Promises, facts and challenges for carbon nanotubes in imaging and therapeutics

Designing inorganic nanomaterials for vaccines and immunotherapies

Vaccines and immunotherapies have changed the face of health care. Biomaterials offer the ability to improve upon these medical technologies through increased control of the types and concentrations of immune signals delivered. Further, these carriers enable targeting, stability, and delivery of poorly soluble cargos. Inorganic nanomaterials possess unique optical, electric, and magnetic properties, as well as defined chemistry, high surface-to-volume- ratio, and high avidity display that make this class of materials particularly advantageous for vaccine design, cancer immunotherapy, and autoimmune treatments. In this review we focus on this understudied area by highlighting recent work with inorganic materials - including gold nanoparticles, carbon nanotubes, and quantum dots. We discuss the intrinsic features of these materials that impact the interactions with immune cells and tissue, as well as recent reports using inorganic materials across a range of emerging immunological applications.

Graphene-Based Nanomaterials: From Production to Integration With Modern Tools in Neuroscience

Graphene, a two-dimensional carbon crystal, has emerged as a promising material for sensing and modulating neuronal activity in vitro and in vivo. In this review, we provide a primer for how manufacturing processes to produce graphene and graphene oxide result in materials properties that may be tailored for a variety of applications. We further discuss how graphene may be composited with other bio-compatible materials of interest to make novel hybrid complexes with desired characteristics for bio-interfacing. We then highlight graphene's ever-widen utility and unique properties that may in the future be multiplexed for cross-modal modulation or interrogation of neuronal network. As the biological effects of graphene are still an area of active investigation, we discuss recent development, with special focus on how surface coatings and surface properties of graphene are relevant to its biological effects. We discuss studies conducted in both non-murine and murine systems, and emphasize the preclinical aspect of graphene's potential without undermining its tangible clinical implementation.

An In Vitro Study on the Cytotoxicity and Genotoxicity of Silver Sulfide Quantum Dots Coated with Meso-2,3-dimercaptosuccinic Acid

Objectives

Silver sulfide (Ag₂S) quantum dots (QDs) are highly promising nanomaterials in bioimaging systems due to their high activities for both imaging and drug/gene delivery. There is insufficient research on the toxicity of Ag₂S QDs coated with meso-2,3-dimercaptosuccinic acid (DMSA). In this study, we aimed to determine the cytotoxicity of Ag₂S QDs coated with DMSA in Chinese hamster lung fibroblast (V79) cells over a wide range of concentrations (5-2000 μg/mL).

Materials and Methods

Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutral red uptake (NRU) assays. The genotoxic and apoptotic effects of DMSA/Ag₂S QDs were also assessed by comet assay and real-time polymerase chain reaction technique, respectively.

Results

Cell viability was 54.0±4.8% and 65.7±4.1% at the highest dose (2000 μg/mL) of Ag₂S QDs using the MTT and NRU assays, respectively. Although cell viability decreased above 400 μg/mL (MTT assay) and 800 μg/mL (NRU assay), DNA damage was not induced by DMSA/Ag₂S QDs at the studied concentrations. The mRNA expression levels of p53, caspase-3, caspase-9, Bax, Bcl-2, and survivin genes were altered in the cells exposed to 500 and 1000 μg/mL DMSA/Ag₂S QDs.

Conclusion

The cytotoxic effects of DMSA/Ag₂S QDs may occur at high doses through the apoptotic pathways. However, DMSA/Ag₂S QDs appear to be biocompatible at low doses, making them well suited for cell labeling applications.

Elevated internalization and cytotoxicity of polydispersed single-walled carbon nanotubes in activated B cells can be basis for preferential depletion of activated B cells in vivo

Uptake of polydispersed acid-functionalized single-walled carbon nanotubes (AF-SWCNTs) in resting and LPS-activated B cells was studied using fluorescence-tagged AF-SWCNTs (FAF-SWCNTs). Activated B cells internalized substantially higher amounts of FAF-SWCNTs [76.5% AF-SWCNT⁺ B cells, mean fluorescence intensity (MFI) 720.6] as compared to the resting B cells [39.5% AF-SWCNT⁺ B cells, MFI 198.5]. B cells in S and G2/M phases were found to have significantly higher uptake of FAF-SWCNTs as compared to cells in G0/G1 phase. Confocal microscopy indicated that AF-SWCNTs were essentially localized on cell membrane in resting B cells, whereas in activated B cells, AF-SWCNTs were distributed throughout the cytoplasm. Targeting of AF-SWCNTs specifically to activated B cells in vivo was examined by first administering intravenously LPS-activated B cells tagged with fluorescence tracer (CFSE) in mice, followed by FAF-SWCNTs through the same route. It was found that FAF-SWCNTs were specifically taken up by CFSE+CD19+-activated B cells (95% FAF-SWCNT⁺ B cells, MFI 3725) as compared to CFSE^- CD19⁺ resting B cells (31.1% FAF-SWCNT⁺ B cells, MFI 428). Administration (i.v.) of LPS resulted in a significant increase in the proportion of B cell in mouse spleen that was reduced by 68% by administering AF-SWCNTs. In control mice, the corresponding decrease in B cell proportion was 49%, which was significantly lower (p < 0.005) than the decline in LPS-treated mice. These results indicate that AF-SWCNTs may have the potential as an agent for depleting activated B cells in vivo.

