Cellular effect of high doses of silica-coated quantum dot profiled with high throughput gene expression analysis and high content cellomics measurements

Screening the cytotoxicity of single-walled carbon nanotubes using novel 3D tissue-mimetic models

Single-walled carbon nanotubes (SWNTs) are promising candidates for a wide range of biomedical applications due to their fascinating properties. However, safety concerns are raised on their potential human toxicity and on the techniques that need to be used to assess such toxicity. Here, we integrate for the first time 3D tissue-mimetic models in the cytotoxicity assessment of purified (p-) and oxidized (o-) SWNTs. An established ultrasound standing wave trap was used to generate the 3D cell aggregates, and results were compared with traditional 2D cell culture models. Protein-based (bovine serum albumin) and surfactant-based (Pluronic F68) nanotube dispersions were tested and compared to a reference suspension in dimethyl sulfoxide. Our results indicated that p- and o-SWNTs were not toxic in the 3D cellular model following a 24 h exposure. In contrast, 2D cell cultures were significantly affected by exposure to p- and o-SWNTs after 24 h, as assessed by high-content screening and analysis (HCSA). Finally, cytokine (IL-6 and TNF-α) secretion levels were elevated in the 2D but remained essentially unchanged in the 3D cell models. Our results strongly indicate that 3D cell aggregates can be used as alternative in vitro models providing guidance on nanomaterial toxicity in a tissue-mimetic manner, thus offering future cost-effective solutions for toxicity screening assays under the experimental conditions more closely related to the physiological scenario in 3D tissue microenvironments.

Fate and toxicity of metallic and metal-containing nanoparticles for biomedical applications

It is important to obtain a better understanding of the uptake, trafficking, pharmacokinetics, clearance, and role of nanomaterials in biological systems, so that their possible undesirable effects can be avoided. A number of metallic or metal-containing nanomaterials, such as gold nanoparticles and nanorods, quantum dots, iron oxides nanoparticles, and endohedral metallofullerenes, have already been or will soon become very promising for biomedical applications. This review presents a summary of currently available data on the fate and toxicity of these metallic or metal-containing nanoparticles based on animal studies. Several issues regarding the nanotoxicity assessment and future directions on the study of the fate of these nanoparticles are also proposed.

Cytotoxicity of single-walled carbon nanotubes on human hepatoma HepG2 cells: an iTRAQ-coupled 2D LC-MS/MS proteome analysis

Single-walled carbon nanotubes (SWCNTs) and its derivatives are promising candidates for applications in electronics, energy, materials and biomedical areas. However, with the growing potential biomedical applications and the rising societal concerns on nanosafety, mechanistic understanding of the interactions between nanomaterials and living systems has become imperative. In the present study, our group applied the iTRAQ-coupled 2D LC-MS/MS approach to analyze the protein profile change of mammalian cells in response to SWCNTs. Specifically, the human hepatoma HepG2 cells were chosen as the in vitro model to study the potential cytotoxicity of SWCNTs on the vital organ of liver. Overall 51 differentially expressed proteins that involved in metabolic pathway, redox regulation, signaling pathway, cytoskeleton formation and cell growth were identified. We found SWCNTs triggered the up-regulation of metabolic enzymes, heat shock proteins and proteins involved in redox regulation, which indicated SWCNTs could induce oxidative stress, perturb protein synthesis and interfere cellular metabolism. Our data also suggested that SWCNTs might induce the activation of apoptosis signal-regulating kinase 1, and finally lead to stress-induced apoptosis. The comparative protein profile obtained here provided molecular evidence on the cellular functions in response to SWCNTs, which should very useful to elucidate the cytotoxicity caused by those nanomaterials.

Magnetic nanomaterials for hyperthermia-based therapy and controlled drug delivery

Previous attempts to review the literature on magnetic nanomaterials for hyperthermia-based therapy focused primarily on magnetic fluid hyperthermia (MFH) using mono metallic/metal oxide nanoparticles. The term "hyperthermia" in the literature was also confined only to include use of heat for therapeutic applications. Recently, there have been a number of publications demonstrating magnetic nanoparticle-based hyperthermia to generate local heat resulting in the release of drugs either bound to the magnetic nanoparticle or encapsulated within polymeric matrices. In this review article, we present a case for broadening the meaning of the term "hyperthermia" by including thermotherapy as well as magnetically modulated controlled drug delivery. We provide a classification for controlled drug delivery using hyperthermia: Hyperthermia-based controlled drug delivery through bond breaking (DBB) and hyperthermia-based controlled drug delivery through enhanced permeability (DEP). The review also covers, for the first time, core-shell type magnetic nanomaterials, especially nanoshells prepared using layer-by-layer self-assembly, for the application of hyperthermia-based therapy and controlled drug delivery. The highlight of the review article is to portray potential opportunities for the combination of hyperthermia-based therapy and controlled drug release paradigms--towards successful application in personalized medicine.

