Synthesis and characterization of polyamidoamine dendrimer-coated multi-walled carbon nanotubes and their application in gene delivery systems

Multi-Walled Carbon Nanotubes Accelerate Leukaemia Development in a Mouse Model

Inflammation is associated with an increased risk of developing various cancers in both animals and humans, primarily solid tumors but also myeloproliferative neoplasms (MPNs), myelodysplastic syndromes (MDS), and acute myeloid leukemia (AML). Multi-walled carbon nanotubes (MWCNTs), a type of carbon nanotubes (CNTs) increasingly used in medical research and other fields, are leading to a rising human exposure. Our study demonstrated that exposing mice to MWCNTs accelerated the progression of spontaneous MOL4070LTR virus-induced leukemia. Additionally, similar exposures elevated pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α and induced reactive oxygen species (ROS) in a murine macrophage cell line. These effects were significantly reduced in immunodeficient mice and when mice were treated with methoxypolyethylene glycol amine (PEG)-modified MWCNTs. These findings underscore the necessity of evaluating the safety of MWCNTs, particularly for those with hematologic cancers.

Application and progress of nanozymes in antitumor therapy

Tumors remain one of the major threats to public health and there is an urgent need to design new pharmaceutical agents for their diagnosis and treatment. In recent years, due to the rapid development of nanotechnology, biotechnology, catalytic science, and theoretical computing, subtlety has gradually made great progress in research related to tumor diagnosis and treatment. Compared to conventional drugs, enzymes can improve drug distribution and enhance drug enrichment at the tumor site, thereby reducing drug side effects and enhancing drug efficacy. Nanozymes can also be used as tumor tracking imaging agents to reshape the tumor microenvironment, providing a versatile platform for the diagnosis and treatment of malignancies. In this paper, we review the current status of research on enzymes in oncology and analyze novel oncology therapeutic approaches and related mechanisms. To date, a large number of nanomaterials, such as noble metal nanomaterials, nonmetallic nanomaterials, and carbon-based nanomaterials, have been shown to be able to function like natural enzymes, particularly with significant advantages in tumor therapy. In light of this, the authors in this review have systematically summarized and evaluated the construction, enzymatic activity, and their characteristics of nanozymes with respect to current modalities of tumor treatment. In addition, the application and research progress of different types of nicknames and their features in recent years are summarized in detail. We conclude with a summary and outlook on the study of nanozymes in tumor diagnosis and treatment. It is hoped that this review will inspire researchers in the fields of nanotechnology, chemistry, biology, materials science and theoretical computing, and contribute to the development of nano-enzymology.

A Review on Carbon Nanotubes Family of Nanomaterials and Their Health Field

The use of carbon nanotubes (CNTs), which are nanometric materials, in pathogen detection, protection of environments, food safety, and in the diagnosis and treatment of diseases, as efficient drug delivery systems, is relevant for the improvement and advancement of pharmacological profiles of many molecules employed in therapeutics and in tissue bioengineering. It has contributed to the advancement of science due to the development of new tools and devices in the field of medicine. CNTs have versatile mechanical, physical, and chemical properties, in addition to their great potential for association with other materials to contribute to applications in different fields of medicine. As, for example, photothermal therapy, due to the ability to convert infrared light into heat, in tissue engineering, due to the mechanical resistance, flexibility, elasticity, and low density, in addition to many other possible applications, and as biomarkers, where the electronic and optics properties enable the transduction of their signals. This review aims to describe the state of the art and the perspectives and challenges of applying CNTs in the medical field. A systematic search was carried out in the indexes Medline, Lilacs, SciELO, and Web of Science using the descriptors "carbon nanotubes", "tissue regeneration", "electrical interface (biosensors and chemical sensors)", "photosensitizers", "photothermal", "drug delivery", "biocompatibility" and "nanotechnology", and "Prodrug design" and appropriately grouped. The literature reviewed showed great applicability, but more studies are needed regarding the biocompatibility of CNTs. The data obtained point to the need for standardized studies on the applications and interactions of these nanostructures with biological systems.

Carbon-Based Nanostructures as Emerging Materials for Gene Delivery Applications

Gene therapeutics are promising for treating diseases at the genetic level, with some already validated for clinical use. Recently, nanostructures have emerged for the targeted delivery of genetic material. Nanomaterials, exhibiting advantageous properties such as a high surface-to-volume ratio, biocompatibility, facile functionalization, substantial loading capacity, and tunable physicochemical characteristics, are recognized as non-viral vectors in gene therapy applications. Despite progress, current non-viral vectors exhibit notably low gene delivery efficiency. Progress in nanotechnology is essential to overcome extracellular and intracellular barriers in gene delivery. Specific nanostructures such as carbon nanotubes (CNTs), carbon quantum dots (CQDs), nanodiamonds (NDs), and similar carbon-based structures can accommodate diverse genetic materials such as plasmid DNA (pDNA), messenger RNA (mRNA), small interference RNA (siRNA), micro RNA (miRNA), and antisense oligonucleotides (AONs). To address challenges such as high toxicity and low transfection efficiency, advancements in the features of carbon-based nanostructures (CBNs) are imperative. This overview delves into three types of CBNs employed as vectors in drug/gene delivery systems, encompassing their synthesis methods, properties, and biomedical applications. Ultimately, we present insights into the opportunities and challenges within the captivating realm of gene delivery using CBNs.

