Multifunctional nanoemulsion platform for imaging guided therapy evaluated in experimental cancer

Lipoproteins and lipoprotein mimetics for imaging and drug delivery

Lipoproteins are a set of natural nanoparticles whose main role is the transport of fats within the body. While much work has been done to develop synthetic nanocarriers to deliver drugs or contrast media, natural nanoparticles such as lipoproteins represent appealing alternatives. Lipoproteins are biocompatible, biodegradable, non-immunogenic and are naturally targeted to some disease sites. Lipoproteins can be modified to act as contrast agents in many ways, such as by insertion of gold cores to provide contrast for computed tomography. They can be loaded with drugs, nucleic acids, photosensitizers or boron to act as therapeutics. Attachment of ligands can re-route lipoproteins to new targets. These attributes render lipoproteins attractive and versatile delivery vehicles. In this review we will provide background on lipoproteins, then survey their roles as contrast agents, in drug and nucleic acid delivery, as well as in photodynamic therapy and boron neutron capture therapy.

Cancer-Targeted Nanotheranostics: Recent Advances and Perspectives

Cancer-targeted nanotechnology is experiencing the trend of finding new materials with multiple functions for imaging and therapeutic applications. With the rapid development of the related fields, there exists a large number of reports regarding theranostic nanomedicine, decreasing the gap between cancer diagnosis and treatment with minimized separate comprehensions. In order to present an overview on the cancer-targeted nanotheranostics, we first describe their essential building blocks, including platforms, therapeutic agents and imaging agents, and then the recently rapidly developed multimodal theranostic systems. Finally we discuss the major challenges and the perspectives of future development of nanotheranostics toward clinical translations and personalized nanomedicine.

Oil/water nano-emulsion loaded with cobalt ferrite oxide nanocubes for photo-acoustic and magnetic resonance dual imaging in cancer: in vitro and preclinical studies

Dual imaging dramatically improves detection and early diagnosis of cancer. In this work we present an oil in water (O/W) nano-emulsion stabilized with lecithin and loaded with cobalt ferrite oxide (Co_0.5Fe_2.5O₄) nanocubes for photo-acoustic and magnetic resonance dual imaging. The nanocarrier is responsive in in vitro photo-acoustic and magnetic resonance imaging (MRI) tests. A clear and significant time-dependent accumulation in tumor tissue is shown in in vivo photo-acoustic studies on a murine melanoma xenograft model. The proposed O/W nano-emulsion exhibits also high values of r₂/r₁ (ranging from 45 to 85, depending on the magnetic field) suggesting a possible use as T₂ weighted image contrast agents. In addition, viability and cellular uptake studies show no significant cytotoxicity on the fibroblast cell line. We also tested the O/W nano-emulsion loaded with curcumin against melanoma cancer cells demonstrating a significant cytotoxicity and thus showing possible therapeutic effects in addition to the in vivo imaging.

Nanometric emulsions encapsulating solid particles as alternative carriers for intracellular delivery

AIM

Formulate nanometric oil droplets for encapsulating solid nanoparticles and assess their interactions with cells.

MATERIALS & METHODS

Soybean oil droplets, stabilized by Pluronic F68 surfactant, incorporating hydrophobically modified fluorescent silica, nanoparticles were obtained. Cytotoxicity over time, internalization, subsequent intracellular localization and internalization pathways were assessed by microscopy (fluoresence and TEM) in vitro with HeLa cells.

RESULTS

Oil droplets encapsulating solid nanoparticles are readily internalized by HeLa cells like free nanoparticles but the intracellular localization differs (nanoemulsions less colocalized with lysosomes) as well as internalization pathway is used (nanoemulsions partially internalized by nonendocytic transport). No cytotoxicity could be observed for either particles tested.

CONCLUSION

Our results confirm that nanometric emulsions encapsulating solid nanoparticles can be used for alternative and multifunctional intracellular delivery.

