DNA and carbon nanotubes as medicine

Nanotechnology strategies to address challenges in topical and cellular delivery of siRNAs in skin disease therapy

Gene therapy is one of the most advanced therapies in current medicine. In particular, interference RNA-based therapy by small interfering RNA (siRNA) has gained attention in recent years as it is a highly versatile, selective and specific therapy. In dermatological conditions, topical delivery of siRNA offers numerous therapeutic advantages, mainly by inhibiting the expression of target transcripts directly in the skin. However, crossing the stratum corneum and overcoming intracellular barriers is an inherent challenge. Substantial efforts by scientists have moved towards the use of multimodal and multifunctional nanoparticles to overcome these barriers and achieve greater bioavailability in their site of action, the cytoplasm. In this review the most innovative strategies based on nanoparticle and physical methods are presented, as well as the design principles and the main factors that contribute to the performance of these systems. This review also highlights the synergistic contributions of medicine, nanotechnology, and molecular biology to advancing translational research into siRNA-based therapeutics for skin diseases.

In Vitro Studies on 3D-Printed PLA/HA/GNP Structures for Bone Tissue Regeneration

The successful regeneration of large-size bone defects remains one of the most critical challenges faced in orthopaedics. Recently, 3D printing technology has been widely used to fabricate reliable, reproducible and economically affordable scaffolds with specifically designed shapes and porosity, capable of providing sufficient biomimetic cues for a desired cellular behaviour. Natural or synthetic polymers reinforced with active bioceramics and/or graphene derivatives have demonstrated adequate mechanical properties and a proper cellular response, attracting the attention of researchers in the bone regeneration field. In the present work, 3D-printed graphene nanoplatelet (GNP)-reinforced polylactic acid (PLA)/hydroxyapatite (HA) composite scaffolds were fabricated using the fused deposition modelling (FDM) technique. The in vitro response of the MC3T3-E1 pre-osteoblasts and RAW 264.7 macrophages revealed that these newly designed scaffolds exhibited various survival rates and a sustained proliferation. Moreover, as expected, the addition of HA into the PLA matrix contributed to mimicking a bone extracellular matrix, leading to positive effects on the pre-osteoblast osteogenic differentiation. In addition, a limited inflammatory response was also observed. Overall, the results suggest the great potential of the newly developed 3D-printed composite materials as suitable candidates for bone tissue engineering applications.

Novel candidate theranostic radiopharmaceutical based on strontium hexaferrite nanoparticles conjugated with azacrown ligand

In this article, we report to the best of our knowledge the first modification of NPs with ligands for combined radiopharmaceuticals. Nanoparticles with suitable magnetic properties can be used both for diagnostics as a contrast for MRI and for therapy, including the insufficiently studied magneto-mechanical therapy. Strontium hexaferrite is one of the few hard-magnetic materials for which stable biocompatible colloidal solutions can be obtained. Strontium hexaferrite nanoparticles coated with silicon dioxide (SHF@SiO₂) were modified with an amino silane coupling agent (3-aminopropyl)triethoxysilane and azacrown ether derivatives with six heteroatoms in rings were covalently linked to the amine group through the carboxyl group. The hard magnetic nanoparticles were then radiolabeled with ²⁰⁷Bi with a labelling yield of up to 99.8%. In vitro experiments showed that the complex SHF@SiO₂-APTES-L2-²⁰⁷Bi is stable enough to be a potential theranostic radiopharmaceutical.

Mechanical Stability of DNA Corona Phase on Gold Nanospheres

Noncovalent adsorption of biopolymers on the surface of gold nanoparticles (AuNPs) forms a corona phase that drastically diversify AuNP functions. However, mechanical stabilities of such corona phase are still obscure, hindering the application of biopolymer-coated AuNPs. Here, using optical tweezers, we have observed, for the first time, that DNA corona phase adsorbed on a 5 nm AuNP via two (dA)21 strands in proximity can withstand an average desorption force of 40 pN, which is higher than the stall force of DNA/RNA polymerases. This suggests a new role for AuNPs to modulate replications or transcriptions after binding to prevalent poly(dA) segments in eukaryotic genomes. We have also revealed that with increasing AuNP size (1.8-10 nm), DNA corona becomes harder to remove, likely due to the larger surfaces and flatter facets on bigger AuNPs. These findings provide guidance to design AuNP corona that can withstand harsh environments for biological and materials applications.

Structure-switchable aptamer-arranged reconfigurable DNA nanonetworks for targeted cancer therapy

The structural DNA nanotechnology holds great potential application in bioimaging, drug delivery and cancer therapy. Herein, an intelligent aptamer-incorporated DNA nanonetwork (Apt-Nnes) is demonstrated for cancer cell imaging and targeted drug delivery, which essentially is a micron-scale pattern with the thickness of double-stranded monolayer. Cancer cell-surface receptors can make it perform magical transformation into small size of nanosheet intermediates and specifically enter target cells. The binding affinity of Apt-Nnes is increased by 3-fold due to multivalent binding effect of aptamers and it can maintain the structural integrity in fetal bovine serum (FBS) for 8 h. More interestingly, target cancer cells can cause the structural disassembly, and each resulting unit transports 4963 doxorubicin (Dox) into target cells, causing the specific cellular cytotoxicity. The cell surface receptor-mediated disassembly of large size of DNA nanostructures into small size of fractions provides a valuable insight into developing intelligent DNA nanostructure suitable for biomedical applications.

