Quantum dots for cancer molecular imaging

Ultrabright Fluorescent Silica Nanoparticles for Multiplexed Detection

Fluorescent tagging is a popular method in biomedical research. Using multiple taggants of different but resolvable fluorescent spectra simultaneously (multiplexing), it is possible to obtain more comprehensive and faster information about various biochemical reactions and diseases, for example, in the method of flow cytometry. Here we report on a first demonstration of the synthesis of ultrabright fluorescent silica nanoporous nanoparticles (Star-dots), which have a large number of complex fluorescence spectra suitable for multiplexed applications. The spectra are obtained via simple physical mixing of different commercially available fluorescent dyes in a synthesizing bath. The resulting particles contain dye molecules encapsulated inside of cylindrical nanochannels of the silica matrix. The distance between the dye molecules is sufficiently small to attain Forster resonance energy transfer (FRET) coupling within a portion of the encapsulated dye molecules. As a result, one can have particles of multiple spectra that can be excited with just one wavelength. We show this for the mixing of five, three, and two dyes. Furthermore, the dyes can be mixed inside of particles in different proportions. This brings another dimension in the complexity of the obtained spectra and makes the number of different resolvable spectra practically unlimited. We demonstrate that the spectra obtained by different mixing of just two dyes inside of each particle can be easily distinguished by using a linear decomposition method. As a practical example, the errors of demultiplexing are measured when sets of a hundred particles are used for tagging.

Ultrabright fluorescent cellulose acetate nanoparticles for imaging tumors through systemic and topical applications

Cellulose acetate (CA), viscose, or artificial silk are biocompatible human-benign derivatives of cellulose, one of the most abundant biopolymers on earth. While various optical materials have been developed from CA, optical CA nanomaterials are nonexistent. Here we report on the assembly of a new family of extremely bright fluorescent CA nanoparticles (CA-dots), which are fully suitable for in vivo imaging / targeting applications. CA-dots can encapsulate a variety of molecular fluorophores. Using various commercially available fluorophores, we demonstrate that the fluorescence of CA-dots can be tuned within the entire UV-VIS-NIR spectrum. We also demonstrate excellent specific targeting of tumors in vivo, when injected in blood in zebrafish (xenograft model of human cervical epithelial cancer), and unusually strong ex-vivo topical labeling of colon cancer in mice utilizing CA folate-functionalized nanoparticles.

Comparison of Toxicity of CdSe: ZnS Quantum Dots on Male Reproductive System in Different Stages of Development in Mice

Background

Quantum dots (QDs) are new types of fluorescent materials for biological labeling. QDs toxicity study is an essential requirement for future clinical applications. Therefore, this study aimed to evaluate cytotoxic effects of CdSe: ZnS QDs on male reproductive system.

Materials and Methods

In this experimental study, the different concentrations of CdSe: ZnS QDs (10, 20 and 40 mg/kg) were injected to 32 male mice (adult group) and 24 pregnant mice (embryo group) on day 8 of gestation. The histological changes of testis and epididymis were studied by a light microscopy, and the number of seminiferous tubules between two groups was compared. One-way analysis of variance (one-way Anova) using the Statistical Package for the Social Sciences (SPSS, SPSS Inc., USA) version 16 were performed for statistical analysis.

Results

In adult group, histological studies of testis tissues showed a high toxicity of CdSe: ZnS in 40 mg/kg dose followed by a decrease in lamina propria; destruction in interstitial tissue; deformation of seminiferous tubules; and a reduction in number of spermatogonia, spermatocytes, and spermatids. However, there was an interesting result in fetal testis development, meaning there was no significant effect on morphology and structure of the seminiferous tubules and number of sperm stem cells. Also histological study of epididymis tissues in both groups (adult and embryo groups) showed no significant effect on morphology and structure of tubule and epithelial cells, but there was a considerable reduction in number of spermatozoa in the lumen of the epididymal duct in 40 mg/kg dose of adult group.

Conclusion

The toxicity of QDs on testicular tissue of the mice embryo and adult are different before and after puberty. Due to lack of research in this field, this study can be an introduction to evaluate the toxicity of QDs on male reproduction system in different stages of development.

