Nanotoxicology. No signs of illness

Renal Clearable Gold Nanoparticle-Functionalized Silk Film for in vivo Fluorescent Temperature Mapping

Implantable optical sensing devices that can continuously monitor physiological temperature changes hold great potential toward applications in healthcare and medical field. Here, we present a conceptual foundation for the design of biocompatible temperature sensing device by integrating renal clearable luminescent gold nanoparticles (AuNPs) with silk film (AuNPs-SF). We found that the AuNPs display strong temperature dependence in both near-IR fluorescence intensity and lifetime over a large temperature range (10-60°C), with a fluorescence intensity sensitivity of 1.72%/°C and lifetime sensitivity of 0.09 μs/°C. When integrated, the AuNPs with biocompatible silk film are implanted in the dorsal region of mice. The fluorescence imaging of the AuNPs-SF in the body shows a linear relationship between the average fluorescence intensity and temperature. More importantly, <3.68% ID gold are left in the body, and no adverse effect is observed for 8 weeks. This AuNPs-SF can be potentially used as a flexible, biocompatible, and implantable sensing device for in vivo temperature mapping.

Molecular interaction of silicon quantum dot micelles with plasma proteins: hemoglobin and thrombin

Protein conformational changes are associated with potential cytotoxicity upon interaction with small molecules or nanomaterials. Protein misfolding leads to protein-mediated diseases; thus, it is important to study the conformational changes in proteins using nanoparticles as drug carriers. In this study, the conformational changes in hemoglobin and thrombin were observed using fluorescence spectroscopy, circular dichroism spectroscopy and molecular modelling studies after interaction with non-toxic, water-soluble near-infrared silicon quantum dot micelles. The molecular docking results indicated that the binding affinities of hemoglobin and thrombin with Si QD micelles are good. In addition, molecular dynamics simulations were performed to obtain more detailed information.

Overall graphical representation of 1-decene, F-127, and crystal structures of hemoglobin and thrombin.

Nanoparticles-Caused Oxidative Imbalance

Application of nanomaterials in nearly every single branch of industry results in their accumulation in both abiotic environment and tissues of living organisms. Despite the common use of nanomaterials, we are not able to precisely define their toxicity towards humans and surrounding biota. Although we were able to determine final effects of chronic exposure to nanoparticles which consist of many pathologies such as respiratory diseases, allergies, diseases of cardiovascular system, disorders in embryonic life differentiation and growth disorders, toxic effects on the immune system and cancers. The most predominantly investigated feature of most nanoparticles is their ability to induce oxidative stress on cellular level. Imbalance in redox state of cells can lead to various malfunctions in their internal metabolism, which in turn can lead to mentioned pathologies on the organismal level if the exposure is persistent and spread wide enough. Imbalance in redox state translate into production of reactive oxygen species in amounts impossible to be scavenged in given time. Many reactive oxygen species play crucial role in physiological processes in properly functioning cells. It was proven on numerous occasions that abundance of ROS, aside from oxidative damage, can lead to more subtle adverse effects tied to disturbances in intra- and intercellular signaling pathways. In this chapter we would like to address the nanoparticle-induced redox imbalance in cells and its effects.

Low-cost, flexible, disinfectant-free and regular-array three-dimensional nanopyramid antibacterial films for clinical applications

In this work, a low-cost, scalable and highly repeatable approach was developed to prepare polystyrene films with three-dimensional nanopyramids on the surface. The nanopyramids have a tunable aspect ratio and more importantly, their anti-bacterial performance has been systematically studied. The effectiveness of the nanopyramids on E. coli growth inhibition and the role of the nanostructure aspect ratio were carefully studied through scanning electron microscopy and confocal laser scanning microscopy. The results showed an excellent antibacterial performance with more than 90% reduction in the E. coli population in all nanopyramid samples after a 168 h prolonged incubation time. The nanopyramid film developed here can be used for clinical and commercial applications to prevent the growth of pathogenic bacteria on various surfaces.