Comparison of Physicochemical, Mechanical, and (Micro-)Biological Properties of Sintered Scaffolds Based on Natural- and Synthetic Hydroxyapatite Supplemented with Selected Dopants

The specific combinations of materials and dopants presented in this work have not been previously described. The main goal of the presented work was to prepare and compare the different properties of newly developed composite materials manufactured by sintering. The synthetic- (SHAP) or natural- (NHAP) hydroxyapatite serves as a matrix and was doped with: (i) organic: multiwalled carbon nanotubes (MWCNT), fullerenes C60, (ii) inorganic: Cu nanowires. Research undertaken was aimed at seeking novel candidates for bone replacement biomaterials based on hydroxyapatite—the main inorganic component of bone, because bone reconstructive surgery is currently mostly carried out with the use of autografts; titanium or other non-hydroxyapatite -based materials. The physicomechanical properties of the developed biomaterials were tested by Scanning Electron Microscopy (SEM), Dielectric Spectroscopy (BSD), Nuclear Magnetic Resonance (NMR), and Differential Scanning Calorimetry (DSC), as well as microhardness using Vickers method. The results showed that despite obtaining porous sinters. The highest microhardness was achieved for composite materials based on NHAP. Based on NMR spectroscopy, residue organic substances could be observed in NHAP composites, probably due to the organic structures that make up the tooth. Microbiology investigations showed that the selected samples exhibit bacteriostatic properties against Gram-positive reference bacterial strain S. epidermidis (ATCC 12228); however, the property was much less pronounced against Gram-negative reference strain E. coli (ATCC 25922). Both NHAP and SHAP, as well as their doped derivates, displayed in good general compatibility, with the exception of Cu-nanowire doped derivates.

Broad-Spectrum Antimicrobial ZnMintPc Encapsulated in Magnetic-Nanocomposites with Graphene Oxide/MWCNTs Based on Bimodal Action of Photodynamic and Photothermal Effects

Microbial diseases have been declared one of the main threats to humanity, which is why, in recent years, great interest has been generated in the development of nanocomposites with antimicrobial capacity. The present work studied two magnetic nanocomposites based on graphene oxide (GO) and multiwall carbon nanotubes (MWCNTs). The synthesis of these magnetic nanocomposites consisted of three phases: first, the synthesis of iron magnetic nanoparticles (MNPs), second, the adsorption of the photosensitizer menthol-Zinc phthalocyanine (ZnMintPc) into MWCNTs and GO, and the third phase, encapsulation in poly (N-vinylcaprolactam-co-poly(ethylene glycol diacrylate)) poly (VCL-co-PEGDA) polymer VCL/PEGDA a biocompatible hydrogel, to obtain the magnetic nanocomposites VCL/PEGDA-MNPs-MWCNTs-ZnMintPc and VCL/PEGDA-MNPs-GO-ZnMintPc. In vitro studies were carried out using Escherichia coli and Staphylococcus aureus bacteria and the Candida albicans yeast based on the Photodynamic/Photothermal (PTT/PDT) effect. This research describes the nanocomposites’ optical, morphological, magnetic, and photophysical characteristics and their application as antimicrobial agents. The antimicrobial effect of magnetics nanocomposites was evaluated based on the PDT/PTT effect. For this purpose, doses of 65 mW·cm⁻² with 630 nm light were used. The VCL/PEGDA-MNPs-GO-ZnMintPc nanocomposite eliminated E. coli and S. aureus colonies, while the VCL/PEGDA-MNPs-MWCNTs-ZnMintPc nanocomposite was able to kill the three types of microorganisms. Consequently, the latter is considered a broad-spectrum antimicrobial agent in PDT and PTT.

Soft Bioelectronics Based on Nanomaterials

Recent advances in nanostructured materials and unconventional device designs have transformed the bioelectronics from a rigid and bulky form into a soft and ultrathin form and brought enormous advantages to the bioelectronics. For example, mechanical deformability of the soft bioelectronics and thus its conformal contact onto soft curved organs such as brain, heart, and skin have allowed researchers to measure high-quality biosignals, deliver real-time feedback treatments, and lower long-term side-effects in vivo. Here, we review various materials, fabrication methods, and device strategies for flexible and stretchable electronics, especially focusing on soft biointegrated electronics using nanomaterials and their composites. First, we summarize top-down material processing and bottom-up synthesis methods of various nanomaterials. Next, we discuss state-of-the-art technologies for intrinsically stretchable nanocomposites composed of nanostructured materials incorporated in elastomers or hydrogels. We also briefly discuss unconventional device design strategies for soft bioelectronics. Then individual device components for soft bioelectronics, such as biosensing, data storage, display, therapeutic stimulation, and power supply devices, are introduced. Afterward, representative application examples of the soft bioelectronics are described. A brief summary with a discussion on remaining challenges concludes the review.

