sequencing revealed no observable regulatory changes in typical stress response pathways. This is surprising considering that previous studies have claimed high cytotoxicity of CNTs, including carboxyl functionalized single-walled CNTs, and suggest that other factors such as trace heavy metals or other impurities are likely responsible for many of the previously reported cytotoxicity in E. coli and possibly other microorganisms.

Engineering biological systems using automated biofoundries

Engineered biological systems such as genetic circuits and microbial cell factories have promised to solve many challenges in the modern society. However, the artisanal processes of research and development are slow, expensive, and inconsistent, representing a major obstacle in biotechnology and bioengineering. In recent years, biological foundries or biofoundries have been developed to automate design-build-test engineering cycles in an effort to accelerate these processes. This review summarizes the enabling technologies for such biofoundries as well as their early successes and remaining challenges.

Carbon nanotubes as gene carriers: Focus on internalization pathways related to functionalization and properties

Carbon nanotubes represent promising transporters for delivery of DNA and other biomolecules into living cells. Various methods of CNTs surface functionalization have been developed. These are essential to improve CNTs dispersibility and permit their interactions with biological structures that broaden their use in advanced biomedical applications. The present review discusses the different single walled carbon nanotubes and multiwalled carbon nanotubes functionalization methods, leading to the formation of optimized and functionalized-CNT complexes with DNA. F-CNTs are recognized as efficient and promising gene carriers. Emphasis is then placed on the processes used by f-CNTs/DNA complexes to cross cell membranes. Energy independent pathways and uptake mechanisms dependent on energy, such as endocytosis or phagocytosis, are reported by many studies, and if these mechanisms seem contradictory at first sight, a detailed review of the literature illustrates that they are rather complementary. Preferential use of one or the other depends on the DNA and CNTs chemical nature and physical parameters, experimental procedures and cell types.

STATEMENT OF SIGNIFICANCE

Efficient non-viral gene delivery is desirable, yet challenging. CNTs appear as a promising solution to penetrate into cells and successfully deliver DNA. Moreover, the field of use of CNTs as gene carrier is large and is currently growing. This critical review summarizes the development and evaluation of CNTs as intracellular gene delivery system and provides an overview of functionalized CNTs/DNA cellular uptake mechanisms, depending on several parameters of CNTs/DNA complexes.

Carbon nanotubes: a novel material for multifaceted applications in human healthcare

Remarkable advances achieved in modern material technology, especially in device fabrication, have facilitated diverse materials to expand the list of their application fields.

Mass Spectrometry Imaging in Oncology Drug Discovery

Over the last decade mass spectrometry imaging (MSI) has been integrated in to many areas of drug discovery and development. It can have significant impact in oncology drug discovery as it allows efficacy and safety of compounds to be assessed against the backdrop of the complex tumour microenvironment. We will discuss the roles of MSI in investigating compound and metabolite biodistribution and defining pharmacokinetic -pharmacodynamic relationships, analysis that is applicable to all drug discovery projects. We will then look more specifically at how MSI can be used to understand tumour metabolism and other applications specific to oncology research. This will all be described alongside the challenges of applying MSI to industry research with increased use of metrology for MSI.

Amphiphilic Helical Peptide Enhances the Uptake of Single-Walled Carbon Nanotubes by Living Cells

The success of many projected applications of carbon nano-tubes (CNTs) to living cells, such as intracellular sensors and nanovectors, will depend on how many CNTs are taken up by cells. Here we report the enhanced uptake by HeLa cells of single-walled CNTs coated with a designed peptide termed nano-1. Atomic force microscopy showed that the dispersions were composed of individual and small bundles of nano-1 CNTs with 0.7- to 32-nm diameters and 100- to 400-nm lengths. Spectroscopic characterizations revealed that nano-1 disperses CNTs in a non-covalent fashion that preserves CNT optical properties. Elemental analyses indicated that our sample preparation protocol involving sonication and centrifugation effectively eliminated metal impurities associated with CNT manufacturing processes. We further showed that the purified CNT dispersions are taken up by HeLa cells in a time- and temperature-dependent fashion, and that they do not affect the HeLa cell growth rate, evidence that the CNTs inside cells are not toxic under these conditions. Finally, we discovered that ~6-fold more CNTs are taken up by cells in the presence of nano-1 compared with medium containing serum but no peptide. The fact that coating CNTs with a peptide enhances uptake offers a strategy for improving the performance of applications that require CNTs to be inside cells.