Quantum dots induced interferon beta expression via TRIF-dependent signaling pathways by promoting endocytosis of TLR4

Quantum dots (QDs) are nano-sized semiconductors. Previously, intratracheal instillation of QD705s induces persistent inflammation and remodeling in the mouse lung. Expression of interferon beta (IFN-β), involved in tissue remodeling, was induced in the mouse lung. The objective of this study was to understand the mechanism of QD705 induced interferon beta (IFN-β) expression. QD705-COOH and QD705-PEG increased IFN-β and IP-10 mRNA levels during day 1 to 90 post-exposure in mouse lungs. QD705-COOH increased IFN-β expression via Toll/interleukin-1 receptor domain-containing adapter protein (TRIF) dependent Toll-like receptor (TLR) signaling pathways in macrophages RAW264.7. Silencing TRIF expression with siRNA or co-treatment with a TRIF inhibitor tremendously abolished QD705s-induced IFN-β expression. Co-treatment with a TLR4 inhibitor completely prevented IFN-β induction by QD705-COOH. QD705-COOH readily entered cells, and co-treatment with either inhibitors of endocytosis or intracellular TLRs prevented IFN-β induction. Thus, activation of the TRIF dependent TLRs pathway by promoting endocytosis of TLR4 is one of the mechanisms for immunomodulatory effects of nanoparticles.

Ultrabright NIR fluorescent mesoporous silica nanoparticles

Near-infrared (NIR) water-dispersible fluorescent tags are of big importance for biomedical imaging. Bright, stable, biocompatible NIR fluorescent nanoparticles have great translation potential to improve diagnosis of early stages of different diseases. Here we report on the synthesis of exceptionally bright ("ultrabright") fluorescent meso(nano)porous silica nanoparticles of 28 ± 3 nm in diameter. The NIR fluorescent dye LS277 is encapsulated inside these silica nanoparticles. The wavelengths of the maximum excitation/fluorescence of the particles are 804/815 nm. The absorptivity coefficient of the particles is 2.1 × 10⁸ M^-1 cm^-1 at 805 nm and the quantum yield of the dye increased by a factor of 5 after encapsulating to 1.5%. The fluorescent brightness of these particles is more than 2000× higher than the fluorescence of one molecule of LS277 in water. When exited in NIR spectral region (>700 nm), these particles are up to 4× brighter than QD800 commercial quantum dots emitting at 800 nm. We demonstrate that the synthesized NIR mesoporous silica nanoparticles easily internalize 4T1luc breast tumor cells, and remain bright for more than 9 weeks whereas the dye is completely bleached by that time.

Multispectral Imaging

The field of anatomic pathology has changed significantly over the last decades and, as a result of the technological developments in molecular pathology and genetics, has had increasing pressures put on it to become quantitative and to provide more information about protein expression on a cellular level in tissue sections. Multispectral imaging (MSI) has a long history as an advanced imaging modality and has been used for over a decade now in pathology to improve quantitative accuracy, enable the analysis of multicolor immunohistochemistry, and drastically reduce the impact of contrast-robbing tissue autofluorescence common in formalin-fixed, paraffin-embedded tissues. When combined with advanced software for the automated segmentation of different tissue morphologies (eg, tumor vs stroma) and cellular and subcellular segmentation, MSI can enable the per-cell quantitation of many markers simultaneously. This article covers the role that MSI has played in anatomic pathology in the analysis of formalin-fixed, paraffin-embedded tissue sections, discusses the technological aspects of why MSI has been adopted, and provides a review of the literature of the application of MSI in anatomic pathology.

Nanotechnology-based approaches in anticancer research

Cancer is a highly complex disease to understand, because it entails multiple cellular physiological systems. The most common cancer treatments are restricted to chemotherapy, radiation and surgery. Moreover, the early recognition and treatment of cancer remains a technological bottleneck. There is an urgent need to develop new and innovative technologies that could help to delineate tumor margins, identify residual tumor cells and micrometastases, and determine whether a tumor has been completely removed or not. Nanotechnology has witnessed significant progress in the past few decades, and its effect is widespread nowadays in every field. Nanoparticles can be modified in numerous ways to prolong circulation, enhance drug localization, increase drug efficacy, and potentially decrease chances of multidrug resistance by the use of nanotechnology. Recently, research in the field of cancer nanotechnology has made remarkable advances. The present review summarizes the application of various nanotechnology-based approaches towards the diagnostics and therapeutics of cancer.

A realistic utilization of nanotechnology in molecular imaging and targeted radiotherapy of solid tumors

Precise dose delivery to malignant tissue in radiotherapy is of paramount importance for treatment efficacy while minimizing morbidity of surrounding normal tissues. Current conventional imaging techniques, such as magnetic resonance imaging (MRI) and computerized tomography (CT), are used to define the three-dimensional shape and volume of the tumor for radiation therapy. In many cases, these radiographic imaging (RI) techniques are ambiguous or provide limited information with regard to tumor margins and histopathology. Molecular imaging (MI) modalities, such as positron emission tomography (PET) and single photon-emission computed-tomography (SPECT) that can characterize tumor tissue, are rapidly becoming routine in radiation therapy. However, their inherent low spatial resolution impedes tumor delineation for the purposes of radiation treatment planning. This review will focus on applications of nanotechnology to synergize imaging modalities in order to accurately highlight, as well as subsequently target, tumor cells. Furthermore, using such nano-agents for imaging, simultaneous coupling of novel therapeutics including radiosensitizers can be delivered specifically to the tumor to maximize tumor cell killing while sparing normal tissue.