Ultrastable Liquid-Liquid Interface as Viable Route for Controlled Deposition of Biodegradable Polymer Nanocapsules

Liquid-liquid interfaces are highly dynamic and characterized by an elevated interfacial tension as compared to solid-liquid interfaces. Therefore, they are gaining an increasing interest as viable templates for ordered assembly of molecules and nanoparticles. However, liquid-liquid interfaces are more difficult to handle compared to solid-liquid interfaces; their intrinsic instability may affect the assembly process, especially in the case of multiple deposition. Indeed, some attempts have been made in the deposition of polymer multilayers at liquid-liquid interfaces, but with limited control over size and stability. This study reports on the preparation of an ultrastable liquid-liquid interface based on an O/W secondary miniemulsion and its possible use as a template for the self-assembly of polymeric multilayer nanocapsules. Such polymer nanocapsules are made of entirely biodegradable materials, with highly controlled size-well under 200 nm-and multi-compartment and multifunctional features enriching their field of application in drug delivery, as well as in other bionanotechnology fields.

Synergistic active targeting of dually integrin αvβ3/CD44-targeted nanoparticles to B16F10 tumors located at different sites of mouse bodies

Conventional enhanced permeation and retention (EPR) mediates the effects of many drugs, including the accumulation of nanocarriers at tumor sites, but its efficiency remains low. In this study, this limitation was overcome by developing a dual-targeting delivery system based on hyaluronan (HA, a major ligand of CD44) and tetraiodothyroacetic acid (tetrac, a specific ligand of αvβ3), which was exploited to carry docetaxel (DTX) for the synergistic active targeting to tumors. First, a tetrac-HA (TeHA) conjugate was synthesized and grafted onto the surfaces of solid lipid nanoparticles (SLNs) (TeHA-SLNs/DTX), with a high encapsulation efficiency of >91.6%. The resulting SLNs exhibited an approximately toroid morphology revealed using TEM. The cellular uptake and cytotoxicity of various formulations on CD44/αvβ3-enriched B16F10 cells were then assessed, and both results confirmed the selective uptake and high cytotoxicity of the TeHA-SLNs/DTX in a TeHA-dependent manner. In vivo imaging and vessel distribution tests revealed the efficiency of synergistic active targeting was higher than that of EPR-mediated passive targeting by the TeHA-SLNs to αvβ3-expressing tumor blood vessels and CD44-expressing tumor cells via selective targeting. Finally, in both xenograft tumor mice and in situ lung metastasis tumor mice, tumor growth was significantly inhibited by TeHA-SLNs/DTX. Therefore, TeHA-SLNs are an efficient system for the dual-targeted delivery of drugs to treat cancer in vivo.

Endoscopic ultrasound-guided inoculation of transmissible venereal tumor in the colon: A large animal model for colon neoplasia

Background:

To develop and evaluate the feasibility of emerging interventions, animal models with accurate anatomical environment are required.

Objectives:

We aimed to establish a clinically relevant colorectal tumor model with canine transmissible venereal tumor (CTVT) utilizing endoscopic ultrasound (EUS) imaging guidance.

Design:

Survival study using a canine model.

Setting:

Endoscopic animal research laboratory at a tertiary cancer center.

Materials and Methods:

This study involved five canines.

Interventions:

A colorectal tumor model was established and evaluated in five canines under cyclosporine immune suppression. Under endoscopic imaging guidance, saline was injected into the submucosal layer forming a bleb. Subsequently, CTVT was inoculated into the bleb under EUS guidance. Endoscopy was the primary method of assessing tumor growth. Tumors developed in 60-130 days. Upon detection of lesions >1 cm, the animals were euthanized and the tumors were harvested for histopathological characterization.

Main outcome measurements:

Success rate of tumor growth. The presence or absence of vasculature inside tumors.

Results:

Colorectal tumor successfully developed in three out of the five animals (60%). Among the ones with tumor growth, average inoculated CTVT volume, incubation time, and tumor size was 1.8 cc, 65.7 days, and 2.0 cm, respectively. The two animals without tumor growth were observed for >100 days. In all the tumors, vascular structure was characterized with CD31 imunohistochemical stain.

Limitations:

Small number of animals.

Conclusion:

We succeeded in creating a new colorectal tumor canine model with CTVT utilizing EUS.

