@article{zhang_baeumer_monteiro-riviere_2011, title={Cellular uptake mechanisms and toxicity of quantum dots in dendritic cells}, volume={6}, ISSN={["1748-6963"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000293335200007&KeyUID=WOS:000293335200007}, DOI={10.2217/nnm.11.73}, abstractNote={ Quantum dots (QDs) are nanoparticles with strong fluorescent emission and are novel tools used in biomedical applications, but the toxicity and mechanism of cellular uptake are poorly understood. QD655-COOH (negative charge, 18 nm) consist of a cadmium/selenide core and a zinc sulfide shell with a carboxylic acid coating with an emission wavelength of 655 nm. Materials & Methods: Peripheral blood mononuclear cells were isolated from porcine blood by gradient centrifugation, and monocytes, which are CD14 positive, were purified. Monocytes were differentiated into dendritic cells (DCs) with GM-CSF and IL-4. Results: Monocytes showed cellular uptake of QD655-COOH, while lymphocytes did not. Monocyte differentiation into DCs increased the cellular uptake by sixfold when dosed with 2 nM of QD655-COOH. Transmission electron microscopy depicted QD655-COOH in the cytoplasmic vacuoles of DCs. Twelve endocytic inhibitors demonstrated QD655-COOH endocytosis in DCs, which was recognized by clathrin and scavenger receptors and regulated by F-actin and phospholipase C. In addition, DC maturation with lipopolysaccharide (LPS) caused an increase in QD655-COOH uptake compared with DCs without LPS stimulation. Viability assays, including 96AQ, CCK-8, alamar blue and ApoTox, exhibited minimal toxicity in DCs dosed with QD655-COOH at 24 h. However, glutathione levels showed a significant decrease with 10 nM of QD655-COOH. Finally, QD655-COOH exposure was associated with a decrease in CD80/CD86 expression after LPS stimulation, suggesting suppression with DC maturation. Conclusion: These findings shed light on the mechanism of QD655-COOH uptake in DCs and that cellular uptake pathways are dependent on cell type and cell differentiation. }, number={5}, journal={NANOMEDICINE}, author={Zhang, Leshuai W. and Baeumer, Wolfgang and Monteiro-Riviere, Nancy A.}, year={2011}, month={Jul}, pages={777–791} }
 @article{zhang_monteiro-riviere_2010, title={Lectins modulate multi-walled carbon nanotubes cellular uptake in human epidermal keratinocytes}, volume={24}, ISSN={["0887-2333"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000275991700026&KeyUID=WOS:000275991700026}, DOI={10.1016/j.tiv.2009.11.007}, abstractNote={The development of nanomaterials for biomedical applications has attracted a great deal of attention. Carbon nanotubes may interact and cross cell membranes and serve as potential carriers for drug delivery studies. The reflection mode in the confocal laser scanning microscope was used to image multi-walled carbon nanotubes (MWCNT) in human neonatal epidermal keratinocytes (HEK) stained with the cytoskeleton protein F-actin. Scanning electron microscopy depicted tight binding of MWCNT on the plasma membrane of HEK, while some MWCNT were located in the cell. Since keratinocytes normally engulf melanosomes, we hypothesized that the melanocyte transfer pathway could be a potential route of entry into keratinocytes. Lectins are inhibitors of the melanosome transfer pathway was used to study the uptake of MWCNT in keratinocytes, to see if they played a role in reducing the cellular uptake of MWCNT in HEK. Three different lectins, Pisum sativum (PS), Lycopersicon esculentum (LE), and Tetragonolobus purpureas (TP) were used as a cocktail. The maximal concentrations of lectins that would be non-toxic to the HEK was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay. These studies confirmed that lectin cocktails (PS 5 μg/ml, LE 25 μg/ml and TP 25 μg/ml) decreased MWCNT interaction at the cell surface and uptake. F-actin, a cytoskeleton protein, was used to visualize how the MWCNT interacted with the cytoskeleton in the cells. MWCNT traversed through the cells’ cytoskeleton and the plasma membrane into adjacent keratinocytes.}, number={2}, journal={TOXICOLOGY IN VITRO}, author={Zhang, Leshuai W. and Monteiro-Riviere, Nancy A.}, year={2010}, month={Mar}, pages={546–551} }