Carbon nanotubes as cancer therapeutic carriers and mediators

Carbon nanotubes (CNTs) have received increasing attention in biomedical fields because of their unique structures and properties, including high aspect ratios, large surface areas, rich surface chemical functionalities, and size stability on the nanoscale. Particularly, they are attractive as carriers and mediators for cancer therapy. Through appropriate functionalization, CNTs have been used as nanocarriers for anticancer drugs including doxorubicin, camptothecin, carboplatin, cisplatin, paclitaxel, Pt(II), and Pt(IV), and genes including plasmid DNA, small-interfering RNA, oligonucleotides, and RNA/DNA aptamers. CNTs can also deliver proteins and immunotherapy components. Using combinations of light energy, they have also been applied as mediators for photothermal therapy and photodynamic therapy to directly destroy cancer cells without severely damaging normal tissue. If limitations such as a long-term cytotoxicity in the body, lack of size uniformity during the synthetic process, loading deviations for drug–CNT complexes, and release controllability at the target point are overcome, CNTs will become one of the strongest tools that are available for various other biomedical fields as well as for cancer therapy.

Tunable and label-free virus enrichment for ultrasensitive virus detection using carbon nanotube arrays

Viral infectious diseases can erupt unpredictably, spread rapidly, and ravage mass populations. Although established methods, such as polymerase chain reaction, virus isolation, and next-generation sequencing have been used to detect viruses, field samples with low virus count pose major challenges in virus surveillance and discovery. We report a unique carbon nanotube size-tunable enrichment microdevice (CNT-STEM) that efficiently enriches and concentrates viruses collected from field samples. The channel sidewall in the microdevice was made by growing arrays of vertically aligned nitrogen-doped multiwalled CNTs, where the intertubular distance between CNTs could be engineered in the range of 17 to 325 nm to accurately match the size of different viruses. The CNT-STEM significantly improves detection limits and virus isolation rates by at least 100 times. Using this device, we successfully identified an emerging avian influenza virus strain [A/duck/PA/02099/2012(H11N9)] and a novel virus strain (IBDV/turkey/PA/00924/14). Our unique method demonstrates the early detection of emerging viruses and the discovery of new viruses directly from field samples, thus creating a universal platform for effectively remediating viral infectious diseases.

Efficient delivery of DNA into bovine preimplantation embryos by multiwall carbon nanotubes

The pellucid zone (PZ) is a protective embryonic cells barrier against chemical, physical or biological substances. This put, usual transfection methods are not efficient for mammal oocytes and embryos as they are exclusively for somatic cells. Carbon nanotubes have emerged as a new method for gene delivery, and they can be an alternative for embryos transfection, however its ability to cross the PZ and mediated gene transfer is unknown. Our data confirm that multiwall carbon nanotubes (MWNTs) can cross the PZ and delivery of pDNA into in vitro-fertilized bovine embryos. The degeneration rate and the expression of genes associated to cell viability were not affected in embryos exposed to MWNTs. Those embryos, however, had lower cell number and higher apoptotic cell index, but this did not impair the embryonic development. This study shows the potential utility of the MWNT for the development of new method for delivery of DNA into bovine embryos.

Repairing Peripheral Nerves: Is there a Role for Carbon Nanotubes?

