Quantum dot loaded immunomicelles for tumor imaging

<p>Abstract</p> <p>Background</p> <p>Optical imaging is a promising method for the detection of tumors in animals, with speed and minimal invasiveness. We have previously developed a lipid coated quantum dot system that doubles the fluorescence of PEG-grafted quantum dots at half the dose. Here, we describe a tumor-targeted near infrared imaging agent composed of cancer-specific monoclonal anti-nucleosome antibody 2C5, coupled to quantum dot (QD)-containing polymeric micelles, prepared from a polyethylene glycol/phosphatidylethanolamine (PEG-PE) conjugate. Its production is simple and involves no special equipment. Its imaging potential is great since the fluorescence intensity in the tumor is twofold that of non-targeted QD-loaded PEG-PE micelles at one hour after injection.</p> <p>Methods</p> <p>Para-nitrophenol-containing (5%) PEG-PE quantum dot micelles were produced by the thin layer method. Following hydration, 2C5 antibody was attached to the PEG-PE micelles and the QD-micelles were purified using dialysis. 4T1 breast tumors were inoculated subcutaneously in the flank of the animals. A lung pseudometastatic B16F10 melanoma model was developed using tail vein injection. The contrast agents were injected via the tail vein and mice were depilated, anesthetized and imaged on a Kodak Image Station. Images were taken at one, two, and four hours and analyzed using a methodology that produces normalized signal-to-noise data. This allowed for the comparison between different subjects and time points. For the pseudometastatic model, lungs were removed and imaged <it>ex vivo </it>at one and twenty four hours.</p> <p>Results</p> <p>The contrast agent signal intensity at the tumor was double that of the passively targeted QD-micelles with equally fast and sharply contrasted images. With the side views of the animals only tumor is visible, while in the dorsal view internal organs including liver and kidney are visible. <it>Ex vivo </it>results demonstrated that the agent detects melanoma nodes in a lung pseudometastatic model after a 24 hours wash-out period, while at one hour, only a uniform signal is detected.</p> <p>Conclusions</p> <p>The targeted agent produces ultrabright tumor images and double the fluorescence intensity, as rapidly and at the same low dose as the passively targeted agents. It represents a development that may potentially serve to enhance early detection for metastases.</p

Magnetic Nanoformulations for Prostate Cancer

Magnetic nanoparticles (MNPs) play a vital role for improved imaging applications. Recently, a number of studies demonstrate MNPs can be applied for targeted delivery, sustained release of therapeutics, and hyperthermia. Based on stable particle size and shape, biocompatibility, and inherent contrast enhancement characteristics, MNPs have been encouraged for pre-clinical studies and human use. As a theranostic platform development, MNPs need to balance both delivery and imaging aspects. Thus, this review provides significant insight and advances in the theranostic role of MNPs through the documentation of unique magnetic nanoparticles used in prostate cancer, their interaction with prostate cancer cells, in vivo fate, targeting, and biodistribution. Specific and custom-made applications of various novel nanoformulations in prostate cancer are discussed

Fluorescent Nanomaterials for Cellular Imaging

This chapter will provide an overview of different nanomaterials, which are being used for nondestructive imaging of living entities such as cells and tissues. The chapter begins with the basics of fluorescence imaging followed by a discussion on the advantages of fluorescent nanomaterials as compared to commonly used molecular fluorophores and imaging probes. Specific features and applications of nanomaterials frequently exploited in bioimaging are summarized. These include fluorescent silicon-based nanomaterials, hydrogels, polymer dots, magnetic nanoparticles, fluorescent quantum dots, carbon dots and other carbon-based nanomaterials, noble metal nanoparticles, micelles, dendrimers, lipid nanoparticles, and so on. Specific examples on their applications in bioimaging including multimodal imaging and targeted imaging are illustrated

Lipid-based nanoparticles for magnetic resonance molecular imaging : design, characterization, and application