Gdn 3+@CNTs-PEG versus Gadovist®: In Vitro Assay

Objectives

Carbon nanotubes (CNTs) are allotropes of carbon with a length-to-diameter ratio greater than 10⁶ with the potential uses as medical diagnostic or therapeutic agents. In vitro studies have revealed that gadolinium (Gd) nanoparticle-catalyzed single-walled carbon nanotubes (SWCNTs) possess superparamagnetic properties, which enable them to be used as contrast agents in magnetic resonance imaging (MRI). Our study synthesized Gd-CNT for use as MRI contrast agents.

Methods

To reduce the toxicity and solubility of CNTs, it was functionalized, and after loading with Gd was coated with polyethylene glycols (PEG). We then synthesized different concentrations of Gd_n³⁺@CNTs-PEG and Gadovist^® to be evaluated as MRI contrast agents.

Results

The analysis showed that the Gd concentration in Gadovist^® was 12.18% higher than synthesized Gd_n³⁺@CNTs-PEG, but the mean signal intensity of the Gd_n³⁺@CNTs-PEG was approximately 3.3% times higher than Gadovist^®.

Conclusions

Our findings indicate that synthesized Gd_n³⁺@CNTs-PEG has the potential to be used as an MRI contrast agent in vitro, but in vivo assessment is necessary to determine the bio-distribution, kinetic, and signal enhancement characteristics.

Effect of polyethylene glycol surface charge functionalization of SWCNT on the in vitro and in vivo nanotoxicity and biodistribution monitored noninvasively using MRI

The current study evaluated in vitro and in vivo toxicity of carboxyl or amine polyethylene glycol (PEG) surface functionalization of single-walled carbon nanotubes (SWCNTs). Assessments of cytotoxicity, genotoxicity, immunotoxicity, and oxidative stress were performed in vitro and in vivo (in a 1-month follow-up study). The SWCNT biodistribution was investigated using noninvasive magnetic resonance imaging (MRI). Results confirmed the enhanced biocompatibility of PEG-functionalized SWCNTs compared to non-functionalized materials with significant decreases (p < 0.05) in the percentage of cell viability and increases in ROS generation, mitochondrial membrane potential, cell apoptosis, oxidative stress generation, and oxidative DNA damage in vitro. PEG-functionalized SWCNTs with amine terminals were found to induce prominent increases in ROS generation, mitochondrial membrane potential, and oxidative stress compared to carboxy functionalization. No significant difference in the biodistribution of either functionalized SWCNTs was observed in MRI. In vivo assessments revealed a statistically significant increase (p < 0.05) in oxidative stress as early as 24 h in serum and liver; however, all values normalized at 2 weeks' investigation time point. DNA damage was minimal with either PEG-COOH or PEG-NH₂ functionalized SWCNTs after 2 weeks' exposure. The negatively charged SWCNTs caused lesser DNA damage compared to positively charged samples. Carboxy-functionalized SWCNTs did not cause substantial changes in inflammatory mediators and were found to be significantly safer than non-functionalized SWCNTs and may pave the way for novel biomedical applications in cancer diagnosis and therapy.

Biological Response to Carbon-Family Nanomaterials: Interactions at the Nano-Bio Interface

During the last few decades, several studies have suggested that carbon-based nanomaterials, owing to their unique properties, could act as promising candidates in biomedical engineering application. Wide-ranging research efforts have investigated the cellular and molecular responses to carbon-based nanomaterials at the nano-bio interfaces. In addition, a number of surface functionalization strategies have been introduced to improve their safety profile in the biological environment. The present review discusses the general principles of immunological responses to nanomaterials. Then, it explains essential physico-chemical properties of carbon-familynanomaterials, including carbon nanotubes (CNTs), graphene, fullerene, carbon quantum dots (CDs), diamond-like carbon (DLC), and mesoporous carbon biomaterials (MCNs), which significantly affect the immunological cellular and molecular responses at the nano-bio interface. The discussions also briefly highlight the recent studies that critically investigated the cellular and molecular responses to various carbon-based nanomaterials. It is expected that the most recent perspective strategies for improving the biological responses to carbon-based nanomaterials can revolutionize their functions in emerging biological applications.