Integrin targeting for tumor optical imaging

Optical imaging has emerged as a powerful modality for studying molecular recognitions and molecular imaging in a noninvasive, sensitive, and real-time way. Some advantages of optical imaging include cost-effectiveness, convenience, and non-ionization safety as well as complementation with other imaging modalities such as positron emission tomography (PET), single-photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI). Over the past decade, considerable advances have been made in tumor optical imaging by targeting integrin receptors in preclinical studies. This review has emphasized the construction and evaluation of diverse integrin targeting agents for optical imaging of tumors in mouse models. They mainly include some near-infrared fluorescent dye-RGD peptide conjugates, their multivalent analogs, and nanoparticle conjugates for targeting integrin αvβ3. Some compounds targeting other integrin subtypes such as α4β1 and α3 for tumor optical imaging have also been included. Both in vitro and in vivo studies have revealed some promising integrin-targeting optical agents which have further enhanced our understanding of integrin expression and targeting in cancer biology as well as related anticancer drug discovery. Especially, some integrin-targeted multifunctional optical agents including nanoparticle-based optical agents can multiplex optical imaging with other imaging modalities and targeted therapy, serving as an attractive type of theranostics for simultaneous imaging and targeted therapy. Continued efforts to discover and develop novel, innovative integrin-based optical agents with improved targeting specificity and imaging sensitivity hold great promises for improving cancer early detection, diagnosis, and targeted therapy in clinic.

Optical nano-constructs composed of genome-depleted brome mosaic virus doped with a near infrared chromophore for potential biomedical applications

We have engineered an optical nanoconstruct composed of genome-depleted brome mosaic virus doped with indocyanine green (ICG), an FDA-approved near-infrared (NIR) chromophore. Constructs are highly monodispersed with standard deviation of ±3.8 nm from a mean diameter of 24.3 nm. They are physically stable and exhibit a high degree of optical stability at physiological temperature (37 °C). Using human bronchial epithelial cells, we demonstrate the effectiveness of the constructs for intracellular optical imaging in vitro, with greater than 90% cell viability after 3 h of incubation. These constructs may serve as a potentially nontoxic and multifunctional nanoplatform for site-specific deep-tissue optical imaging, and therapy of disease.

Radiofrequency field-induced thermal cytotoxicity in cancer cells treated with fluorescent nanoparticles

BACKGROUND

Nonionizing radiation, such as radiofrequency field and near infrared laser, induces thermal cytotoxicity in cancer cells treated with gold nanoparticles. Quantum dots are fluorescent semiconducting nanoparticles that were hypothesized to induce similar injury after radiofrequency field irradiation.

METHODS

Gold nanoparticles and 2 types of quantum dot (cadmium-selenide and indium-gallium-phosphide) conjugated to cetuximab (C225), a monoclonal antibody against human epidermal growth factor receptor (EGFR)-1, demonstrated concentration-dependent heating in a radiofrequency field. The authors investigated the effect of radiofrequency field exposure after targeted nanoparticle treatment in a coculture of 2 human cancer cell lines that have differential EGFR-1 expression (a high-expressing pancreatic carcinoma, Panc-1, and a low-expressing breast carcinoma, Cama-1).

RESULTS

Radiofrequency revealed that Panc-1 or Cama-1 cells not containing gold nanoparticles or quantum dots had a viability of > 92%. The viability of Panc-1 cells exposed to the radiofrequency field after treatment with 50 nM Au-C225 was 39.4% +/- 8.3% without injury to bystander Cama-1 cells (viability was 93.7% +/- 1.0%; P approximately .0006). Panc-1 cells treated with targeted cadmium-selenide quantum dots were only 47.5% viable after radiofrequency field exposure (P< .0001 compared with radiofrequency only Panc-1 control cells). Targeted indium-gallium-phosphide quantum dots decreased Panc-1 viability to 58.2% +/- 3.4% after radiofrequency field exposure (P = approximately .0004 compared with Cama-1 and Panc-1 controls).

CONCLUSIONS

The authors selectively induced radiofrequency field cytotoxicity in Panc-1 cells without injury to bystander Cama-1 cells using EGFR-1-targeted nanoparticles, and demonstrated an interesting bifunctionality of fluorescent nanoparticles as agents for both cancer cell imaging and treatment.

Iron nanoparticles increase 7-ketocholesterol-induced cell death, inflammation, and oxidation on murine cardiac HL1-NB cells

OBJECTIVE

To evaluate the cytotoxicity of iron nanoparticles on cardiac cells and to determine whether they can modulate the biological activity of 7-ketocholesterol (7KC) involved in the development of cardiovascular diseases. Nanoparticles of iron labeled with Texas Red are introduced in cultures of nonbeating mouse cardiac cells (HL1-NB) with or without 7-ketocholesterol 7KC, and their ability to induce cell death, pro-inflammatory and oxidative effects are analyzed simultaneously.

