Ishita Matai

Perturbation of cellular mechanistic system by silver nanoparticle toxicity: Cytotoxic, genotoxic and epigenetic potentials

Currently the applications of silver nanoparticles (Ag NPs) are gaining overwhelming response due to the advancement of nanotechnology. However, only limited information is available with regard to their toxicity mechanism in different species. It is very essential to understand the complete molecular mechanism to explore the functional and long term applications of Ag NPs. Ag NPs could be toxic at cellular, subcellular, biomolecular, and epigenetic levels. Toxicity effects induced by Ag NPs have been evaluated using numerous in vitro and in vivo models, but still there are contradictions in interpretations due to disparity in methodology, test endpoints and several other model parameters which needs to be considered. Thus, this review article focuses on the progressive elucidation of molecular mechanism of toxicity induced by Ag NPs in various in vitro and in vivo models. Apart from these, this review also highlights the various ignored factors which are to be considered during toxicity studies.

A novel one-step synthesis of PEG passivated multicolour fluorescent carbon dots for potential biolabeling application

Poly(ethylene glycol) passivated multicolour fluorescent carbon dots (CPs) were synthesised by a novel one-step method and their biolabeling mechanism was studied using S. aureus and recombinant green fluorescent protein (GFP)-expressing E.coli as model systems. The mechanism of formation of fluorescent carbon nanorods from CPs was also explored.

Emerging applications of nanoparticles for lung cancer diagnosis and therapy

Lung cancer is by far the leading cause of cancer-related mortality worldwide, most of them being active tobacco smokers. Non small cell lung cancer accounts for around 85% to 90% of deaths, whereas the rest is contributed by small cell lung cancer. The extreme lethality of lung cancer arises due to lack of suitable diagnostic procedures for early detection of lung cancer and ineffective conventional therapeutic strategies. In course with desperate attempts to address these issues independently, a multifunctional nanotherapeutic or diagnostic system is being sought as a favorable solution. The manifestation of physiochemical properties of such nanoscale systems is tuned favorably to come up with a versatile cancer cell targeted diagnostic and therapeutic system. Apart from this, the aspect of being at nanoscale by itself confers the system with an advantage of passive accumulation at the site of tumor. This review provides a broad perspective of three major subclasses of such nanoscale therapeutic and diagnostic systems which include polymeric nanoparticles-based approaches, metal nanoparticles-based approaches, and bio-nanoparticles-based approaches. This review work also serves the purpose of gaining an insight into the pros and cons of each of these approaches with a prospective improvement in lung cancer therapeutics and diagnostics.

Self-Assembled Hybrids of Fluorescent Carbon Dots and PAMAM Dendrimers for Epirubicin Delivery and Intracellular Imaging

Advanced nanomaterials integrating imaging and therapeutic modalities on a single platform offers a new horizon in current cancer treatment strategies. Recently, carbon dots (CQDs) have been successfully employed for bioimaging of cancer cells. In the present study, luminescent CQDs with anionic terminus and cationic acetylated G5 poly(amido amine) (G5-Ac85) dendrimers were combined via noncovalent interactions to form self-assembled fluorescent hybrids. The fluorescence of CQDs in hybrids is enhanced in the vicinity of primary amine groups of dendrimers, making them suitable as cellular imaging probes. Encapsulation of chemo-drug epirubicin (EPI) in the dendrimer interiors endowed the fluorescent hybrids with therapeutic potential. The in vitro release of an entrapped EPI drug from CQDs@EPI⊂G5-Ac85 hybrids was faster in an acidic environment than under physiological conditions. Herein, multifunctional CQDs@EPI⊂G5-Ac85 hybrids serve as a dual-emission delivery system, to track the intracellular distribution and cytotoxic effects of EPI drugs. Green emission properties of CQDs were used for fluorescence microscopic imaging and cellular uptake by flow cytometry. Cell cycle analysis, field-emission scanning electron microscopy (FE-SEM), reactive oxygen species (ROS) generation, and up-regulation of apoptotic signaling genes unanimously demonstrated the apoptosis inducing ability of CQDs@EPI⊂G5-Ac85 hybrids in breast cancer (MCF-7) cells. Therefore, we have evaluated CQDs@EPI⊂G5-Ac85 hybrids as prospective candidates to achieve simultaneous imaging and drug delivery in cancer cells.