Molecular Dynamics Simulations of Water-Mediated Cholesterol Capture within an Open-Ended Single-Walled Carbon Nanotube

The excess concentration of cholesterol in the bloodstream can be brought down to a safer level by utilizing a potential cholesterol-binding agent such as a carbon nanotube (CNT). Here, we have probed solvent-mediated interactions between cholesterol and CNT by performing molecular dynamics simulations and potential-of-mean force (PMF) calculations. Simulations predict favorable interactions between water-mediated cholesterol and CNT owing to strong mutual interactions between them, whereas water plays an opposing role in the association. The breakdown of PMF into its enthalpic and entropic contributions indicates that contrary to traditional entropy-driven hydrophobic association, the cholesterol encapsulation within a CNT is primarily driven by enthalpy.

Threshold Rigidity Values for the Asbestos-like Pathogenicity of High-Aspect-Ratio Carbon Nanotubes in a Mouse Pleural Inflammation Model

The qualitative and quantitative evaluation of the physicochemical parameters associated with the pathogenicity of high-aspect-ratio nanomaterials is important for comprehensive regulation efforts and safety-by-design approaches. Here, we report quantitative data on the correlations between the rigidity of these nanomaterials and toxicity endpoints in vitro and in vivo. As measured by new ISO standards published in 2017, rigidity shows a strong positive correlation with inflammogenic potential, as indicated by inflammatory cell counts and IL-1β (a biomarker for frustrated phagocytosis) levels in both the acute and chronic phases. In vitro experiments using differentiated THP-1 cells find that only highly rigid multiwalled carbon nanotubes (MWCNTs) and asbestos fibers lead to piercing and frustrated phagocytosis. Thus, this study suggests a bending ratio of 0.97 and a static bending persistence length of 1.08 as threshold rigidity values for asbestos-like pathogenicity. However, additional research using MWCNTs with rigidity values that lie between those of non-inflammogenic ( D_b = 0.66 and SBPL = 0.87) and inflammogenic fibers ( D_b = 0.97 and SBPL = 1.09) is required to identify more accurate threshold values, which would be useful for comprehensive regulation and safety-by-design approaches based on MWCNTs.

Unique Photochemo-Immuno-Nanoplatform against Orthotopic Xenograft Oral Cancer and Metastatic Syngeneic Breast Cancer

Sophisticated self-assembly may endow materials with a variety of unique functions that are highly desirable for therapeutic nanoplatform. Herein, we report the coassembly of two structurally defined telodendrimers, each comprised of hydrophilic linear PEG and hydrophobic cholic acid cluster as a basic amphiphilic molecular subunit. One telodendrimer has four added indocyanine green derivatives, leading to excellent photothermal properties; the other telodendrimer has four sulfhydryl groups designed for efficient intersubunit cross-linking, contributing to superior stability during circulation. The coassembled nanoparticle (CPCI-NP) possesses superior photothermal conversion efficiency as well as efficient encapsulation and controlled release of cytotoxic molecules and immunomodulatory agents. CPCI-NP loaded with doxorubicin has proven to be a highly efficacious combination photothermal/chemotherapeutic nanoplatform against orthotopic OSC-3 oral cancer xenograft model. When loaded with imiquimod, a potent small molecule immunostimulant, CPCI-NP is found to be highly effective against 4T1 syngeneic murine breast cancer model, particularly when photothermal/immuno-therapy is given in combination with PD-1 checkpoint blockade antibody. Such triple therapy not only eradicates the light-irradiated primary tumors, but also activates systemic antitumor immunoactivity, causing tumor death at light-unexposed distant tumor sites. This coassembled multifunctional, versatile, and easily scalable photothermal immuno-nanoplatform shows great promise for clinical translation.

Supramolecular chemotherapy based on host-guest molecular recognition: a novel strategy in the battle against cancer with a bright future

Chemotherapy is currently one of the most effective ways to treat cancer. However, traditional chemotherapy faces several obstacles to clinical trials, such as poor solubility/stability, non-targeting capability and uncontrollable release of the drugs, greatly limiting their anticancer efficacy and causing severe side effects towards normal tissues. Supramolecular chemotherapy integrating non-covalent interactions and traditional chemotherapy is a highly promising candidate in this regard and can be appropriately used for targeted drug delivery. By taking advantage of supramolecular chemistry, some limitations impeding traditional chemotherapy for clinical applications can be solved effectively. Therefore, we present here a review summarizing the progress of supramolecular chemotherapy in cancer treatment based on host-guest recognition and provide guidance on the design of new targeting supramolecular chemotherapy combining diagnostic and therapeutic functions. Based on a large number of state-of-the-art studies, our review will advance supramolecular chemotherapy on the basis of host-guest recognition and promote translational clinical applications.