Membrane activity of a supramolecular peptide-based chemotherapeutic enhancer

Self-assembly of de novo designed multidomain peptides (MDPs) resulted in functional membrane-active supramolecular nanofibers. The membrane activity was analyzed through fluorescence membrane localization and patch-clamp electrophysiology yielding important information that can be used for the development of a new type of supramolecular peptide-based chemotherapeutic enhancer.

Characterization of cellulose membranes modified with luminescent silicon quantum dots nanoparticles

A highly hydrophilic planar membrane fabricated with regenerated cellulose (RC-4 membrane), a biocompatible polymer, was modified by inclusion of water-soluble silicon quantum dot nanoparticles (SiQDs). Both bare SiQDs and SiQDs coated with a PAMAM-OH dendrimer were employed in order to obtain luminescent and thermally stable membrane systems (RC-4/SiQDs and RC-4/SiQDs-PAMAM-OH membranes). Original and SiQDs-modified membranes were characterized by fluorescence spectroscopy (steady and confocal), derivative thermogravimetric analysis and impedance spectroscopy measurements. According to these results, both SiQDs-regenerated cellulose composite membranes present luminescent character as well as higher thermal resistance and conductivity than the original sample, although the dendrimer coverage of the SiQDs might partially shield such effects. Moreover, the permanence of SiQDs nanoparticles in the structure of the cellulosic support in aqueous environments and their effect on diffusive transport were determined by water uptake as well as by membrane potential measurements at different concentrations of a model electrolyte (KCl). These results demonstrate the possible use of these stable nano-engineered membranes, which are based on SiQDs nanoparticles, in electrochemical devices under flow conditions.

Evaluation of CdTe/CdS/ZnS core/shell/shell quantum dot toxicity on three-dimensional spheroid cultures

In this work, three-dimensional (3D) spheroid cultures of human adipose-derived mesenchymal stem cells (hAD-MSCs), with tissue-mimetic morphology through well developed cell-cell and cell-matrix interactions and distinct diffusion/transport characteristics, were assessed for dose-dependent toxic effects of red-emitting CdTe/CdS/ZnS quantum dots (Qdots). Morphological investigations and time-resolved microscopy analysis in addition to cell metabolic activity studies revealed that 3D spheroid cultures are more resistant to Qdot-induced cytotoxicity in comparison to conventional 2D cultures. The obtained results suggest the presence of two distinct cell populations in 2D cultures with different sensitivity to Qdots, however that effect wasn't observed in 3D spheroids. Our investigations were aimed to improve the prediction of nanotoxicity of Qdot on tissue-level and provide the essential screening steps prior to any in vivo application. Moreover, penetration ability of highly fluorescent Qdots to densely-packed spheroids will fortify the biological application of developed Qdots in tissue-like structures.

Size-dependent lymphatic uptake of nanoscale-tailored particles as tumor mass increases

Aim:

To investigate the size-dependent lymphatic uptake of nanoparticles in mice with rapidly growing syngeneic tumors.

Materials & methods:

Mice were inoculated subcutaneously with EL4 lymphoma cells and on day 5 or day 6 of tumor growth, injected peritumorally with either 29 nm or 58 nm of ultra-small superparamagnetic iron oxide nanoparticles. Twenty-four hours later the animals were imaged using MRI.

Results & conclusion:

The larger of the two particles can only be detected in the lymph node when injected in animals with 6-day-old tumors while the 29 nm ultra-small superparamagnetic iron oxide nanoparticle is observed on both time points. Tumor mass greatly impacts the size of particles that are transported to the lymph nodes.

This study aims to improve the way the spreading of certain forms of cancer is detected. The method, known as sentinel lymph node detection, locates and removes the first lymph node that drains the tumor to examine it for cancer cells. The authors want to improve the way this is done by using a new contrast agent based on nanoparticles. Two different sizes of particles were injected around the implanted tumors in mice and imaged with MRI. The results indicate that the mass of the tumor plays a crucial role in the transport of nanoparticles to the lymph node.