Augmenting drug-carrier compatibility improves tumour nanotherapy efficacy

A major goal of cancer nanotherapy is to use nanoparticles as carriers for targeted delivery of anti-tumour agents. The drug-carrier association after intravenous administration is essential for efficient drug delivery to the tumour. However, a large number of currently available nanocarriers are self-assembled nanoparticles whose drug-loading stability is critically affected by the in vivo environment. Here we used in vivo FRET imaging to systematically investigate how drug-carrier compatibility affects drug release in a tumour mouse model. We found the drug's hydrophobicity and miscibility with the nanoparticles are two independent key parameters that determine its accumulation in the tumour. Next, we applied these findings to improve chemotherapeutic delivery by augmenting the parent drug's compatibility; as a result, we achieved better antitumour efficacy. Our results help elucidate nanomedicines' in vivo fate and provide guidelines for efficient drug delivery.

Nanoemulsions: formation, properties and applications

Nanoemulsions are kinetically stable liquid-in-liquid dispersions with droplet sizes on the order of 100 nm. Their small size leads to useful properties such as high surface area per unit volume, robust stability, optically transparent appearance, and tunable rheology. Nanoemulsions are finding application in diverse areas such as drug delivery, food, cosmetics, pharmaceuticals, and material synthesis. Additionally, they serve as model systems to understand nanoscale colloidal dispersions. High and low energy methods are used to prepare nanoemulsions, including high pressure homogenization, ultrasonication, phase inversion temperature and emulsion inversion point, as well as recently developed approaches such as bubble bursting method. In this review article, we summarize the major methods to prepare nanoemulsions, theories to predict droplet size, physical conditions and chemical additives which affect droplet stability, and recent applications.

A new target ligand Ser-Glu for PEPT1-overexpressing cancer imaging

Nanoparticles functionalized with active target ligands have been widely used for tumor-specific diagnosis and therapy. The target ligands include antibodies, peptides, proteins, small molecules, and nucleic acid aptamers. Here, we utilize dipeptide Ser–Glu (DIP) as a new ligand to functionalize polymer-based fluorescent nanoparticles (NPs) for pancreatic cancer target imaging. We demonstrate that in the first step, Ser–Glu-conjugated NPs (NPs-DIP) efficiently bind to AsPC-1 and in the following NPs-DIP are internalized into AsPC-1 in vitro. The peptide transporter 1 inhibition experiment reveals that the targeting effects mainly depend on the specific binding of DIP to peptide transporter 1, which is remarkably upregulated in pancreatic cancer cells compared with varied normal cells. Furthermore, NPs-DIP specifically accumulate in the site of pancreatic tumor xenograft and are further internalized into the tumor cells in vivo after intravenous administration, indicating that DIP successfully enhanced nanoparticles internalization efficacy into tumor cells in vivo. This work establishes Ser–Glu to be a new tumor-targeting ligand and provides a promising tool for future tumor diagnostic or therapeutic applications.

AMP-guided tumour-specific nanoparticle delivery via adenosine A1 receptor

Active targeting-ligands have been increasingly used to functionalize nanoparticles for tumour-specific clinical applications. Here we utilize nucleotide adenosine 5'-monophosphate (AMP) as a novel ligand to functionalize polymer-based fluorescent nanoparticles (NPs) for tumour-targeted imaging. We demonstrate that AMP-conjugated NPs (NPs-AMP) efficiently bind to and are following internalized into colon cancer cell CW-2 and breast cancer cell MDA-MB-468 in vitro. RNA interference and inhibitor assays reveal that the targeting effects mainly rely on the specific binding of AMP to adenosine A1 receptor (A1R), which is greatly up-regulated in cancer cells than in matched normal cells. More importantly, NPs-AMP specifically accumulate in the tumour site of colon and breast tumour xenografts and are further internalized into the tumour cells in vivo via tail vein injection, confirming that the high in vitro specificity of AMP can be successfully translated into the in vivo efficacy. Furthermore, NPs-AMP exhibit an active tumour-targeting behaviour in various colon and breast cancer cells, which is positively related to the up-regulation level of A1R in cancer cells, suggesting that AMP potentially suits for more extensive A1R-overexpressing cancer models. This work establishes AMP to be a novel tumour-targeting ligand and provides a promising strategy for future diagnostic or therapeutic applications.