Nanomedicine in cancer stem cell therapy: from fringe to forefront

Nanomedicine is the spin-off of modern medicine and nanotechnology and aims to prevent and treat diseases using nanoscale materials such as biocompatible nanoparticles and nanorobots. Targeted cellular and tissue-specific clinical applications with maximal therapeutic effects and insignificant side effects could be achieved by the pursuit of nanotechnology in medicine and healthcare regimen. The majority of conventional cancer therapies eliminate the cells of the tumor but not the cancer stem cells (CSCs). Conversely, the use of nanotechnology in CSC-based therapies is an emerging field of biomedical sciences. This article summarizes the recent trends and application of nanomedicine especially in CSC therapy along with its limitations.

Carbon Nanomaterials in Optical Detection

Owing to their unique optical, electronic, mechanical, and chemical properties, flexible chemical modification, large surface coverage and ready cellular uptake, various carbon nanomaterials such as carbon nanotubes (CNTs), graphene and its derivatives, carbon dots (CDs), graphene quantum dots, fullerenes, carbon nanohorns (CNHs) and carbon nano-onions (CNOs), have been widely explored for use in optical detection. Most of them are based on fluorescence changes. In this chapter, we will focus on carbon nanomaterials-based optical detection applications, mainly including fluorescence sensing and bio-imaging. Moreover, perspectives on future exploration of carbon nanomaterials for optical detection are also given.

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.

Carrageenan based hydrogels for drug delivery, tissue engineering and wound healing

Carrageenan is a class of naturally occurring sulphated polysaccharides, which is currently a promising candidate in tissue engineering and regenerative medicine as it resemblances native glycosaminoglycans. From pharmaceutical drug formulations to tissue engineered scaffolds, carrageenan has broad range of applications. Here we provide an overview of developing various forms of carrageenan based hydrogels. We focus on how these fabrication processes has an effect on physiochemical properties of the hydrogel. We outline the application of these hydrogels not only pertaining to sustained drug release but also their application in bone and cartilage tissue engineering as well as in wound healing and antimicrobial formulations. Administration of these hydrogels through various routes for drug delivery applications has been critically reviewed. Finally, we conclude by summarizing the current and future outlook that promotes the seaweed-derived polysaccharide as versatile, promising biomaterial for a variety of bioengineering applications.

Advancement in Photothermal Effect of Carbon Nanotubes by Grafting of Poly(amidoamine) and Deposition of CdS Nanocrystallites

A robust, near-infrared (NIR) active photothermal agent, CNTs-PAMAM/G4-CdS, is designed by covalent grafting of fourth generation poly(amidoamine) (PAMAM) to carbon nanotubes (CNTs) and successive deposition of cadmium sulfide (CdS) nanocrystallites. The systematic advancement in photothermal effect of CNTs was achieved by grafting of first, second, third, and fourth generation PAMAM through the repeated process of Michael's addition. The subsequent deposition of CdS nanocrystallites over fourth generation PAMAM grafted CNTs has further improved the photothermal effect (PTE) of CNTs. The photothermal effect of CNTs-PAMAM/G4-CdS was accessed by illuminating with 980 nm NIR laser. During measurement of PTE, maximum temperature attained by CNTs-PAMAM/G4-CdS was 64.1 °C which far exceeds the survival temperature of cancer cells. The photothermal conversion efficiency estimated for CNTs-PAMAM/G4-CdS was 32%, which is higher than the value reported for popular gold and copper based photothermal agents. Apart from its outstanding photothermal effect, CNTs-PAMAM/G4-CdS possessed excellence in both antiphoto-bleaching and antiphoto-corrosiveness.

Scanning Techniques for Nanobioconjugates of Carbon Nanotubes

Nanobioconjugates using carbon nanotubes (CNTs) are attractive and promising hybrid materials. Various biological applications using the CNT nanobioconjugates, for example, drug delivery systems and nanobiosensors, have been proposed by many authors. Scanning techniques such as scanning electron microscopy (SEM) and scanning probe microscopy (SPM) have advantages to characterize the CNT nanobioconjugates under various conditions, for example, isolated conjugates, conjugates in thin films, and conjugates in living cells. In this review article, almost 300 papers are categorized based on types of CNT applications, and various scanning data are introduced to illuminate merits of scanning techniques.