Peripheral nerve injury continues to be a major global health problem that can result in debilitating neurological deficits and neuropathic pain. Current state-of-the-art treatment involves reforming the damaged nerve pathway using a nerve autograft. Engineered nerve repair conduits can provide an alternative to the nerve autograft avoiding the inevitable tissue damage caused at the graft donor site. Commercially available nerve repair conduits are currently only considered suitable for repairing small nerve lesions; the design and performance of engineered conduits requires significant improvements to enable their use for repairing larger nerve defects. Carbon nanotubes (CNTs) are an emerging novel material for biomedical applications currently being developed for a range of therapeutic technologies including scaffolds for engineering and interfacing with neurological tissues. CNTs possess a unique set of physicochemical properties that could be useful within nerve repair conduits. This progress report aims to evaluate and consolidate the current literature pertinent to CNTs as a biomaterial for supporting peripheral nerve regeneration. The report is presented in the context of the state-of-the-art in nerve repair conduit design; outlining how CNTs may enhance the performance of next generation peripheral nerve repair conduits.

Carbon nanotube modification of microbial fuel cell electrodes

The use of carbon nanotubes (CNTs) for energy harvesting devices is preferable due to their unique mechanical, thermal, and electrical properties. On the other hand, microbial fuel cells (MFCs) are promising devices to recover carbon-neutral energy from the organic matters, and have been hindered with major setbacks towards commercialization. Nanoengineered CNT-based materials show remarkable electrochemical properties, and therefore have provided routes towards highly effective modification of MFC compartments to ultimately reach the theoretical limits of biomass energy recovery, low-cost power production, and thus the commercialization of MFCs. Moreover, these CNT-based composites offer significant flexibility in the design of MFCs that enable their use for a broad spectrum of applications ranging from scaled-up power generation to medically related devices. This article reviews the recent advances in the modification of MFCs using CNTs and CNT-based composites, and the extent to which each modification route impacts MFC power and current generation.

Nanoparticles and DNA - a powerful and growing functional combination in bionanotechnology

Functionally integrating DNA and other nucleic acids with nanoparticles in all their different physicochemical forms has produced a rich variety of composite nanomaterials which, in many cases, display unique or augmented properties due to the synergistic activity of both components. These capabilities, in turn, are attracting greater attention from various research communities in search of new nanoscale tools for diverse applications that include (bio)sensing, labeling, targeted imaging, cellular delivery, diagnostics, therapeutics, theranostics, bioelectronics, and biocomputing to name just a few amongst many others. Here, we review this vibrant and growing research area from the perspective of the materials themselves and their unique capabilities. Inorganic nanocrystals such as quantum dots or those made from gold or other (noble) metals along with metal oxides and carbon allotropes are desired as participants in these hybrid materials since they can provide distinctive optical, physical, magnetic, and electrochemical properties. Beyond this, synthetic polymer-based and proteinaceous or viral nanoparticulate materials are also useful in the same role since they can provide a predefined and biocompatible cargo-carrying and targeting capability. The DNA component typically provides sequence-based addressability for probes along with, more recently, unique architectural properties that directly originate from the burgeoning structural DNA field. Additionally, DNA aptamers can also provide specific recognition capabilities against many diverse non-nucleic acid targets across a range of size scales from ions to full protein and cells. In addition to appending DNA to inorganic or polymeric nanoparticles, purely DNA-based nanoparticles have recently surfaced as an excellent assembly platform and have started finding application in areas like sensing, imaging and immunotherapy. We focus on selected and representative nanoparticle-DNA materials and highlight their myriad applications using examples from the literature. Overall, it is clear that this unique functional combination of nanomaterials has far more to offer than what we have seen to date and as new capabilities for each of these materials are developed, so, too, will new applications emerge.