Nanocarrier-delivered small interfering RNA for chemoresistant ovarian cancer therapy

Ovarian cancer is the fifth leading cause of cancer-related death in women in the United States. Because success in early screening is limited, and most patients with advanced disease develop resistance to multiple treatment modalities, the overall prognosis of ovarian cancer is poor. Despite the revolutionary role of surgery and chemotherapy in curing ovarian cancer, recurrence remains a major challenge in treatment. Thus, improving our understanding of the pathogenesis of ovarian cancer is essential for developing more effective treatments. In this review, we analyze the underlying molecular mechanisms leading to chemotherapy resistance. We discuss the clinical benefits and potential challenges of using nanocarrier-delivered small interfering RNA to treat chemotherapy-resistant ovarian cancer. We aim to elicit collaborative studies on nanocarrier-delivered small interfering RNA to improve the long-term survival rate and quality of life of patients with ovarian cancer. This article is categorized under: RNA Methods > RNA Nanotechnology Regulatory RNAs/RNAi/Riboswitches > RNAi: Mechanisms of Action.

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.

Biomolecule-Directed Carbon Nanotube Self-Assembly

The strategy of combining biomolecules and synthetic components to develop biohybrids is becoming increasingly popular for preparing highly customized and biocompatible functional materials. Carbon nanotubes (CNTs) benefit from bioconjugation, allowing their excellent properties to be applied to biomedical applications. This study reviews the state-of-the-art research in biomolecule-CNT conjugates and discusses strategies for their self-assembly into hierarchical structures. The review focuses on various highly ordered structures and the interesting properties resulting from the structural order. Hence, CNTs conjugated with the most relevant biomolecules, such as nucleic acids, peptides, proteins, saccharides, and lipids are discussed. The resulting well-defined composites allow the nanoscale properties of the CNTs to be exploited at the micro- and macroscale, with potential applications in tissue engineering, sensors, and wearable electronics. This review presents the underlying chemistry behind the CNT-based biohybrid materials and discusses the future directions of the field.

Small interfering RNA for cancer treatment: overcoming hurdles in delivery

In many ways, cancer cells are different from healthy cells. A lot of tactical nano-based drug delivery systems are based on the difference between cancer and healthy cells. Currently, nanotechnology-based delivery systems are the most promising tool to deliver DNA-based products to cancer cells. This review aims to highlight the latest development in the lipids and polymeric nanocarrier for siRNA delivery to the cancer cells. It also provides the necessary information about siRNA development and its mechanism of action. Overall, this review gives us a clear picture of lipid and polymer-based drug delivery systems, which in the future could form the base to translate the basic siRNA biology into siRNA-based cancer therapies.

A systematic review on carbohydrate biopolymers for adsorptive remediation of copper ions from aqueous environments-part A: Classification and modification strategies

Copper is one of the most toxic heavy metals which must be eliminated from aqueous environments, according to the environmental standards. Carbohydrate biopolymers are promising candidates for synthesizing copper-adsorbent composites. It is due to unique properties such as having potential adsorptive functional sites, availability, biocompatibility and biodegradability, formability, blending capacity, and reusability. Different types of copper-adsorbent carbohydrate biopolymers like chitosan and cellulose with particular focus on the synthesizing and modification approaches have been tackled in this review. Composites, functionality and morphological aspects of the biopolymer adsorbents have also been surveyed. Further progress in the fabrication and application of biopolymer adsorbents would be achievable with special attention to some critical challenges such as the process economy, copolymer and/or (nano) additive selection, and the physicochemical stability of the biopolymer composites in aqueous media.

A Review of Theranostics Applications and Toxicities of Carbon Nanomaterials

BACKGROUND

In the last few years, the use of modified Carbon Nanomaterials (CNMs) for theranostics (therapeutic and diagnosis) applications is a new and rapidly growing area in pharmacy and medical fields. Owing to this, their specific physicochemical behaviors like high stability, drug loading, surface area to volume ratio, with low toxicity and immunogenicity are mainly responsible to be considered those as smart nanomaterials.

OBJECTIVES

This review describes the different dimensions of carbon-based nanocarriers including 0-D fullerene, 1-D Carbon Nanotubes (CNTs), and 2-D graphene and Graphene Oxide (GO) and their surface modification with different biocompatible and biodegradable molecules via covalent or non-covalent functionalization. The major focus of this article is on the different theranostics applications of CNMs like targeted drugs and genes delivery, photodynamic therapy, photothermal therapy, bioimaging, and biosensing. The therapeutic efficacy of drugs could be enhanced by delivering them directly on a specific site using different targeted ligands such as vitamins, peptide, carbohydrates, proteins, etc. A section of the article also discusses the toxicity of the CNMs to the living systems.

CONCLUSIONS

In brief, this review article discusses the numerous theranostics applications and toxicities of CNMs.