Carbon Nanotubes for Targeted Therapy: Safety, Efficacy, Feasibility and Regulatory Aspects

It is crucial that novel and efficient drug delivery techniques be created in order to improve the pharmacological profiles of a wide variety of classes of medicinal compounds. Carbon nanotubes (CNTs) have recently come to the forefront as an innovative and very effective technique for transporting and translocating medicinal compounds. CNTs were suggested and aggressively researched as multifunctional novel transporters designed for targeted pharmaceutical distribution and used in diagnosis. CNTs can act as vectors for direct administration of pharmaceuticals, particularly chemotherapeutic medications. Multi-walled CNTs make up the great majority of CNT transporters, and these CNTs were used in techniques to target cancerous cells. It is possible to employ Carbon nanotubes (CNTs) to transport bioactive peptides, proteins, nucleic acids, and medicines by functionalizing them with these substances. Due to their low toxicity and absence of immunogenicity, carbon nanotubes are not immunogenic. Ammonium-functionalized carbon nanotubes are also attractive vectors for gene-encoding nucleic acids. CNTs that have been coupled with antigenic peptides have the potential to be developed into a novel and efficient approach for the use of synthetic vaccines. CNTs bring up an enormous number of new avenues for future medicine development depending on targets within cells, which have until now been difficult to access. This review focuses on the numerous applications of various CNT types used as medicine transport systems and on the utilization of CNTs for therapeutical purposes.

Nanomedicine as potential cancer therapy via targeting dysregulated transcription factors

Cancer as a disease possess quite complicated pathophysiological implications and is among the prominent causes of morbidity and mortality on global scales. Anti-cancer chemotherapy, surgery, and radiation therapy are some of the present-day conventional treatment options. However, these therapeutic paradigms own several retreats, including lack of specificity, non-targeted toxicological implications, inefficient drug delivery to targeted cells, and emergence of cancer resistance, ultimately causing ineffective cancer management. Owing to the advanced and better biophysical characteristic features and potentiality for the tailoring and customizations and in several fashions, nanotechnology can entirely transubstantiate the cancer identification and its managements. Additionally, nanotechnology also renders several answers to present-day mainstream limitations springing-up in anti-cancer therapeutics. Nanocarriers, owing to their outstanding physicochemical features including but not limited to their particle size, surface morphological features viz. shape etc., have been employed in nanomedicinal platforms for targeting various transcription factors leading to worthy pharmacological outcomes. This transcription targeting activates the wide array of cellular and molecular events like antioxidant enzyme-induction, apoptotic cell death, cell-cycle arrest etc. These outcomes are obtained after the activation or inactivation of several transcription factors and cellular pathways. Further, nanoformulations have been precisely calibrated and functionalized with peculiar targeting groups for improving their efficiency to deliver the drug-payload to specified and targeted cancerous cells and tissues. This review undertakes an extensive, across-the-board and all-inclusive approach consisting of various studies encompassing different types of tailored and customized nanoformulations and nanomaterials designed for targeting the transcription factors implicated in the process of carcinogenesis, tumor-maturation, growth and metastasis. Various transcription factors viz. nuclear factor kappa (NF-κB), signal transducer and activators of transcription (STAT), Cmyc and Twist-related protein 1 (TWIST1) along with several types of nanoparticles targeting these transcription factors have been summarized here. A section has also been dedicated to the different types of nanoparticles targeting the hypoxia inducing factors. Efforts have been made to summarize several other transcription factors implicated in various stages of cancer development, growth, progression and invasion, and their targeting with different kinds of nanomedicinal agents.

Amine-terminated dendritic polymers as promising nanoplatform for diagnostic and therapeutic agents' modification: A review

It is often challenging to design diagnostic and therapeutic agents that fulfill all functional requirements. So, bulk and surface modifications as a common approach for biomedical applications have been suggested. There have been considerable research interests in using nanomaterials to the prementioned methods. Among all nanomaterials, dendritic materials with three-dimensional structures, host-guest properties, and nano-polymeric dimensions have received considerable attention. Amine-terminated dendritic structures including, polyamidoamine (PAMAM), polypropyleneimine (PPI), and polyethyleneimine (PEI), have been enormously utilized in bio-modification. This review briefly described the structure of these three common dendritic polymers and their use to modify diagnostic and therapeutic agents in six major applications, including drug delivery, gene delivery, biosensor, bioimaging, tissue engineering, and antimicrobial activity. The current review covers amine-terminated dendritic polymers toxicity challenging and improvement strategies as well.

Derivatized Carbon Nanotubes for Gene Therapy in Mammalian and Plant Cells

The concept of gene vectors for therapeutic applications has been known for several years, but it is far from revealing its actual potential. With the advent of hollow cylindrical carbon nanomaterials such as carbon nanotubes (CNTs), researchers have invented several new tools to deliver genes at the required site of action in mammalian and plant cells. The ease of diversified functionalization has allowed CNTs to be by far the most adaptable non-viral vector for gene therapy. This Minireview addresses the dexterity with which CNTs undergo surface modifications and their applications as a potent vector in gene therapy of humans and plants. Specifically, we will discuss the new tools that scientific communities have invented to achieve gene therapy using plasmid DNA, RNA silencing, suicide gene therapy, and plant genetic engineering. Additionally, we will shed some light on the mechanism of gene transportation using carbon nanotubes in cancer cells and plants.

