Publications by authors named "Bella B Manshian"

40 Publications

Massive Intracellular Remodeling of CuS Nanomaterials Produces Nontoxic Bioengineered Structures with Preserved Photothermal Potential.

ACS Nano 2021 06 25;15(6):9782-9795. Epub 2021 May 25.

Laboratoire Matière et Systèmes Complexes MSC, UMR 7057, CNRS and University of Paris, 75205, Paris Cedex 13, France.

Despite efforts in producing nanoparticles with tightly controlled designs and specific physicochemical properties, these can undergo massive nano-bio interactions and bioprocessing upon internalization into cells. These transformations can generate adverse biological outcomes and premature loss of functional efficacy. Hence, understanding the intracellular fate of nanoparticles is a necessary prerequisite for their introduction in medicine. Among nanomaterials devoted to theranostics is copper sulfide (CuS), which provides outstanding optical properties along with easy synthesis and low cost. Herein, we performed a long-term multiscale study on the bioprocessing of hollow CuS nanoparticles (CuS NPs) and rattle-like iron oxide [email protected] core-shell hybrids ([email protected] NPs) when inside stem cells and cancer cells, cultured as spheroids. In the spheroids, both CuS NPs and [email protected] NPs are rapidly dismantled into smaller units (day 0 to 3), and hair-like nanostructures are generated (day 9 to 21). This bioprocessing triggers an adaptation of the cellular metabolism to the internalized metals without impacting cell viability, differentiation, or oxidative stress response. Throughout the remodeling, a loss of IONF-derived magnetism is observed, but, surprisingly, the CuS photothermal potential is preserved, as demonstrated by a full characterization of the photothermal conversion across the bioprocessing process. The maintained photothermal efficiency correlated well with synchrotron X-ray absorption spectroscopy measurements, evidencing a similar chemical phase for Cu but not for Fe over time. These findings evidence that the intracellular bioprocessing of CuS nanoparticles can reshape them into bioengineered nanostructures without reducing the photothermal function and therapeutic potential.
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http://dx.doi.org/10.1021/acsnano.1c00567DOI Listing
June 2021

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition).

Autophagy 2021 Jan 8;17(1):1-382. Epub 2021 Feb 8.

University of Crete, School of Medicine, Laboratory of Clinical Microbiology and Microbial Pathogenesis, Voutes, Heraklion, Crete, Greece; Foundation for Research and Technology, Institute of Molecular Biology and Biotechnology (IMBB), Heraklion, Crete, Greece.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.
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http://dx.doi.org/10.1080/15548627.2020.1797280DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7996087PMC
January 2021

Whither Magnetic Hyperthermia? A Tentative Roadmap.

Materials (Basel) 2021 Feb 3;14(4). Epub 2021 Feb 3.

IMDEA Nanoscience, Faraday 9, 28049 Madrid, Spain.

The scientific community has made great efforts in advancing magnetic hyperthermia for the last two decades after going through a sizeable research lapse from its establishment. All the progress made in various topics ranging from nanoparticle synthesis to biocompatibilization and in vivo testing have been seeking to push the forefront towards some new clinical trials. As many, they did not go at the expected pace. Today, fruitful international cooperation and the wisdom gain after a careful analysis of the lessons learned from seminal clinical trials allow us to have a future with better guarantees for a more definitive takeoff of this genuine nanotherapy against cancer. Deliberately giving prominence to a number of critical aspects, this opinion review offers a blend of state-of-the-art hints and glimpses into the future of the therapy, considering the expected evolution of science and technology behind magnetic hyperthermia.
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http://dx.doi.org/10.3390/ma14040706DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7913249PMC
February 2021

The Use of Alternative Strategies for Enhanced Nanoparticle Delivery to Solid Tumors.

Chem Rev 2021 02 14;121(3):1746-1803. Epub 2021 Jan 14.

NanoHealth and Optical Imaging Group, Translational Cell and Tissue Research Unit, Department of Imaging and Pathology, KU Leuven, Herestraat 49, B3000 Leuven, Belgium.

Nanomaterial (NM) delivery to solid tumors has been the focus of intense research for over a decade. Classically, scientists have tried to improve NM delivery by employing passive or active targeting strategies, making use of the so-called enhanced permeability and retention (EPR) effect. This phenomenon is made possible due to the leaky tumor vasculature through which NMs can leave the bloodstream, traverse through the gaps in the endothelial lining of the vessels, and enter the tumor. Recent studies have shown that despite many efforts to employ the EPR effect, this process remains very poor. Furthermore, the role of the EPR effect has been called into question, where it has been suggested that NMs enter the tumor active mechanisms and not through the endothelial gaps. In this review, we provide a short overview of the EPR and mechanisms to enhance it, after which we focus on alternative delivery strategies that do not solely rely on EPR in itself but can offer interesting pharmacological, physical, and biological solutions for enhanced delivery. We discuss the strengths and shortcomings of these different strategies and suggest combinatorial approaches as the ideal path forward.
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http://dx.doi.org/10.1021/acs.chemrev.0c00779DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7883342PMC
February 2021

A Multiparametric Evaluation of Quantum Dot Size and Surface-Grafted Peptide Density on Cellular Uptake and Cytotoxicity.

Bioconjug Chem 2020 04 1;31(4):1077-1087. Epub 2020 Apr 1.

NanoHealth and Optical Imaging Group, Department of Imaging and Pathology, KU Leuven, Herestraat 49, B3000 Leuven, Belgium.

Despite the progress in nanotechnology for biomedical applications, great efforts are still being employed in optimizing nanoparticle (NP) design parameters to improve functionality and minimize bionanotoxicity. In this study, we developed CdSe/CdS/ZnS core/shell/shell quantum dots (QDs) that are compact ligand-coated and surface-functionalized with an HIV-1-derived TAT cell-penetrating peptide (CPP) analog to improve both biocompatibility and cellular uptake. Multiparametric studies were performed in different mammalian and murine cell lines to compare the effects of varying QD size and number of surface CPPs on cellular uptake, viability, generation of reactive oxygen species, mitochondrial health, cell area, and autophagy. Our results showed that the number of cell-associated NPs and their respective toxicity are higher for the larger QDs. Meanwhile, increasing the number of surface CPPs also enhanced cellular uptake and induced cytotoxicity through the generation of mitoROS and autophagy. Thus, here we report the optimal size and surface CPP combinations for improved QD cellular uptake.
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http://dx.doi.org/10.1021/acs.bioconjchem.0c00078DOI Listing
April 2020

Model-Based Nanoengineered Pharmacokinetics of Iron-Doped Copper Oxide for Nanomedical Applications.