Can Carbon Nanotubes Deliver on Their Promise in Biology? Harnessing Unique Properties for Unparalleled Applications

Carbon nanotubes (CNTs) are cylindrical sheets of hexagonally ordered carbon atoms, giving tubes with diameters on the order of a few nanometers and lengths typically in the micrometer range. They may be single- or multiwalled (SWCNTs and MWCNTs respectively). Since the seminal report of their synthesis in 1991, CNTs have fascinated scientists of all stripes. Physicists have been intrigued by their electrical, thermal, and vibrational potential. Materials scientists have worked on integrating them into ultrastrong composites and electronic devices, while chemists have been fascinated by the effects of curvature on reactivity and have developed new synthesis and purification techniques. However, to date no large-scale, real-life biotechnological CNT breakthrough has been industrially adopted and it is proving difficult to justify taking these materials forward into the clinic. We believe that these challenges are not the end of the story, but that a viable carbon nanotube biotechnology is one in which the unique properties of nanotubes bring about an effect that would be otherwise impossible. In this Outlook, we therefore seek to reframe the field by highlighting those biological applications in which the singular properties of CNTs provide some entirely new activity or biological effect as a pointer to "what could be".

Induction of Calcium Influx in Cortical Neural Networks by Nanomagnetic Forces

Nanomagnetic force stimulation with ferromagnetic nanoparticles was found to trigger calcium influx in cortical neural networks without observable cytotoxicity. Stimulated neural networks showed an average of 20% increment in calcium fluorescence signals and a heightened frequency in calcium spiking. These effects were also confined spatially to areas with engineered high magnetic field gradients. Furthermore, blockage of N-type calcium channels inhibited the stimulatory effects of the nanomagnetic forces, suggesting the role of mechano-sensitive ion channels in mediating calcium influx.

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.

Improving the dissolution of fenofibrate with yeast cell-derived hollow core/shell carbon microparticles

Hollow-mesoporous core/shell carbon microparticles that aid the adsorption and release properties of poorly soluble drugs are synthesized from yeast cells.

Biotechnological promises of Fe-filled CNTs for cell shepherding and magnetic fluid hyperthermia applications

Fe-filled carbon nanotubes (Fe@CNTs) recently emerged as an effective class of hybrid nanoparticles for biotechnological applications, such as magnetic cell sorting and magnetic fluid hyperthermia. Aiming at studying the effects of both the Fe loading and the magnetocrystalline characteristics in these applications, we describe herein the preparation of Fe@CNTs containing different Fe phases that, upon functionalization with the antibody Cetuximab (Ctxb), allow the targeting of cancer cells. Our experimental findings reveal that an optimal Ctxb/Fe weight ratio of 1.2 is needed for efficient magnetic cell shepherding, whereas enhanced MFH-induced mortality (70 vs. 15%) can be reached with hybrids enriched in the coercive Fe(3)C phase. These results suggest that a synergistic effect between the Ab loading and the Fe distribution in each nanotube exists, for which the maximum shepherding and hyperthermia effects are observed when higher densities of Fe@CNTs featuring the more coercive phase are interfaced with the cells.

Use of nanoparticles to deliver immunomodulatory oligonucleotides

Synthetic oligonucleotides (ODNs) containing unmethylated 'CpG motifs' stimulate the innate immune system to produce cytokines, chemokines, and polyreactive antibodies. CpG ODNs have shown promise as vaccine adjuvants and for the treatment of infectious diseases and cancer. The immunostimulatory activity of CpG ODNs is inhibited by DNA-containing 'suppressive' motifs. ODNs expressing suppressive motifs (Sup ODNs) reduce ongoing immune reactions and show promise in the treatment of autoimmune and inflammatory diseases. This work reviews recent progress in the use of nanoparticles as carriers of CpG and Sup ODNs to target their delivery to the GI tract and lungs. WIREs Nanomed Nanobiotechnol 2016, 8:631-637. doi: 10.1002/wnan.1382 For further resources related to this article, please visit the WIREs website.

Photoacoustic "nanobombs" fight against undesirable vesicular compartmentalization of anticancer drugs

Undesirable intracellular vesicular compartmentalization of anticancer drugs in cancer cells is a common cause of chemoresistance. Strategies aimed at circumventing this problem may improve chemotherapeutic efficacy. We report a novel photophysical strategy for controlled-disruption of vesicular sequestration of the anticancer drug doxorubicin (DOX). Single-walled carbon nanotubes (SWCNTs), modified with folate, were trapped in acidic vesicles after entering lung cancer cells. Upon irradiation by near-infrared pulsed laser, these vesicles were massively broken by the resulting photoacoustic shockwave, and the vesicle-sequestered contents were released, leading to redistribution of DOX from cytoplasm to the target-containing nucleus. Redistribution resulted in 12-fold decrease of the EC50 of DOX in lung cancer cells, and enhanced antitumor efficacy of low-dose DOX in tumor-bearing mice. Side effects were not observed. These findings provide insights of using nanotechnology to improve cancer chemotherapy, i.e. not only for drug delivery, but also for overcoming intracellular drug-transport hurdles.