In this thesis research is described which was aimed to develop lipidic nanoparticles for the investigation and visualization of atherosclerosis and angiogenesis with both magnetic resonance molecular imaging and optical techniques. The underlying rationale for this is that conventional MR imaging techniques are only capable of visualizing physiological and morphological changes, while magnetic resonance molecular imaging aims to depict cellular and molecular processes that are associated with or lie at the basis of pathological processes. This may lead to earlier detection, and improved diagnosis and prognosis of disease processes. Furthermore this technique may be very useful for the evaluation of a given therapy. The introduction of MRI as a molecular imaging modality is hampered by its low sensitivity compared to nuclear methods like PET and SPECT. With recent developments in chemistry and the synthesis of powerful, innovative, specific, and multimodal contrast agents, e.g. by introducing fluorescent properties as well, MRI is becoming increasingly important for molecular imaging. Therefore, the first aim of the research described in this thesis was to develop biocompatible nanoparticles that can be made target specific and can be detected by both MRI and optical techniques to allow the investigation of disease processes with two highly complementary imaging methods. Chapter 1 gives a general introduction in magnetic resonance molecular imaging and its potential use for the investigation of several pathological processes. Furthermore, contrast enhanced MRI based on differences in T1 and T2 relaxation times is explained. Lastly, different classes of contrast agents and their contrast generating properties are described. Amphphilic molecules are widely applied to serve as building blocks for nanoparticles in biomedical applications. In the field of drug targeting for example, liposomes comprised of amphiphilic molecules hold great promise and have been used extensively the last several decades. Furthermore, micelles, microemulsions, and other amphiphilic aggregates are also under investigation to serve as drug carriers. A relatively new application of lipidic nanoparticles is their use as contrast generating materials for MRI. In Chapter 2 the properties of amphiphilic molecules and their assembly in a wide range of aggregated structures are described. This is followed by an overview of different strategies that are employed to conjugate targeting ligand to such lipid based nanoparticles. The emphasis of this chapter is a literature overview of what has been realized in this research field thus far. Chapter 3 describes the physical characterization of novel liposomal contrast agents. The morphology of different formulations was investigated with electron microscopy, which revealed the necessity of incorporating cholesterol in the liposomal bilayer. Furthermore the relaxation properties of these contrast agent were measured as a function of temperature and magnetic field strength. In Chapter 4 a liposomal contrast agent with both fluorescent and magnetic properties is described. The liposomes were made target specific by conjugating multiple E-selectin specific antibodies to the surface of the nanoparticle. Its feasibility to serve as molecular imaging contrast agent for the detection of the inflammation marker E-selectin is demonstrated in vitro. The specific uptake of the liposomes by human endothelial cells stimulated to express E-selectin was visualized by MRI and fluorescence microscopy. Chapter 5 describes a superparamagnetic nanoparticle encapsulated in a micellular shell. Fluorescent properties were introduced to this contrast agent by the incorporation of fluorescent lipids in the lipid layer. The contrast agent has a very high r2/r1 ratio and therefore is especially suitable to be used for T2 (*) enhanced MRI. The nanoparticle can be made target specific by covalently linking targeting ligands distally to the PEG chains of lipids incorporated in the micellular shell via maleimide-sulfhydryl coupling. Specificity for apoptotic cells was realized by conjugating multiple Annexin A5 proteins. The feasibility to use this contrast agent for molecular imaging purposes was demonstrated in vitro on apoptotic Jurkat cells. In Chapter 6 the synthesis and characterization of a novel bimodal nanoparticle based on semiconductor nanocrystals encapsulated within the corona of paramagnetic micelles is described. The CdSe nanoparticle, also referred to as quantum dot, serves as the contrast generating material for fluorescence imaging, while the paramagnetic micellular coating is employed for contrast enhanced MRI. The in vitro association of this nanoparticle with isolated cells by either conjugating multiple avß3-integrin specific RGDpeptides or multiple phosphatidyl serine specific Annexin A5 proteins was demonstrated with both fluorescence microscopy and MRI. The second aim of the research described in this thesis was to apply the novel nanoparticles for the investigation of atherosclerosis and tumor angiogenesis in mouse models with magnetic resonance molecular imaging. Chapter 7 describes the application of non targeted paramagnetic liposomes for the improved and sustained visualization of neointimal lesions induced after placing a constrictive collar around the right carotid artery of apoE-KO mice. Commercially available Gd-DTPA (Magnevist) showed little potential for the detection of such lesion. In Chapter 8 pegylated micelles conjugated with macrophage scavenger receptor (MSR) specific antibodies were employed for improved atherosclerotic plaque detection and characterization. Existing nanoparticulate agents that are used to detect macrophages, such as USPIO or lipophilic micelles, show little specificity. The micelles used for this study have a hydrophilic PEG coating, and therefore show minimal non-specific interaction with plaque, which results in negligible background signal. In case of the MSR micelles a pronounced enhancement of atherosclerotic plaque was observed. Furthermore, the micelles exhibit fluorescent properties by the incorporation of either quantum dots or fluorescent lipids. This allowed the detection of macrophages with optical techniques as well. Chapter 9 and Chapter 10 describe the application of avß3 targeted bimodal liposomes for the visualization of angiogenically activated tumor blood vessels with both MRI in vivo and fluorescence microscopy ex vivo. The specificity of the contrast agent was demonstrated with an MRI competition experiment, while the exclusive association with endothelial cells was demonstrated with fluorescence microscopy. The follow-up study demonstrates the usefulness of contrast enhanced MRI after applying this contrast agent for the evaluation of angiostatic therapies, i.e. using endostatin and anginex, at two time points after onset of therapy. Most importantly, the in vivo MRI data show very good correlation with ex vivo microvessel density determinations. In the last experimental Chapter 11 of this thesis a sophisticated method for the parallel visualization of angiogenic tumor blood vessels with both intravital microscopy (IVM) and MRI is described. The nanoparticulate contrast agent conjugated with avß3-specific RGDpeptides described in Chapter 6 was administrated to tumor bearing mice. IVM allowed the investigation of the disease process at the cellular level, while MRI was used to investigate angiogenesis at the anatomical level. The contrast agent possesses excellent contrast generating properties for these complementary imaging techniques. Widespread angiogenic activity within the rim of the tumor, and up to 1 cm from the tumor boundary could be observed by using both techniques