Peptide-based nanoprobes for molecular imaging and disease diagnostics

Pathological changes in a diseased site are often accompanied by abnormal activities of various biomolecules in and around the involved cells. Identifying the location and expression levels of these biomolecules could enable early-stage diagnosis of the related disease, the design of an appropriate treatment strategy, and the accurate assessment of the treatment outcomes. Over the past two decades, a great diversity of peptide-based nanoprobes (PBNs) have been developed, aiming to improve the in vitro and in vivo performances of water-soluble molecular probes through engineering of their primary chemical structures as well as the physicochemical properties of their resultant assemblies. In this review, we introduce strategies and approaches adopted for the identification of functional peptides in the context of molecular imaging and disease diagnostics, and then focus our discussion on the design and construction of PBNs capable of navigating through physiological barriers for targeted delivery and improved specificity and sensitivity in recognizing target biomolecules. We highlight the biological and structural roles that low-molecular-weight peptides play in PBN design and provide our perspectives on the future development of PBNs for clinical translation.

Electromagnetic Nanoparticles for Sensing and Medical Diagnostic Applications

A modeling and design approach is proposed for nanoparticle-based electromagnetic devices. First, the structure properties were analytically studied using Maxwell's equations. The method provides us a robust link between nanoparticles electromagnetic response (amplitude and phase) and their geometrical characteristics (shape, geometry, and dimensions). Secondly, new designs based on "metamaterial" concept are proposed, demonstrating great performances in terms of wide-angle range functionality and multi/wide behavior, compared to conventional devices working at the same frequencies. The approach offers potential applications to build-up new advanced platforms for sensing and medical diagnostics. Therefore, in the final part of the article, some practical examples are reported such as cancer detection, water content measurements, chemical analysis, glucose concentration measurements and blood diseases monitoring.

Design of Protein-Coated Carbon Nanotubes Loaded with Hydrophobic Drugs through Sacrificial Templating of Mesoporous Silica Shells

One key challenge in the fields of nanomedicine and tissue engineering is the design of theranostic nanoplatforms able to monitor their therapeutic effect by imaging. Among current developed nano-objects, carbon nanotubes (CNTs) were found suitable to combine imaging, photothermal therapy, and to be loaded with hydrophobic drugs. However, a main problem is their resulting low hydrophilicity. To face this problem, an innovative method is developed here, which consists in loading the surface of carbon nanotubes (CNTs) with drugs followed by a protein coating around them. The originality of this method relies on first covering CNTs with a sacrificial template mesoporous silica (MS) shell grafted with isobutyramide (IBAM) binders on which a protein nanofilm is strongly adhered through IBAM-mediated physical cross-linking. This concept is first demonstrated without drugs, and is further improved with the suitable loading of hydrophobic drugs, curcumin (CUR) and camptothecin (CPT), which are retained between the CNTs and human serum albumin (HSA) layer. Such novel nanocomposites with favorable photothermal properties are very promising for theranostic systems, drug delivery, and phototherapy applications.

Epoxidation of Carbon Nanocapsules: Decoration of Single-Walled Carbon Nanotubes Filled with Metal Halides

Methyl(trifluoromethyl)dioxirane (TFDO) can be used for the oxyfunctionalization of SWCNTs filled with NaI and LuCl₃ under mild conditions. The chosen metal halides are of interest for theranostics, both for imaging and therapy when in their radioactive form. The applied functionalization methodology does not require metal catalyst, preserves the integrity of the nanotubes during treatment, avoiding the release of the filling material. In this way, epoxidation can be considered as an efficient methodology for the functionalization of carbon nanocapsules, where the traditional harsh oxidation conditions by acids are not applicable.

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

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

Optimum morphology of gold nanorods for light-induced hyperthermia

Owing to their unique chemical and physical properties, colloidal gold nanoparticles have prompted a wide variety of biocompatible nano-agents for cancer imaging, diagnosis and treatment. In this context, biofunctionalized gold nanorods (AuNRs) are promising candidates for light-induced hyperthermia, to cause local and selective damage in malignant tissue. Yet, the efficacy of AuNR-based hyperthermia is highly dependent on several experimental parameters; in particular, the AuNR morphology strongly affects both physical and biological processes. In the present work, we systematically study the influence of different structural parameters like the AuNR aspect ratio, length and molecular weight on in vitro cytotoxicity, cellular uptake and heat generation efficiency. Our results enable us to identify the optimum AuNR morphology to be used for in vivo hyperthermia treatment.

A New Co-P Nanocomposite with Ultrahigh Relaxivity for In Vivo Magnetic Resonance Imaging-Guided Tumor Eradication by Chemo/Photothermal Synergistic Therapy

Design of new nanoagents that intrinsically have both diagnostic imaging and therapeutic capabilities is highly desirable for personalized medicine. In this work, a novel nanotheranostic agent is fabricated based on polydopamine (PDA)-functionalized Co-P nanocomposites (Co-P@PDA) for magnetic resonance imaging (MRI)-guided combined photothermal therapy and chemotherapy. The ultrahigh relaxivity of 224.61 mm^-1 s^-1 can enable Co-P@PDA to be applied as an excellent contrast agent for MRI in vitro and in vivo, providing essential and comprehensive information for tumor clinical diagnosis. Moreover, Co-P@PDA exhibit excellent photothermal performance owing to the strong near-infrared (NIR) absorbance of both Co-P nanocomposite and PDA. Highly effective ablation of tumors is achieved in a murine tumor model because the NIR laser not only induces photothermal effects but also triggers the chemotherapeutic drug on-demand release, which endows the Co-P@PDA with high curative effects but little toxicity and few side effects. These findings demonstrate that Co-P@PDA are promising agents for highly effective and precise antitumor treatment and warrant exploration as novel theranostic nanoagents with good potential for future clinical translation.