Effects of DMSA-coated Fe3O4 magnetic nanoparticles on global gene expression of mouse macrophage RAW264.7 cells

Fe(3)O(4) magnetic nanoparticles (MNPs) coated with 2,3-dimercaptosuccinnic acid (DMSA) are considered to be a promising nanomaterial with biocompatibility. In the present study, the effects of DMSA-coated Fe(3)O(4) MNPs on the expression of all identified mouse genes, which regulate various cellular biological processes, were determined to establish whether this nanoparticle is cytotoxic to mammalian cells. Mouse macrophage RAW264.7 cells were treated with 100μg/ml of DMSA-coated Fe(3)O(4) MNPs for 4, 24 and 48h, and the global gene expression was detected via Affymetrix Mouse Genome 430 2.0 GeneChips(®) microarrays. It was found that gene expression of 711, 545 and 434 transcripts was significantly altered by 4-, 24- and 48-h treatments, respectively. Of these genes, 27 were consistently upregulated and 6 were consistently downregulated at the three treatment durations. Bioinformatic analysis of all differentially expressed genes revealed that this nanoparticle can strongly activate inflammatory and immune responses and can inhibit the biosynthesis and metabolism of RAW264.7 cells at a dose of 100μg/ml. These results demonstrated that DMSA-coated Fe(3)O(4) MNPs display cytotoxicity in this type of macrophage at high doses.

Probing the Chemical Stability of Mixed Ferrites: Implications for MR Contrast Agent Design

Nanomaterials with mixed composition, in particular magnetic spinel ferrites, are emerging as efficient contrast agents for magnetic resonance imaging (MRI). Many factors, including size, composition, atomic structure, and surface properties are crucial in the design of such nanoparticle-based probes due to their influence on the magnetic properties. Silica-coated iron oxide (IO-SiO(2)) and cobalt ferrite (CoIO-SiO(2)) nanoparticles were synthesized using standard high temperature thermal decomposition and base-catalyzed water-in-oil microemulsion techniques. Under neutral aqueous conditions, it was found that 50-75% of the cobalt content in the CoIO-SiO(2) nanoparticles leached out of the core structure. Leaching caused a 7.2-fold increase in longitudinal relaxivity and an increase in the saturation magnetization from ~48 emu/g core to ~65 emu/g core. X-ray absorption fine structure studies confirmed that the atomic structure of the ferrite core was altered following leaching, while TEM and DLS confirmed that the morphology and size of the nanoparticle remained unchanged. The CoIO-SiO(2) nanoparticles converted from a partially inverted spinel cation arrangement (unleached state) to an inverse spinel arrangement (leached state). The control IO-SiO(2) nanoparticles remained stable with no change in structure and negligible changes in magnetic behavior. This detailed analysis highlights how important understanding the properties of nanomaterials is in the development of reliable agents for diagnostic and therapeutic applications.

A modular phase transfer and ligand exchange protocol for quantum dots

In this paper, we describe a quantum dot (qdot) phase transfer protocol using ligand exchange and the amino acid histidine. The phase transfer from nonpolar solvents to aqueous buffers is homogeneous, and no appreciable precipitation occurs. The molecule histidine was chosen in order to first displace the organic encapsulation and second to provide a weakly chemisorbing intermediate at the qdot ionic interface. This allows the histidine to act as an intermediate shell upon which further direct ligand exchange can occur. Since this intermediate encapsulation is easily displaced by an assortment of different molecules while in aqueous buffers, we refer to this approach as modular. Characterization via FTIR and NMR revealed the extent of ligand exchange, and provides insights into the interfacial binding mechanism. The colloidal stability and photostability of the qdots was probed via UV-vis and steady state fluorescence, which revealed promising quantum yield stability of greater than 1 year. The qdots have hydrodynamic diameters of <12 nm and surface charges dependent upon ligand type and coverage. The modularity of this approach is shown by tailoring the qdot surface charge via sequential ligand exchange using mixed monolayers of carboxylic acid and poly(ethylene glycol)-terminated thiols.

Biocompatible fluorescence-enhanced ZrO₂-CdTe quantum dot nanocomposite for in vitro cell imaging

With advances of quantum dots (QDs) in bioimaging applications, various materials have been used to coat QDs to reduce their nanotoxicity; however, the coating could introduce new toxic sources and quench the fluorescence in bioimaging applications. In this work, ZrO₂, an excellent ceramic material with low extinction coefficient and good biocompatibility, is utilized to coat CdTe QDs for the first time. Experimental results show that ZrO₂-QD nanocomposites with the size of ~30 nm possess enhanced fluorescence emission, lower nanotoxicity and gradually increased fluorescence under 350 nm light illumination. After functionalization with folic acid, they were applied to label cultured HeLa cells effectively. Therefore, the ZrO₂-QD nanocomposites could be promising biocompatible nanomaterials with strong fluorescence emission to replace or complement QDs in biomedical applications.