Nanomaterials towards Biosensing of Alzheimer's Disease Biomarkers

Alzheimer's disease (AD) is an incurable and highly debilitating condition characterized by the progressive degeneration and/or death of nerve cells, which leads to manifestation of disabilities in cognitive functioning. In recent years, the development of biosensors for determination of AD's main biomarkers has made remarkable progress, particularly based on the tremendous advances in nanoscience and nanotechnology. The unique and outstanding properties of nanomaterials (such as graphene, carbon nanotubes, gold, silver and magnetic nanoparticles, polymers and quantum dots) have been contributing to enhance the electrochemical and optical behavior of transducers while offering a suitable matrix for the immobilization of biological recognition elements. Therefore, optical and electrochemical immuno- and DNA-biosensors with higher sensitivity, selectivity and longer stability have been reported. Nevertheless, strategies based on the detection of multiple analytes still need to be improved, as they will play a crucial role in minimizing misdiagnosis. This review aims to provide insights into the conjugation of nanomaterials with different transducers highlighting their crucial role in the construction of biosensors for detection of AD main biomarkers.

Small interfering RNAs (siRNAs) in cancer therapy: a nano-based approach

Cancer is one of the most complex diseases that has resulted in multiple genetic disorders and cellular abnormalities. Globally, cancer is the most common health concern disease that is affecting human beings. Great efforts have been made over the past decades in biology with the aim of searching novel and more efficient tools in therapy. Thus, small interfering RNAs (siRNAs) have been considered one of the most noteworthy developments which are able to regulate gene expression following a process known as RNA interference (RNAi). RNAi is a post-transcriptional mechanism that involves the inhibition of gene expression through promoting cleavage on a specific area of a target messenger RNA (mRNA). This technology has shown promising therapeutic results for a good number of diseases, especially in cancer. However, siRNA therapeutics have to face important drawbacks in therapy including stability and successful siRNA delivery in vivo. In this regard, the development of effective siRNA delivery systems has helped addressing these issues by opening novel therapeutic windows which have allowed to build up important advances in Nanomedicine. In this review, we discuss the progress of siRNA therapy as well as its medical application via nanoparticle-mediated delivery for cancer treatment.

In vitro cytotoxicity of calcium phosphate cement reinforced with multiwalled carbon nanotubes

The in vitro cytotoxicity of both the multiwalled carbon nanotubes (MWCNT) in suspension with culture medium and the tetracalcium phosphate/monetite cement with addition of 0.8 wt% of MWCNTs on fibroblasts and osteoblasts were studied. The cytotoxicity was evaluated by MTS test (formazan) and live/dead staining. No cytotoxicity of MWCNT extract was measured contrary to about 60% reduction in proliferation of fibroblasts in MWCNT suspension as compared with negative control. The several contact cytotoxicity of MWCNT composite cement surfaces on seeded cells was demonstrated by MTS test and live/dead staining of damaged fibroblasts and dead osteoblasts after 72 h of culture. The detailed microstructure analysis showed a significant refinement of the surface texture due to the formation of thin needle-like hydroxyapatite particles on MWCNTs and this effect could be responsible for cytotoxicity of composites.

Carbon Nanotubes as A High-Performance Platform for Target Delivery of Anticancer Quinones

BACKGROUND

In spite of considerable efforts of researchers the cancer deseases remain to be incurable and a percentage of cancer deseases in the structure of mortality increases every year. At that, high systemic toxicity of antitumor drugs hampers their effective use. Because of this fact, the development of nanosystems for targeted delivery of antitumor drugs is one of the leading problem in nanomedicine and nanopharmacy.

OBJECTIVE

To critically examine the modern strategies for carbon nanotubes (CNTs)-based delivery of anticancer quinones and to summarize the mechanisms which can provide high effectiveness and multifunctionality of the CNT-based quinone delivery platform.

RESULTS

Quinones, including anthracycline antibiotics - doxorubicin and daunorubicin, are among the most prospective group of natural and syntetic compounds which exhibit high antitumor activity against different type of tumors. In this review, we focus on the possibilities of using CNTs for targeted delivery of antitumor compounds with quinoid moiety which is ordinarily characterized by high specific interaction with DNA molecules. Quinones can be non-covalently adsorbed on CNT surface due to their aromatic structure and π-conjugated system of double bonds. The characteristic features of doxorubicine-CNT complex are high loading efficiency, pH-dependent release in acidic tumor microenviroment, enough stability in biological fluid. Different types of CNT functionalization, targeting strategies and designs for multifunctional CNT-based doxorubicine delivery platform are disscussed.

CONCLUSION

Nanosystems based on functionalized CNTs are very promising platform for quinone delivery resulting in significant enhancement of cancer treatment efficiency. Functionalization of CNTs with the polymeric shell, especially DNA-based shells, can provide the greatest affinity and mimicry with biological structures.

Carbon Nanomaterials for Targeted Cancer Therapy Drugs: A Critical Review

Cancer represents one of the main causes of human death in developed countries. Most current therapies, unfortunately, carry a number of side effects, such as toxicity and damage to healthy cells, as well as the risk of resistance and recurrence. Therefore, cancer research is trying to develop therapeutic procedures with minimal negative consequences. The use of nanomaterial-based systems appears to be one of them. In recent years, great progress has been made in the field using nanomaterials with high potential in biomedical applications. Carbon nanomaterials, thanks to their unique physicochemical properties, are gaining more and more popularity in cancer therapy. They are valued especially for their ability to deliver drugs or small therapeutic molecules to these cells. Through surface functionalization, they can specifically target tumor tissues, increasing the therapeutic potential and significantly reducing the adverse effects of therapy. Their potential future use could, therefore, be as vehicles for drug delivery. This review presents the latest findings of research studies using carbon nanomaterials in the treatment of various types of cancer. To carry out this study, different databases such as Web of Science, PubMed, MEDLINE and Google Scholar were employed. The findings of research studies chosen from more than 2000 viewed scientific publications from the last 15 years were compared.