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.

An Immunologically Modified Nanosystem Based on Noncovalent Binding Between Single-Walled Carbon Nanotubes and Glycated Chitosan

Functionalized single-walled carbon nanotubes are currently being explored as novel delivery vehicles for proteins and therapeutic agents to treat various diseases. In order to maximize treatment efficacy, a strong binding between single-walled carbon nanotubes and their functionalized molecules is necessary. Glycated chitosan, a polymer with potent immunostimulatory properties for cancer treatment, has been used as a surfactant of single-walled carbon nanotubes to form an immunologically modified nanosystem for biomedical applications. In this study, we investigated the binding characteristics of single-walled carbon nanotube and glycated chitosan using molecular dynamics simulations. The mean square displacement, radius of gyration, interaction energy, and radial distribution function of the single-walled carbon nanotube-glycated chitosan system were analyzed. The results from the simulations demonstrated that glycated chitosan was bound to single-walled carbon nanotubes by a strong, noncovalent interaction. The stability of glycated chitosan on the single-walled carbon nanotubes surface was enhanced by the length of glycated chitosan, and the binding energy of the 2 molecules was closely related to the diameter and chirality of single-walled carbon nanotubes, with the most stable single-walled carbon nanotube-glycated chitosan system being formed by the combination of long polymer, large single-walled carbon nanotube, and armchair single-walled carbon nanotube. The understanding of the interactions between single-walled carbon nanotube and glycated chitosan and the structure of single-walled carbon nanotube-glycated chitosan allows the modifications of the novel nanosystem for disease diagnostics and therapeutics.

Titanium dioxide nanoparticles induce mitochondria-associated apoptosis in HepG2 cells

Widespread applications of nanosized materials over the past decade have prompted investigations of desirable properties and potential hazards to humans and the environment.

Mesoporous Carbon Nanospheres as a Multifunctional Carrier for Cancer Theranostics

Optical nanomaterials with intense absorption in near-infrared (NIR) region hold great promise for biomedical applications such as photothermal therapy (PTT) and photoacoustic imaging (PAI). In this work, we report mesoporous carbon nanospheres (Meso-CNs) with broadband and intense absorption in the UV-Vis-NIR region (300-1400 nm) and explore their potential as a multifunctional platform for photoacoustic imaging and chemo-photothermal therapy. Methods: Meso-CNs were prepared by a "silica-assisted" synthesis strategy and characterized by transmission electron microscope and optical spectroscopy. We investigated the photothermal conversion and photoacoustic imaging of Meso-CNs in comparison with single-walled carbon nanotubes (SWCNTs), graphene and gold nanorods (GNRs). In vitro cellular assays and in vivo chemo-photothermal combination therapy were performed. Results: The absorption coefficients of Meso-CNs are 1.5-2 times higher than those of SWCNTs and graphene and are comparable to those of GNRs in both the first and the second near-infrared optical windows (NIR-I and NIR-II) of tissues. When exposed to an NIR laser, the photothermal and photoacoustic signal generation of Meso-CNs are also stronger than those of SWCNTs, graphene, and GNRs. DOX was loaded into Meso-CNs with a high efficiency (35 wt%) owing to the unique mesoporous structure. Particularly, the drug release from Meso-CNs is sensitive to both pH and NIR light stimulation. In vivo chemo-photothermal combination therapy demonstrates a remarkable inhibition effect on tumor growth under NIR laser treatment. Conclusions: We have developed Meso-CNs for photothermal conversion and photoacoustic imaging. The porous structure also serves as a drug carrier and the drug release can be controlled by pH and external light. The high drug loading capacity, superior photothermal and photoacoustic generation, together with the apparent chemo-photothermal therapeutic effect, make Meso-CNs a promising platform for cancer theranostics.