Quantum dots trigger immunomodulation of the NFκB pathway in human skin cells

The immunological effects of quantum dots are dependent on a variety of factors including, but not limited to, exposure time and dosing concentrations. In this study, we investigated the influence of 15 nm CdSe/ZnS-COOH quantum dot nanocrystals (QDs) on cell density, viability, and morphology in human epidermal keratinocytes (HEK) and human dermal fibroblasts (HDF). Furthermore, inflammatory and non-inflammatory immune responses were measured using protein and real time PCR array analysis from HDF cells exposed to predetermined sub-lethal concentrations of QDs. CdSe/ZnS-COOH QDs caused concentration-dependent (1-120 nM exposure concentrations) and time-dependent (8 h or 48 h) cell death, as evidenced by metabolic activity and morphological changes. QD exposure induced upregulation of apoptotic, inflammatory and immunoregulatory proteins such as TNF-α, IL-1B and IL-10. HMOX1, an indicator of stress due to reactive oxygen intermediates (ROIs) and/or metals, was upregulated at the later time point as well. QDs also caused modulation of genes known to be associated with inflammatory (IL1-β, CCL2, IRAK-2), immune (IL-1, IL-6, PGLYRP1, SERPINA1, IL-10), stress due to ROIs and/or heavy metals (HMOX1), and apoptotic (CASP1, ADORA2A) responses. Cellular effects from QD exposure were found to primarily follow the NFκB pathway. In addition, QDs induced a differential cytotoxicity in keratinocytes and fibroblasts at different exposure concentrations and time points, even at physiologically relevant dosing concentrations, thus emphasizing the need to investigate potential mechanisms of action among different cell types within the same target organ.

Toxicity of nanocrystal quantum dots: the relevance of surface modifications

With the development of nanotechnology, nanometer-sized products smaller than several 100 nm have been applied for all areas of science and technology. The nanometer-sized products, including carbon nanotubes, fullerene derivatives, and nanocrystals made of various materials, are widely employed as novel tools in various fields, not only in material engineering, electronics, plastics, automobile, aviation, and aerospace industries, but also even in cellular biology, molecular biology, and basic and clinical medical fields. In particular, nanocrystal quantum dots (QDs) have been widely used in biological and medical studies because of their far brighter photoemission and photostability. The physical and chemical properties of QDs have been circumstantially investigated, but little is known about the potential harmful effects of QDs on human health. In addition to the physical and chemical properties of the QDs, their toxicity and biological behavior are generally regulated by three other conditions: (1) the QD core material itself, (2) the surface modifications of the QD, and (3) the external environmental condition of the QDs. We herein report on the in vitro and in vivo toxicity and biological behavior of nanocrystals such as QDs. Accumulating evidence suggests that the QD-capping material, rather than the core metalloid complex, is responsible for the majority of their toxicity and biological activity. For example, molecules covered with a toxic agent showed cytotoxicity, whereas QDs conjugated with biomolecules retained the biological effects of the conjugate.

Nanomaterial interactions with and trafficking across the lung alveolar epithelial barrier: implications for health effects of air-pollution particles

Studies on the health effects of air-pollution particles suggest that injury may result from inhalation of airborne ultrafine particles (<100 nm in diameter). Engineered nanomaterials (<100 nm in at least one dimension) may also be harmful if inhaled. Nanomaterials deposited on the respiratory epithelial tract are thought to cross the air-blood barrier, especially via the expansive alveolar region, into the systemic circulation to reach end organs (e.g., myocardium, liver, pancreas, kidney, and spleen). Since ambient ultrafine particles are difficult to track, studies of defined engineered nanomaterials have been used to obtain valuable information on how nanomaterials interact with and traffic across the air-blood barrier of mammalian lungs. Since specific mechanistic information on how nanomaterials interact with the lung is difficult to obtain using in vivo or ex vivo lungs due to their complex anatomy, in vitro alveolar epithelial models have been of considerable value in determining nanomaterial-lung interactions. In this review, we provide information on mechanisms underlying lung alveolar epithelial injury caused by various nanomaterials and on nanomaterial trafficking across alveolar epithelium that may lead to end-organ injury.