Near-infrared light-induced imaging and targeted anti-cancer therapy based on a yolk/shell structure

Yolk/shell mesoporous NaYF₄:Yb,Er@MgSiO₃–ZnPc–RGD spheres have been fabricated to combine photodynamic therapy (PDT) and bio-imaging for improved antitumor efficacy under NIR laser irradiation.

Drug delivery and drug targeting with parenteral lipid nanoemulsions - A review

Lipid nanosized emulsions or nanoemulsions (NE) are oil in water dispersions with an oil droplet size of about 200nm. This size of oil droplets dispersed in a continuous water phase is a prerequisite for the parenteral, namely intravenous administration. Many parenteral nutrition and drug emulsions on the market confirm the safe use of NE over years. Parenteral emulsions loaded with APIs (active pharmaceutical ingredients) are considered as drug delivery systems (DDS). DDS focuses on the regulation of the in vivo dynamics, such as absorption, distribution, metabolism, and extended bioavailability, thereby improving the effectiveness and the safety of the drugs. Using an emulsion as a DDS, or through the use of surface diversification of the dispersed oil droplets of emulsions, a targeted increase of the API concentration in some parts of the human body can be achieved. This review focuses on NE similar to the marketed once with no or only low amount of additional surfactants beside the emulsifier from a manufacturing point of view (technique, used raw materials).

Nanomedicines for Endothelial Disorders

The endothelium lines the internal surfaces of blood and lymphatic vessels and has a critical role in maintaining homeostasis. Endothelial dysfunction is involved in the pathology of many diseases and conditions, including disorders such as diabetes, cardiovascular diseases, and cancer. Given this common etiology in a range of diseases, medicines targeting an impaired endothelium can strengthen the arsenal of therapeutics. Nanomedicine - the application of nanotechnology to healthcare - presents novel opportunities and potential for the treatment of diseases associated with an impaired endothelium. This review discusses therapies currently available for the treatment of these disorders and highlights the application of nanomedicine for the therapy of these major disease complications.

Anti-tumor Efficacy Study using Irreversible Electroporation and Doxorubicin-loaded Polymeric Micelles

Irreversible electroporation (IRE) is a novel non-thermal ablative treatment for cancer patients with unresectable tumor. IRE kills tumor cells by applying a strong electric field across the cell membrane, thereby creating irreparable pores. Compared to conventional thermal ablation, IRE is effective in perivascular tissues and can preserve the surrounding sensitive structures. However, tumor cells may survive in the regions exposed to insufficient electric field strength, and cause tumor relapse afterwards. We prepared a doxorubicin-loaded polymeric micelles system (M-Dox) using oil-in-water emulsion. The resultant M-Dox was 37.9 ± 3.2 nm in size with a Dox loading of 4.3% by weight. M-Dox is toxic to multiple human cancer cell lines with IC₅₀ values in nanomolar and micromolar range. When combined with IRE in a hepatic carcinoma mouse xenograft model, the tumor treated with the combination therapy (IRE + M-Dox) was the highest in both M-Dox uptake and percentage of necrosis. Immunohistochemical staining also confirmed that the fewest proliferating cells were present after the combination therapy. Our data suggested that M-Dox was an effective adjuvant treatment to enhance the anti-tumor efficacy of IRE.

Density-tunable conjugation of cyclic RGD ligands with polyion complex vesicles for the neovascular imaging of orthotopic glioblastomas