 @article{zhang_yang_barron_monteiro-riviere_2009, title={Endocytic mechanisms and toxicity of a functionalized fullerene in human cells}, volume={191}, ISSN={["1879-3169"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000272760200007&KeyUID=WOS:000272760200007}, DOI={10.1016/j.toxlet.2009.08.017}, abstractNote={Derivatized fullerenes could be used in biomedical applications and be suitable vectors for drug delivery due to their small size, large surface area and solubility. However, the interactions of derivatized fullerenes with biological systems and cells are not well understood. A water-soluble fullerene-substituted phenylalanine (Bucky amino acid, Baa) poly-lysine derivative with a FITC label (Baa-Lys(FITC)-(Lys)(8)-OH) was characterized by dynamic light scattering, transmission electron microscopy with negative staining, gel electrophoresis, zeta-potential, and UV/vis spectroscopy. Viability assays depicted the cytotoxicity was time, concentration and assay dependent. A decrease in ATP and glutathione at the high concentrations suggests that reactive oxygen species may be involved. Baa-Lys(FITC)-(Lys)(8)-OH was present near the cell membrane at 15 min and entered into the cytoplasm by 30 min but did not localize in the lysosomes. Endocytic inhibitors were used to investigate the uptake mechanism. These results showed that the endocytic pathways could be mediated by caveolae/lipid rafts and cytoskeletal components. A scavenger receptor inhibitor completely blocked the uptake of Baa-Lys(FITC)-(Lys)(8)-OH, suggesting a specific endocytic pathway was strongly involved in Baa-Lys(FITC)-(Lys)(8)-OH cellular uptake.}, number={2-3}, journal={TOXICOLOGY LETTERS}, author={Zhang, Leshuai W. and Yang, Jianzhong and Barron, Andrew R. and Monteiro-Riviere, Nancy A.}, year={2009}, month={Dec}, pages={149–157} }
 @article{gunderson_nordone_lavoy_zhang_klaenhammer_dean_2009, title={Immunogenicity of Lactobacillus gasseri-FliC as an oral mucosal vaccine adjuvant for HIV}, volume={6}, ISSN={["1742-4690"]}, DOI={10.1186/1742-4690-6-s3-p163}, abstractNote={Background Transmission of HIV-1 across mucosal surfaces is the most prevalent mode of viral infection. Therefore, a successful vaccine must induce broad anti-viral immunity at the mucosal surface. In the present study, we investigated the immunogenicity of a novel Lactobacillus gasseri mucosal vaccine vector for use in oral delivery of HIV antigens. L. gasseri was genetically engineered to express Salmonella spp. flagellin (L. gasseri-FliC) – the agonist for Toll-like receptor 5 (TLR5) and a potent activator of innate immune cells.}, journal={RETROVIROLOGY}, author={Gunderson, S. and Nordone, S. and LaVoy, A. and Zhang, L. and Klaenhammer, T. and Dean, G.}, year={2009} }
 @article{monteiro-riviere_inman_zhang_2009, title={Limitations and relative utility of screening assays to assess engineered nanoparticle toxicity in a human cell line}, volume={234}, ISSN={["1096-0333"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000262761600008&KeyUID=WOS:000262761600008}, DOI={10.1016/j.taap.2008.09.030}, abstractNote={Single-walled carbon nanotubes (SWCNT), fullerenes (C(60)), carbon black (CB), nC(60), and quantum dots (QD) have been studied in vitro to determine their toxicity in a number of cell types. Here, we report that classical dye-based assays such as MTT and neutral red (NR) that determine cell viability produce invalid results with some NM (nanomaterials) due to NM/dye interactions and/or NM adsorption of the dye/dye products. In this study, human epidermal keratinocytes (HEK) were exposed in vitro to