Angew Chem Int Ed Engl 2020 01 9;59(5):1828-1836. Epub 2020 Jan 9.

NanoHealth and Optical Imaging Group, KU Leuven, Department of Imaging and Pathology, Belgium.

The progress in nanomedicine (NM) using nanoparticles (NPs) is mainly based on drug carriers for the delivery of classical chemotherapeutics. As low NM delivery rates limit therapeutic efficacy, an entirely different approach was investigated. A homologous series of engineered CuO NPs was designed for dual purposes (carrier and drug) with a direct chemical composition-biological functionality relationship. Model-based dissolution kinetics of CuO NPs in the cellular interior at post-exposure conditions were controlled through Fe-doping for intra/extra cellular Cu and biological outcome. Through controlled ion release and reactions taking place in the cellular interior, tumors could be treated selectively, in vitro and in vivo. Locally administered NPs enabled tumor cells apoptosis and stimulated systemic anti-cancer immune responses. We clearly show therapeutic effects without tumor cells relapse post-treatment with 6 % Fe-doped CuO NPs combined with myeloid-derived suppressor cell silencing.
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http://dx.doi.org/10.1002/anie.201912312DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7004194PMC
January 2020

Longitudinal In Vivo Assessment of Host-Microbe Interactions in a Murine Model of Pulmonary Aspergillosis.

iScience 2019 Oct 18;20:184-194. Epub 2019 Sep 18.

Biomedical MRI/Molecular Small Animal Imaging Center (MoSAIC), KU Leuven, Leuven, Belgium. Electronic address:

The fungus Aspergillus fumigatus is ubiquitous in nature and the most common cause of invasive pulmonary aspergillosis (IPA) in patients with a compromised immune system. The development of IPA in patients under immunosuppressive treatment or in patients with primary immunodeficiency demonstrates the importance of the host immune response in controlling aspergillosis. However, study of the host-microbe interaction has been hampered by the lack of tools for their non-invasive assessment. We developed a methodology to study the response of the host's immune system against IPA longitudinally in vivo by using fluorine-19 magnetic resonance imaging (F MRI). We showed the advantage of a perfluorocarbon-based contrast agent for the in vivo labeling of macrophages and dendritic cells, permitting quantification of pulmonary inflammation in different murine IPA models. Our findings reveal the potential of F MRI for the assessment of rapid kinetics of innate immune response against IPA and the permissive niche generated through immunosuppression.
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http://dx.doi.org/10.1016/j.isci.2019.09.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6817634PMC
October 2019

Targeting tumor cells and neovascularization using RGD-functionalized magnetoliposomes.

Int J Nanomedicine 2019 29;14:5911-5924. Epub 2019 Jul 29.

Biomedical MRI/MoSAIC, Department of Imaging and Pathology, Biomedical Sciences Group, Leuven B-3000, Belgium.

Purpose: Magnetoliposomes (MLs) have shown great potential as magnetic resonance imaging contrast agents and as delivery vehicles for cancer therapy. Targeting the MLs towards the tumor cells or neovascularization could ensure delivery of drugs at the tumor site. In this study, we evaluated the potential of MLs targeting the αvβ3 integrin overexpressed on tumor neovascularization and different tumor cell types, including glioma and ovarian cancer.

Methods: MLs functionalized with a Texas Red fluorophore (anionic MLs), and with the fluorophore and the cyclic Arginine-Glycine-Aspartate (cRGD; cRGD-MLs) targeting the αvβ3 integrin, were produced in-house. Swiss nude mice were subcutaneously injected with 10 human ovarian cancer SKOV-3 cells. Tumors were allowed to grow for 3 weeks before injection of anionic or cRGD-MLs. Biodistribution of MLs was followed up with a 7T preclinical magnetic resonance imaging (MRI) scanner and fluorescence imaging (FLI) right after injection, 2h, 4h, 24h and 48h post injection. Ex vivo intratumoral ML uptake was confirmed using FLI, electron paramagnetic resonance spectroscopy (EPR) and histology at different time points post injection.

Results: In vivo, we visualized a higher uptake of cRGD-MLs in SKOV-3 xenografts compared to control, anionic MLs with both MRI and FLI. Highest ML uptake was seen after 4h using MRI, but only after 24h using FLI indicating the lower sensitivity of this technique. Furthermore, ex vivo EPR and FLI confirmed the highest tumoral ML uptake at 4 h. Last, a Perl's stain supported the presence of our iron-based particles in SKOV-3 xenografts.

Conclusion: Uptake of cRGD-MLs can be visualized using both MRI and FLI, even though the latter was less sensitive due to lower depth penetration. Furthermore, our results indicate that cRGD-MLs can be used to target SKOV-3 xenograft in Swiss nude mice. Therefore, the further development of this particles into theranostics would be of interest.
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http://dx.doi.org/10.2147/IJN.S214041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6681073PMC
November 2019

Fe-Doped ZnO nanoparticle toxicity: assessment by a new generation of nanodescriptors.

Nanoscale 2018 Nov;10(46):21985-21993

Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia.

In the search for novel tools to combat cancer, nanoparticles (NPs) have attracted a lot of attention. Recently, the controlled release of cancer-cell-killing metal ions from doped NPs has shown promise, but fine tuning of dissolution kinetics is required to ensure specificity and minimize undesirable toxic side-effects. Theoretical tools to help in reaching a proper understanding and finally be able to control the dissolution kinetics by NP design have not been available until now. Here, we present a novel set of true nanodescriptors to analyze the charge distribution, the effect of doping and surface coating of whole metal oxide NP structures. The polarizable model of oxygen atoms enables light to be shed on the charge distribution on the NP surface, allowing the in detail study of the factors influencing the release of metal ions from NPs. The descriptors and their capabilities are demonstrated on a Fe-doped ZnO nanoparticle system, a system with practical outlook and available experimental data.
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http://dx.doi.org/10.1039/c8nr05220dDOI Listing
November 2018

The impact of nanoparticle-driven lysosomal alkalinization on cellular functionality.