EGFR Targeted Nanocarriers for Cancer Diagnosis and Therapy

Conventional cancer management is directly associated with many problems, including accurate therapeutic delivery to tumours and serious side effects of chemotherapeutics. A specific and efficient anticancer delivery to the tumour site without damaging normal tissues is the ultimate goal of all cancer treatment strategies. Nanomedicine has immense potential for cancer therapy that focuses on improving treatment efficacy, while reducing toxicity to normal tissues as well. However, the biodistribution and targeting capability of nanoparticles lacking targeting ligands rely solely on their physicochemical properties and the pathophysiological parameters of the body. Targeting is a promising strategy for selective and efficient therapeutic delivery to tumour cells with reduced detrimental side effects. Taking advantage of the fact that molecular markers and receptors over-express on the tumour cell surface as compared to a normal cell, the active targeting approach would be beneficial for cancer therapy. The epidermal growth factor receptors (EGFR), abnormally overexpressed in many epithelial tumours, have received much attention for molecular targeting in cancer diagnostics and therapeutics. This review presents the role of EGFR targeting in cancer imaging and therapy, and some recent researches on treatment of EGFR overexpressing cancers by using targeted nanoparticulate platforms. It also discusses illustrative examples of various ligands, including antibodies, antibody fragments, nanobodies, and peptides.HighlightsHighlights the potential of EGFR targeted nanocarriers for cancer diagnosis and therapy.Summarizes the role of EGFR targeting in cancer therapy.Describes various examples of recent researches on EGFR targeted nanocarriers.Explains illustrative examples of various ligands for EGFR targeting.

Can nanotechnology potentiate photodynamic therapy?

Photodynamic therapy (PDT) uses the combination of nontoxic dyes and harmless visible light to produce reactive oxygen species that can kill cancer cells and infectious microorganisms. Due to the tendency of most photosensitizers (PS) to be poorly soluble and to form nonphotoactive aggregates, drug-delivery vehicles have become of high importance. The nanotechnology revolution has provided many examples of nanoscale drug-delivery platforms that have been applied to PDT. These include liposomes, lipoplexes, nanoemulsions, micelles, polymer nanoparticles (degradable and nondegradable), and silica nanoparticles. In some cases (fullerenes and quantum dots), the actual nanoparticle itself is the PS. Targeting ligands such as antibodies and peptides can be used to increase specificity. Gold and silver nanoparticles can provide plasmonic enhancement of PDT. Two-photon excitation or optical upconversion can be used instead of one-photon excitation to increase tissue penetration at longer wavelengths. Finally, after sections on in vivo studies and nanotoxicology, we attempt to answer the title question, “can nanotechnology potentiate PDT?”National Institutes of Health (U.S.) (RO1 AI050875)United States. Air Force (Medical Free Electron Laser Program (FA9550-04-1-0079)