Emergence in the functionalized carbon nanotubes as smart nanocarriers for drug delivery applications

Carbon nanotubes (CNTs) are the newer generation advanced materials for diverse applications, starting from physical, mechanical, chemical and biological sciences. However, the present era of healthcare industry is extensively using CNTs for exploring their applications in mitigating diverse needs. The considered attention in CNTs is due to their inimitable properties such as size and aspect ratio covering surface area to the length, and amenable electrical, thermal and mechanical properties. Available in diverse forms, viz. single-walled, double walled or multi-walled structures, CNTs of different forms possess multiple advantages in various healthcare segments, and especially in drug delivery for the treatment of diseases. CNTs have proven to be useful in specific drug delivery applications such as controlled and targeted drug delivery to desired sites such as lymphatic and ocular systems, brain and other cancerous tissues. Multiple research reports have been published till date, which unequivocally gives testimony to the potential applications of CNTs. The present book chapter, in this regard, endeavor to provide an overview on synthesis, characterization and drug delivery applications of CNTs. The chapter highlights on recent regulatory standards on commercial production and safety testing of the CNTs for translating them into market.

Ultrasound-promoted direct functionalization of multi-walled carbon nanotubes in water via Diels-Alder "click chemistry"

A facile and environmentally friendly strategy for grafting polymers onto the surface of multi-walled carbon nanotubes (CNTs) was demonstrated by Diels-Alder "click chemistry". Firstly, the copolymers of poly(styrene-alt-maleic anhydride) (PSM) were prepared by the reversible addition-fragmentation chain transfer (RAFT) polymerization and subsequently functionalized with furfuryl amine to introduce anchoring groups. The copolymers were then grafted on CNTs via the Diels-Alder reaction in water through a conventional heating-stirring route and ultrasound-assisted method. The obtained nanocomposite materials were characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. The results indicated that the reaction rate under ultrasound irradiation was accelerated about 12 times than the one under the conventional heating-stirring condition without losing the grafting efficiency. The direct functionalization of CNTs formed a stably dispersed solution in water, promising a green and effective method for industrial process.

Single Near-Infrared Emissive Polymer Nanoparticles as Versatile Phototheranostics

Attaining consistently high performance of diagnostic and therapeutic functions in one single nanoplatform is of great significance for nanomedicine. This study demonstrates the use of donor-acceptor (D-A) structured polymer (TBT) to develop a smart "all-five-in-one" theranostic that conveniently integrates fluorescence/photoacoustic/thermal imaging and photodynamic/photothermal therapy into single nanoparticle. The prepared nanoparticles (TBTPNPs) exhibit near-infrared emission, high water solubility, excellent light resistance, good pH stability, and negligible toxicity. Additionally, the TBTPNPs exhibit an excellent singlet oxygen (1O2) quantum yield (40%) and high photothermal conversion efficiency (37.1%) under single-laser irradiation (635 nm). Apart from their two phototherapeutic modalities, fluorescence, photoacoustic signals, and thermal imaging in vivo can be simultaneously achieved because of their enhanced permeability and retention effects. This work demonstrates that the prepared TBTPNPs are "all-five-in-one" phototheranostic agents that can exhibit properties to satisfy the "one-fits-all" requirement for future phototheranostic applications. Thus, the prepared TBTPNPs can provide fundamental insights into the development of PNP-based nanoagents for cancer therapy.

Mode of PEG Coverage on Carbon Nanotubes Affects Binding of Innate Immune Protein C1q

Surface modification of nanoparticles with poly(ethylene glycol) (PEG) is used in biomedicine to increase the circulation time of the particles after intravenous injection. Here, we study the interaction of PEG-covered carbon nanotubes (CNTs) with the serum complement protein C1q. Besides being the target-recognizing unit of the initiating complex for the classical pathway of complement in our innate immune system, C1q is involved in a range of important physiological processes. We modified the surface of multiwalled CNTs with covalently grafted PEG and physically adsorbed PEG. Transmission electron microscopy revealed the interaction of these PEG-coated CNTs with C1q. We found abundant C1q coverage on the PEG-grafted CNTs but not on the CNTs with adsorbed PEG. We tested the ability of these CNTs to activate the complement system using in vitro complement activation assays. None of the CNTs studied activated the C1q-dependent classical complement pathway. These findings are pertinent to the safe design and novel biomedical applications of PEGylated CNTs.

Aggregated Single-Walled Carbon Nanotubes Absorb and Deform Dopamine-Related Proteins Based on Molecular Dynamics Simulations