J Nanobiotechnology 2018 Oct 31;16(1):85. Epub 2018 Oct 31.

NanoHealth and Optical Imaging Group, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.

Background: The biomedical use of nanosized materials is rapidly gaining interest, which drives the quest to elucidate the behavior of nanoparticles (NPs) in a biological environment. Apart from causing direct cell death, NPs can affect cellular wellbeing through a wide range of more subtle processes that are often overlooked. Here, we aimed to study the effect of two biomedically interesting NP types on cellular wellbeing.

Results: In the present work, gold and SiO NPs of similar size and surface charge are used and their interactions with cultured cells is studied. Initial screening shows that at subcytotoxic conditions gold NPs induces cytoskeletal aberrations while SiO NPs do not. However, these transformations are only transient. In-depth investigation reveals that Au NPs reduce lysosomal activity by alkalinization of the lysosomal lumen. This leads to an accumulation of autophagosomes, resulting in a reduced cellular degradative capacity and less efficient clearance of damaged mitochondria. The autophagosome accumulation induces Rac and Cdc42 activity, and at a later stage activates RhoA. These transient cellular changes also affect cell functionality, where Au NP-labelled cells display significantly impeded cell migration and invasion.

Conclusions: These data highlight the importance of in-depth understanding of bio-nano interactions to elucidate how one biological parameter (impact on cellular degradation) can induce a cascade of different effects that may have significant implications on the further use of labeled cells.
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http://dx.doi.org/10.1186/s12951-018-0413-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6208102PMC
October 2018

Magnetoliposomes as Contrast Agents for Longitudinal in vivo Assessment of Transplanted Pancreatic Islets in a Diabetic Rat Model.

Sci Rep 2018 07 31;8(1):11487. Epub 2018 Jul 31.

Biomedical MRI/MoSAIC, Department of Imaging and Pathology, Biomedical Sciences Group, KU LEUVEN, Herestraat 49, 3000, Leuven, Belgium.

Magnetoliposomes (MLs) were synthesized and tested for longitudinal monitoring of transplanted pancreatic islets using magnetic resonance imaging (MRI) in rat models. The rat insulinoma cell line INS-1E and isolated pancreatic islets from outbred and inbred rats were used to optimize labeling conditions in vitro. Strong MRI contrast was generated by islets exposed to 50 µg Fe/ml for 24 hours without any increased cell death, loss of function or other signs of toxicity. In vivo experiments showed that pancreatic islets (50-1000 units) labeled with MLs were detectable for up to 6 weeks post-transplantation in the kidney subcapsular space. Islets were also monitored for two weeks following transplantation through the portal vein of the liver. Hereby, islets labeled with MLs and transplanted under the left kidney capsule were able to correct hyperglycemia and had stable MRI signals until nephrectomy. Interestingly, in vivo MRI of streptozotocin induced diabetic rats transplanted with allogeneic islets demonstrated loss of MRI contrast between 7-16 days, indicative of loss of islet structure. MLs used in this study were not only beneficial for monitoring the location of transplanted islets in vivo with high sensitivity but also reported on islet integrity and hereby indirectly on islet function and rejection.
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http://dx.doi.org/10.1038/s41598-018-29136-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6068133PMC
July 2018

A Magnetic Chameleon: Biocompatible Lanthanide Fluoride Nanoparticles with Magnetic Field Dependent Tunable Contrast Properties as a Versatile Contrast Agent for Low to Ultrahigh Field MRI and Optical Imaging in Biological Window.

Chemistry 2018 May 26;24(29):7388-7397. Epub 2018 Apr 26.

Laboratory of Bioinorganic Chemistry, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium.

A novel type of multimodal, magnetic resonance imaging/optical imaging (MRI/OI) contrast agent was developed, based on core-shell lanthanide fluoride nanoparticles composed of a β-NaHoF4 core plus a β-NaGdF4:Yb , Tm shell with an average size of ∼24 nm. The biocompatibility of the particles was ensured by a surface modification with poly acrylic acid (PAA) and further functionalization with an affinity ligand, folic acid (FA). When excited using 980 nm near infrared (NIR) radiation, the contrast agent (CA) shows intense emission at 802 nm with lifetime of 791±3 μs, due to the transition H → H of Tm . Proton nuclear magnetic relaxation dispersion ( H-NMRD) studies and magnetic resonance (MR) phantom imaging showed that the newly synthesized nanoparticles, decorated with poly(acrylic acid) and folic acid on the surface (NP-PAA-FA), can act mainly as a T -weighted contrast agent below 1.5 T, a T /T dual-weighted contrast agent at 3 T, and as highly efficient T -weighted contrast agent at ultrahigh fields. In addition, NP-PAA-FA showed very low cytotoxicity and no detectable cellular damage up to a dose of 500 μg mL .
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http://dx.doi.org/10.1002/chem.201800283DOI Listing
May 2018

Nanoparticle-induced inflammation can increase tumor malignancy.

Acta Biomater 2018 03 20;68:99-112. Epub 2017 Dec 20.