TGA/Chemometrics addressing innovative preparation strategies for functionalized carbon nanotubes

In this work, functionalized carbon nanotubes (CNTs) using two polyamine polymers, polyethyleneimine (PEI) and polyamidoamine dendrimer (PAMAM), were investigated by thermal analysis in order to address preparation strategies to obtain low cytotoxic compounds with the ability to conjugate microRNAs and, at the same time, to transfect efficiently endothelial cells. Thermogravimetric analysis (TGA) was coupled to chemometrics as a novel analytical strategy to characterize functionalized CNTs from different preparation conditions. In particular, two starting materials were considered: very small CNTs and carboxylated CNTs (CNT-COOH) in order to examine the affinity with polymers. Chemometrics permitted to compare results from TGA and to investigate the effect of a number of factors affecting the synthesis of coated nanotubes including a different amount of involved polymer and the time required for the suspension for a satisfactory and reproducible preparation procedure. The results demonstrated the effectiveness of TGA as a tool able to address synthesis of coated CNTs to be employed as efficient drug delivery vectors in biomedical applications.

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TGA/Chemometrics addresses the preparation of functionalized carbon nanotubes for biomedical applications.

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Characterization of innovative polymer based biovectors by multivariate statistical analysis applied to thermogravimetry.

Carbon Nanotubes: An Emerging Drug Delivery Carrier in Cancer Therapeutics

BACKGROUND

The scope of nanotechnology has been extended to almost every sphere of our daily life. As a result of this, nanocarriers like Carbon Nanotubes (CNTs) are gaining considerable attention for their use in various therapeutic and diagnostic applications.

OBJECTIVE

The objective of the current article is to review various important features of CNTs that make them as efficient carriers for anticancer drug delivery in cancer therapeutics.

METHODS

In this review article, different works of literature are reported on various prospective applications of CNTs in the targeting of multiple kinds of cancerous cells of different organs via; the loading of various anticancer agents.

RESULTS

Actually, CNTs are the 3rd allotropic type of the carbon-fullerenes that are a part of the cylindrical tubular architecture. CNTs possess some excellent physicochemical characteristics and unique structural features that provide an effective platform to deliver anticancer drugs to target specific sites for achieving a high level of therapeutic effectiveness even in cancer therapeutics. For better results, CNTs are functionalized and modified with different classes of therapeutically bioactive molecules via; the formation of stable covalent bonding or by the use of supramolecular assemblies based on the noncovalent interaction(s). In recent years, the applications of CNTs for the delivery of various kinds of anticancer drugs and targeting of tumor sites have been reported by various research groups.

CONCLUSION

CNTs represent an emerging nanocarrier material for the delivery and targeting of numerous anticancer drugs in cancer therapeutics.

Influence cationic and anionic PAMAM dendrimers of low generation on selected hemostatic parameters in vitro

BACKGROUND

Polyamidoamine (PAMAM) dendrimers are a new class of monodisperse polymers that are used for drug delivery in systemic administrations. The influence of PAMAM dendrimers on components of the blood coagulation system has been extensively studied, but their effect on the activity of the fibrinolysis system has not been studied to date.

METHODS

The effect of cationic (G1-G3) and anionic (G1.5-G3.5) PAMAM dendrimers on the conformation and function of the main components of the coagulation and fibrinolysis systems was comparatively studied. Changes in overall plasma hemostatic potential, thrombin generation, prothrombin time, thrombin and tPA activities, the fluorescence of fibrinogen and plasminogen, zeta potential, polymerization of fibrinogen, and activation of plasminogen were analyzed to assess coagulofibrinolytic mechanisms of influence of the charge of the dendrimers.

RESULTS

Cationic dendrimers increased prothrombin time, suppressed thrombin generation in plasma, and changed the conformation and coagulability of fibrinogen, while anionic dendrimers did not have such effects. Anionic dendrimers slightly reduced tPA activity and altered plasminogen conformation much more strongly than the cationic dendrimers. Plasminogen activation by tPA was strongly inhibited by anionic dendrimers and weakly stimulated by cationic dendrimers. All these effects were enhanced with increasing generation and concentration of the dendrimers.

CONCLUSIONS

PAMAM-NH₂ dendrimers inhibit the extrinsic activation pathway of the coagulation system and alter the conformation and function of fibrinogen. PAMAM-COOH dendrimers change the conformation of plasminogen and inhibit its activation by tPA. This study gives new insight into the effect of anionic PAMAM dendrimers on the activity of the fibrinolytic system. For intravenous applications, the antifibrinolytic effect of anionic PAMAM dendrimers of generation ≥G2.5 should be considered.

Hybrid carbon-based materials for gene delivery in cancer therapy

Accumulation at tumor tissue without any damage to healthy normal tissues is an ultimate goal in cancer therapy. Despite many efforts in the field of cancer therapy, this disease remains as the major reason of mortality all over the world. Gene therapy has introduced great opportunity to fight against cancer disease. It should be noted that still some obstacles limit clinical application of gene delivery approach, which have to be overcome for efficient transportation of therapeutic gene to the site of action. In this regard, carbon nanomaterials and their unique physical and chemical properties such as their capability of DNA protection have attracted much attention in the field of nanomedicine and non-viral carriers for therapeutic genes. Although, negligible solubility of carbon nanomaterials in biological environments has limited their biomedical application but their structural characteristics facilitate their chemical modifications thereby overcoming their solubility problem. Moreover, hybridization of modified carbon materials with different polymers provides more biocompatible and capable systems for gene delivery purposes. In the current review, we summarized hybrid carbon-based materials as non-viral carriers for gene delivery.