Introduction of ligands into 100 nm scaled hollow capsules has great potential for diagnostic and therapeutic applications in drug delivery systems. Polyethylene glycol-conjugated (PEGylated) polyion complex vesicles (PICsomes) are promising hollow nano-capsules that can survive for long periods in the blood circulation and can be used to deliver water-soluble macromolecules to target tissues. In this study, cyclic RGD (cRGD) peptide, which is specifically recognized by αVβ3 and αvβ5 integrins that are expressed at high levels in the neovascular system, was conjugated onto the distal end of PEG strands on PICsomes for active neovascular targeting. Density-tunable cRGD-conjugation was achieved using PICsomes with definite fraction of end-functionalized PEG, to substitute 20, 40, and 100% of PEG distal end of the PICsomes to cRGD moieties. Compared with control-PICsomes without cRGD, cRGD-PICsomes exhibited increased uptake into human umbilical vein endothelial cells. Intravital confocal laser scanning microscopy revealed that the 40%-cRGD-PICsomes accumulated mainly in the tumor neovasculature and remained in the perivascular region even after 24 h. Furthermore, we prepared superparamagnetic iron oxide (SPIO)-loaded cRGD-PICsomes for magnetic resonance imaging (MRI) and successfully visualized the neovasculature in an orthotopic glioblastoma model, which suggests that SPIO-loaded cRGD-PICsomes might be useful as a MRI contrast reagent for imaging of the tumor microenvironment, including neovascular regions that overexpress αVβ3 integrins.

A smart all-in-one theranostic platform for CT imaging guided tumor microwave thermotherapy based on IL@ZrO2 nanoparticles

This paper develops a simple multifunctional theranostic platform using an IL@ZrO₂ nanostructure for CT imaging guided tumor microwave thermotherapy.

This study develops a simple hollow ZrO₂ nanostructure as a carrier to encapsulate ionic liquid (IL), which integrates the CT imaging function of the ZrO₂ shell and the microwave susceptibility function of the IL core. The simple nanostructure can be used as a multifunctional theranostic agent via combining diagnostic and therapeutic modalities into one “package”. Based on the microwave susceptibility properties, the tumor inhibiting ratio can be over 90% in mice models after one-time thermal therapy upon microwave irradiation. In vitro and in vivo imaging results prove the potential of CT imaging application for real-time monitoring of biodistribution and metabolic processes, and assessing therapeutic outcomes. To our best knowledge, our study is the first example to achieve CT imaging and microwave thermal therapy simultaneously through a simple nanostructure. We anticipate that the simple IL@ZrO₂ nanostructure may build a useful platform for the clinical imaging guided therapy of tumors.

Two-dimensional magnetic WS2@Fe3O4 nanocomposite with mesoporous silica coating for drug delivery and imaging-guided therapy of cancer

Integrating multiple imaging and therapy functionalities into one single nanoscale platform has been proposed to be a promising strategy in cancer theranostics. In this work, WS2 nanosheets with their surface pre-adsorbed with iron oxide (IO) nanoparticles via self-assembly are coated with a mesoporous silica shell, on to which polyethylene glycol (PEG) is attached. The obtained WS2-IO@MS-PEG composite nanoparticles exhibit many interesting inherent physical properties, including high near-infrared (NIR) light and X-ray absorbance, as well as strong superparamagnetism. In the mean time, the mesoporous silica shell in WS2-IO@MS-PEG could be loaded with a chemotherapy drug, doxorubicin (DOX), whose intracellular release afterwards may be triggered by NIR-induced photothermal heating for enhanced cancer cell killing. Upon systemic administration of such drug-loaded nano-theranostics, efficient tumor homing of WS2-IO@MS-PEG/DOX is observed in tumor-bearing mice as revealed by three-modal fluorescence, magnetic resonance (MR), and X-ray computed tomography (CT) imaging. In vivo combined photothermal & chemotherapy is then carried out with WS2-IO@MS-PEG/DOX, achieving a remarkably synergistic therapeutic effect superior to the respective mono-therapies. Our study highlights the promise of developing multifunctional nanoscale theranostics based on two-dimensional transition metal dichalcogenides (TMDCs) such as WS2 for multimodal imaging-guided combination therapy of cancer.

Preparation and Evaluation of Multiple Nanoemulsions Containing Gadolinium (III) Chelate as a Potential Magnetic Resonance Imaging (MRI) Contrast Agent

PURPOSE

The objective was to develop, characterize and assess the potentiality of W1/O/W2 self-emulsifying multiple nanoemulsions to enhance signal/noise ratio for Magnetic Resonance Imaging (MRI).

METHODS

For this purpose, a new formulation, was designed for encapsulation efficiency and stability. Various methods were used to characterize encapsulation efficiency ,in particular calorimetric methods (Differential Scanning Calorimetry (DSC), thermogravimetry analysis) and ultrafiltration. MRI in vitro relaxivities were assessed on loaded DTPA-Gd multiple nanoemulsions.

