Alokita Karmakar

Toxicity and efficacy of carbon nanotubes and graphene: the utility of carbon-based nanoparticles in nanomedicine

Abstract Carbon-based nanomaterials have attracted great interest in biomedical applications such as advanced imaging, tissue regeneration, and drug or gene delivery. The toxicity of the carbon nanotubes and graphene remains a debated issue although many toxicological studies have been reported in the scientific community. In this review, we summarize the biological effects of carbon nanotubes and graphene in terms of in vitro and in vivo toxicity, genotoxicity and toxicokinetics. The dose, shape, surface chemistry, exposure route and purity play important roles in the metabolism of carbon-based nanomaterials resulting in differential toxicity. Careful examination of the physico-chemical properties of carbon-based nanomaterials is considered a basic approach to correlate the toxicological response with the unique properties of the carbon nanomaterials. The reactive oxygen species-mediated toxic mechanism of carbon nanotubes has been extensively discussed and strategies, such as surface modification, have been proposed to reduce the toxicity of these materials. Carbon-based nanomaterials used in photothermal therapy, drug delivery and tissue regeneration are also discussed in this review. The toxicokinetics, toxicity and efficacy of carbon-based nanotubes and graphene still need to be investigated further to pave a way for biomedical applications and a better understanding of their potential applications to humans.

Synergistic enhancement of cancer therapy using a combination of carbon nanotubes and anti-tumor drug

AIM In previous pharmacological applications, single-wall carbon nanotubes (CNTs) have primarily been explored as potential drug carriers and delivery vehicles. Here, we investigate and demonstrate for the first time, that CNTs can be considered as anti-tumor agents and, when in combination with conventional drugs, can significantly enhance their chemotherapeutic effects. METHOD & MATERIALS HeLa and human Panc1 cancer cells were treated with CNTs (24 h, 10 and 20 microg/ml), etoposide (6 h, 75 x 10(-6) M) and their combination. The cell viability was controlled by flow cytometry, caspase-3 assay and trypan blue dye. RESULTS A highly increased anti-tumor activity of the combination of etoposide and CNTs against cancer cells, compared with the administration of etoposide and CNTs alone, is reported. Data provided by viability assays suggest a strong interaction between CNTs and the cellular structures, thereby improving the effectiveness of conventional chemotherapeutic agents. CONCLUSION We believe this finding could lead to the development of new cancer therapies by carefully selecting the cytostatic drugs and nanostructural materials that, in combination, may provide synergistic curative rates.

Multifunctional Magnetic Nanoparticles for Synergistic Enhancement of Cancer Treatment by Combinatorial Radio Frequency Thermolysis and Drug Delivery

Few-layer, carbon-coated, iron (C/Fe) magnetic nanoparticles (MNPs) were synthesized with controlled sizes ranging from 7 to 9 nm. The additional loading of two anti-cancer drugs, doxorubicin and erlotinib, was achieved through - stacking onto the carbon shells. Controlled release of the drugs was successfully triggered by radio frequency (RF) heating or pH variation. Based on the experimental results, C/Fe MNPs act as heat-inducing agents and are able to thermally destroy cancer cells when RF is applied. It was found that the combination of anti-cancer drugs (in particular a low dose of doxorubicin) and RF treatment demonstrates a synergistic effect in inducing cell death in pancreatic cancer cells. Our findings demonstrate that MNPs can be used as highly efficient multimodal nanocarrier agents for an integrated approach to cancer treatment involving triggered delivery of antineoplastic drugs and RF-induced thermal therapy.

Ethylenediamine functionalized-single-walled nanotube (f-SWNT)-assisted in vitro delivery of the oncogene suppressor p53 gene to breast cancer MCF-7 cells

A gene delivery concept based on ethylenediamine-functionalized single-walled carbon nanotubes (f-SWCNTs) using the oncogene suppressor p53 gene as a model gene was successfully tested in vitro in MCF-7 breast cancer cells. The f-SWCNTs-p53 complexes were introduced into the cell medium at a concentration of 20 μg mL−1 and cells were exposed for 24, 48, and 72 hours. Standard ethidium bromide and acridine orange assays were used to detect apoptotic cells and indicated that a significantly larger percentage of the cells (approx 40%) were dead after 72 hours of exposure to f-SWCNTs-p53 as compared to the control cells, which were exposed to only p53 or f-SWCNTs, respectively. To further support the uptake and expression of the genes within the cells, green fluorescent protein-tagged p53, attached to the f-SWCNTs was added to the medium and the complex was observed to be strongly expressed in the cells. Moreover, caspase 3 activity was found to be highly enhanced in cells incubated with the f-SWCNTs-p53 complex, indicating strongly induced apoptosis. This system could be the foundation for novel gene delivery platforms based on the unique structural and morphological properties of multi-functional nanomaterials.

Magnetic nanoparticles as contrast agents in biomedical imaging: recent advances in iron- and manganese-based magnetic nanoparticles.