Magnetic-silk/polyethyleneimine core-shell nanoparticles for targeted gene delivery into human breast cancer cells

The lack of efficient and cost-effective methods for gene delivery has significantly hindered the applications of gene therapy. In this paper, a simple one step and cost effective salting-out method has been explored to fabricate silk-PEI nanoparticles (SPPs) and magnetic-silk/PEI core-shell nanoparticles (MSPPs) for targeted delivery of c-myc antisense oligodeoxynucleotides (ODNs) into MDA-MB-231 breast cancer cells. The size and zeta potential of the particles were controlled by adjusting the amount of silk fibroin in particle synthesis. Lower surface charges and reduced cytotoxicity were achieved for MSPPs compared with PEI coated magnetic nanoparticles (MPPs). Both SPPs and MSPPs were capable of delivering the ODNs into MDA-MB-231 cells and significantly inhibited the cell growth. Through magnetofection, high ODN uptake efficiencies (over 70%) were achieved within 20 min using MSPPs as carriers, exhibiting a significantly enhanced uptake effect compared to the same carriers via non-magnetofection. Both SPPs and MSPPs exhibited a significantly higher inhibition effect against MDA-MB-231 breast cancer cells compared to human dermal fibroblast (HDF) cells. Targeted ODN delivery was achieved using MSPPs with the help of a magnet, making them promising candidates for targeted gene therapy applications.

Fullerenes as photosensitizers in photodynamic therapy: pros and cons

One class of carbon nanomaterials is the closed cages known as fullerenes. The first member to be discovered in 1985 was C60, called "buckminsterfullerene" as its cage structure resembled a geodesic dome. Due to their extended π-conjugation they absorb visible light, possess a high triplet yield and can generate reactive oxygen species upon illumination, suggesting a possible role of fullerenes in photodynamic therapy (PDT). Pristine C60 is highly hydrophobic and prone to aggregation, necessitating functionalization to provide aqueous solubility and biocompatibility. The most common functional groups attached are anionic (carboxylic or sulfonic acids) or cationic (various quaternary ammonium groups). Depending on the functionalization, these fullerenes can be designed to be taken up into cancer cells, or to bind to microbial cells (Gram-positive, Gram-negative bacteria, fungi). Fullerenes can be excited with a wide range of wavelengths, UVA, blue, green or white light. We have reported a series of functionalized fullerenes (C60, C70, C82) with attached polycationic chains and additional light-harvesting antennae that can be used in vitro and in animal models of localized infections. Advantages of fullerenes as photosensitizers are: (a) versatile functionalization; (b) light-harvesting antennae; (c) ability to undergo Type 1, 2, and 3 photochemistry; (d) electron transfer can lead to oxygen-independent photokilling; (e) antimicrobial activity can be potentiated by inorganic salts; (f) can self-assemble into supramolecular fullerosomes; (g) components of theranostic nanoparticles; (h) high resistance to photobleaching. Disadvantages include: (a) highly hydrophobic and prone to aggregation; (b) overall short wavelength absorption; (c) relatively high molecular weight; (d) paradoxically can be anti-oxidants; (e) lack of fluorescence emission for imaging.

Synthesis and Catalytic Applications of Multi-Walled Carbon Nanotube-Polyamidoamine Dendrimer Hybrids

Polyamidoamine (PAMAM) dendrimers were covalently immobilized on multi-walled carbon nanotubes (MWNT) by two "grafting to" strategies. We demonstrate the existence of non-covalent interactions between the two components but outline the superiority of our two grafting approaches, namely xanthate and click chemistry. MWNT surfaces were functionalized with activated ester and propargylic moieties prior to their reaction with PAMAM or azido-PAMAM dendrimers, respectively. The grafting of PAMAM generations 0 to 3 was evaluated with X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The versatility of our hybrids was demonstrated by post-functionalization sequences involving copper alkyne-azide cycloaddition (CuAAC). We synthesized homogeneous supported iridium complexes at the extremities of the dendrimers. In addition, our materials were used as templates for the encapsulation of Pd nanoparticles (NPs), validating our nanocomposites for catalytic applications. The palladium-based catalyst was active for carbonylative coupling over five consecutive runs without loss of activity.

Functionalized carbon nanotubes as emerging delivery system for the treatment of cancer

In recent time, carbon nanotubes (CNTs) have gained vital importance for pharmaceutical formulation scientist for delivering drugs and genes, owing to their excellent surface properties. For example, their aspect ratio is thought to be responsible for their excellent cell penetration aptitude; anisotropic conductivity/semi-conductivity along their axis is ideal for integration with nervous and muscular tissue; an ultrahigh surface area maximizes their ability to "talk" with biological matter; the hollow interior provides an enormous cargo-carrying capacity for drug delivery; and their exteriors are readily functionalized to permit tailoring of solubility and biological recognition. Despite their immense capabilities for the delivery of drugs, genes and other biomedically essential materials, there use is restricted primarily because of the severe toxicity. However, the reactive nature of the surface of the CNTs allowed attaching the guest molecules (drug, siRNA, and diagnostics) of interest which helps in increasing the biocompatibility of these novel nanocarriers. As per the need, CNTs can be modified with peptides, organic molecules, carbohydrates, polymers and used mainly for cancer targeting and tumor cell accumulation. This review expounds different functionalization strategies employed for CNTs that created new opportunities for scientists to improve the potential of delivered therapeutics.