Properties of ultrathin cholesterol and phospholipid layers surrounding silicon-carbide nanotube: MD simulations

Computer simulation technique was used to study the dynamics of cholesterol and POPC phospholipid molecules forming a thin layer on the surface of the carbon and silicon-carbide nanotubes. Each nanotube was surrounded by an ultra-thin film formed by n lipid molecules, where n varies from 15 to 50. All studies were done for five temperatures, including physiological one (T=260, 285, 310, 335 and 360K). The influence of a nanotube on the dynamics of cholesterol or phospholipid molecules in a layer is presented and discussed. The water is ubiquitous in all biological milieus, where the cholesterol or lipids occur. Thus, simulations were performed in a water environment. Moreover, to show different behavior of lipids in systems with water the results were compared with the samples without it. The dynamical and structural observables, such as the mean square displacement, diffusion coefficient, radial distribution function, and activation energy were calculated to qualitatively investigate the behavior of cholesterol and phospholipid molecules in the layers. We observed remarkable differences between the cholesterol dynamics depending whether the ultrathin film surrounds carbon or silicon-carbide nanotube and whether the water environment appeared.

Micro/nanofabricated platforms for oral drug delivery

The oral route of drug administration is most preferred due to its ease of use, low cost, and high patient compliance. However, the oral uptake of many small molecule drugs and biotherapeutics is limited by various physiological barriers, and, as a result, drugs suffer from issues with low solubility, low permeability, and degradation following oral administration. The flexibility of micro- and nanofabrication techniques has been used to create drug delivery platforms designed to address these barriers to oral drug uptake. Specifically, micro/nanofabricated devices have been designed with planar, asymmetric geometries to promote device adhesion and unidirectional drug release toward epithelial tissue, thereby prolonging drug exposure and increasing drug permeation. Furthermore, surface functionalization, nanotopography, responsive drug release, motion-based responses, and permeation enhancers have been incorporated into such platforms to further enhance drug uptake. This review will outline the application of micro/nanotechnology to specifically address the physiological barriers to oral drug delivery and highlight technologies that may be incorporated into these oral drug delivery systems to further enhance drug uptake.

Design of Cationic Multiwalled Carbon Nanotubes as Efficient siRNA Vectors for Lung Cancer Xenograft Eradication

Polo-Like Kinase (PLK1) has been identified as a potential target in cancer gene therapy via chemical or genetic inhibitory approaches. The biomedical applications of chemically functionalized carbon nanotubes (f-CNTs) in cancer therapy have been studied due to their ability to efficiently deliver siRNA intracellularly. In this study, we established the capacity of cationic MWNT-NH3(+) to deliver the apoptotic siRNA against PLK1 (siPLK1) in Calu6 tumor xenografts by direct intratumoral injections. A direct comparison with cationic liposomes was made. This study validates the PLK1 gene as a potential target in cancer gene therapy including lung cancer, as demonstrated by the therapeutic efficacy of siPLK1:MWNT-NH3(+) complexes and their ability to significantly improve animal survival. Biological analysis of the siPLK1:MWNT-NH3(+) treated tumors by qRT-PCR and Western blot, in addition to TUNEL staining confirmed the biological functionality of the siRNA intratumorally, suggesting that tumor eradication was due to PLK1 knockdown. Furthermore, by using a fluorescently labeled, noncoding siRNA sequence complexed with MWNT-NH3(+), we established for the first time that the improved therapeutic efficacy observed in f-CNT-based siRNA delivery is directly proportional to the enhanced siRNA retention in the solid tumor and subsequent uptake by tumor cells after local administration in vivo.