CB, SWCNT, C(60), nC(60), and QD to assess viability with calcein AM (CAM), Live/Dead (LD), NR, MTT, Celltiter 96 AQueous One (96 AQ), alamar Blue (aB), Celltiter-Blue (CTB), CytoTox Onetrade mark (CTO), and flow cytometry. In addition, trypan blue (TB) was quantitated by light microscopy. Assay linearity (R(2) value) was determined with HEK plated at concentrations from 0 to 25,000 cells per well in 96-well plates. HEK were treated with serial dilutions of each NM for 24 h and assessed with each of the viability assays. TB, CAM and LD assays, which depend on direct staining of living and/or dead cells, were difficult to interpret due to physical interference of the NM with cells. Results of the dye-based assays varied a great deal, depending on the interactions of the dye/dye product with the carbon nanomaterials (CNM). Results show the optimal high throughput assay for use with carbon and noncarbon NM was 96 AQ. This study shows that, unlike small molecules, CNM interact with assay markers to cause variable results with classical toxicology assays and may not be suitable for assessing nanoparticle cytotoxicity. Therefore, more than one assay may be required when determining nanoparticle toxicity for risk assessment.}, number={2}, journal={TOXICOLOGY AND APPLIED PHARMACOLOGY}, author={Monteiro-Riviere, N. A. and Inman, A. O. and Zhang, L. W.}, year={2009}, month={Jan}, pages={222–235} }
 @article{zhang_monteiro-riviere_2009, title={Mechanisms of Quantum Dot Nanoparticle Cellular Uptake}, volume={110}, ISSN={["1096-0929"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000267227800013&KeyUID=WOS:000267227800013}, DOI={10.1093/toxsci/kfp087}, abstractNote={Due to the superior photoemission and photostability characteristics, quantum dots (QD) are novel tools in biological and medical applications. However, the toxicity and mechanism of QD uptake are poorly understood. QD nanoparticles with an emission wavelength of 655 nm are ellipsoid in shape and consist of a cadmium/selenide core with a zinc sulfide shell. We have shown that QD with a carboxylic acid surface coating were recognized by lipid rafts but not by clathrin or caveolae in human epidermal keratinocytes (HEKs). QD were internalized into early endosomes and then transferred to late endosomes or lysosomes. In addition, 24 endocytic interfering agents were used to investigate the mechanism by which QD enter cells. Our results showed that QD endocytic pathways are primarily regulated by the G-protein-coupled receptor associated pathway and low density lipoprotein receptor/scavenger receptor, whereas other endocytic interfering agents may play a role but with less of an inhibitory effect. Lastly, low toxicity of QD was shown with the 20 nM dose in HEK at 48 h but not at 24 h by the live/dead cell assay. QD induced more actin filaments formation in the cytoplasm, which is different from the actin depolymerization by cadmium. These findings provide insight into the specific mechanism of QD nanoparticle uptake in cells. The surface coating, size, and charge of QD nanoparticles are important parameters in determining how nanoparticle uptake occurs in mammalian cells for cancer diagnosis and treatment, and drug delivery.}, number={1}, journal={TOXICOLOGICAL SCIENCES}, author={Zhang, Leshuai W. and Monteiro-Riviere, Nancy A.}, year={2009}, month={Jul}, pages={138–155} }