Abstract Improvements in diagnostic measures for biomedical applications have been investigated in various studies for better interpretations of biological abnormalities and several medical conditions. The use of imaging techniques, such as magnetic resonance imaging (MRI), is widespread and becoming a standard procedure for such specialized applications. A major avenue being studied in MRI is the use of magnetic nanoparticles (NPs) as contrast agents (CAs). Among various approaches, current research also incorporates use of superparamagnetic iron oxide NPs and manganese-based NPs with biocompatible coatings for improved stability and reduced biodegradation when exposed to a biological environment. In this review, recent advances with these types of magnetic NPs and their potential use as CAs in MRI are reported, as well as new insights into the selectivity and cellular transport mechanism that occurs following injection.

Nanostructural materials increase mineralization in bone cells and affect gene expression through miRNA regulation

We report that several nanomaterials induced enhanced mineralization (increased numbers and larger areas of mineral nests) in MC3T3‐E1 bone cells, with the highest response being induced by silver nanoparticles (AgNPs). We demonstrate that AgNPs altered microRNA expression resulting in specific gene expression associated with bone formation. We suggest that the identified essential transcriptional factors and bone morphogenetic proteins play an important role in activation of the process of mineralization in bone cells exposed to AgNPs.

Raman spectroscopy as a detection and analysis tool for in vitro specific targeting of pancreatic cancer cells by EGF‐conjugated, single‐walled carbon nanotubes

Single‐walled carbon nanotubes (SWCNTs) were covalently linked to epidermal growth factor (EGF) proteins through an esterification process that was found to be responsible for the docking of SWCNTs on the human pancreatic cancer cells (PANC‐1) surface, thus providing a mechanism for the enhanced delivery and internalization of the nanotubes. Micro Raman spectroscopy and enzyme‐linked immunosorbent assay were used to evaluate the delivery process and kinetics of the SWCNTs. In vitro studies indicated that the delivery kinetics of SWCNT–EGF conjugates, at a concentration of 85 µg ml−1, to the PANC‐1 cell surfaces was significant in the first 30 min of incubation, but reached a plateau with time in accordance with the establishment of equilibrium between the association and the dissociation of EGF with the cell receptors. SWCNT–EGF conjugates could act as strong thermal ablation agents and could induce higher percentages of cellular death compared with the nontargeted SWCNTs alone. Copyright

Carbon nanotubes enhance the internalization of drugs by cancer cells and decrease their chemoresistance to cytostatics

Etoposide is a semisynthetic, chemotherapeutic drug widely recommended to treat an extensive range of human cancers. Our studies indicate that, while etoposide is capable of killing human cancer cells, exposure to single-walled carbon nanotubes (SWCNTs) and etoposide results in enhanced cell death that appears to be synergistic and not merely additive. In this study, we used high pressure liquid chromatography and mass spectrometry to quantify the internal effective dose of etoposide when the human pancreatic cancer cell (PANC-1) was exposed to the combination of these agents. Our results unequivocally indicate that SWCNTs improve etoposide uptake and increase its capacity to kill cancer cells. We suggest that a combination of SWCNTs and etoposide may prove to be a more efficient chemotherapeutic protocol, especially because of the potential to lower toxic drug doses to levels that may be useful in decreasing adverse side effects, as well as in lowering the probability of inducing chemoresistance in exposed cancer cells.

Impact of Gold Nanoparticle Concentration on their Cellular Uptake by MC3T3-E1 Mouse Osteocytic Cells as Analyzed by Transmission Electron Microscopy

The uptake mechanisms and kinetics of gold nanoparticles (AuNPs) by mouse calvaria osteoblastic cells have been studied by transmission electron microscopy (TEM). The average size of the as-synthesized AuNPs used in this study was 12.2 (± 1.3) nm, and they were used to expose MC3T3-E1 osteoblastic cells at two concentrations (10 and 160 μg/ml) for 6, 24, and 96 hours before TEM imaging. Based on this analysis, we propose that the uptake mechanism of AuNPs is concentration-dependent. At the higher concentration (160 μg/ml), the particles seem to penetrate inside the cells primarily by endocytosis as the cells engulf AuNPs as agglomerates formed on the outer cellular membrane. At the lower concentrations of 10 μg/ml, AuNPs are more likely to cross the plasma membrane individually through diffusion. Therefore, the average diameters of the nanoparticles are expected to have a significant role only when exposed to cells in low concentrations. Moreover, cytotoxicity assays showed no toxic effects of the AuNPs when MC3T3-E1 cells were exposed to concentrations used in the experiments.

Single-walled carbon nanotubes as specific targeting and Raman spectroscopic agents for detection and discrimination of single human breast cancer cells

Abstract. Raman active nano-complex agents based on single-walled carbon nanotubes (SWCNTs) are prepared and used for the swift and specific detection of breast cancer cells. SWCNTs are functionalized to bond covalently with the anti-epithelial cell adhesion molecule (anti-EpCAM) antibody, which is specific to the highly expressed EpCAM antigen on the surface of breast cancer cells (MCF-7), but not on normal cells. The Raman nano-complexes demonstrate excellent ability to detect in vitro single breast cancer cells (MCF-7) and discriminate between them and normal fibroblast cells during the first 30 min of the targeting process. Raman linearity scanning is collected from a monolayer cell mixture, including both cancer cells and normal cells incubated with anti-EpCAM-SWCNTs, using a 633-nm laser excitation. The results shows that the Raman signal collected from targeted MCF-7 cells is extremely high, whereas there is little signal from the normal cells.