Antibody–biopolymer conjugates in oncology: a review

Cancer is one of the most prevalent diseases and affects a large proportion of the population worldwide. Conventional treatments in the management include chemotherapy, radiotherapy, and surgery. Although being well-accepted, they have many lacunas in the form of severe side effect resulting from lack of targeted delivery. Antibody biopolymer conjugates are a novel method which is an add-on to older methods of immunization. It is used in various diseases and disorders. It ensures the targeted delivery of molecules to increase its efficacy and reduce unwanted effects of the molecule/drug to normal cells. It shows miraculous results in the treatment and management of several cancers even in advanced stages. Herein, we present the chemistry between biopolymer and antibody, their effects on cancer as well as the basic differences between antibody–drug conjugates and antibody–biopolymer conjugates

Signaling pathways influencing tumor microenvironment and their exploitation for targeted drug delivery

In the recent years, the "tumor microenvironment" has been receiving growing attention due to its involvement in neoplastic transformation, tumor growth, invasion, and protection of tumor cells from host immune response. All these events are facilitated by chemical signals produced by the tumor as well as the surrounding stromal cells. This review is divided into two main parts in which the first part discusses the receptor tyrosine kinase (RTK)-mediated growth factor signaling, steroid hormone (SH) signaling, ancient signaling pathways, and other molecules that are involved in tumorigenesis and how they interact with each other to create a complex tumor microenvironment. In the second part, we bring together the recent nanocarrier-mediated drug delivery approaches to target the signaling pathways/molecules present in the tumor microenvironment.Foundation for Science and Technology (FCT) [(SFRH/BPD/89493/2012]; FCT [SFRH/BD/72809/2010]; Portuguese Government; FCT national funds (PIDDAC) [PTDC/AGR-GPL/119211/2010, PEst-C/AGR/UI4033/2011]; European Fund for Regional Development (FEDER) through COMPETE Operational Programme Competitive Factors (POFC)info:eu-repo/semantics/publishedVersio

Tuning and targeting semiconducting polymer nanoparticles to enhance in vivo photoacoustic imaging

Photoacoustic imaging (PAI) is a promising imaging modality which combines high spatial resolution with excellent contrast generation. To fulfil the potential of using PAI in clinical settings for cancer detection, the development of novel contrast agents with strong absorptions in the near infrared and high tumour specificity in vivo is required. Semiconducting polymer nanoparticles (SPNs) encapsulating organic semiconducting polymers in lipid nanoparticles have emerged as excellent candidates for photoacoustic (PA) contrast generation: they retain the polymer’s ability to generate high PA contrast, and the lipid formulation grants SPNs excellent physiological properties. However, these SPNs rely so far on the enhanced retention and permeability (EPR) effect for tumour accumulation. The reliability of this passive mode of accumulation in clinical settings has been recently called into question. To address this, the formulation of targeted SPNs using EGFR-targeting peptides was explored. SPNs based on novel semiconducting polymers as well as commercially available polymers were formulated via the mini-emulsion and nanoprecipitation methods. Lipid formulations included PEGylated lipids as well as functional PEG lipids on which N-terminal Cysteine-modified EGFR-targeting peptides were conjugated via the thiol-maleimide Michael addition. The synthetic accessibility of both the pre- and post-formulation functionalisation strategies was assessed in Chapter 3. To quantify surface functionalisation, a novel NMR characterisation strategy for the routine quantification of maleimide moieties tethered to the surface of nanoparticles was proposed. To compare the targeting efficiency of EGFR-targeting peptides A-R, D4 and GE11, a library of peptide-dye conjugates was constructed using fluorescein-5-maleimide. This library included scrambled controls and short PEG spacers introduced between the targeting sequence and the cysteine residue. The synthesis of these conjugates is described in Chapter 4. While synthesising these peptides, preliminary data supporting the intramolecular transcyclisation of the thiol-maleimide adducts was obtained. The intramolecular transcyclisation of thiol-maleimide adducts is underreported in the literature and clinically relevant. The thiazine rearrangement products are protected from thiol-exchange which, in physiological conditions, can lead to the partial loss of functionality of targeting ligands synthesised using the thiol-maleimide reaction