Carbon nanotubes part II: a remarkable carrier for drug and gene delivery

INTRODUCTION

Carbon nanotubes (CNT) have recently been studied as novel and versatile drug and gene delivery vehicles. When CNT are suitably functionalized, they can interact with various cell types and are taken up by endocytosis.

AREAS COVERED

Anti-cancer drugs cisplatin and doxorubicin have been delivered by CNT, as well as methotrexate, taxol and gemcitabine. The delivery of the antifungal compound amphotericin B and the oral administration of erythropoietin have both been assisted using CNT. Frequently, targeting moieties such as folic acid, epidermal growth factor or various antibodies are attached to the CNT-drug nanovehicle. Different kinds of functionalization (e.g., polycations) have been used to allow CNT to act as gene delivery vectors. Plasmid DNA, small interfering RNA and micro-RNA have all been delivered by CNT vehicles. Significant concerns are raised about the nanotoxicology of the CNT and their potentially damaging effects on the environment.

EXPERT OPINION

CNT-mediated drug delivery has been studied for over a decade, and both in vitro and in vivo studies have been reported. The future success of CNTs as vectors in vivo and in clinical application will depend on achievement of efficacious therapy with minimal adverse effects and avoidance of possible toxic and environmentally damaging effects.

Multifunctional carbon nanomaterial hybrids for magnetic manipulation and targeting

Nanosized materials and multifunctional nanoscale platforms have attracted in the last years considerable interest in a variety of different fields including biomedicine. Carbon nanotubes and graphene are some of the most widely used carbon nanomaterials (CNMs) due to their unique morphology and structure and their characteristic physicochemical properties. Their high surface area allows efficient drug loading and bioconjugation and makes them the ideal platforms for decoration with magnetic nanoparticles (MNPs). In the biomedical area, MNPs are of particular importance due to their broad range of potential applications in drug delivery, non-invasive tumor imaging and early detection based on their optical and magnetic properties. The remarkable characteristics of CNMs and MNPs can be combined leading to CNM/MNP hybrids which offer numerous promising, desirable and strikingly advantageous properties for improved performance in comparison to the use of either material alone. In this minireview, we attempt to comprehensively report the most recent advances made with CNMs conjugated to different types of MNPs for magnetic targeting, magnetic manipulation, capture and separation of cells towards development of magnetic carbon-based devices.

A systems toxicology approach on the mechanism of uptake and toxicity of MWCNT in Caenorhabditis elegans

The increased volumes of carbon nanotubes (CNTs) being utilized in industrial and biomedical processes carries with it an increased risk of unintentional release into the environment, requiring a thorough hazard and risk assessment. In this study, the toxicity of pristine and hydroxylated (OH-) multiwall CNTs (MWCNTs) was investigated in the nematode Caenorhabditis elegans using an integrated systems toxicology approach. To gain an insight into the toxic mechanism of MWCNTs, microarray and proteomics were conducted for C. elegans followed by pathway analyses. The results of pathway analyses suggested endocytosis, phagocytosis, oxidative stress and endoplasmic reticulum (ER) stress, as potential mechanisms of uptake and toxicity, which were subsequently investigated using loss-of-function mutants of genes of those pathways. The expression of phagocytosis related genes (i.e. ced-10 and rab-7) were significantly increased upon exposure to OH-MWCNT, concomitantly with the rescued toxicity by loss-of-function mutants of those genes, such as ced-10(n3246) and rab-7(ok511). An increased sensitivity of the hsp-4(gk514) mutant by OH-MWCNT, along with a decreased expression of hsp-4 at both gene and protein level suggests that MWCNTs may affect ER stress response in C. elegans. Collectively, the results implied phagocytosis to be a potential mechanism of uptake of MWCNTs, and ER and oxidative stress as potential mechanisms of toxicity. The integrated systems toxicology approach applied in this study provided a comprehensive insight into the toxic mechanism of MWCNTs in C. elegans, which may eventually be used to develop an "Adverse Outcome Pathway (AOP)", a recently introduced concept as a conceptual framework to link molecular level responses to higher level effects.