Bio-distribution and toxicity assessment of intravenously injected anti-HER2 antibody conjugated CdSe/ZnS quantum dots in Wistar rats

Anti-HER2 antibody conjugated with quantum dots (anti-HER2ab-QDs) is a very recent fluorescent nanoprobe for HER2+ve breast cancer imaging. In this study we investigated in-vivo toxicity of anti-HER2ab conjugated CdSe/ZnS QDs in Wistar rats. For toxicity evaluation of injected QDs sample, body weight, organ coefficient, complete blood count (CBC), biochemistry panel assay (AST, ALT, ALP, and GGTP), comet assay, reactive oxygen species, histology, and apoptosis were determined. Wistar rat (8-10 weeks old) were randomly divided into 4 treatment groups (n = 6). CBC and biochemistry panel assay showed nonsignificant changes in the anti-HER2ab-QDs treated group but these changes were significant (P < 0.05) in QDs treated group. No tissue damage, inflammation, lesions, and QDs deposition were found in histology and TEM images of the anti-HER2ab-QDs treated group. Apoptosis in liver and kidney was not found in the anti-HER2ab-QDs treated group. Animals treated with nonconjugated QDs showed comet formation and apoptosis. Cadmium deposition was confirmed in the QDs treated group compared with the anti-HER2ab-QDs treated group. The QDs concentration (500 nM) used for this study is suitable for in-vivo imaging. The combine data of this study support the biocompatibility of anti-HER2ab-QDs for breast cancer imaging, suggesting that the antibody coating assists in controlling any possible adverse effect of quantum dots.

Effects of engineered nanomaterials on microbial catalyzed biogeochemical processes in sediments

Engineered nanomaterials (ENMs) are anticipated to find use in many human activities and commercial products. Concerns are therefore being raised regarding their environmental fate and toxicological implications, which remain largely unknown. In this study, we investigate the effects of C(60), nano-Ag and CdSe quantum dots (QD) on microbial-catalyzed oxidation of organic matter in freshwater sediments. Sediment slurries spiked with sodium acetate at a final concentration of 150 mg/L were separately treated with pre-identified toxic levels of the tested ENMs. The study focused primarily on acetate oxidation by nitrate reducing bacteria. Sediment slurries were incubated under anaerobic conditions in parallel with control samples, and changes in concentrations of acetate, nitrate and nitrite tracked over time. The results showed that tested C(60) concentration completely inhibited the microbial oxidation of acetate, whereas the addition of nano-Ag and CdSe QD to sediment slurries negatively affected the rates of acetate oxidation. Under conditions with nitrate as prevalent electron acceptor, reaction rates of acetate degradation decreased from 0.44 day(-1) in control slurries to 0.24 day(-1) and 0.20 day(-1) in slurries treated with nano-Ag and CdSe QD, respectively. These preliminary results call for further investigations on potential long-term effects of ENMs on microbial driven basic ecosystem services.

PEGylated inorganic nanoparticles

Application of inorganic nanoparticles in diagnosis and therapy has become a critical component in the targeted treatment of diseases. The surface modification of inorganic oxides is important for providing diversity in size, shape, solubility, long-term stability, and attachment of selective functional groups. This Minireview describes the role of polyethylene glycol (PEG) in the surface modification of oxides and focuses on their biomedical applications. Such a PEGylation of surfaces provides "stealth" characteristics to nanomaterials otherwise identified as foreign materials by human body. The role of PEG as structure-directing agent in synthesis of oxides is also presented.

Studies of intracorneal distribution and cytotoxicity of quantum dots: risk assessment of eye exposure

The cornea is a potential route of exposure and drug administration for nanoparticles. In this work, we use noninvasive two-photon microscopic imaging to study the distribution and permeability pathway of CdSe/ZnS core/shell quantum dots (QDs) capped with three different functional groups through the cornea. With no additional staining, the two-photon image clearly discloses that fluorescent QDs penetrate and reside within the interlamellar space of second harmonic generating collagenous stroma when the corneal epithelium barrier is injured. An in vitro cytotoxicity test using bovine corneal stromal cells incubated individually with all three kinds of QDs indicates that the cell viability decreases significantly as the QD concentration and incubation period increased. The results also show that the specific QDs influence corneal stromal cell viability up to a significant magnitude of 50% under a relatively low concentration (5-20 nM) and short exposure period (24-48 h). Furthermore, two-photon imaging shows that QDs can be retained within the cornea up to 26 days in an in vivo mouse model. On the basis of our in vivo and in vitro data, we conclude that QDs can penetrate and be retained within cornea long enough to cause consequential cytotoxicity, under the circumstance in which the corneal epithelium barrier is injured. Since corneal abrasion is quite a common situation in daily life, our work raises public attention to the potential risk of eye exposure to nanoparticles.

Quantum dots, lighting up the research and development of nanomedicine

Quantum dots (QDs) have proven themselves as powerful inorganic fluorescent probes, especially for long term, multiplexed imaging and detection. The newly developed QDs labeling techniques have facilitated the study of drug delivery on the level of living cells and small animals. Moreover, based on QDs and fluorescence imaging system, multifunctional nanocomplex integrated targeting, imaging and therapeutic functionalities have become effective materials for synchronous cancer diagnosis and treatment. In this review, we will summarize the recent advances of QDs in the research of drug delivery system from the following aspects: surface modification strategies of QDs for drug delivery, QDs as drug nanocarriers, QD-labeled drug nanocarriers, QD-based fluorescence resonance energy transfer (FRET) technique for drug release study as well as the development of multifunctional nanomedicines. Possible perspective in this field will also be discussed.