Biophysical and biological contributions of polyamine-coated carbon nanotubes and bidimensional buckypapers in the delivery of miRNAs to human cells

Recent findings in nanomedicine have revealed that carbon nanotubes (CNTs) can be used as potential drug carriers, therapeutic agents and diagnostics tools. Moreover, due to their ability to cross cellular membranes, their nanosize dimension, high surface area and relatively good biocompatibility, CNTs have also been employed as a novel gene delivery vector system. In our previous work, we functionalized CNTs with two polyamine polymers, polyethyleneimine (PEI) and polyamidoamine dendrimer (PAMAM). These compounds have low cytotoxicity, ability to conjugate microRNAs (such as miR-503) and, at the same time, transfect efficiently endothelial cells. The parameters contributing to the good efficiency of transfection that we observed were not investigated in detail. In fact, the diameter and length of CNTs are important parameters to be taken into account when evaluating the effects on drug delivery efficiency. In order to investigate the biophysical and biological contributions of polymer-coated CNTs in delivery of miRNAs to human cells, we decided to investigate three different preparations, characterized by different dimensions and aspect ratios. In particular, we took into account very small CNTs, a suspension of CNTs starting from the commercial product and a 2D material based on CNTs (ie, buckypapers [BPs]) to examine the transfection efficiency of a rigid scaffold. In conclusion, we extensively investigated the biophysical and biological contributions of polyamine-coated CNTs and bidimensional BPs in the delivery of miRNAs to human cells, in order to optimize the transfection efficiency of these compounds to be employed as efficient drug delivery vectors in biomedical applications.

Biophysical and biological contributions of polyamine-coated carbon nanotubes and bidimensional buckypapers in the delivery of miRNAs to human cells

Recent findings in nanomedicine have revealed that carbon nanotubes (CNTs) can be used as potential drug carriers, therapeutic agents and diagnostics tools. Moreover, due to their ability to cross cellular membranes, their nanosize dimension, high surface area and relatively good biocompatibility, CNTs have also been employed as a novel gene delivery vector system. In our previous work, we functionalized CNTs with two polyamine polymers, polyethyleneimine (PEI) and polyamidoamine dendrimer (PAMAM). These compounds have low cytotoxicity, ability to conjugate microRNAs (such as miR-503) and, at the same time, transfect efficiently endothelial cells. The parameters contributing to the good efficiency of transfection that we observed were not investigated in detail. In fact, the diameter and length of CNTs are important parameters to be taken into account when evaluating the effects on drug delivery efficiency. In order to investigate the biophysical and biological contributions of polymer-coated CNTs in delivery of miRNAs to human cells, we decided to investigate three different preparations, characterized by different dimensions and aspect ratios. In particular, we took into account very small CNTs, a suspension of CNTs starting from the commercial product and a 2D material based on CNTs (ie, buckypapers [BPs]) to examine the transfection efficiency of a rigid scaffold. In conclusion, we extensively investigated the biophysical and biological contributions of polyamine-coated CNTs and bidimensional BPs in the delivery of miRNAs to human cells, in order to optimize the transfection efficiency of these compounds to be employed as efficient drug delivery vectors in biomedical applications.

Synergistic Suppression of Tumor Angiogenesis by the Co-delivering of Vascular Endothelial Growth Factor Targeted siRNA and Candesartan Mediated by Functionalized Carbon Nanovectors

Single-walled carbon nanotubes (SWNTs) with unique physicochemical properties have exhibited promising biomedical applications as drug and gene carriers. In this study, polyethylenimine (PEI)-modified SWNT conjugates linked with candesartan (CD) were developed to deliver vascular endothelial growth factor (VEGF)-targeted siRNA (siVEGF) for the synergistic and targeted treatment of tumor angiogenesis. The characterization results revealed that SWNT-PEI-CD conjugates were successfully synthesized and exhibited desirable dispersibility and superior stability. Confocal laser scanning microscopy (CLSM) and flow cytometry (FCM) results showed that SWNT-PEI-CD/siVEGF complexes could achieve high cellular uptake and specific intracellular distribution of siRNA in AT₁R overexpressed PANC-1 cells. Strong down-regulation of VEGF was also verified by qualitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blot in complex-treated PANC-1 cells. The in vitro angiogenesis assay showed that SWNT-PEI-CD/siVEGF complexes highly inhibited tube formation of human umbilical vein endothelial cells. Furthermore, in vivo observation in PANC-1 xenografted nude mice demonstrated that SWNT-PEI-CD/siVEGF complexes exhibited significant distribution at tumor sites and caused obvious inhibition of tumor growth and tumor-associated angiogenesis repression induced by the drug combination of CD and siVEGF. Finally, a WST-1 assay indicated that SWNT-PEI-CD possessed low cytotoxicity, and a hemolysis test showed good biocompatibility of SWNT-PEI-CD. Hematological and histological analyses confirmed that SWNT-PEI-CD/siVEGF complexes did not cause any obvious toxic effects to blood and major organs. These findings suggested that the SWNT-PEI-CD/siVEGF co-delivery system with tumor-targeting specificity, improved endosomal escaping properties, and collaboration of angiogenesis inhibition could be a prospective method for efficient tumor antiangiogenic therapy.

Systematic evaluation of oligodeoxynucleotide binding and hybridization to modified multi-walled carbon nanotubes

BACKGROUND

In addition to conventional chemotherapeutics, nucleic acid-based therapeutics like antisense oligodeoxynucleotides (AS-ODN) represent a novel approach for the treatment of bladder cancer (BCa). An efficient delivery of AS-ODN to the urothelium and then into cancer cells might be achieved by the local application of multi-walled carbon nanotubes (MWCNT). In the present study, pristine MWCNT and MWCNT functionalized with hydrophilic moieties were synthesized and then investigated regarding their physicochemical characteristics, dispersibility, biocompatibility, cellular uptake and mucoadhesive properties. Finally, their binding capacity for AS-ODN via hybridization to carrier strand oligodeoxynucleotides (CS-ODN), which were either non-covalently adsorbed or covalently bound to the different MWCNT types, was evaluated.