Carbon Nanotropes: A Contemporary Paradigm in Drug Delivery

Discovery of fullerenes and other nanosized carbon allotropes has opened a vast new field of possibilities in nanotechnology and has become one of the most promising research areas. Carbon nanomaterials have drawn interest as carriers of biologically pertinent molecules due to their distinctive physical, chemical and physiological properties. We have assigned the nomenclature “Carbon Nanotropes” to the nanosized carbon allotropes. Carbon nanotropes such as fullerenes, carbon nanotubes (CNTs) and graphenes, have exhibited wide applicability in drug delivery, owing to their small size and biological activity. The nanotherapeutics/diagnostics will allow a deeper understanding of human ills including cancer, neurodegenerative diseases, genetic disorders and various other complications. Recently, nanomaterials with multiple functions, such as drug carrier, MRI, optical imaging, photothermal therapy, etc., have become more and more popular in the domain of cancer and other areas of research. This review is an endeavor to bring together the usefulness of the carbon nanomaterials in the field of drug delivery. The last section of the review encompasses the recent patents granted on carbon nanotropes at United State Patent Trademark Office (USPTO) in the related field.

Magnetically Active Carbon Nanotubes at Work

Endohedral and exohedral assembly of magnetic nanoparticles (MNPs) and carbon nanotubes (CNTs) recently gave birth to a large body of new hybrid nanomaterials (MNPs-CNTs) featuring properties that are otherwise not in reach with only the graphitic or metallic cores themselves. These materials feature enhanced magnetically guided motions (rotation and translation), magnetic saturation and coercivity, large surface area, and thermal stability. By guiding the reader through the most significant examples in this Concept paper, we describe how researchers in the field engineered and exploited the synergistic combination of these two types of nanoparticles in a large variety of current and potential applications, such as magnetic fluid hyperthermia therapeutics and in magnetic resonance imaging to name a few.

The influence of blood on targeted microbubbles

The ability to successfully target the delivery of drugs and other therapeutic molecules has been a key goal of biomedical research for many decades. Despite highly promising in vitro results, however, successful translation of targeted drug delivery into clinical use has been extremely limited. This study investigates the significance of the characteristics of whole blood, which are rarely accounted for in vitro assays, as a possible explanation for the poor correlation between in vitro and in vivo experiments. It is shown using two separate model systems employing either biochemical or magnetic targeting that blood causes a substantial reduction in targeting efficiency relative to saline under the same flow conditions. This finding has important implications for the design of targeted drug delivery systems and the assays used in their development.

Single-walled carbon nanotubes functionalized with aptamer and piperazine-polyethylenimine derivative for targeted siRNA delivery into breast cancer cells

Epithelial cell adhesion molecule (EpCAM) is a glycosylated type 1 membrane protein which is frequently over expressed in most solid tumors and it has recently been identified as a cancer stem cell (CSC) marker. Specific targeting of CSCs using nano-carriers would enhance treatment efficacy of cancer. In this study, we used a RNA aptamer against EpCAM (EpDT3) attached physically to our newly synthesized non-viral vector, based on single-walled carbon nanotube (SWNT) conjugated to piperazine-polyethylenimine derivative. The DNA transfection efficiency and siRNA delivery activity of the synthesized vector was investigated against upregulated BCL9l, which has been associated with breast and colorectal cancers. The complexes of the vector-aptamer/siRNA could specifically induce apoptosis by more than 20% in MCF-7 cell line as a positive EpCAM than MDA-MB-231 cells which are EpCAM negative. The decrease of BCL9l protein level was observed with western blot analysis in MCF-7 cells indicating the targeted silencing activity of the complex.