FROM THE CLINICAL EDITOR

This review discusses the role and significance of quantum dots (QDs) from the following aspects: surface modification strategies of QDs for drug delivery, QDs as drug nanocarriers, QD-labeled drug nanocarriers, QD-based fluorescence resonance energy transfer (FRET) technique for drug release study as well as the development of multifunctional nanomedicines.

Nanoparticles in molecular diagnostics

The aim of this chapter is to provide an overview of the available and emerging molecular diagnostic methods that take advantage of the unique nanoscale properties of nanoparticles (NPs) to increase the sensitivity, detection capabilities, ease of operation, and portability of the biodetection assemblies. The focus will be on noble metal NPs, especially gold NPs, fluorescent NPs, especially quantum dots, and magnetic NPs, the three main players in the development of probes for biological sensing. The chapter is divided into four sections: a first section covering the unique physicochemical properties of NPs of relevance for their utilization in molecular diagnostics; the second section dedicated to applications of NPs in molecular diagnostics by nucleic acid detection; and the third section with major applications of NPs in the area of immunoassays. Finally, a concluding section highlights the most promising advances in the area and presents future perspectives.

Quantum dots for molecular diagnostics of tumors

Semiconductor quantum dots (QDs) are a new class of fluorophores with unique physical and chemical properties, which allow to appreciably expand the possibilities for the current methods of fluorescent imaging and optical diagnostics. Here we discuss the prospects of QD application for molecular diagnostics of tumors ranging from cancer-specific marker detection on microplates to non-invasive tumor imagingin vivo. We also point out the essential problems that require resolution in order to clinically promote QD, and we indicate innovative approaches to oncology which are implementable using QD.

Differential stability of lead sulfide nanoparticles influences biological responses in embryonic zebrafish

As the number of nanoparticle-based products increase in the marketplace, there will be increased potential for human exposures to these engineered materials throughout the product life cycle. We currently lack sufficient data to understand or predict the inherent nanomaterial characteristics that drive nanomaterial-biological interactions and responses. In this study, we utilized the embryonic zebrafish (Danio rerio) model to investigate the importance of nanoparticle (NP) surface functionalization, in particular as it pertains to nanoparticle stability, on in vivo biological responses. This is a comparative study where two lead sulfide nanoparticles (PbS-NPs) with nearly identical core sizes, but functionalized with either sodium 3-mercaptopropanesulfonate (MT) or sodium 2,3-dimercaptopropanesulfonate (DT) ligand, were used. Developmental exposures and assessments revealed differential biological responses to these engineered nanoparticles. Exposures beginning at 6 h post fertilization (hpf) to MT-functionalized nanoparticles (PbS-MT) led to 100% mortality by 120 hpf while exposure to DT-functionalized nanoparticles (PbS-DT) produced less than a 5% incident in mortality at the same concentration. Exposure to the MT and DT ligands themselves did not produce adverse developmental effects when not coupled to the NP core. Following exposure, we confirmed that the embryos took up both PbS-MT and PbS-DT material using inductively coupled plasma-mass spectrometry (ICP-MS). The stability of the nanoparticles in the aqueous solution was also characterized. The nanoparticles decompose and precipitate upon exposure to air. Soluble lead ions were observed following nanoparticle precipitation and in greater concentration for the PbS-MT sample compared to the PbS-DT sample. These studies demonstrate that in vivo assessments can be effectively used to characterize the role of NP surface functionalization in predicting biological responses.

Nanotoxicology: no small matter

Engineered nanomaterials i.e. materials deliberately manufactured on a nanoscale offer exciting new opportunities in technology and medicine. However, the increasing use of nanomaterials in society also raises concerns as to their possible adverse effects on human health and the environment. This review considers the potential application of high-throughput screening approaches to assess hazards of engineered nanomaterials. The disciplinary identity of toxicology is also discussed as attention shifts towards nanoscale objects.

Designing multifunctional quantum dots for bioimaging, detection, and drug delivery

The emerging field of bionanotechnology aims at revolutionizing biomedical research and clinical practice via introduction of nanoparticle-based tools, expanding capabilities of existing investigative, diagnostic, and therapeutic techniques as well as creating novel instruments and approaches for addressing challenges faced by medicine. Quantum dots (QDs), semiconductor nanoparticles with unique photo-physical properties, have become one of the dominant classes of imaging probes as well as universal platforms for engineering of multifunctional nanodevices. Possessing versatile surface chemistry and superior optical features, QDs have found initial use in a variety of in vitro and in vivo applications. However, careful engineering of QD probes guided by application-specific design criteria is becoming increasingly important for successful transition of this technology from proof-of-concept studies towards real-life clinical applications. This review outlines the major design principles and criteria, from general ones to application-specific, governing the engineering of novel QD probes satisfying the increasing demands and requirements of nanomedicine and discusses the future directions of QD-focused bionanotechnology research (critical review, 201 references).