RESULTS

Pristine MWCNT were successfully functionalized with hydrophilic moieties (MWCNT-OH, -COOH, -NH2, -SH), which led to an improved dispersibility and an enhanced dispersion stability. A viability assay revealed that MWCNT-OH, MWCNT-NH2 and MWCNT-SH were most biocompatible. All MWCNT were internalized by BCa cells, whereupon the highest uptake was observed for MWCNT-OH with 40% of the cells showing an engulfment. Furthermore, all types of MWCNT could adhere to the urothelium of explanted mouse bladders, but the amount of the covered urothelial area was with 2-7% rather low. As indicated by fluorescence measurements, it was possible to attach CS-ODN by adsorption and covalent binding to functionalized MWCNT. Adsorption of CS-ODN to pristine MWCNT, MWCNT-COOH and MWCNT-NH2 as well as covalent coupling to MWCNT-NH2 and MWCNT-SH resulted in the best binding capacity and stability. Subsequently, therapeutic AS-ODN could be hybridized to and reversibly released from the CS-ODN coupled via both strategies to the functionalized MWCNT. The release of AS-ODN at experimental conditions (80 °C, buffer) was most effective from CS-ODN adsorbed to MWCNT-OH and MWCNT-NH2 as well as from CS-ODN covalently attached to MWCNT-COOH, MWCNT-NH2 and MWCNT-SH. Furthermore, we could exemplarily demonstrate that AS-ODN could be released following hybridization to CS-ODN adsorbed to MWCNT-OH at physiological settings (37 °C, urine).

CONCLUSIONS

In conclusion, functionalized MWCNT might be used as nanotransporters in antisense therapy for the local treatment of BCa.

A review on current nanomaterials and their drug conjugate for targeted breast cancer treatment

Breast cancer is the most common malignancy worldwide, especially among women, with substantial after-treatment effects. The survival rates of breast cancer have decreased over the years even with the existence of various therapeutic strategies, specifically, chemotherapy. Clinical drugs administered for breast cancer appear to be non-targeting to specific cancer sites leading to severe side effects and potentially harming healthy cells instead of just killing cancer cells. This leads to the need for designing a targeted drug delivery system. Nanomaterials, both organic and inorganic, are potential drug nanocarriers with the ability of targeting, imaging and tracking. Various types of nanomaterials have been actively researched together with their drug conjugate. In this review, we focus on selected nanomaterials, namely solid-lipid, liposomal, polymeric, magnetic nanoparticles, quantum dots, and carbon nanotubes and their drug conjugates, for breast cancer studies. Their advantages, disadvantages and previously conducted studies were highlighted.

Understanding the sorption behavior of Pu4+ on poly(amidoamine) dendrimer functionalized carbon nanotube: sorption equilibrium, mechanism, kinetics, radiolytic stability, and back-extraction studies

Poly(amidoamine) dendrimer functionalized carbon nanotube was demonstrated as highly efficient sorbent of the Pu4+ from radioactive waste solution. The second generation dendrimer was found to have more efficiency as compared to the 1st generation might be due to the availability of more functionality for coordinating to the Pu4+ ion. Analysis of different isotherm models revealed that, Langmuir isotherm was predominantly operating through chemi-sorption (with the sorption energy 10.07 and 16.95 kJ mol−1 for 1st and 2nd generation dendrimer) with the sorption capacity 89.22 mg g−1 and 92.48 mg g−1 for 1st and 2nd generation dendrimer, respectively. Analysis of different sorption kinetics model revealed that the sorption proceeded via pseudo 2nd order reaction. The 2nd generation dendrimer was found to be radiolytically more stable while oxalic acid was found to be suitable for quantitative back extraction of Pu4+.

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.

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.

Applications of Functionalized Carbon Nanotubes for the Therapy and Diagnosis of Cancer

Carbon nanotubes (CNTs) are attractive nanostructures that serve as multifunctional transporters in biomedical applications, especially in the field of cancer therapy and diagnosis. Owing to their easily tunable nature and remarkable properties, numerous functionalizations and treatments of CNTs have been attempted for their utilization as hybrid nano-carriers in the delivery of various anticancer drugs, genes, proteins, and immunotherapeutic molecules. In this review, we discuss the current advances in the applications of CNT-based novel delivery systems with an emphasis on the various functionalizations of CNTs. We also highlight recent findings that demonstrate their important roles in cancer imaging applications, demonstrating their potential as unique agents with high-level ultrasonic emission, strong Raman scattering resonance, and magnetic properties.

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.

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.