Implications of surface passivation on physicochemical and bioimaging properties of carbon dots

The prevalence of surface functionalized carbon dots (CDs) with intriguing fluorescence properties has given a new dimension to the field of bioimaging and is perceived as a promising alternative to quantum dots (QDs). In the present work, polyethylene glycol (PEG) and polyethyleneimine (PEI) passivated CDs have been synthesized by one-step hydrothermal carbonization of chitosan. We have made a comparative analysis of the physicochemical and bioimaging properties of PEI based carbon dots (CD-PEI) and PEG based carbon dots (CD-PEG). This article further provides an insight into the role of surface functionality in controlling the bioimaging efficiencies of CDs. The concentration dependent cytotoxic effects of CD-PEI and CD-PEG were studied on normal (BHK-21) and cancer (A549) cell lines and we explored the competitive performance of CD-PEI compared to CD-PEG for bio-applications.

Bionanotherapeutics: niclosamide encapsulated albumin nanoparticles as a novel drug delivery system for cancer therapy

One of the major unresolved challenges among the scientific community is to develop anticancer drugs that are safe and effective. A large number of anticancer drugs have been screened so far in this campaign. Among them niclosamide has shown tremendous anti-cancer potential as demonstrated in a surfeit of human cancer cell lines and animal models. But the extreme hydrophobicity and consequently, minimal systemic bioavailability associated with this drug limited its widespread clinical applications. Nanoparticles based drug delivery systems have the potential for realizing water soluble formulation of highly hydrophobic anticancer drugs like niclosamide, thus evading the drawbacks of poor solubility. In this work niclosamide was encapsulated into albumin nanoparticles through a desolvation method to improve its scope of application in cancer therapy. Physico-chemical characterization confirms that the prepared nanoparticles are spherical, highly monodispersed, and stable in aqueous systems. These drug encapsulated albumin nanoparticles, unlike the free drug demonstrate better in vitro therapeutic efficacy against human lung and breast cancer cell lines, as assessed by cell viability assay and morphological analyses. Further, the proficient induction of apoptosis by these nanoparticles was confirmed by semi-quantitative RT-PCR. This work open up a new avenue to extend the clinical gamut of this effectual agent by enabling its aqueous dispersion.

Dual-functional carbon dots–silver@zinc oxide nanocomposite: in vitro evaluation of cellular uptake and induction of apoptosis

Carbon dots (CDs) are novel bioimaging tools with fascinating fluorescence properties. We report here the development of novel CDs decorated on a silver-zinc oxide (CD-Ag@ZnO) nanocomposite (NC) consisting of highly fluorescent CDs and Ag@ZnO. The CD-Ag@ZnO NC was characterized by various analytical techniques. Our work provides an insight into the application of this CD-Ag@ZnO NC in monitoring cellular uptake and mediating apoptotic effects in MCF-7 and A549 cancer cell lines. By monitoring the simultaneous green fluorescence emission of the CDs, the distribution of the CD-Ag@ZnO NC could be followed, eliminating the need to use fluorescent organic dyes. Fluorescence microscopy and atomic absorption spectrometry were used for the qualitative and quantitative assessment of cellular uptake. In vitro studies of cancer cells treated with CD-Ag@ZnO NC revealed concentration-dependent cytotoxic effects via the induction of apoptosis. Fluorescence and scanning electron microscopy were used to study the characteristic nuclear and morphological changes during apoptosis. We used flow cytometry to quantify the reactive oxygen species and the reverse transcriptase polymerase chain reaction to study apoptotic gene expression. The role of reactive oxygen species in eliciting the apoptotic gene cascade was also studied. Intriguingly, the multifunctional CD-Ag@ZnO NC has a tendency to evoke apoptosis while allowing real-time intracellular trafficking, which may be of huge relevance in cancer theranostic applications.