Silica-polymer dual layer-encapsulated quantum dots with remarkable stability

Semiconductor quantum dots (QDs) are important fluorescent probes due to their high brightness, multiplexing capability, and photostability. However, applications in quantitative and in vivo imaging are hampered by their sensitivity to chemical environments and potential toxicity. Here we report a surprising finding that the combination of silica and amphiphilic polymer can stabilize CdSe/ZnS QDs in a broad range of chemical conditions including strong acidic solutions, which is unavailable for any of the current encapsulation technologies (e.g., mercapto compounds, silica, and amphiphilic polymers) used alone. We further demonstrate the use of these ultrastable QDs as internal references in pH sensing applications. We expect this work will open exciting opportunities for in vivo and quantitative applications, and may help solve the toxicity problem of QDs.

Cellular uptake, cytotoxicity, and innate immune response of silica-titania hollow nanoparticles based on size and surface functionality

Silica-titania hollow nanoparticles (HNPs) with uniform diameters of 25, 50, 75, 100, and 125 nm were fabricated by dissolution and redeposition method in order to evaluate size dependent cellular response. Surface-modified HNPs with cationic, anionic, and neutral functional group were prepared by silane treatment. We systematically investigated cellular internalization, toxicity, and innate immune response of HNPs in human breast cancer (SK-BR-3) and mouse alveolar macrophage (J774A.1) cells. Size- and surface functionality-dependent cellular uptake of HNPs was investigated by fluorescence labeling (fluorescein isothiocyanate), inductively coupled plasma-emission spectroscopy, and ultrastructural resolution using transmission electron microscopy. Viability, reactive oxygen species, and apoptosis/necrosis of HNP-treated J774A.1 revealed the size-dependent phenomenon. Innate immune response of HNP-treated macrophages was measured by three cytokines such as interleukin-1, interleukin-6, and tumor necrosis factor α. Among the HNPs of different sizes, 50-nm HNPs demonstrated the highest toxic influence on macrophages. Among the HNPs with surface functionalities, cationic HNPs demonstrated the most toxic effect on J774A.1 and the highest uptake efficiency. The toxicity results of HNP-treated macrophages were consistent with the cellular internalization efficiency. These findings provide size- and surface functionality-dependent nanotoxicity and uptake of HNPs, and lead to HNPs for bioapplications such as drug delivery and imaging probe.

Fluorescence imaging agents in cancerology

Background

One of the major challenges in cancer therapy is to improve early detection and prevention using novel targeted cancer diagnostics. Detection requests specific recognition. Tumor markers have to be ideally present on the surface of cancer cells. Their targeting with ligands coupled to imaging agents make them visible/detectable.

Conclusions

Fluorescence imaging is a newly emerging technology which is becoming a complementary medical method for cancer diagnosis. It allows detection with a high spatio-temporal resolution of tumor markers in small animals and in clinical studies. In this review, we focus on the recent outcome of basic studies in the design of new approaches (probes and devices) used to detect tumor cells by fluorescence imaging.

Nanomaterials in the construction industry: a review of their applications and environmental health and safety considerations

The extraordinary chemical and physical properties of materials at the nanometer scale enable novel applications ranging from structural strength enhancement and energy conservation to antimicrobial properties and self-cleaning surfaces. Consequently, manufactured nanomaterials (MNMs) and nanocomposites are being considered for various uses in the construction and related infrastructure industries. To achieve environmentally responsible nanotechnology in construction, it is important to consider the lifecycle impacts of MNMs on the health of construction workers and dwellers, as well as unintended environmental effects at all stages of manufacturing, construction, use, demolition, and disposal. Here, we review state-of-the-art applications of MNMs that improve conventional construction materials, suggest likely environmental release scenarios, and summarize potential adverse biological and toxicological effects and their mitigation. Aligned with multidisciplinary assessment of the environmental implications of emerging technologies, this review seeks to promote awareness of potential benefits of MNMs in construction and stimulate the development of guidelines to regulate their use and disposal to mitigate potential adverse effects on human and environmental health.