RESULTS

Characterization of the formulation, in particular of encapsulation efficiency was a challenge due to interactions found with ultrafiltration method. Thanks to the specifically developed DSC protocol, we were able to confirm the formation of multiple nanoemulsions, differentiate loaded from unloaded nanoemulsions and measure the encapsulation efficiency which was found to be quite high with a 68% of drug loaded. Relaxivity studies showed that the self-emulsifying W/O/W nanoemulsions were positive contrast agents, exhibiting higher relaxivities than those of the DTPA-Gd solution taken as a reference.

CONCLUSION

New self-emulsifying multiple nanoemulsions that were able to load satisfactory amounts of contrasting agent were successfully developed as potential MRI contrasting agents. A specific DSC protocol was needed to be developed to characterize these complex systems as it would be useful to develop these self-formation formulations.

Thermodynamic signature of secondary nano-emulsion formation by isothermal titration calorimetry

The stabilization of oil in water nano-emulsions by means of a polymer coating is extremely important; it prolongs the shelf life of the product and makes it suitable for a variety of applications ranging from nutraceutics to cosmetics and pharmaceutics. To date, an effective methodology to assess the best formulations in terms of thermodynamic stability has yet to be designed. Here, we perform a complete physicochemical characterization based on isothermal titration calorimetry (ITC) compared to conventional dynamic light scattering (DLS) to identify polymer concentration domains that are thermodynamically stable and to define the degree of stability through thermodynamic functions depending upon any relevant parameter affecting the stability itself, such as type of polymer coating, droplet distance, etc. For instance, the method was proven by measuring the energetics in the case of two different biopolymers, chitosan and poly-L-lysine, and for different concentrations of the emulsion coated with poly-L-lysine.

Cancer immunotherapy: nanodelivery approaches for immune cell targeting and tracking

Cancer is one of the most common diseases afflicting people globally. New therapeutic approaches are needed due to the complexity of cancer as a disease. Many current treatments are very toxic and have modest efficacy at best. Increased understanding of tumor biology and immunology has allowed the development of specific immunotherapies with minimal toxicity. It is important to highlight the performance of monoclonal antibodies, immune adjuvants, vaccines and cell-based treatments. Although these approaches have shown varying degrees of clinical efficacy, they illustrate the potential to develop new strategies. Targeted immunotherapy is being explored to overcome the heterogeneity of malignant cells and the immune suppression induced by both the tumor and its microenvironment. Nanodelivery strategies seek to minimize systemic exposure to target therapy to malignant tissue and cells. Intracellular penetration has been examined through the use of functionalized particulates. These nano-particulate associated medicines are being developed for use in imaging, diagnostics and cancer targeting. Although nano-particulates are inherently complex medicines, the ability to confer, at least in principle, different types of functionality allows for the plausible consideration these nanodelivery strategies can be exploited for use as combination medicines. The development of targeted nanodelivery systems in which therapeutic and imaging agents are merged into a single platform is an attractive strategy. Currently, several nanoplatform-based formulations, such as polymeric nanoparticles, micelles, liposomes and dendrimers are in preclinical and clinical stages of development. Herein, nanodelivery strategies presently investigated for cancer immunotherapy, cancer targeting mechanisms and nanocarrier functionalization methods will be described. We also intend to discuss the emerging nano-based approaches suitable to be used as imaging techniques and as cancer treatment options.

Surface tailoring of nanoparticles via mixed-charge monolayers and their biomedical applications

The recent convergence of nanomaterials and medicine has provided an expanding horizon for people to achieve encouraging advances in many biomedical applications such as cancer diagnosis and therapy. However, to realize desirable functions in the rather complex biological systems, a suitable surface coating is greatly in need for nanoparticles (NPs), regardless of the species. In this review, a recently developed surface modification strategy is highlighted--mixed-charge monolayers--with an emphasis on the nanointerfaces of inorganic NPs. Two typical mixed-charge gold NPs (AuNPs) prepared from surface modifications with different combinations of oppositely charged alkanethiols are shown as detailed examples to discuss how the mixed-charge monolayer can help NPs meet the criteria for in vitro and in vivo biomedical applications, including those critical issues like colloidal stability, nonfouling properties, and smart responses (pH-sensitivity) for tumor targeting.