Biomedical MRI Unit/MoSAIC, Department of Imaging and Pathology, KU Leuven, Herestraat 49, B3000 Leuven, Belgium. Electronic address:

Nanomaterials, such as aluminum oxide, have been regarded with high biomedical promise as potential immune adjuvants in favor of their bulk counterparts. For pathophysiological conditions where elevated immune activity already occurs, the contribution of nanoparticle-activated immune reactions remains unclear. Here, we investigated the effect of spherical and wire-shaped aluminum oxide nanoparticles on primary splenocytes and observed a clear pro-inflammatory effect of both nanoparticles, mainly for the high aspect ratio nanowires. The nanoparticles resulted in a clear activation of NLRP3 inflammasome, and also secreted transforming growth factor β. When cancer cells were exposed to these cytokines, this resulted in an increased level of epithelial-to-mesenchymal-transition, a hallmark for cancer metastasis, which did not occur when the cancer cells were directly exposed to the nanoparticles themselves. Using a syngeneic tumor model, the level of inflammation and degree of lung metastasis were significantly increased when the animals were exposed to the nanoparticles, particularly for the nanowires. This effect could be abrogated by treating the animals with inflammatory inhibitors. Collectively, these data indicate that the interaction of nanoparticles with immune cells can have secondary effects that may aggravate pathophysiological conditions, such as cancer malignancy, and conditions must be carefully selected to finely tune the induced aspecific inflammation into cancer-specific antitumor immunity.

Statement Of Significance: Many different types of nanoparticles have been shown to possess immunomodulatory properties, depending on their physicochemical parameters. This can potentially be harnessed as a possible antitumor therapy. However, in the current work we show that inflammation elicited by nanomaterials can have grave effects in pathophysiological conditions, where non-specific inflammation was found to increase cancer cell mobility and tumor malignancy. These data show that immunomodulatory properties of nanomaterials must be carefully controlled to avoid any undesired side-effects.
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http://dx.doi.org/10.1016/j.actbio.2017.12.020DOI Listing
March 2018

Assessing cell-nanoparticle interactions by high content imaging of biocompatible iron oxide nanoparticles as potential contrast agents for magnetic resonance imaging.

Sci Rep 2017 08 10;7(1):7850. Epub 2017 Aug 10.

Biophysics Group, Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK.

Stem cell tracking in cellular therapy and regenerative medicine is an urgent need, superparamagnetic iron oxide nanoparticles (IONPs) could be used as contrast agents in magnetic resonance imaging (MRI) that allows visualization of the implanted cells ensuring they reach the desired sites in vivo. Herein, we report the study of the interaction of 3,4-dihydroxyhydrocinnamic acid (DHCA) functionalized IONPs that have desirable properties for T - weighted MRI, with bone marrow-derived primary human mesenchymal stem cells (hMSCs). Using the multiparametric high-content imaging method, we evaluate cell viability, formation of reactive oxygen species, mitochondrial health, as well as cell morphology and determine that the hMSCs are minimally affected after labelling with IONPs. Their cellular uptake is visualized by transmission electron microscopy (TEM) and Prussian Blue staining, and quantified using an iron specific colourimetric method. In vitro and in vivo studies demonstrate that these IONPs are biocompatible and can produce significant contrast enhancement in T-weighted MRI. Iron oxide nanoparticles are detected in vivo as hypointense regions in the liver up to two weeks post injection using 9.4 T MRI. These DHCA functionalized IONPs are promising contrast agents for stem cell tracking by T-weighted MRI as they are biocompatible and show no evidence of cytotoxic effects on hMSCs.
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http://dx.doi.org/10.1038/s41598-017-08092-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5552868PMC
August 2017

Colloidal Gold Nanoparticles Induce Changes in Cellular and Subcellular Morphology.

ACS Nano 2017 08 18;11(8):7807-7820. Epub 2017 Jul 18.

CIC biomaGUNE , 20009 San Sebastian, Spain.

Exposure of cells to colloidal nanoparticles (NPs) can have concentration-dependent harmful effects. Mostly, such effects are monitored with biochemical assays or probes from molecular biology, i.e., viability assays, gene expression profiles, etc., neglecting that the presence of NPs can also drastically affect cellular morphology. In the case of polymer-coated Au NPs, we demonstrate that upon NP internalization, cells undergo lysosomal swelling, alterations in mitochondrial morphology, disturbances in actin and tubulin cytoskeleton and associated signaling, and reduction of focal adhesion contact area and number of filopodia. Appropriate imaging and data treatment techniques allow for quantitative analyses of these concentration-dependent changes. Abnormalities in morphology occur at similar (or even lower) NP concentrations as the onset of reduced cellular viability. Cellular morphology is thus an important quantitative indicator to verify harmful effects of NPs to cells, without requiring biochemical assays, but relying on appropriate staining and imaging techniques.
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http://dx.doi.org/10.1021/acsnano.7b01760DOI Listing
August 2017

The role of intracellular trafficking of CdSe/ZnS QDs on their consequent toxicity profile.

J Nanobiotechnology 2017 Jun 15;15(1):45. Epub 2017 Jun 15.

Biomedical NMR Unit/MoSAIC, KU Leuven Campus Gasthuisberg, Herestraat 49, 3000, Louvain, Belgium.

Background: Nanoparticle interactions with cellular membranes and the kinetics of their transport and localization are important determinants of their functionality and their biological consequences. Understanding these phenomena is fundamental for the translation of such NPs from in vitro to in vivo systems for bioimaging and medical applications. Two CdSe/ZnS quantum dots (QD) with differing surface functionality (NH or COOH moieties) were used here for investigating the intracellular uptake and transport kinetics of these QDs.

Results: In water, the COOH- and NH-QDs were negatively and positively charged, respectively, while in serum-containing medium the NH-QDs were agglomerated, whereas the COOH-QDs remained dispersed. Though intracellular levels of NH- and COOH-QDs were very similar after 24 h exposure, COOH-QDs appeared to be continuously internalised and transported by endosomes and lysosomes, while NH-QDs mainly remained in the lysosomes. The results of (intra)cellular QD trafficking were correlated to their toxicity profiles investigating levels of reactive oxygen species (ROS), mitochondrial ROS, autophagy, changes to cellular morphology and alterations in genes involved in cellular stress, toxicity and cytoskeletal integrity. The continuous flux of COOH-QDs perhaps explains their higher toxicity compared to the NH-QDs, mainly resulting in mitochondrial ROS and cytoskeletal remodelling which are phenomena that occur early during cellular exposure.

Conclusions: Together, these data reveal that although cellular QD levels were similar after 24 h, differences in the nature and extent of their cellular trafficking resulted in differences in consequent gene alterations and toxicological effects.
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http://dx.doi.org/10.1186/s12951-017-0279-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5472855PMC
June 2017

Choose your cell model wisely: The in vitro nanoneurotoxicity of differentially coated iron oxide nanoparticles for neural cell labeling.