Facile synthesis, silanization, and biodistribution of biocompatible quantum dots

A facile strategy for the synthesis of silica-coated quantum dots (QDs) for in vivo imaging is reported. All the QD synthesis and silanization steps are conducted in water and methanol under mild conditions without involving any organometallic precursors or high-temperature, oxygen-free environments. The as-prepared silica-coated QDs possess high quantum yields and are extremely stable in mouse serum. In addition, the silanization method developed here produces nanoparticles with small sizes that are difficult to achieve via conventional silanization methods. The silica coating helps to prevent the exposure of the QD surface to the biological milieu and therefore increases the biocompatibility of QDs for in vivo applications. Interestingly, the silica-coated QDs exhibit a different biodistribution pattern from that of commercially available Invitrogen QD605 (carboxylate) with a similar size and emission wavelength. The Invitrogen QD605 exhibits predominant liver (57.2% injected dose (ID) g(-1)) and spleen (46.1% ID g(-1)) uptakes 30 min after intravenous injection, whereas the silica-coated QDs exhibit much lower liver (16.2% ID g(-1)) and spleen (3.67% ID g(-1)) uptakes but higher kidney uptake (8.82% ID g(-1)), blood retention (15.0% ID g(-1)), and partial renal clearance. Overall, this straightforward synthetic strategy paves the way for routine and customized synthesis of silica-coated QDs for biological use.

DNA-based applications in nanobiotechnology

Biological molecules such as deoxyribonucleic acid (DNA) have shown great potential in fabrication and construction of nanostructures and devices. The very properties that make DNA so effective as genetic material also make it a very suitable molecule for programmed self-assembly. The use of DNA to assemble metals or semiconducting particles has been extended to construct metallic nanowires and functionalized nanotubes. This paper highlights some important aspects of conjugating the unique physical properties of dots or wires with the remarkable recognition capabilities of DNA which could lead to miniaturizing biological electronics and optical devices, including biosensors and probes. Attempts to use DNA-based nanocarriers for gene delivery are discussed. In addition, the ecological advantages and risks of nanotechnology including DNA-based nanobiotechnology are evaluated.

Getting across the plasma membrane and beyond: intracellular uses of colloidal semiconductor nanocrystals

Semiconductor nanocrystals (NCs) are increasingly being used as photoluminescen markers in biological imaging. Their brightness, large Stokes shift, and high photostability compared to organic fluorophores permit the exploration of biological phenomena at the single-molecule scale with superior temporal resolution and spatial precision. NCs have predominantly been used as extracellular markers for tagging and tracking membrane proteins. Successful internalization and intracellular labelling with NCs have been demonstrated for both fixed immunolabelled and live cells. However, the precise localization and subcellular compartment labelled are less clear. Generally, live cell studies are limited by the requirement of fairly invasive protocols for loading NCs and the relatively large size of NCs compared to the cellular machinery, along with the subsequent sequestration of NCs in endosomal/lysosomal compartments. For long-period observation the potential cytotoxicity of cytoplasmically loaded NCs must be evaluated. This review focuses on the challenges of intracellular uses of NCs.

Delivering quantum dots to cells: bioconjugated quantum dots for targeted and nonspecific extracellular and intracellular imaging

Bioconjugated nanomaterials offer endless opportunities to advance both nanobiotechnology and biomedical technology. In this regard, semiconductor nanoparticles, also called quantum dots, are of particular interest for multimodal, multifunctional and multiplexed imaging of biomolecules, cells, tissues and animals. The unique optical properties, such as size-dependent tunable absorption and emission in the visible and NIR regions, narrow emission and broad absorption bands, high photoluminescence quantum yields, large one- and multi-photon absorption cross-sections, and exceptional photostability are the advantages of quantum dots. Multimodal imaging probes are developed by interfacing the unique optical properties of quantum dots with magnetic or radioactive materials. Besides, crystalline structure of quantum dots adds scope for high-contrast X-ray and TEM imaging. Yet another unique feature of a quantum dot is its spacious and flexible surface which is promising to integrate multiple ligands and antibodies and construct multi-functional probes for bioimaging. In this critical review, we will summarize recent advancements in the preparation of biocompatible quantum dots, bioconjugation of quantum dots, and applications of quantum dots and their bioconjugates for targeted and nonspecific imaging of extracellular and intracellular proteins, organelles and functions (181 references).

Shape-dependent cytotoxicity and proinflammatory response of poly(3,4-ethylenedioxythiophene) nanomaterials

Poly(3,4-ethylenedioxythiophene) (PEDT) is recognized as one of the most promising conducting polymers for future applications in the fields of electronics, optics, energy storage/conversion, and biomedical science. The toxicity of PEDT could be considered to affect the potential for its widespread application. Herein, the cytotoxicity and proinflammatory response of PEDT nanomaterials of three different shapes toward human lung fibroblast (IMR90) and mouse alveolar macrophage (J774A.1) cells are investigated. The shape-dependent toxicity of the PEDT nanomaterials is evaluated by examining cell morphological change, cytotoxicity, apoptosis/necrosis, oxidative stress, and immune response. The cytotoxicity and apoptosis of the nanomaterials increase with their decreasing aspect ratio in both cell lines. The formation of reactive oxygen species in cells treated with PEDT nanomaterials is dependent on the shape and concentration of the nanomaterial. Proinflammatory cytokines, such as interleukin-1, interleukin-6, and tumor necrosis factor alpha from macrophages, are induced by PEDT nanomaterial-treated cells.