The effects of oil-in-water nanoemulsion polyethylene glycol surface density on intracellular stability, pharmacokinetics, and biodistribution in tumor bearing mice

PURPOSE

Lipid-based nanoparticles are extensively studied for drug delivery. These nanoparticles are often surface-coated with polyethylene glycol (PEG) to improve their biodistribution. Until now, the effects of varying PEG surface density have been studied in a narrow and low range. Here, the effects of high and a broad range of PEG surface densities on the in vivo performance of lipid-based nanoparticles were studied.

METHODS

Oil-in-water nanoemulsions were prepared with PEG surface densities of 5-50 mol%. Confocal microscopy was used to assess intracellular disintegration in vitro. In vivo pharmacokinetics and biodistribution in tumor bearing mice were studied using a small animal optical imager.

RESULTS

PEG surface density did not affect intracellular nanoemulsion stability. Surprisingly, circulation half-lives decreased with increasing PEG surface density. A plausible explanation was that nanoemulsion with high (50 mol%) PEG surface density activated the complement in a whole blood assay, whereas nanoemulsion with low (5 mol%) PEG density did not. In vivo, nanoemulsion with low PEG surface density was mostly confined to the tumor and organs of the mononuclear phagocyte system, whereas nanoemulsion with high PEG density accumulated throughout the mouse.

CONCLUSIONS

Optimal PEG surface density of lipid-based nanoparticles for tumor targeting was found to be below 10 mol%.

A smart "sense-act-treat" system: combining a ratiometric pH sensor with a near infrared therapeutic gold nanocage

Herein, we design a "sense-act-treat" system via the combination of a ratiometric pH sensor with a therapeutic gold nanocage. Our design could "sense" the tumor through two-state switching of fluorescence and further provide chemotherapy and hyperthermia for "treating" the tumor, showing the potential for future biomedical applications.

Targeted nanotechnology for cancer imaging

Targeted nanoparticle imaging agents provide many benefits and new opportunities to facilitate accurate diagnosis of cancer and significantly impact patient outcome. Due to the highly engineerable nature of nanotechnology, targeted nanoparticles exhibit significant advantages including increased contrast sensitivity, binding avidity and targeting specificity. Considering the various nanoparticle designs and their adjustable ability to target a specific site and generate detectable signals, nanoparticles can be optimally designed in terms of biophysical interactions (i.e., intravascular and interstitial transport) and biochemical interactions (i.e., targeting avidity towards cancer-related biomarkers) for site-specific detection of very distinct microenvironments. This review seeks to illustrate that the design of a nanoparticle dictates its in vivo journey and targeting of hard-to-reach cancer sites, facilitating early and accurate diagnosis and interrogation of the most aggressive forms of cancer. We will report various targeted nanoparticles for cancer imaging using X-ray computed tomography, ultrasound, magnetic resonance imaging, nuclear imaging and optical imaging. Finally, to realize the full potential of targeted nanotechnology for cancer imaging, we will describe the challenges and opportunities for the clinical translation and widespread adaptation of targeted nanoparticles imaging agents.

Tunable stability of monodisperse secondary O/W nano-emulsions

Stable and biodegradable oil in water (O/W) nano-emulsions can have a huge impact on a wide range of bio-applications, from food to cosmetics and pharmaceuticals. Emulsions, however, are immiscible systems unstable over time; polymer coatings are known to be helpful, but an effective procedure to stabilize monodisperse and biodegradable O/W nano-emulsions is yet to be designed. Here, we coat biodegradable O/W nano-emulsions with a molecular layer of biodegradable polyelectrolytes such as polysaccharides--like chitosan--and polypeptides--like polylysine--and effectively re-disperse and densify the polymer coating at high pressure, thus obtaining monodisperse and stable systems. In particular, focusing on chitosan, our tests show that it is possible to obtain unprecedented ultra-stable O/W secondary nano-emulsions (diameter sizes tunable from ∼ 80 to 160 nm and polydispersion indices below 0.1) by combining this process with high concentrations of polymers. Depending on the polymer concentration, it is possible to control the level of coating that results in a tunable stability ranging from a few weeks to several months. The above range of concentrations has been investigated using a fluorescence-based approach with new insights into the coating evolution.