Mass spectrometry imaging reveals the sub-organ distribution of carbon nanomaterials

Label and label-free methods to image carbon-based nanomaterials exist. However, label-based approaches are limited by the risk of tag detachment over time, and label-free spectroscopic methods have slow imaging speeds, weak photoluminescence signals and strong backgrounds. Here, we present a label-free mass spectrometry imaging method to detect carbon nanotubes, graphene oxide and carbon nanodots in mice. The large molecular weights of nanoparticles are difficult to detect using conventional mass spectrometers, but our method overcomes this problem by using the intrinsic carbon cluster fingerprint signal of the nanomaterials. We mapped and quantified the sub-organ distribution of the nanomaterials in mice. Our results showed that most carbon nanotubes and nanodots were found in the outer parenchyma of the kidney, and all three materials were seen in the red pulp of the spleen. The highest concentrations of nanotubes in the spleen were found within the marginal zone.

Magnetic single-walled carbon nanotubes as efficient drug delivery nanocarriers in breast cancer murine model: noninvasive monitoring using diffusion-weighted magnetic resonance imaging as sensitive imaging biomarker

Purpose

Targeting doxorubicin (DOX) by means of single-walled carbon nanotube (SWCNT) nanocarriers may help improve the clinical utility of this highly active therapeutic agent. Active targeting of SWCNTs using tumor-specific antibody and magnetic attraction by tagging the nanotubes with iron oxide nanoparticles can potentially reduce the unnecessary side effects and provide enhanced theranostics. In the current study, the in vitro and in vivo efficacy of DOX-loaded SWCNTs as theranostic nanoprobes was evaluated in a murine breast cancer model.

Methods

Iron-tagged SWCNTs conjugated with Endoglin/CD105 antibody with or without DOX were synthetized and extensively characterized. Their biocompatibility was assessed in vitro in luciferase (Luc2)-expressing 4T1 (4T1-Luc2) murine breast cancer cells using TiterTACS™ Colorimetric Apoptosis Detection Kit (apoptosis induction), poly (ADP-ribose) polymerase (marker for DNA damage), and thiobarbituric acid-reactive substances (oxidative stress generation) assays, and the efficacy of DOX-loaded SWCNTs was evaluated by measuring the radiance efficiency using bioluminescence imaging (BLI). Tumor progression and growth were monitored after 4T1-Luc2 cells inoculation using noninvasive BLI and magnetic resonance imaging (MRI) before and after subsequent injection of SWCNT complexes actively and magnetically targeted to tumor sites.

Results

Significant increases in apoptosis, DNA damage, and oxidative stress were induced by DOX-loaded SWCNTs. In addition, a tremendous decrease in bioluminescence was observed in a dose- and time-dependent manner. Noninvasive BLI and MRI revealed successful tumor growth and subsequent attenuation along with metastasis inhibition following DOX-loaded SWCNTs injection. Magnetic tagging of SWCNTs was found to produce significant discrepancies in apparent diffusion coefficient values providing a higher contrast to detect treatment-induced variations as noninvasive imaging biomarker. In addition, it allowed their sensitive noninvasive diagnosis using susceptibility-weighted MRI and their magnetic targeting using an externally applied magnet.

Conclusion

Enhanced therapeutic efficacy of DOX delivered through antibody-conjugated magnetic SWCNTs was achieved. Further, the superiority of apparent diffusion coefficient measurements using diffusion-weighted MRI was found to be a sensitive imaging biomarker for assessment of treatment-induced changes.

Carbon Nanotubes as Drug Delivery Vehicles

Various biomedical applications of nanomaterials have been proposed in the last few years leading to the emergence of a new field in diagnostics and therapeutics. Most of these applications involve the administration of nanoparticles into patients. Carbon Nanotubes are enjoying increasing popularity as building blocks for novel drug delivery systems as well as for bioimaging and biosensing. The recent strategies to functionalize carbon nanotubes have resulted in the generation of biocompatible and water-soluble carbon nanotubes that are well suited for high treatment efficacy and minimum side effects for future cancer therapies with low drug doses. The toxicological profile of such carbon nanotube systems developed as nanomedicines will have to be determined prior to any clinical studies undertaken.