Carbon nanotubes as nanovectors for intracellular delivery of laronidase in Mucopolysaccharidosis type I

The immobilization of proteins on carbon nanotubes (CNTs) has been widely reported mainly for the preparation of sensors while the conjugation of enzymes for therapeutic purposes has scarcely been considered. Herein we report, to the best of our knowledge, the first example of intracellular delivery of a therapeutic enzyme by means of CNTs, retaining its activity. Mucopolysaccharidosis I is a rare genetic disease characterized by the deficiency or absence of the activity of the α-l-iduronidase (IDUA) enzyme. We evaluated the capacity of the recombinant form of the human IDUA enzyme, laronidase (Aldurazyme®), conjugated with CNTs to be internalized by fibroblasts from subjects affected with Mucopolysaccharidosis type I and the capacity of the enzyme to retain its activity after internalization. The enzyme was successfully delivered into the lysosomal space and the enzymatic activity of the conjugate was preserved after internalization up to 48 hours. This paves the way towards the use of such a kind of construct for therapeutic applications.

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.

Mesoporous carbon nanomaterials in drug delivery and biomedical application

Recent development of nano-technology provides highly efficient and versatile treatment methods to achieve better therapeutic efficacy and lower side effects of malignant cancer. The exploration of drug delivery systems (DDSs) based on nano-material shows great promise in translating nano-technology to clinical use to benefit patients. As an emerging inorganic nanomaterial, mesoporous carbon nanomaterials (MCNs) possess both the mesoporous structure and the carbonaceous composition, endowing them with superior nature compared with mesoporous silica nanomaterials and other carbon-based materials, such as carbon nanotube, graphene and fullerene. In this review, we highlighted the cutting-edge progress of carbon nanomaterials as drug delivery systems (DDSs), including immediate/sustained drug delivery systems and controlled/targeted drug delivery systems. In addition, several representative biomedical applications of mesoporous carbon such as (1) photo-chemo synergistic therapy; (2) delivery of therapeutic biomolecule and (3) in vivo bioimaging are discussed and integrated. Finally, potential challenges and outlook for future development of mesoporous carbon in biomedical fields have been discussed in detail.

Nanoescapology: progress toward understanding the endosomal escape of polymeric nanoparticles

Using nanoparticles to deliver drugs to cells has the potential to revolutionize the treatment of many diseases, including HIV, cancer, and diabetes. One of the major challenges facing this field is controlling where the drug is trafficked once the nanoparticle is taken up into the cell. In particular, if drugs remain localized in an endosomal or lysosomal compartment, the therapeutic can be rendered completely ineffective. To ensure the design of more effective delivery systems we must first develop a better understanding of how nanoparticles and their cargo are trafficked inside cells. This needs to be combined with an understanding of what characteristics are required for nanoparticles to achieve endosomal escape, along with methods to detect endosomal escape effectively. This review is focused into three sections: first, an introduction to the mechanisms governing internalization and trafficking in cells, second, a discussion of methods to detect endosomal escape, and finally, recent advances in controlling endosomal escape from polymer- and lipid-based nanoparticles, with a focus on engineering materials to promote endosomal escape. WIREs Nanomed Nanobiotechnol 2017, 9:e1452. doi: 10.1002/wnan.1452 For further resources related to this article, please visit the WIREs website.

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.

Recent advances in green nanoparticulate systems for drug delivery: efficient delivery and safety concern

Nanotechnology manipulates therapeutic agents at the nanoscale for the development of nanomedicines. However, there are current concerns over nanomedicines, mainly related to the possible toxicity of nanomaterials used for health medications. Due to their small size, they can enter the human body more readily than larger sized particles. Green chemistry encompasses the green synthesis of drug-loaded nanoparticles by reducing the use of hazardous materials in the synthesis process, thus reducing the adverse health impacts of pharmaceutics. This would greatly expand their potential in biomedical treatments. This review highlights the potential risks of nanomedicine formulations to health, delivery routes of green nanomedicines, recent advances in the development of green nanoscale systems for biomedical applications and future perspectives for the green development of nanomedicines.