A combination hepatoma-targeted therapy based on nanotechnology: pHRE-Egr1-HSV-TK/(131)I-antiAFPMcAb-GCV/MFH

Combination targeted therapy is a promising cancer therapeutic strategy. Here, using PEI-Mn0.5Zn0.5Fe2O4 nanoparticles (PEI-MZF-NPs) as magnetic media for MFH (magnetic fluid hyperthermia) and gene transfer vector for gene-therapy, a combined therapy, pHRE-Egr1-HSV-TK/(131)I-antiAFPMcAb-GCV/MFH, for hepatoma is developed. AntiAFPMcAb (Monoclonal antibody AFP) is exploited for targeting. The plasmids pHRE-Egr1-HSV-TK are achieved by incorporation of pEgr1-HSV-TK and pHRE-Egr1-EGFP. Restriction enzyme digestion and PCR confirm the recombinant plasmids pHRE-Egr1-HSV-TK are successfully constructed. After exposure to the magnetic field, PEI-MZF-NPs/pHRE-Egr1-EGFP fluid is warmed rapidly and then the temperature is maintained at 43 °C or so, which is quite appropriate for cancer treatment. The gene expression reaches the peak when treated with 200 μCi (131)I for 24 hours, indicating that the dose of 200 μCi might be the optimal dose for irradiation and 24 h irradiation later is the best time to initiate MFH. The in vitro and in vivo experiments demonstrate that pHRE-Egr1-HSV-TK/(131)I-antiAFPMcAb-GCV/MFH can greatly suppress hepatic tumor cell proliferation and induce cell apoptosis and necrosis and effectively inhibit the tumor growth, much better than any monotherapy does alone. Furthermore, the combination therapy has few or no adverse effects. It might be applicable as a strategy to treat hepatic cancer.

Carbon dots on based folic acid coated with PAMAM dendrimer as platform for Pt(IV) detection

Carbon quantum dots (CQDs) coated with poly(amidoamine) (PAMAM-NH2) dendrimer are prepared from folic acid and phosphoric acid under a hydrothermal procedure. The obtained nanoparticles are successfully used as fluorescent sensor for Pt(IV) (in the form of chloroplatinate ion). CQDs possess many attractive features including uniform dispersion with average size about 13nm for unmodified particles and, ∼30nm when they are coated with PAMAM-NH2 dendrimer. The synthesized nanoparticles have been characterized by elemental analysis, attenuated total reflectance (ATR), X-ray photoelectron (XPS) and Raman spectroscopies, transmission electron microscopy (TEM), dynamic light scattering (DLS), and steady-state and life-time fluorescence. CQDs are used as fluorescent sensor of Pt(IV) ion in aqueous media showing linear quenching effect of their fluorescence. The results obtained demonstrated a limit of detection of 657nM with an accuracy of the method of 0.13% (as RSD, n=10) and sensitivity of 78nM. Moreover, with the presence of other interference species, good results are obtained when applied in real samples from platinum nanoparticles synthesis. The dissolved platinum ions can be quantified in the range 6-96μM with an accuracy of 2.5%.

Functionalized carbon nanotubes and their promising applications in therapeutics and diagnostics

Carbon nanotubes (CNTs) have attracted much attention from researchers worldwide in recent years due to their high aspect ratio, high surface area, and excellent material properties, such as electrical and thermal conductivities and mechanical strength. These rolled-up seamless cylinders of graphene sheets possess nanosized hollow-tube-shaped structures. The CNTs can be single-walled, double-walled or multi-walled, depending upon the number of graphene layers from which a single nanotube is composed. The CNTs, favoring encapsulation of drug molecules or by possible attachment of theranostic agents on the nanotube walls, have enabled their use in controlled drug delivery, and in targeting of drug molecules to specific sites such as the lymphatic system, brain, ocular system, and cancerous tissue. This chapter provides an overview of various types of CNTs, methods utilized for their commercial production, and the functionalization approaches employed in drug-delivery applications. In addition, the chapter also endeavors to provide a thoughtful insight into the toxicity and regulatory concerns that need to be addressed before the CNTs can be launched in the market.

How do the full-generation poly(amido)amine (PAMAM) dendrimers activate blood platelets? Activation of circulating platelets and formation of "fibrinogen aggregates" in the presence of polycations

Direct use of poly(amido)amine (PAMAM) dendrimers as drugs may be limited, due to uncertain (cyto)toxicity. Peripheral blood components, which constitute the first line of a contact with administered pharmaceuticals, may become vastly affected by PAMAM dendrimers. The aim of this study was to explore how PAMAMs' polycationicity might affect blood platelet activation and reactivity, and thus trigger various haemostatic events. We monitored blood platelet reactivity in rats with experimental diabetes upon a long-term administration of the unmodified PAMAM dendrimers. In parallel, the effects on blood flow in a systemic circulation was recorded intravitally in mice administered with PAMAM G2, G3 or G4. Compounding was the in vitro approach to monitor the impact of PAMAM dendrimers on blood platelet activation and reactivity and on selected haemostatic and protein conformation parameters. We demonstrated the activating effects of polycations on blood platelets. Some diversity of the revealed outcomes considerably depended on the used approach and the particular technique employed to monitor blood platelet function. We discovered undesirable impact of plain PAMAM dendrimers on primary haemostasis and their prothrombotic influence. We emphasize the need of a more profound verifying of all the promising findings collected for PAMAMs with the use of well-designed in vivo preclinical studies.

Multifunctional hybrid-carbon nanotubes: new horizon in drug delivery and targeting

Carbon nanotubes (CNTs) have emerged as an intriguing nanotechnological tool for numerous biomedical applications including biocompatible modules for the bioactives delivery ascribed to their unique properties, such as greater loading efficiency, biocompatibility, non-immunogenicity, high surface area and photoluminescence, that make them ideal candidate in pharmaceutical and biomedical science. The design of multifunctional hybrid-CNTs for drug delivery and targeting may differ from the conventional drug delivery system. The conventional nanocarriers have few limitations, such as inappropriate availability of surface-chemical functional groups for conjugation, low entrapment/loading efficiency as well as stability as per ICH guidelines with generally regarded as safe (GRAS) prominences. The multifunctional hybrid-CNTs will sparked and open a new door for researchers, scientist of the pharmaceutical and biomedical arena. This review summarizes the vivid aspects of CNTs like characterization, supramolecular chemistry of CNTs-dendrimer, CNTs-nanoparticles, CNTs-quantum dots conjugate for delivery of bioactives, not discussed so far.