STUDY DESIGN

Flow cytometry (FCM), confocal laser scanning microscopy (CLSM), and subsequent factor analysis image processing (FAMIS) are used to characterize the action of iron nanoparticles and to define their cytotoxicity which is evaluated by enhanced permeability to SYTOX Green, and release of lactate deshydrogenase (LDH). Pro-inflammatory effects are estimated by ELISA in order to quantify IL-8 and MCP-1 secretions. Pro-oxidative effects are measured with hydroethydine (HE).

RESULTS

Iron Texas Red nanoparticles accumulate at the cytoplasmic membrane level. They induce a slight LDH release, and have no inflammatory or oxidative effects. However, they enhance the cytotoxic, pro-inflammatory and oxidative effects of 7KC. The accumulation dynamics of SYTOX Green in cells is measured by CLSM to characterize the toxicity of nanoparticles. The emission spectra of SYTOX Green and nanoparticles are differentiated, and corresponding factor images specify the possible capture and cellular localization of nanoparticles in cells.

CONCLUSION

The designed protocol makes it possible to show how Iron Texas Red nanoparticles are captured by cardiomyocytes. Interestingly, whereas these fluorescent iron nanoparticles have no cytotoxic, pro-inflammatory or oxidative activities, they enhance the side effects of 7KC.

Quantum dot mediated imaging of atherosclerosis

The progression of atherosclerosis is associated with leukocyte infiltration within lesions. We describe a technique for the ex vivo imaging of cellular recruitment in atherogenesis which utilizes quantum dots (QD) to color-code different cell types within lesion areas. Spectrally distinct QD were coated with the cell-penetrating peptide maurocalcine to fluorescently-label immunomagnetically isolated monocyte/macrophages and T lymphocytes. QD-maurocalcine bioconjugates labeled both cell types with a high efficiency, preserved cell viability, and did not perturb native leukocyte function in cytokine release and endothelial adhesion assays. QD-labeled monocyte/macrophages and T lymphocytes were reinfused in an ApoE(-/-) mouse model of atherosclerosis and age-matched controls and tracked for up to four weeks to investigate the incorporation of cells within aortic lesion areas, as determined by oil red O (ORO) and immunofluorescence ex vivo staining. QD-labeled cells were visible in atherosclerotic plaques within two days of injection, and the two cell types colocalized within areas of subsequent ORO staining. Our method for tracking leukocytes in lesions enables high signal-to-noise ratio imaging of multiple cell types and biomarkers simultaneously within the same specimen. It also has great utility in studies aimed at investigating the role of distinct circulating leukocyte subsets in plaque development and progression.

In vitro and In vivo Assessment of CdTe and CdHgTe Toxicity and Clearance

Semiconductor QDs are being developed as fluorescent tags for biomedical applications such as imaging, targeting, therapeutic carriers, drug delivery, nanomedicine, and in vitro and in vivo biological labeling. However, potential toxicity and clearance of semiconductor QDs in biological systems are of concerned. We have tested toxicity and clearance in vitro and in vivo (subcutaneous)of CdTe and CdHgTe semiconductor QDs in human breast cancer MCF7 and MBA-MD-231 cells and prostate cancer PC3 cells over a period of 40 days. Our results show that both CdTe and CdHgTe QDs are cytotoxic to human breast and prostate cancer cells. CdHgTe ODs were cleared rapidly from the site of injection, while CdTe were still detectable 18 days after injection, but were cleared by 30 days.

Nanoscale organization of CD4 molecules of human T helper cell mapped by NSOM and quantum dots

CD4 molecule, the surface marker of T helper cell, has been confirmed to be the main cellular receptor for the human immunodeficiency viruses HIV-1, HIV-2 and SIV. Recent research demonstrated the importance of the spatial arrangement of CD4 on the cell membrane to its binding efficiency to virus. In this article, the combined near-field scanning optical microscopy (NSOM) and quantum dots (QDs) fluorescent labeling technology were performed to investigate the nanoscale organization of CD4 molecules with a spatial resolution about 100 nm. Simultaneous topographic image of the T helper cell and fluorescent image of QDs have been directly gained by NSOM/QDs-based system. Intensity- and size-distribution histograms of the QDs fluorescent spots verify that approximately 80% of the CD4 molecules are organized in nanosized domains randomly distributed on the cell surface. Intensity-size correlation analysis revealed heterogeneity in the molecular packing density of the domains. Our results also illustrated the combination of NSOM imaging and QDs labeling is an ultrasensitive, high-resolution technique to probe nanoscale organization of molecules on the cell surface.