One-pot large-scale synthesis of robust ultrafine silica-hybridized CdTe quantum dots

A facile one-pot strategy for synthesis of silica-hybridized CdTe quantum dots (SiO(2)-h-CdTe QDs) in aqueous solution is presented, and subkilogram scale fluorescent SiO(2)-h-QDs can be readily produced in one batch. This approach also makes the tuning of emission wavelength and absorption bandgap of SiO(2)-h-QDs accessible for the first time. In the case of using MPA as ligand, the emission wavelength and absorption bandgap can be tuned in the range of 546-584 nm (the corresponding diameter of QDs increased from 2.0 to 3.2 nm) and 2.55-2.27 eV, respectively. The content of QDs in the resulting nanohybrids can also be readily adjusted in a wide range of 2-95 wt % by the feed ratio of QDs to silica precursors. The resulting SiO(2)-h-QDs are ultrafine with diameters 8-16 nm, and show excellent optical properties, high stability, low toxicity, and versatile surface functionality compared with the neat QDs. Various functional groups such as amino, epoxy, and hydroxyl can be readily introduced to the surface of SiO(2)-h-QDs by silane-coupling chemistry and surface-initiated polymerization. Our strategy opens up enormous opportunities to make full use of these robust fluorescent nanohybrids in various applications because of their facile availability, cost-effective productivity, and high stability.

Near-infrared quantum dots for deep tissue imaging

Developments in nanotechnology have paved the way for the early detection, treatment, and prevention of several tumors which affect mankind. In the past few years, near-infrared (NIR) fluorescence imaging techniques have emerged that enable the in vivo imaging of physiological, metabolic, and molecular function. The NIR window, also known as the diagnostic window (700-900 nm), can be explored for sensitive detection techniques. Nanoparticles, particularly semiconductor quantum dots (QDs), can be utilized for the purpose of optical imaging. These semiconductor QDs possess novel electronic, optical, magnetic, and structural properties which are quite different from those of bulk materials. NIR QDs with these unique properties can be utilized as contrast agents for optical imaging, particularly for deep tissue imaging. Deep tissue imaging provides more information about the pathological status of the disease, which makes the treatment more effective and efficient. In this review we highlight the importance of NIR QDs as probes for optical imaging. We describe the different types of NIR QDs, their synthesis, and their application for deep tissue imaging along with recently developed self-illuminating NIR QDs.

Probing the dynamic effect of cys-CdTe quantum dots toward cancer cells in vitro

The application of quantum dots (QDs) in various biomedical areas requires detailed studies of their toxicity. We report a new strategy for probing the biocompatibility of these nanocrystals, namely, a dynamic investigation of cellular uptake images, cell growth curves, metabolic activity changes, and apoptosis aspects of cadmium telluride QDs capped with cysteamine (Cys-CdTe QDs) on human hepatocellular carcinoma SMMC-7721 cells. We used a real-time cell electronic sensing (RT-CES) system in combination with fluorescence microscopy, 3-(4,5-dimethyl-thiazol-zyl)-2,5-diphenyltetrazolium bromide assay, and flow cytometry (FCM) analysis. As observed from fluorescence images and RT-CES system results, Cys-CdTe QDs can readily bind on the cell plasma membrane and then enter into the cancer cell, causing decreased adherence of cancer cells during the initial 6-12 h, while the metabolic activity apparently decreased. After 24 h, the metabolic activity of the cancer cells was significantly reduced, with continued reduction in metabolic activity observed at even longer incubation times. Moreover, FCM observation and DNA fragmentation analysis clearly indicate apoptosis-related phenomena when SMMC-7721 cells were treated with the Cys-CdTe QDs. Thus, our study reveals details of the cellular aging and death process induced by Cys-CdTe QDs.

Better safe than sorry: Understanding the toxicological properties of inorganic nanoparticles manufactured for biomedical applications

The development of nanoparticles for biomedical applications including medical imaging and drug delivery is currently undergoing a dramatic expansion. However, as the range of nanoparticle types and applications increases, it is also clear that the potential toxicities of these novel materials and the properties driving such toxic responses must also be understood. Indeed, a detailed assessment of the factors that influence the biocompatibility and/or toxicity of nanoparticles is crucial for the safe and sustainable development of the emerging nanotechnologies. This review summarizes some of the recent developments in the field of nanomedicine with particular emphasis on inorganic nanoparticles for drug delivery. The synthesis routes, physico-chemical characteristics, and cytotoxic properties of inorganic nanoparticles are thus explored and lessons learned from the toxicological investigation of three common types of engineered nanomaterials of titania, gold, and mesoporous silica are discussed. Emphasis is placed on the recognition versus non-recognition of engineered nanomaterials by the immune system, the primary surveillance system against microorganisms and particles, which, in turn, is intimately linked to the issue of targeted drug delivery using such nanomaterials as carrier systems.