A New Carbon Nanotube-Based Breast Cancer Drug Delivery System: Preparation and In Vitro Analysis Using Paclitaxel

Paclitaxel (PTX) is one of the most important drugs for breast cancer; however, the drug effects are limited by its systematic toxicity and poor water solubility. Nanoparticles have been applied for delivery of cancer drugs to overcome their limitations. Toward this goal, a novel single-walled carbon nanotube (SWNT)-based drug delivery system was developed by conjugation of human serum albumin (HSA) nanoparticles for loading of antitumor agent PTX. The nanosized macromolecular SWNT-drug carrier (SWNT-HSA) was characterized by TEM, UV-Vis-NIR spectrometry, and TGA. The SWNT-based drug carrier displayed high intracellular delivery efficiency (cell uptake rate of 80%) in breast cancer MCF-7 cells, as examined by fluorescence-labeled drug carriers, suggesting the needle-shaped SWNT-HSA drug carrier was able to transport drugs across cell membrane despite its macromolecular structure. The drug loading on SWNT-based drug carrier was through high binding affinity of PTX to HSA proteins. The PTX formulated with SWNT-HSA showed greater growth inhibition activity in MCF-7 breast cancer cells than PTX formulated with HSA nanoparticle only (cell viability of 63 vs 70% in 48 h and 53 vs 62% in 72 h). The increased drug efficacy could be driven by SWNT-mediated cell internalization. These data suggest that the developed SWNT-based antitumor agent is functional and effective. However, more studies for in vivo drug delivery efficacy and other properties are needed before this delivery system can be fully realized.

Smart Carbon Nanotubes with Laser-Controlled Behavior in Gene Delivery and Therapy through a Non-Digestive Trafficking Pathway

Near-infrared (NIR) laser-controlled gene delivery presents some benefits in gene therapy, inducing enhanced gene transfection efficiency. In this study, a "photothermal transfection" agent is obtained by wrapping poly(ethylenimine)-cholesterol derivatives (PEI-Chol) around single-walled carbon nanotubes (SWNTs). The PEI-Chol modified SWNTs (PCS) are effective in compressing DNA molecules and protecting them from DNaseI degradation. Compared to the complexes formed by PEI with DNA (PEI/DNA), complexes of PCS and DNA that are formed (PCS/DNA) exhibit a little lower toxicity to HEK293 and HeLa cells under the same PEI molecule weight and weight ratios. Notably, caveolae-mediated cellular uptake of PCS/DNA occurs, which results in a safer intracellular transport of the gene due to the decreased lysosomal degradation in comparison with that of PEI/DNA whose internalization mainly depends on clathrin rather than caveolae. Furthermore, unlike PEI/DNA, PCS/DNA exhibits a photothermal conversion ability, which promotes DNA release from PCS under NIR laser irradiation. The NIR laser-mediated photothermal transfection of PCS_10K /plasmid TP53 (pTP53) results in more apoptosis and necrosis of HeLa cells in vitro than other groups, and achieves a higher tumor-growth inhibition in vivo than naked pTP53, PEI_25K /pTP53, and PCS_10K /pTP53 alone. The enhanced transfection efficiency of PCS/DNA can be attributed to more efficient DNA internalization into the tumor cells, promotes detachment of DNA from PCS under the mediation of NIR laser and higher DNA stability in the cells due to caveolae-mediated cellular uptake of the complexes.

Carbon Nanomaterials Interfacing with Neurons: An In vivo Perspective

Developing new tools that outperform current state of the art technologies for imaging, drug delivery or electrical sensing in neuronal tissues is one of the great challenges in neurosciences. Investigations into the potential use of carbon nanomaterials for such applications started about two decades ago. Since then, numerous in vitro studies have examined interactions between these nanomaterials and neurons, either by evaluating their compatibility, as vectors for drug delivery, or for their potential use in electric activity sensing and manipulation. The results obtained indicate that carbon nanomaterials may be suitable for medical therapies. However, a relatively small number of in vivo studies have been carried out to date. In order to facilitate the transformation of carbon nanomaterial into practical neurobiomedical applications, it is essential to identify and highlight in the existing literature the strengths and weakness that different carbon nanomaterials have displayed when probed in vivo. Unfortunately the current literature is sometimes sparse and confusing. To offer a clearer picture of the in vivo studies on carbon nanomaterials in the central nervous system, we provide a systematic and critical review. Hereby we identify properties and behavior of carbon nanomaterials in vivo inside the neural tissues, and we examine key achievements and potentially problematic toxicological issues.

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.

The Nucleophilic Addition of In Situ Generated Calcium Thiolate of Benzonitrile to the Sidewall of Single-Walled Carbon Nanotubes: A New and Direct Approach for Thioamidation

A new and efficient method for the thioamidation of single-walled carbon nanotubes (SWCNTs) has been introduced by direct addition of an intermediately generated nitrogen-based nucleophile. In this approach, there is a synergistic effect between benzonitrile, CaH2, and thioacetic acid leading to the formation of calcium thiolate which subsequently added to the sidewalls of the tubes. This finding was also confirmed when SWCNTs with benzonitrile moieties on their sidewalls were tested. The successful covalent functionalization of SWCNTs has been proven by thermogravimetric analysis, Raman, IR, and X-ray photoelectron spectroscopy techniques.

