Protein-Mediated Shape Control of Silver Nanoparticles

Silver nanoparticles were grown in aqueous solution, without the presence of typical surfactant molecules, but under the presence of different proteins. The shape of the resulting silver nanoparticles could be tuned by the selection of the types of proteins. The amount of accessible lysine groups was found to be mainly responsible for the anisotropy in nanoparticle formation. Viability measurements of cells exposed to protein capped spherical or prism-shaped NPs did not reveal differences between both geometries. Thus, in the case of protein-only coated Ag NPs, no shape-induced toxicity was found under the investigated exposure conditions

One-Step Synthesis and Characterization of N‑Doped Carbon Nanodots for Sensing in Organic Media

Photoluminescent nitrogen-doped carbon nanodots (N-doped CNDs) soluble in organic media are synthesized in a one-step synthesis from a single-source precursor (an amphiphilic polymer), which exhibits a very high quantum yield (QY = 78%), excitation wavelength-dependent emission, and upconversion emission properties. The evolution of N-doped CND formation is studied via ultraviolet–visible and photoluminescence spectroscopy. Their analytical application as an effective sensor for the direct determination of nitroaromatic explosives and byproducts is shown based on their selective response via a fluorescence quenching mechanism. The proposed method is validated in soil samples by directly using the sensor in organic media without any further treatment or additional functionalization, which is an interesting aspect for practical applications

Cell-Imprinted Substrates Direct the Fate of Stem Cells

Smart nanoenvironments were obtained by cell-imprinted substrates based on mature and dedifferentiated chondrocytes as templates. Rabbit adipose derived mesenchymal stem cells (ADSCs) seeded on these cell-imprinted substrates were driven to adopt the specific shape (as determined in terms of cell morphology) and molecular characteristics (as determined in terms of gene expression) of the cell types which had been used as template for the cell-imprinting. This method might pave the way for a reliable, efficient, and cheap way of controlling stem cell differentiation. Data also suggest that besides residual cellular fragments, which are presented on the template surface, the imprinted topography of the templates plays a role in the differentiation of the stem cells

Adenosine Triphosphate-Triggered Release of Macromolecular and Nanoparticle Loads from Aptamer/DNA-Cross-Linked Microcapsules

The synthesis of stimuli-responsive DNA microcapsules acting as carriers for different payloads, and being dissociated through the formation of aptamer–ligand complexes is described. Specifically, stimuli-responsive anti-adenosine triphosphate (ATP) aptamer-cross-linked DNA-stabilized microcapsules loaded with tetramethylrhodamine-modified dextran (TMR-D), CdSe/ZnS quantum dots (QDs), or microperoxidase-11 (MP-11) are presented. In the presence of ATP as trigger, the microcapsules are dissociated through the formation of aptamer–ATP complexes, resulting in the release of the respective loads. Selective unlocking of the capsules is demonstrated, and CTP, GTP, or TTP do not unlock the pores. The ATP-triggered release of MP-11 from the microcapsules enables the MP-11-catalyzed oxidation of Amplex UltraRed by H₂O₂ to the fluorescent product resorufin

Surface Enhanced Raman Scattering Encoded Gold Nanostars for Multiplexed Cell Discrimination

Labeled nanoparticles have attracted much interest toward applications in bioimaging and diagnostics. In particular, surface enhanced Raman scattering (SERS) nanotags have been demonstrated to be excellent candidates for multiplexed imaging and biological detection. We propose an alternative, effective method to easily prepare gold nanostars exhibiting plasmon bands in the near-infrared range, encoded with Raman reporter molecules, concomitantly acting as capping agents which are then protected with an amphiphilic polymer. The resulting nanotags are noncytotoxic and display long-term stability against aggregation and reporter leakage, while showing reproducible SERS signals suitable for multiplexing. These tags were used to distinguish five different types of breast cancer cells by imaging of a <i>quintuple</i> cell coculture. Time-lapse SERS imaging of the coculture was additionally performed, demonstrating the applicability of these nanotags for cell tracing over time scales above 24 h

Light-Addressable and Degradable Silica Capsules for Delivery of Molecular Cargo to the Cytosol of Cells

Degradable and light-addressable silica capsules have been prepared on the basis of CaCO₃ template particles. It was possible to load these capsules with an array of molecules such as anticancer drugs (doxorubicin), proteins (bovine serum albumin), and nucleic acids (mRNA encoding green fluorescent protein). <i>In vitro</i> degradation and release of these molecules was demonstrated and quantitatively compared with several kinds of polyelectrolyte multilayer capsules as examples of other delivery vehicles. The data suggests hydrolysis as a mechanism involved in intracellular degradation of silica capsules. Photothermal heating (by integrating plasmonic nanoparticles in the silica shell) was further used to induce remote molecular release

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

<p>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-<i>stat</i>-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.</p

Dual Enzymatic Reaction-Assisted Gemcitabine Delivery Systems for Programmed Pancreatic Cancer Therapy

Dual enzymatic reactions were introduced to fabricate programmed gemcitabine (GEM) nanovectors for targeted pancreatic cancer therapy. Dual-enzyme-sensitive GEM nanovectors were prepared by conjugation of matrix metalloproteinase-9 (MMP-9) detachable poly­(ethylene glycol) (PEG), cathepsin B-cleavable GEM, and targeting ligand CycloRGD to CdSe/ZnS quantum dots (QDs). The GEM nanovectors decorated with a PEG corona could avoid nonspecific interactions and exhibit prolonged blood circulation time. After GEM nanovectors were accumulated in tumor tissue by the enhanced permeability and retention (EPR) effect, the PEG corona can be removed by overexpressed MMP-9 in tumor tissue and RGD would be exposed, which was capable of facilitating cellular internalization. Once internalized into pancreatic cancer cells, the elevated lysosomal cathepsin B could further promote the release of GEM. By employing dual enzymatic reactions, the GEM nanovectors could achieve prolonged circulation time while maintaining enhanced cellular internalization and effective drug release. The proposed mechanism of the dual enzymatic reaction-assisted GEM delivery system was fully investigated both <i>in vitro</i> and <i>in vivo</i>. Meanwhile, compared to free GEM, the deamination of GEM nanovectors into inactive 2′,2′-difluorodeoxyuridine (dFdU) could be greatly suppressed, while the concentration of the activated form of GEM (gemcitabine triphosphate, dFdCTP) was significantly increased in tumor tissue, thus exhibiting superior tumor inhibition activity with minimal side effects

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

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-<i>alt</i>-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

Investigation of the Viability of Cells upon Co-Exposure to Gold and Iron Oxide Nanoparticles

Cell lines were exposed either to mixtures of gold and iron oxide nanoparticles, or to a hybrid nanoparticle with gold and iron oxide domain. In the case of simultaneous exposure to gold and iron oxide nanoparticles, enhanced toxicity as compared to the exposure to only one type of nanoparticles was observed. An indication was found that, at equivalent concentrations, the hybrid nanoparticles may slightly reduce cell viability more strongly than mixtures of both nanoparticle types. The results suggest that composite nanomaterials, in which different materials are present in particle form, need to be analyzed carefully, as not only the concentration of the respective materials but also their arrangement may influence their toxicity