 @article{zhang_yu_colvin_monteiro-riviere_2008, title={Biological interactions of quantum dot nanoparticles in skin and in human epidermal keratinocytes}, volume={228}, ISSN={["1096-0333"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000255494300008&KeyUID=WOS:000255494300008}, DOI={10.1016/j.taap.2007.12.022}, abstractNote={Quantum dots nanoparticles have novel optical properties for biomedical applications and electronics, but little is known about their skin permeability and interaction with cells. QD621 are nail-shaped nanoparticles that contain a cadmium/selenide core with a cadmium sulfide shell coated with polyethylene glycol (PEG) and are soluble in water. QD were topically applied to porcine skin flow-through diffusion cells to assess penetration at 1 μM, 2 μM and 10 μM for 24 h. QD were also studied in human epidermal keratinocytes (HEK) to determine cellular uptake, cytotoxicity and inflammatory potential. Confocal microscopy depicted the penetration of QD621 through the uppermost stratum corneum (SC) layers of the epidermis and fluorescence was found primarily in the SC and near hair follicles. QD were found in the intercellular lipid bilayers of the SC by transmission electron microscopy (TEM). Inductively coupled plasma-optical emission spectroscopy (ICP-OES) analysis for cadmium (Cd) and fluorescence for QD both did not detect Cd nor fluorescence signal in the perfusate at any time point or concentration. In HEK, viability decreased significantly (p < 0.05) from 1.25 nM to 10nM after 24 h and 48 h. There was a significant increase in IL-6 at 1.25 nM to 10 nM, while IL-8 increased from 2.5nM to 10nM after 24 h and 48 h. TEM of HEK treated with 10 nM of QD621 at 24 h depicted QD in cytoplasmic vacuoles and at the periphery of the cell membranes. These results indicate that porcine skin penetration of QD621 is minimal and limited primarily to the outer SC layers, yet if the skin were damaged allowing direct QD exposure to skin or keratinocytes, an inflammatory response could be initiated.}, number={2}, journal={TOXICOLOGY AND APPLIED PHARMACOLOGY}, author={Zhang, Leshuai W. and Yu, William W. and Colvin, Vicki L. and Monteiro-Riviere, Nancy A.}, year={2008}, month={Apr}, pages={200–211} }
 @article{zhang_zeng_barron_monteiro-riviere_2007, title={Biological interactions of functionalized single-wall carbon nanotubes in human epidermal keratinocytes}, volume={26}, ISSN={["1092-874X"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000245792700002&KeyUID=WOS:000245792700002}, DOI={10.1080/10915810701225133}, abstractNote={ Carbon nanotube–based nanovectors, especially functionalized nanotubes, have shown potential for therapeutic drug delivery. 6-Aminohexanoic acid–derivatized single-wall carbon nanotubes (AHA-SWNTs) are soluble in aqueous stock solutions over a wide range of physiologically relevant conditions; however, their interactions with cells and their biological compatibility has not been explored. Human epidermal keratinocytes (HEKs) were dosed with AHA-SWNTs ranging in concentration from 0.00000005 to 0.05 mg/ml. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) cell viability decreased significantly ( p < .05) from 0.00005 to 0.05 mg/ml after 24 h. The proinflammatory mediators of inflammation cytokines interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)- α, IL-10, and IL-1 β were also assessed. Cytokine analysis did not show a significant increase in IL-6 and IL-8 in the medium containing 0.000005 mg/ml of AHA-SWNTs from 1 to 48 h. IL-6 increased in cells treated with 0.05 mg/ml of AHA-SWNTs from 1 to 48 h, whereas IL-8 showed a significant increase at 24 and 48 h. No significant difference ( p < .05) was noted with TNF- α, IL-10, and IL-1 β expression at any time point. Transmission electron microscopy of HEKs treated with 0.05 mg/ml AHA-SWNTs for 24 h depicted AHA-SWNTs localized within intracytoplasmic vacuoles in HEKs. Treatment with the surfactant 1% Pluronic F127 caused dispersion of the AHA-SWNT aggregates in the culture medium and less toxicity. These data showed that the lower concentration of 0.000005 mg/ml of AHA-SWNTs maintains cell viability and induces a mild cytotoxicity, but 0.05 mg/ml of AHA-SWNTs demonstrated an irritation response by the increase in IL-8. }, number={2}, journal={INTERNATIONAL JOURNAL OF TOXICOLOGY}, author={Zhang, Leshuai W. and Zeng, Liling and Barron, Andrew R. and Monteiro-Riviere, Nancy A.}, year={2007}, pages={103–113} }