Efficient Radioisotope Energy Transfer by Gold Nanoclusters for Molecular Imaging

Beta-emitting isotopes Fluorine-18 and Yttrium-90 are tested for their potential to stimulate gold nanoclusters conjugated with blood serum proteins (AuNCs). AuNCs excited by either medical radioisotope are found to be highly effective ionizing radiation energy transfer mediators, suitable for in vivo optical imaging. AuNCs synthesized with protein templates convert beta-decaying radioisotope energy into tissue-penetrating optical signals between 620 and 800 nm. Optical signals are not detected from AuNCs incubated with Technetium-99m, a pure gamma emitter that is used as a control. Optical emission from AuNCs is not proportional to Cerenkov radiation, indicating that the energy transfer between the radionuclide and AuNC is only partially mediated by Cerenkov photons. A direct Coulombic interaction is proposed as a novel and significant mechanism of energy transfer between decaying radionuclides and AuNCs.

Preparation, cytotoxicity and in vivo bioimaging of highly luminescent water-soluble silicon quantum dots

Designing various inorganic nanomaterials that are cost effective, water soluble, optically photostable, highly fluorescent and biocompatible for bioimaging applications is a challenging task. Similar to semiconducting quantum dots (QDs), silicon QDs are another alternative and are highly fluorescent, but non-water soluble. Several surface modification strategies were adopted to make them water soluble. However, the photoluminescence of Si QDs was seriously quenched in the aqueous environment. In this report, highly luminescent, water-dispersible, blue- and green-emitting Si QDs were prepared with good photostability. In vitro studies in monocytes reveal that Si QDs exhibit good biocompatibility and excellent distribution throughout the cytoplasm region, along with the significant fraction translocated into the nucleus. The in vivo zebrafish studies also reveal that Si QDs can be evenly distributed in the yolk-sac region. Overall, our results demonstrate the applicability of water-soluble and highly fluorescent Si QDs as excellent in vitro and in vivo bioimaging probes.

Comprehensive evaluation of microRNA expression profiling reveals the neural signaling specific cytotoxicity of superparamagnetic iron oxide nanoparticles (SPIONs) through N-methyl-D-aspartate receptor

Though nanomaterials are considered as drug carriers or imaging reagents targeting the central nervous system their cytotoxicity effect on neuronal cells has not been well studied. In this study, we treated PC12 cells, a model neuronal cell line, with a nanomaterial that is widely accepted for medical use, superparamagnetic iron oxide nanoparticles (SPIONs). Our results suggest that, after treated with SPIONs, the expression pattern of the cellular miRNAs changed widely in PC12 cells. As potential miRNA targets, NMDAR, one of the candidate mRNAs that were selected using GO and KEGG pathway enrichment, was significantly down regulated by SPIONs treatment. We further illustrated that SPIONs may induce cell death through NMDAR suppression. This study revealed a NMDAR neurotoxic effect of SPIONs and provides a reliable approach for assessing the neurocytotoxic effects of nanomaterials based on the comprehensive annotation of miRNA profiling.

Selective inhibition of liver cancer growth realized by the intrinsic toxicity of a quantum dot-lipid complex

Using the intrinsic toxicity of nanomaterials for anticancer therapy is an emerging concept. In this work, we discovered that CdTe/CdS quantum dots, when coated with lipids (QD-LC) instead of popular liposomes, polymers, or dendrimers, demonstrated extraordinarily high specificity for cancer cells, which was due to the difference in the macropinocytosis uptake pathways of QD-LC between the cancer cells and the normal cells. QD-LC-induced HepG2 cell apoptosis was concomitant with the activation of the JNK/caspase-3 signaling pathway. Moreover, QD-LC treatment resulted in a delay in the latent period for microtumor formation of mouse hepatocarcinoma H22 cells and inhibited tumor growth, with a reduction of 53.2% in tumor volume without toxicity in major organs after intratumoral administrations to tumor-bearing mice. Our results demonstrate that QD-LC could be a very promising theranostic agent against liver cancer.