Acta Biomater 2017 06 1;55:204-213. Epub 2017 Apr 1.

Lab of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, B-9000 Ghent, Belgium.

Currently, there is a large interest in the labeling of neural stem cells (NSCs) with iron oxide nanoparticles (IONPs) to allow MRI-guided detection after transplantation in regenerative medicine. For such biomedical applications, excluding nanotoxicity is key. Nanosafety is primarily evaluated in vitro where an immortalized or cancer cell line of murine origin is often applied, which is not necessarily an ideal cell model. Previous work revealed clear neurotoxic effects of PMA-coated IONPs in distinct cell types that could potentially be applied for nanosafety studies regarding neural cell labeling. Here, we aimed to assess if DMSA-coated IONPs could be regarded as a safer alternative for this purpose and how the cell model impacted our nanosafety optimization study. Hereto, we evaluated cytotoxicity, ROS production, calcium levels, mitochondrial homeostasis and cell morphology in six related neural cell types, namely neural stem cells, an immortalized cell line and a cancer cell line from human and murine origin. The cell lines mostly showed similar responses to both IONPs, which were frequently more pronounced for the PMA-IONPs. Of note, ROS and calcium levels showed opposite trends in the human and murine NSCs, indicating the importance of the species. Indeed, the human cell models were overall more sensitive than their murine counterpart. Despite the clear cell type-specific nanotoxicity profiles, our multiparametric approach revealed that the DMSA-IONPs outperformed the PMA-IONPs in terms of biocompatibility in each cell type. However, major cell type-dependent variations in the observed effects additionally warrant the use of relevant human cell models.

Statement Of Significance: Inorganic nanoparticle (NP) optimization is chiefly performed in vitro. For the optimization of iron oxide (IO)NPs for neural stem cell labeling in the context of regenerative medicine human or rodent neural stem cells, immortalized or cancer cell lines are applied. However, the use of certain cell models can be questioned as they phenotypically differ from the target cell. The impact of the neural cell model on nanosafety remains relatively unexplored. Here we evaluated cell homeostasis upon exposure to PMA- and DMSA-coated IONPs. Of note, the DMSA-IONPs outperformed the PMA-IONPs in each cell type. However, distinct cell type-specific effects were witnessed, indicating that nanosafety should be evaluated in a human cell model that represents the target cell as closely as possible.
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http://dx.doi.org/10.1016/j.actbio.2017.03.053DOI Listing
June 2017

Personalized medicine and follow-up of therapeutic delivery through exploitation of quantum dot toxicity.

Biomaterials 2017 05 6;127:1-12. Epub 2017 Mar 6.

Biomedical NMR Unit/MoSAIC, Department of Imaging and Pathology, KU Leuven, Herestraat 49, B3000 Leuven, Belgium. Electronic address:

Tumor therapy using nanoparticles (NPs) is mainly aimed at using the NPs as carriers for therapeutic drugs or as mediators for external stimuli to generate heat. Recent studies have shown that the toxicity of NPs can also be specifically exploited to kill cancer cells. In the present work, we employ core-only CdTe quantum dots and study their cytotoxicity using a validated high-content screening approach. The data revealed a clear correlation between toxicity and quantum dot degradation, which could be monitored through loss of fluorescence intensity. Based on the in vitro data obtained, the in vivo dose was calculated relative to the estimated number of tumor cells based on luminescence measurements. The obtained results show a clear increase in reproducibility of the therapeutic effect compared to normal conditions, where a set dose of quantum dots was administered regardless of the tumor size. The therapeutic delivery could also be monitored in vivo, where the loss of fluorescence intensity correlated with the anticancer efficacy. The present work highlights the benefits of noninvasive imaging to monitor therapeutic delivery and to optimize treatment via personalized medicine.
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http://dx.doi.org/10.1016/j.biomaterials.2017.02.039DOI Listing
May 2017

In Silico Design of Optimal Dissolution Kinetics of Fe-Doped ZnO Nanoparticles Results in Cancer-Specific Toxicity in a Preclinical Rodent Model.

Adv Healthc Mater 2017 May 23;6(9). Epub 2017 Feb 23.

Department of Imaging and Pathology, KU Leuven, Herestraat 49, B3000, Leuven, Belgium.

Cancer cells have unique but widely varying characteristics that have proven them difficult to be treated by classical therapeutics and calls for novel and selective treatment options. Nanomaterials (NMs) have been shown to display biological effects as a function of their chemical composition, and the extent and exact nature of these effects can vary between different biological environments. Here, ZnO NMs are doped with increasing levels of Fe, which allows to finely tune their dissolution rate resulting in significant differences in their biological behavior on cancer or normal cells. Based on in silico analysis, 2% Fe-doped ZnO NMs are found to be optimal to cause selective cancer cell death, which is confirmed in both cultured cells and syngeneic tumor models, where they also reduce metastasis formation. These results show that upon tuning NM chemical composition, NMs can be designed as a targeted selective anticancer therapy.
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http://dx.doi.org/10.1002/adhm.201601379DOI Listing
May 2017

Standard Cellular Testing Conditions Generate an Exaggerated Nanoparticle Cytotoxicity Profile.

Chem Res Toxicol 2017 02 16;30(2):595-603. Epub 2016 Dec 16.

MoSAIC/Biomedical MRI Unit, Faculty of Medicine, KU Leuven , Herestraat 49, B3000 Leuven, Belgium.

Cellular internalization of nanoparticles (NPs) is key to many biomedical applications and serves as a model to investigate the potential toxicity of NPs on entire organisms. Large discrepancies between in vitro and in vivo nanotoxicity data however exist, suggesting that cellular systems may not be optimal for predictive in vivo toxicology. Here, we use validated multiparametric high-content imaging protocols to evaluate the impact of common cell culture conditions on NP cytotoxicity studies. The data show that high NP to cell ratios, typical for cellular studies, stress the cells by high endocytosis levels that overstimulate mitochondria, resulting in oxidative stress-mediated mitochondrial damage, which induces autophagy. Using proliferation-restricted models, we show that lowering endocytosis levels overcomes most toxicity while resulting in higher final cellular NP numbers. The data suggest that many common NP cytotoxicity mechanisms may partially be an artifact caused by overstimulated endocytosis.
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http://dx.doi.org/10.1021/acs.chemrestox.6b00340DOI Listing
February 2017

Presence of an Immune System Increases Anti-Tumor Effect of Ag Nanoparticle Treated Mice.