Single-walled carbon nanotubes (SWCNTs) have attracted considerable attention owing to their applications in various fields such as biotechnology and biomedicine. Recently, aggregated SWCNTs have shown more significant effects on the treatment of methamphetamine addiction (Nat. Nanotech. 2016, 11, 613). However, the mechanisms underlying these actions are unclear. By using all-atom molecular dynamics simulations, we investigate the effects of single and aggregated SWCNTs (single-(10,10)CNT, aggregated-7-(10,10)CNTs, and single-(35,35)CNT with the same diameter as that of the aggregated one) on the activity of dopamine-related proteins [tyrosine hydroxylase (TyrOH) and dopamine transporter (DAT), which are related to the synthesis and transport of dopamine, respectively]. We find that both TyrOH and DAT can adsorb onto these SWCNTs. For TyrOH, the aggregated-7-(10,10)CNTs mainly affect the conformation of the active site of the protein, and hence, they are more effective in inhibiting the expression of TyrOH. For DAT, our results suggest that the aggregated-7-(10,10)CNTs allow DAT to maintain an outward-facing conformation and hence are favorable to the reuptake of dopamine. The binding of a dopamine reuptake inhibitor, [³H]-WIN35,428, to DAT is significantly disrupted by aggregated-7-(10,10)CNTs and hence improve the ability to transport dopamine. Our results provide the dynamic interactions of proteins with single/aggregated SWCNTs, which illustrate the mechanism of aggregated SWCNTs for the treatment of drug addiction.

Magnetic Targeting and Delivery of Drug-Loaded SWCNTs Theranostic Nanoprobes to Lung Metastasis in Breast Cancer Animal Model: Noninvasive Monitoring Using Magnetic Resonance Imaging

PURPOSE

In this study, we aimed to develop novel therapeutic and diagnostic approaches by improving the targeting of doxorubicin-loaded single-walled carbon nanotubes (SWCNTs) to metastatic regions, and monitor their preferential homing and enhanced therapeutic effect using noninvasive free-breathing magnetic resonance imaging (MRI) and bioluminescence imaging.

PROCEDURES

High-energy flexible magnets were specifically positioned over the metastatic tumor sites in the lungs. SWCNTs biodistribution, tumor progression, and subsequent treatment efficiency were assessed following administration of the magnetically attracted doxorubicin-loaded anti-CD105 conjugated nanocarriers.

RESULTS

The use of high-energy magnets offered improved theranostic effect of doxorubicin-loaded nanocarriers, by magnetically targeting them towards metastatic tumor sites in the lungs. MRI allowed sensitive monitoring of nanocarriers biodistribution in the abdominal organs, their preferential homing towards the metastatic sites, and their enhanced therapeutic effect.

CONCLUSIONS

Combination of noninvasive MRI to localize sensitively the tumor sites, with specific positioning of magnets that can enhance the magnetic targeting of nanocarriers, allowed increasing the treatment efficiency.

Three-Dimensional Electroconductive Hyaluronic Acid Hydrogels Incorporated with Carbon Nanotubes and Polypyrrole by Catechol-Mediated Dispersion Enhance Neurogenesis of Human Neural Stem Cells

Electrically conductive hyaluronic acid (HA) hydrogels incorporated with single-walled carbon nanotubes (CNTs) and/or polypyrrole (PPy) were developed to promote differentiation of human neural stem/progenitor cells (hNSPCs). The CNT and PPy nanocomposites, which do not easily disperse in aqueous phases, dispersed well and were efficiently incorporated into catechol-functionalized HA (HA-CA) hydrogels by the oxidative catechol chemistry used for hydrogel cross-linking. The prepared electroconductive HA hydrogels provided dynamic, electrically conductive three-dimensional (3D) extracellular matrix environments that were biocompatible with hNSPCs. The HA-CA hydrogels containing CNT and/or PPy significantly promoted neuronal differentiation of human fetal neural stem cells (hfNSCs) and human induced pluripotent stem cell-derived neural progenitor cells (hiPSC-NPCs) with improved electrophysiological functionality when compared to differentiation of these cells in a bare HA-CA hydrogel without electroconductive motifs. Calcium channel expression was upregulated, depolarization was activated, and intracellular calcium influx was increased in hNSPCs that were differentiated in 3D electroconductive HA-CA hydrogels; these data suggest a potential mechanism for stem cell neurogenesis. Overall, our bioinspired, electroconductive HA hydrogels provide a promising cell-culture platform and tissue-engineering scaffold to improve neuronal regeneration.

Advanced Photoacoustic Imaging Applications of Near-Infrared Absorbing Organic Nanoparticles

Progress of nanotechnology in recent years has stimulated fast development of nanoparticles in biomedical research. Photoacoustic (PA) imaging as an emerging non-invasive technique in molecular imaging has improved imaging depth relative to conventional optical imaging, demonstrating great potential in clinical applications. The convergence of nanotechnology and PA imaging has enabled a broad spectrum of new opportunities in fundamental biology and translation medicine. This review focuses on the recent advances of organic nanoparticles in PA imaging applications. Near-infrared absorbing organic nanoparticles are classified and discussed according to their different imaging applications, which include tumor imaging, gastrointestinal imaging, sentinel lymph node imaging, disease microenvironment imaging and real-time drug imaging. The chemistry and PA properties of organic nanoparticles are discussed in details to highlight their own merits, and their challenges and perspectives in PA imaging are also discussed.