Regression of Gastric Cancer by Systemic Injection of RNA Nanoparticles Carrying both Ligand and siRNA

Gastric cancer is the second leading cause of cancer-related death worldwide. RNA nanotechnology has recently emerged as an important field due to recent finding of its high thermodynamic stability, favorable and distinctive in vivo attributes. Here we reported the use of the thermostable three-way junction (3WJ) of bacteriophage phi29 motor pRNA to escort folic acid, a fluorescent image marker and BRCAA1 siRNA for targeting, imaging, delivery, gene silencing and regression of gastric cancer in animal models. In vitro assay revealed that the RNA nanoparticles specifically bind to gastric cancer cells, and knock-down the BRCAA1 gene. Apoptosis of gastric cancer cells was observed. Animal trials confirmed that these RNA nanoparticles could be used to image gastric cancer in vivo, while showing little accumulation in crucial organs and tissues. The volume of gastric tumors noticeably decreased during the course of treatment. No damage to important organs by RNA nanoparticles was detectible. All the results indicated that this novel RNA nanotechnology can overcome conventional cancer therapeutic limitations and opens new opportunities for specific delivery of therapeutics to stomach cancer without damaging normal cells and tissues, reduce the toxicity and side effect, improve the therapeutic effect, and exhibit great potential in clinical tumor therapy.

Functionalized fullerenes in photodynamic therapy

Since the discovery of C60 fullerene in 1985, scientists have been searching for biomedical applications of this most fascinating of molecules. The unique photophysical and photochemical properties of C60 suggested that the molecule would function well as a photosensitizer in photodynamic therapy (PDT). PDT uses the combination of non-toxic dyes and harmless visible light to produce reactive oxygen species that kill unwanted cells. However the extreme insolubility and hydrophobicity of pristine CO60, mandated that the cage be functionalized with chemical groups that provided water solubility and biological targeting ability. It has been found that cationic quaternary ammonium groups provide both these features, and this review covers work on the use of cationic fullerenes to mediate destruction of cancer cells and pathogenic microorganisms in vitro and describes the treatment of tumors and microbial infections in mouse models. The design, synthesis, and use of simple pyrrolidinium salts, more complex decacationic chains, and light-harvesting antennae that can be attached to C60, C70 and C84 cages are covered. In the case of bacterial wound infections mice can be saved from certain death by fullerene-mediated PDT.

CD44v6 Monoclonal Antibody-Conjugated Gold Nanostars for Targeted Photoacoustic Imaging and Plasmonic Photothermal Therapy of Gastric Cancer Stem-like Cells

Developing safe and effective nanoprobes for targeted imaging and selective therapy of gastric cancer stem cells (GCSCs) has become one of the most promising anticancer strategies. Herein, gold nanostars-based PEGylated multifunctional nanoprobes were prepared with conjugated CD44v6 monoclonal antibodies (CD44v6-GNS) as the targeting ligands. It was observed that the prepared nanoprobes had high affinity towards GCSC spheroid colonies and destroyed them completely with a low power density upon near-infrared (NIR) laser treatment (790 nm, 1.5 W/cm(2), 5 min) in vitro experiment. Orthotopic and subcutaneous xenografted nude mice models of human gastric cancer were established. Subsequently, biodistribution and photothermal therapeutic effects after being intravenously injected with the prepared nanoprobes were assessed. Photoacoustic imaging revealed that CD44v6-GNS nanoprobes could target the gastric cancer vascular system actively at 4 h post-injection, while the probes inhibited tumor growth remarkably upon NIR laser irradiation, and even extended survivability of the gastric cancer-bearing mice. The CD44v6-GNS nanoprobes exhibited great potential for applications of gastric cancer targeted imaging and photothermal therapy in the near future.

EGF-coated nano-dendriplexes for tumor-targeted nucleic acid delivery in vivo

The clinical success of therapeutic DNA is still hindered due to the lack of effective delivery carriers. Here, we designed a tumor-targeted gene nano delivery system based on EGFR targeting strategy. Epidermal growth factor (EGF) was introduced to nano-complexes of PAMAM dendrimer and DNA via electrostatic interactions to form self-assembled PAMAM/DNA/EGF nano-complexes. The properties of self-assembled complexes were characterized by gel retardation assay and particle size and zeta potential analysis. Meanwhile, the toxicity of EGF-dendriplexes was evaluated by the MTT assay, which indicated that the complexes exhibited decreased cytotoxicity with the incorporation of EGF. We labeled polyamidoamine (PAMAM) dendrimers with FITC or a near-infrared (NIR) dye Lss670 and tested the cellular uptake in vitro and biodistribution in xenograft mouse tumor models. As compared to dendriplexes, the ternary EGF-dendriplexes showed a significantly higher cellular uptake into HepG2 cells due to the specific binding between EGF and EGF receptor (EGFR) over expressed on HepG2 cells, which resulted in the enhanced gene transfection efficiency. The biodistribution of EGF-dendriplexes in vivo was monitored with in vivo imaging technique, which indicated that EGF-dendriplexes enhanced EGFR-positive tumor-targeted biodistribution. These findings indicate that this novel nano-vector realized efficiently tumor-targeting gene delivery and high efficient gene expression in vivo, and it may possess a potential targeting gene delivery system in cancer therapy.