Adv Healthc Mater 2017 Jan 25;6(1). Epub 2016 Nov 25.

Biomedical MRI Unit, KU Leuven, Department of Imaging and Pathology, Herestraat 49, B3000, Leuven, Belgium.

To date, most nanomedical studies rely on the use of immune-deficient mice in which the contribution of the immune system on the applied therapy is ignored. Here, the degradation of silver nanoparticles (Ag NPs) is exploited as a means to treat subcutaneous tumor models in mice. To investigate the impact of the immune system, the same tumor cell type (KLN 205 murine squamous cell carcinoma) is used in a xenograft model in NOD SCIDγ immune-deficient mice and as a syngeneic model in immune-competent DBA/2 mice. The Ag NPs are screened for their cytotoxicity on various cancer cell lines, indicating a concentration-dependent induction of oxidative stress, mitochondrial damage, and autophagy on all cell types tested. At subcytotoxic concentrations, prolonged cellular exposure to the Ag NPs results in toxicity due to NP degradation and the generation of toxic Ag ions. At subcytotoxic conditions, the NPs are found to cause inflammation in vitro. Similar results are obtained in the immune-competent mouse model, where clear inflammation is observed after treatment of the implanted tumors with Ag NPs. This inflammation leads to an ongoing antitumoral effect, which results in a significantly reduced tumor growth compared to Ag NP-treated tumors in an immune-deficient model.
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http://dx.doi.org/10.1002/adhm.201601099DOI Listing
January 2017

Coating of Quantum Dots strongly defines their effect on lysosomal health and autophagy.

Acta Biomater 2017 01 17;48:195-205. Epub 2016 Oct 17.

Lab of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, B9000 Ghent, Belgium; Ghent Research Group on Nanomedicines, Ghent University, Ottergemsesteenweg 460, B9000 Ghent, Belgium.

In the last decade the interest in autophagy got an incredible boost and the phenomenon quickly turned into an extensive research field. Interestingly, dysfunction of this cytoplasmic clearance system has been proposed to lie at the root of multiple diseases including cancer. We therefore consider it crucial from a toxicological point of view to investigate if nanomaterials that are developed for biomedical applications interfere with this cellular process. Here, we study the highly promising 'gradient alloyed' Quantum Dots (QDs) that differ from conventional ones by their gradient core composition which allows for better fluorescent properties. We carefully examined the toxicity of two identical gradient alloyed QDs, differing only in their surface coatings, namely 3-mercaptopropionic (MPA) acid and polyethylene glycol (PEG). Next to more conventional toxicological endpoints like cytotoxicity and oxidative stress, we examined the influence of these QDs on the autophagy pathway. Our study shows that the cellular effects induced by QDs on HeLa cells were strongly dictated by the surface coat of the otherwise identical particles. MPA-coated QDs proved to be highly biocompatible as a result of lysosomal activation and ROS reduction, two cellular responses that help the cell to cope with nanomaterial-induced stress. In contrast, PEGylated QDs were significantly more toxic due to increased ROS production and lysosomal impairment. This impairment next results in autophagy dysfunction which likely adds to their toxic effects. Taken together, our study shows that coating QDs with MPA is a better strategy than PEGylation for long term cell tracking with minimal cytotoxicity.

Statement Of Significance: Gradient alloyed Quantum Dots (GA-QDs) are highly promising nanomaterials for biomedical imaging seeing they exhibit supremely fluorescent properties over conventional QDs. The translation of these novel QDs to the clinic requires a detailed toxicological examination, though the data on this is very limited. We therefore applied a systematic approach to examine the toxicity of GA-QDs coated with two commonly applied surface ligands, this while focusing on the autophagy pathway. The impact of QDs on this pathway is of importance since it has been connected with various diseases, including cancer. Our data accentuates that the coating defines the impact on autophagy and therefore the toxicity induced by QDs on cells: while MPA coated QDs were highly biocompatible, PEGylated QDs were toxic.
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http://dx.doi.org/10.1016/j.actbio.2016.10.022DOI Listing
January 2017

The impact of species and cell type on the nanosafety profile of iron oxide nanoparticles in neural cells.

J Nanobiotechnology 2016 Sep 9;14(1):69. Epub 2016 Sep 9.

Lab of General Biochemistry and Physical Pharmacy, Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium.

Background: While nanotechnology is advancing rapidly, nanosafety tends to lag behind since general mechanistic insights into cell-nanoparticle (NP) interactions remain rare. To tackle this issue, standardization of nanosafety assessment is imperative. In this regard, we believe that the cell type selection should not be overlooked since the applicability of cell lines could be questioned given their altered phenotype. Hence, we evaluated the impact of the cell type on in vitro nanosafety evaluations in a human and murine neuroblastoma cell line, neural progenitor cell line and in neural stem cells. Acute toxicity was evaluated for gold, silver and iron oxide (IO)NPs, and the latter were additionally subjected to a multiparametric analysis to assess sublethal effects.

Results: The stem cells and murine neuroblastoma cell line respectively showed most and least acute cytotoxicity. Using high content imaging, we observed cell type- and species-specific responses to the IONPs on the level of reactive oxygen species production, calcium homeostasis, mitochondrial integrity and cell morphology, indicating that cellular homeostasis is impaired in distinct ways.

Conclusions: Our data reveal cell type-specific toxicity profiles and demonstrate that a single cell line or toxicity end point will not provide sufficient information on in vitro nanosafety. We propose to identify a set of standard cell lines for screening purposes and to select cell types for detailed nanosafety studies based on the intended application and/or expected exposure.
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http://dx.doi.org/10.1186/s12951-016-0220-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5017038PMC
September 2016

Evaluation of quantum dot cytotoxicity: interpretation of nanoparticle concentrations versus intracellular nanoparticle numbers.