A Review of Patterned Organic Bioelectronic Materials and their Biomedical Applications

Organic electronic materials are rapidly emerging as superior replacements for a number of conventional electronic materials, such as metals and semiconductors. Conducting polymers, carbon nanotubes, graphenes, organic light-emitting diodes, and diamond films fabricated via chemical vapor deposition are the most popular organic bioelectronic materials that are currently under active research and development. Besides the capability to translate biological signals to electrical signals or vice versa, organic bioelectronic materials entail greater biocompatibility and biodegradability compared to conventional electronic materials, which makes them more suitable for biomedical applications. When patterned, these materials bring about numerous capabilities to perform various tasks in a more-sophisticated and high-throughput manner. Here, we provide an overview of the unique properties of organic bioelectronic materials, different strategies applied to pattern these materials, and finally their applications in the field of biomedical engineering, particularly biosensing, cell and tissue engineering, actuators, and drug delivery.

Studying Different Binding and Intracellular Delivery Efficiency of ssDNA Single-Walled Carbon Nanotubes and Their Effects on LC3-Related Autophagy in Renal Mesangial Cells via miRNA-382

Single-walled carbon nanotubes (SWCNTs) have been used to deliver single-stranded (ssDNA). ssDNA in oligonucleotide can act as an inhibitor of microRNA to regulate cellular functions. However, these ssDNA are difficult to bind carbon nanotubes with low transferring efficiency to cells. To this end, we designed ssDNA with regulatory and functional units to form ssDNA-SWCNT hybrids to study their binding effects and transferring efficiency. The functional unit on ssDNA mimics the inhibitor (MI) of miRNA-382, which plays a crucial role in the progress of many diseases such as renal interstitial fibrosis. After verification of overexpression of miRNA-382 in a coculture system, we designed oligonucleotide sequences (GCG)5-MI, (TAT)5-MI, and N23-MI as regulatory units added to the 5'-terminal end of the functional DNA fragment, respectively. These regulatory units lead to different secondary structures and thus exhibit different affinity ability to SWCNTs, and finally decide their deliver efficacy to cells. Autophagy, apoptosis and necrosis were observed in renal mesangial cells.

Diseases originate and terminate by genes: unraveling nonviral gene delivery

The world is driving in to the era of transformation of chemical therapeutic molecules to biological genetic material therapeutics, and that is where the biological drugs especially "genes" come into existence. These genes worked as "magical bullets" to specifically silence faulty genes responsible for progression of diseases. Viral gene delivery research is far ahead of nonviral gene delivery technique. However, with more advancement in polymer science, new ways are opening for better and efficient nonviral gene delivery. But efficient delivery method is always considered as a bottleneck for gene delivery as success of which will decide the fate of gene in cells. During the past decade, it became evident that extracellular as well as intracellular barriers compromise the transfection efficiency of nonviral vectors. The challenge for gene therapy research is to pinpoint the rate-limiting steps in this complex process and implement strategies to overcome the biological physiochemical and metabolic barriers encountered during targeting. The synergy between studies that investigate the mechanism of breaking in and breaking out of nonviral gene delivery carrier through various extracellular and intracellular barriers with desired characteristics will enable the rational design of vehicles and revolutionize the treatment of various diseases.

Inorganic nanovectors for nucleic acid delivery

Nucleic acids show immense potential to treat cancer, acquired immune deficiency syndrome, neurological diseases and other incurable human diseases. Upon systemic administration, they encounter a series of barriers and hence barely reach the site of action, the cell. Intracellular delivery of nucleic acids is facilitated by nanovectors, both viral and non-viral. A major advantage of non-viral vectors over viral vectors is safety. Nanovectors evaluated specifically for nucleic acid delivery include polyplexes, lipoplexes and other cationic carrier-based vectors. However, more recently there is an increased interest in inorganic nanovectors for nucleic acid delivery. Nevertheless, there is no comprehensive review on the subject. The present review would cover in detail specific properties and types of inorganic nanovectors, their preparation techniques and various biomedical applications as therapeutics, diagnostics and theranostics. Future prospects are also suggested.

Theranostic applications of carbon nanomaterials in cancer: Focus on imaging and cargo delivery

Carbon based nanomaterials have attracted significant attention over the past decades due to their unique physical properties, versatile functionalization chemistry, and biological compatibility. In this review, we will summarize the current state-of-the-art applications of carbon nanomaterials in cancer imaging and drug delivery/therapy. The carbon nanomaterials will be categorized into fullerenes, nanotubes, nanohorns, nanodiamonds, nanodots and graphene derivatives based on their morphologies. The chemical conjugation/functionalization strategies of each category will be introduced before focusing on their applications in cancer imaging (fluorescence/bioluminescence, magnetic resonance (MR), positron emission tomography (PET), single-photon emission computed tomography (SPECT), photoacoustic, Raman imaging, etc.) and cargo (chemo/gene/therapy) delivery. The advantages and limitations of each category and the potential clinical utilization of these carbon nanomaterials will be discussed. Multifunctional carbon nanoplatforms have the potential to serve as optimal candidates for image-guided delivery vectors for cancer.

Spectroscopic studies on sidewall carboxylic acid functionalization of multi-walled carbon nanotubes with valine

The valine functionalized multi-walled carbon nanotubes (MWCNTS) were prepared and characterized by using XRD, UV-Vis, FT-IR, EPR, SEM, and EDX, spectroscopic techniques. The enhanced XRD peak (002) intensity was observed for valine functionalized MWCNTs compared with oxidized MWCNTs, which is likely due to sample purification by acid washing. UV-Vis study shows the formation of valine functionalized MWCNTs. FT-IR study confirms the presence of functional groups of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed EPR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using SEM. The EDX spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The functionalization has been chosen because, functionalization of CNTs with amino acids makes them soluble and biocompatible. Thus, they have potential applications in the field of biosensors and targeted drug delivery.