Differentially cross-linkable core–shell nanofibers for tunable delivery of anticancer drugs: synthesis, characterization and their anticancer efficacy

This work introduces a new dimension for controlled drug delivery by nanofiber based scaffolds for anticancer therapy. The model anticancer drugs adopted in this work are curcumin and 5-fluorouracil (5-FU). Most of the drug loaded nanofibers synthesized thus far have failed to address the needs of personalized medication due to poor scalability of drug loading and delivery kinetics. This work opens up new avenues for circumventing such complications by altering the drug release profile by a simple one-step crosslinking reaction. With an aim to emphasize the role of polymer crosslinking in drug release kinetics, two variations of dual drug loaded core–shell nanofibers were synthesized with different extents of crosslinking and polymer composition. These two variations of drug loaded nanofibers exhibited contrasting 5-FU release profiles and thus manifested different therapeutic efficacy at different time points against A549 (Non-Small Cell Lung cancer) cells. The drug release profile of these fibers was further corroborated by different kinetic models to gain a perspective on the underlying mechanism driving the drug release from type I and type II nanofibers. The synergistic therapeutic potential of curcumin and 5-FU loaded core–shell nanofibers (type I and type II nanofibers) was also validated against A549 cells. As an outcome of this work, a clear correlation of cell viability with time lag in drug delivery in the case of type I and type II nanofibers could be drawn, which makes nanofiber based drug delivery even more flexible and therapeutically effective with minimal side effects.

Carbon dots incorporated polymeric hydrogels as multifunctional platform for imaging and induction of apoptosis in lung cancer cells.

Multifunctional hydrogels offer a seemingly efficient system for delivery of drugs and bioimaging modalities. The present study deals with the facile development of chitosan-based hydrogel formulation composed of highly fluorescent carbon dots (CDs) and loaded with a model anticancer drug, 5-Fluorouracil (5-FU). Herein, CDs were embedded firmly within the hydrogel matrices (CD-HY) via non-covalent interactions during the ionic cross-linking reaction. Furthermore, these hydrogels could effectively encapsulate 5-FU through hydrophobic interactions to form 5-FU@CD-HY. In this way, it was possible to combine the merits of both CDs and 5-FU on a common platform for monitoring the cellular uptake as well as therapeutic effects. Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) illustrated the porous nature and formation of 5-FU@CD-HY. Besides, functional characteristics of 5-FU@CD-HY such as surface area, mechanical strength, swelling behavior and drug release were investigated. In vitro studies revealed the multifunctional aspects of 5-FU@CD-HY in monitoring the cellular uptake and inflicting apoptosis in A549 cells. Green fluorescence of CDs in 5-FU@CD-HY aided the qualitative and quantitative assessment of cellular uptake. In addition to this, the fluorescence of CDs could be used to detect apoptosis instigated by 5-FU, eliminating the need for multiplex dyes. Induction of apoptosis in 5-FU@CD-HY treated cells was evidenced by changes in cell cycle distributions and visualization of characteristic apoptotic bodies through FE-SEM. Apoptotic gene expression studies further elucidate the molecular mechanism involved in eliciting apoptosis. Thus, hydrogels mediated integration of fluorescent CDs with chemotherapeutic agents provides a new dimension for the potential use of hydrogels in cancer theranostics.

Hydrophobic myristic acid modified PAMAM dendrimers augment the delivery of tamoxifen to breast cancer cells

In the present study, cationic generation 5 polyamido amine (G5 PAMAM) dendrimers were hydrophobically modified by grafting the surface with lipid-like myristic acid (My) tails to augment their potential as a drug delivery vector in vitro. Nuclear magnetic resonance (1H NMR) measurements confirmed the presence of myristic acid tails at the dendrimer periphery (My-g-G5). Tamoxifen (TAM) an estrogen agonist, was entrapped in the My-g-G5 domains to impart them with anticancer properties. Transmission electron microscopy (TEM) observations indicate these My-g-G5/TAM complexes to be around 6–8 nm in size. Further, in vitro drug release studies ascertained the ability of My-g-G5/TAM complexes to release TAM in a sustained fashion under acidic conditions (pH 5.5). Cellular uptake studies revealed lysosomes as the target organelles of these nanocomplexes. MTT assay suggested good cell viability of My-g-G5 dendrimers and strong inhibitory effects of My-g-G5/TAM complexes in MCF-7 (human breast adenocarcinoma, estrogen receptor (ER) positive) cells. Dual fluorescence staining, reactive oxygen species (ROS) generation, cell cycle analysis, field emission scanning electron microscopy (FE-SEM), change in mitochondrial membrane potential (MMP, ΔΨ) and gene expression studies revealed the apoptosis-inducing ability of My-g-G5/TAM in MCF-7 cells. Based on our findings, we present these hydrophobically modified G5 PAMAM dendrimers as prospective nanocarriers for TAM delivery for anticancer applications.