Nanotoxicology 2016 11 28;10(9):1318-28. Epub 2016 Jul 28.

a Department of Imaging and Pathology , Biomedical NMR Unit/MoSAIC, KU Leuven Campus Gasthuisberg , Leuven , Belgium .

While substantial progress has been achieved in the design of more biocompatible nanoparticles (NP), detailed data are required on the precise interactions of NPs and their environment for more reliable interpretation of toxicity results. Therefore, this study aims to investigate the interaction of two quantum dots (QDs) of the same core material CdSe/ZnS coated with two different amphiphilic polymers, with two well-established mammalian cell lines representing possible sites of QD accumulation. Results are linked to either extracellular QD concentrations (given dose) or cellular QD levels (number of internalized particles). In this study, QD internalization, effects on cellular homeostasis, and consequent inflammatory and cytoskeletal alterations caused by these QDs were explored. Fluorescence imaging techniques, including; image-based flow cytometry, confocal microscopy and high-content imaging with the InCell analyzer were used in a multiparametric methodology to evaluate cell viability, induction of oxidative stress, mitochondrial health, cell cytoskeletal functionality and changes in cellular morphology. Gene expression arrays were also carried out on 168 key genes involved in the cytoskeletal architecture and inflammatory pathway accompanied with the analysis of focal adhesions as key markers for actin-mediated signaling. Our results show distinct differences between the PMA and PTMAEMA-stat-PLMA coated QDs, which could mainly be attributed to differences in their cellular uptake levels. The toxicity profiles of both QD types changed drastically depending on whether effects were expressed in terms of given dose or internalized particles. Both QDs triggered alterations to important but different genes, most remarkably the up-regulation of tumor suppression and necrosis genes and the down regulation of angiogenesis and metastasis genes at sub-cytotoxic concentrations of these QDs.
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http://dx.doi.org/10.1080/17435390.2016.1210691DOI Listing
November 2016

Basic Physicochemical Properties of Polyethylene Glycol Coated Gold Nanoparticles that Determine Their Interaction with Cells.

Angew Chem Int Ed Engl 2016 04 29;55(18):5483-7. Epub 2016 Mar 29.

Fachbereich Physik, Philipps Universität Marburg, Marburg, Germany.

A homologous nanoparticle library was synthesized in which gold nanoparticles were coated with polyethylene glycol, whereby the diameter of the gold cores, as well as the thickness of the shell of polyethylene glycol, was varied. Basic physicochemical parameters of this two-dimensional nanoparticle library, such as size, ζ-potential, hydrophilicity, elasticity, and catalytic activity ,were determined. Cell uptake of selected nanoparticles with equal size yet varying thickness of the polymer shell and their effect on basic structural and functional cell parameters was determined. Data indicates that thinner, more hydrophilic coatings, combined with the partial functionalization with quaternary ammonium cations, result in a more efficient uptake, which relates to significant effects on structural and functional cell parameters.
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http://dx.doi.org/10.1002/anie.201511733DOI Listing
April 2016

The clastogenicity of 4NQO is cell-type dependent and linked to cytotoxicity, length of exposure and p53 proficiency.

Mutagenesis 2016 Mar 11;31(2):171-80. Epub 2015 Sep 11.

Drug Safety and Metabolism, AstraZeneca, Unit 310, Darwin Building, Cambridge Science Park, Milton Road, Cambridge CB40WG, UK.

4-Nitroquinoline 1-oxide (4NQO) is used as a positive control in various genotoxicity assays because of its known mutagenic and carcinogenic properties. The chemical is converted into 4-hydroxyaminoquinoline 1-oxide and gives rise to three main DNA adducts, N-(deoxyguanosin-8-yl)-4AQO, 3-(desoxyguanosin-N (2)-yl)-4AQO and 3-(deoxyadenosin-N (6)-yl)-4AQO. This study was designed to assess the shape of the dose-response curve at low concentrations of 4NQO in three human lymphoblastoid cell lines, MCL-5, AHH-1 and TK6 as well as the mouse lymphoma L5178Y cell line in vitro. Chromosomal damage was investigated using the in vitro micronucleus assay, while further gene mutation and DNA damage studies were carried out using the hypoxanthine-guanine phosphoribosyltransferase forward mutation and comet assays. 4NQO showed little to no significant increases in micronucleus induction in the human lymphoblastoid cell lines, even up to 55±5% toxicity. A dose-response relationship could only be observed in the mouse lymphoma cell line L5178Y after 4NQO treatment, even at concentrations with no reduction in cell viability. Further significant increases in gene mutation and DNA damage induction were observed. Hence, 4NQO is a more effective point mutagen than clastogen, and its suitability as a positive control for genotoxicity testing has to be evaluated for every individual assay.
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http://dx.doi.org/10.1093/mutage/gev069DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4748179PMC
March 2016

High content analysis at single cell level identifies different cellular responses dependent on nanomaterial concentrations.

Sci Rep 2015 Sep 8;5:13890. Epub 2015 Sep 8.

MoSAIC/Biomedical MRI Unit, Faculty of Medicine, KU Leuven, Herestraat 49, B3000 Leuven, Belgium.

A mechanistic understanding of nanomaterial (NM) interaction with biological environments is pivotal for the safe transition from basic science to applied nanomedicine. NM exposure results in varying levels of internalized NM in different neighboring cells, due to variances in cell size, cell cycle phase and NM agglomeration. Using high-content analysis, we investigated the cytotoxic effects of fluorescent quantum dots on cultured cells, where all effects were correlated with the concentration of NMs at the single cell level. Upon binning the single cell data into different categories related to NM concentration, this study demonstrates, for the first time, that quantum dots activate both cytoprotective and cytotoxic mechanisms, resulting in a zero net result on the overall cell population, yet with significant effects in cells with higher cellular NM levels. Our results suggest that future NM cytotoxicity studies should correlate NM toxicity with cellular NM numbers on the single cell level, as conflicting mechanisms in particular cell subpopulations are commonly overlooked using classical toxicological methods.
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http://dx.doi.org/10.1038/srep13890DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4561960PMC
September 2015

High-Content Imaging and Gene Expression Approaches To Unravel the Effect of Surface Functionality on Cellular Interactions of Silver Nanoparticles.