The heritable effects of nanotoxicity

The widespread entry of nanomaterials into manifold life fields posed serious concerns on environmental health and safety issues. Potential adverse effects of nanoparticles (NPs) are continuously faced using in vitro cell systems and by mean of cell and molecular biology tools, several mechanisms have been found beyond their toxicity. The evaluation of the in vivo possible consequences derived from exposure of living organisms to NPs is instead more complex but compulsory in view of their application for diagnosis or therapeutic purposes. Here the effects of NP-induced genetic alteration on the progeny of treated animals will be treated, considering selected species from invertebrate and vertebrates as examples of transgenerational transmission of NP toxicity. The effects on reproductive capability, fertility and embryogenesis observed in different animal species upon treatment with different materials will provide an overview of the current knowledge on the heritable feature of nanotoxicity.

Time-resolved botulinum neurotoxin A activity monitored using peptide-functionalized Au nanoparticle energy transfer sensors

A peptide mimicking SNAP-25 was immobilized on Au nanoparticles for the monitoring of botulinum neurotoxin light chain A activity.

Nanoparticle accumulation in angiogenic tissues: towards predictable pharmacokinetics

Nanoparticles are increasingly used in medical applications such as drug delivery, imaging, and biodiagnostics, particularly for cancer. The design of nanoparticles for tumor delivery has been largely empirical, owing to a lack of quantitative data on angiogenic tissue sequestration. Using fluorescence correlation spectroscopy, the deposition rate constants of nanoparticles into angiogenic blood vessel tissue are determined. It is shown that deposition is dependent on surface charge. Moreover, the size dependency strongly suggests that nanoparticles are taken up by a passive mechanism that depends largely on geometry. These findings imply that it is possible to tune nanoparticle pharmacokinetics simply by adjusting nanoparticle size.

Nanotoxicity assessment of quantum dots: from cellular to primate studies

Tremendous research efforts have been devoted to fabricating high quality quantum dots (QDs) for applications in biology and medicine. Much of this research was pursued with an ultimate goal of using QDs in clinical applications. However, a great deal of concern has been voiced about the potential hazards of QDs due to their heavy-metal content. Many studies have demonstrated toxicity of various QDs in cell culture studies. However, in a smaller number of studies using small animal models (mice and rats), no abnormal behaviour or tissue damage was noticed over periods of months after the systemic administration of QDs. Nevertheless, the correlation of these results with the potential for negative effects of QD on humans remains unclear. Many urgent questions must be answered before the QDs community moves into the clinical research phase. This review provides an overview of the toxicity assessment of QDs, ranging from cell culture studies to animal models and discusses their findings. Guidelines for using various nonhuman primate models for QD toxicity studies are highlighted. This review article is intended to promote the awareness of current developments of QD applications in biology, the potential toxicity of QDs, and approaches to minimizing toxicity.

Quantum dots in bioanalysis: a review of applications across various platforms for fluorescence spectroscopy and imaging

Semiconductor quantum dots (QDs) are brightly luminescent nanoparticles that have found numerous applications in bioanalysis and bioimaging. In this review, we highlight recent developments in these areas in the context of specific methods for fluorescence spectroscopy and imaging. Following a primer on the structure, properties, and biofunctionalization of QDs, we describe select examples of how QDs have been used in combination with steady-state or time-resolved spectroscopic techniques to develop a variety of assays, bioprobes, and biosensors that function via changes in QD photoluminescence intensity, polarization, or lifetime. Some special attention is paid to the use of Förster resonance energy transfer-type methods in bioanalysis, including those based on bioluminescence and chemiluminescence. Direct chemiluminescence, electrochemiluminescence, and charge transfer quenching are similarly discussed. We further describe the combination of QDs and flow cytometry, including traditional cellular analyses and spectrally encoded barcode-based assay technologies, before turning our attention to enhanced fluorescence techniques based on photonic crystals or plasmon coupling. Finally, we survey the use of QDs across different platforms for biological fluorescence imaging, including epifluorescence, confocal, and two-photon excitation microscopy; single particle tracking and fluorescence correlation spectroscopy; super-resolution imaging; near-field scanning optical microscopy; and fluorescence lifetime imaging microscopy. In each of the above-mentioned platforms, QDs provide the brightness needed for highly sensitive detection, the photostability needed for tracking dynamic processes, or the multiplexing capacity needed to elucidate complex systems. There is a clear synergy between advances in QD materials and spectroscopy and imaging techniques, as both must be applied in concert to achieve their full potential.