Programmable nanomedicine: synergistic and sequential drug delivery systems

Recent developments in nanomedicine for the cancer therapy have enabled programmable delivery of therapeutics by exploiting the stimuli-responsive properties of nanocarriers. These therapeutic systems were designed with the relevant chemical and physical properties that respond to different triggers for enhanced anticancer efficacy, including the reduced development of drug-resistance, lower therapeutic dose, site-specific transport, and spatiotemporally controlled release. This minireview discusses the current advances in programmable nanocarriers for cancer therapy with particular emphasis on synergistic and sequential drug delivery systems.

Preparation and characterization of chitosan/silver nanoparticle/copper nanoparticle/carbon nanotube multifunctional nano-composite for water treatment: heavy metals removal; kinetics, isotherms and competitive studies

A chitosan/Ag NP/Cu NP/CNT multifunctional composite has superior water treatment efficiency compared with bare chitosan and bi-composite systems.

Selective assembly of DNA-conjugated single-walled carbon nanotubes from the vascular secretome

Colloidal dispersion of single-walled carbon nanotubes (SWCNTs) is often the first processing step to many of their unique applications. However, dispersed SWCNTs often exist in kinetically trapped states where aggregation can be of concern. Recent work revealed prominent DNA-SWCNT aggregation following intravascular injection. In this study, we performed detailed analysis of DNA-SWCNT aggregate formation, structure, and composition in the context of endothelial cell condition media. Interestingly, we found that aggregates formed within condition media from cells that have undergone a stress response differ in size and organization from that of the control. We also found that temperature increases also promote DNA-SWCNT associations. A mathematical model was developed to describe the kinetics of SWCNT extraction from solution. Through orthogonal optical analysis and imaging modalities, we verified that proteins form the bulk of the aggregate structure and dictate aggregate assembly at multiple levels of organization. Finally, physiochemical analysis indicated preferential extraction of low-abundance hydrophobic and charged proteins. The formed aggregates also remain relatively stable in solution, making them potential macroscopic indicators of solution content.

USNCTAM perspectives on mechanics in medicine

Over decades, the theoretical and applied mechanics community has developed sophisticated approaches for analysing the behaviour of complex engineering systems. Most of these approaches have targeted systems in the transportation, materials, defence and energy industries. Applying and further developing engineering approaches for understanding, predicting and modulating the response of complicated biomedical processes not only holds great promise in meeting societal needs, but also poses serious challenges. This report, prepared for the US National Committee on Theoretical and Applied Mechanics, aims to identify the most pressing challenges in biological sciences and medicine that can be tackled within the broad field of mechanics. This echoes and complements a number of national and international initiatives aiming at fostering interdisciplinary biomedical research. This report also comments on cultural/educational challenges. Specifically, this report focuses on three major thrusts in which we believe mechanics has and will continue to have a substantial impact. (i) Rationally engineering injectable nano/microdevices for imaging and therapy of disease. Within this context, we discuss nanoparticle carrier design, vascular transport and adhesion, endocytosis and tumour growth in response to therapy, as well as uncertainty quantification techniques to better connect models and experiments. (ii) Design of biomedical devices, including point-of-care diagnostic systems, model organ and multi-organ microdevices, and pulsatile ventricular assistant devices. (iii) Mechanics of cellular processes, including mechanosensing and mechanotransduction, improved characterization of cellular constitutive behaviour, and microfluidic systems for single-cell studies.

Poly(ethyleneimine) functionalized carbon nanotubes as efficient nano-vector for transfecting mesenchymal stem cells

For gene and drug delivery applications, carbon nanotubes (CNTs) have to be functionalized in order to become compatible with aqueous media and bind with genetic materials. In this study, combination of polyethyleneimine (PEI) grafted multi-walled carbon nanotubes (PEI-g-MWCNTs) and chitosan substrate is used as an efficient gene delivery system for transfection of hard-to-transfect bone marrow mesenchymal stem cells (BMSCs) with enhanced green fluorescent protein (EGFP) gene. Fourier transform infrared (FT-IR) spectra, dynamic light scattering (DLS) analysis and zeta potential measurements are used to characterize binding of PEI, particle size distribution and colloidal stability of the functionalized CNTs, respectively. DNA binding affinity, cellular uptake, transfection efficiency and possible cytotoxicity are also tested by agarose gel electrophoresis, flow cytometry, cytochemisty and MTT assay. The results demonstrate that cytotoxic effect of PEI-g-MWCNTs is negligible under optimal transfection condition. In consistency with high cellular uptake (>82%), PEI-g-MWCNTs give higher delivery of EGFP into the BMSCs which results in a more sustained expression of the model gene (EGFP) in short-term culture. These results suggest that PEI-g-MWCNTs in corporation with chitosan substrates would be a promising delivery system for BMSCs, a cell type with relevancy in the regenerative medicine and clinical applications.

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

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