ACS Nano 2015 Oct 3;9(10):10431-44. Epub 2015 Sep 3.

MoSAIC/Biomedical MRI Unit, Department of Medicine, Catholic University of Leuven , Herestraat 49, B3000 Leuven, Belgium.

The toxic effects of Ag nanoparticles (NPs) remain an issue of debate, where the respective contribution of the NPs themselves and of free Ag(+) ions present in the NP stock suspensions and after intracellular NP corrosion are not fully understood. Here, we employ a recently set up methodology based on high-content (HC) imaging combined with high-content gene expression studies to examine the interaction of three types of Ag NPs with identical core sizes, but coated with either mercaptoundecanoic acid (MUA), dodecylamine-modified poly(isobutylene-alt-maleic anhydride) (PMA), or poly(ethylene glycol) (PEG)-conjugated PMA with two types of cultured cells (primary human umbilical vein endothelial cells (HUVEC) and murine C17.2 neural progenitor cells). As a control, cells were also exposed to free Ag(+) ions at the same concentration as present in the respective Ag NP stock suspensions. The data reveal clear effects of the NP surface properties on cellular interactions. PEGylation of the NPs significantly reduces their cellular uptake efficiency, whereas MUA-NPs are more prone to agglomeration in complex tissue culture media. PEG-NPs display the lowest levels of toxicity, which is in line with their reduced cell uptake. MUA-NPs display the highest levels of toxicity, caused by autophagy, cell membrane damage, mitochondrial damage, and cytoskeletal deformations. At similar intracellular NP levels, PEG-NPs induce the highest levels of reactive oxygen species (ROS), but do not affect the cell cytoskeleton, in contrast to MUA- and PMA-NPs. Gene expression studies support the findings above, defining autophagy and cell membrane damage-related necrosis as main toxicity pathways. Additionally, immunotoxicity, DNA damage responses, and hypoxia-like toxicity were observed for PMA- and especially MUA-NPs. Together, these data reveal that Ag(+) ions do contribute to Ag NP-associated toxicity, particularly upon intracellular degradation. The different surface properties of the NPs however result in distinct toxicity profiles for the three NPs, indicating clear NP-associated effects.
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http://dx.doi.org/10.1021/acsnano.5b04661DOI Listing
October 2015

The Effect of Intracellular Degradation on Cytotoxicity and Cell Labeling Efficacy of Inorganic Ligand-Stabilized Colloidal CdSe/CdS Quantum Dots.

J Biomed Nanotechnol 2015 Apr;11(4):631-43

Quantum dots (QDots) are explored in biomedicine as highly fluorescent, photostable nanomaterials, but their use is impeded by their hydrophobic nature. In the present work, we evaluate the potential biomedical use of QDots that have been transferred into the aqueous phase by means of inorganic ligands. CdSe/CdS QDots were prepared and transferred to water upon ligand exchange to S(2-) ions. However, a multiparametric evaluation of the effect of these QDots on multiple cell types revealed significant QDot cytotoxicity. Using optimized methods, the QDots were found to rapidly degrade under endosomal pH, resulting in leached Cd(2+). Together with the induction of oxidative stress, this significantly affected cell viability. Using proliferation-restricted cells, QDot degradation was found to augment cytotoxicity with time resulting in mitochondrial and DNA damage, effects on cell morphology and cell functionality. The final non-cytotoxic concentration was defined at 2 nM, enabling cells to be tracked up to 2 cell divisions. A direct comparison with other QDots and fluorescent particles studied resulted in similar concentrations; however, the functionality of previously analyzed particles was much higher. These data reveal that comparing NP toxicity based on particle concentrations is extremely difficult. A comparison of NPs is better obtained by evaluating NP functionality using a straightforward approach, such as follow-up of QDot fluorescence in dividing cells. These data highlight the importance of (1) considering QDot stability in the intracellular microenvironment, (2) the protective nature of the QDot-stabilizing coating, (3) the need for comparison of particle functionality to understand any observed effects.
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http://dx.doi.org/10.1166/jbn.2015.1853DOI Listing
April 2015

Genotoxic capacity of Cd/Se semiconductor quantum dots with differing surface chemistries.

Mutagenesis 2016 Jan 14;31(1):97-106. Epub 2015 Aug 14.

Institute of Life Science, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP, UK,

Quantum dots (QD) have unique electronic and optical properties promoting biotechnological advances. However, our understanding of the toxicological structure-activity relationships remains limited. This study aimed to determine the biological impact of varying nanomaterial surface chemistry by assessing the interaction of QD with either a negative (carboxyl), neutral (hexadecylamine; HDA) or positive (amine) polymer coating with human lymphoblastoid TK6 cells. Following QD physico-chemical characterisation, cellular uptake was quantified by optical and electron microscopy. Cytotoxicity was evaluated and genotoxicity was characterised using the micronucleus assay (gross chromosomal damage) and the HPRT forward mutation assay (point mutagenicity). Cellular damage mechanisms were also explored, focusing on oxidative stress and mitochondrial damage. Cell uptake, cytotoxicity and genotoxicity were found to be dependent on QD surface chemistry. Carboxyl-QD demonstrated the smallest agglomerate size and greatest cellular uptake, which correlated with a dose dependent increase in cytotoxicity and genotoxicity. Amine-QD induced minimal cellular damage, while HDA-QD promoted substantial induction of cell death and genotoxicity. However, HDA-QD were not internalised by the cells and the damage they caused was most likely due to free cadmium release caused by QD dissolution. Oxidative stress and induced mitochondrial reactive oxygen species were only partially associated with cytotoxicity and genotoxicity induced by the QD, hence were not the only mechanisms of importance. Colloidal stability, nanoparticle (NP) surface chemistry, cellular uptake levels and the intrinsic characteristics of the NPs are therefore critical parameters impacting genotoxicity induced by QD.
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http://dx.doi.org/10.1093/mutage/gev061DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4696518PMC
January 2016
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