MR imaging techniques for nano-pathophysiology and theranostics

The advent of nanoparticle DDSs (drug delivery systems, nano-DDSs) is opening new pathways to understanding physiology and pathophysiology at the nanometer scale. A nano-DDS can be used to deliver higher local concentrations of drugs to a target region and magnify therapeutic effects. However, interstitial cells or fibrosis in intractable tumors, as occurs in pancreatic or scirrhous stomach cancer, tend to impede nanoparticle delivery. Thus, it is critical to optimize the type and size of nanoparticles to reach the target. High-resolution 3D imaging provides a means of "seeing" the nanoparticle distribution and therapeutic effects. We introduce the concept of "nano-pathophysiological imaging" as a strategy for theranostics. The strategy consists of selecting an appropriate nano-DDS and rapidly evaluating drug effects in vivo to guide the next round of therapy. In this article we classify nano-DDSs by component carrier materials and present an overview of the significance of nano-pathophysiological MRI.

Nanoemulsions in translational research-opportunities and challenges in targeted cancer therapy

Nanoemulsion dosage form serves as a vehicle for the delivery of active pharmaceutical ingredients and has attracted great attention in drug delivery and pharmacotherapy. In particular, nanoemulsions act as an excellent vehicle for poorly aqueous soluble drugs, which are otherwise difficult to formulate in conventional dosage forms. Nanoemulsions are submicron emulsions composed of generally regarded as safe grade excipients. Particle size at the nanoscale and larger surface area lead to some very interesting physical properties that can be exploited to overcome anatomical and physiological barriers associated in drug delivery to the complex diseases such as cancer. Along these lines, nanoemulsions have been engineered with specific attributes such as size, surface charge, prolonged blood circulation, target specific binding ability, and imaging capability. These attributes can be tuned to assist in delivering drug/imaging agents to the specific site of interest, based on active and passive targeting mechanisms. This review focuses on the current state of nanoemulsions in the translational research and its role in targeted cancer therapy. In addition, the production, physico-chemical characterization, and regulatory aspects of nanoemulsion are addressed.

Multifunctional pH-sensitive polymeric nanoparticles for theranostics evaluated experimentally in cancer

A multifunctional pH-sensitive polymeric nanoparticle system was developed for simultaneous tumor magnetic resonance imaging (MRI) and therapy. The nanoparticles were self-assembled using the multi-block polymer poly(lactic acid)-poly(ethylene glycol)-poly(l-lysine)-diethylenetriamine pentaacetic acid (PLA-PEG-PLL-DTPA) and the pH-sensitive material poly(l-histidine)-poly(ethylene glycol)-biotin (PLH-PEG-biotin). The anti-hepatocellular carcinoma (HCC) drug sorafenib was encapsulated inside the nanoparticles. Gd ions were chelated to the DTPA groups which were distributed on the nanoparticle surface. Biotinylated vascular endothelial growth factor receptor (VEGFR) antibodies were linked to the surface biotin groups of nanoparticles through the avidin linker to form the target pH-sensitive theranostic nanoparticles (TPTN). TPTN exhibited spherical or ellipsoidal shapes, uniform particle size distribution (181.4 ± 3.4 nm), positive zeta potential (14.95 ± 0.60 mV), high encapsulation efficiency (95.02 ± 1.47%) and drug loading (2.38 ± 0.04%). The pH-sensitive sorafenib release from TPTN was observed under different pH values (47.81% at pH = 7.4 and 99.32% at pH = 5.0, respectively). In cell cytotoxicity studies, TPTN showed similar antitumor effect against HepG2 cells compared to solubilized sorafenib solution after pre-incubation in acid PBS (pH = 5.0) for 1 h in vitro (P > 0.05). In in vivo anti-tumor studies, TPTN showed significantly higher antitumor effect in H22 tumor (VEGFR overexpressed cell line) bearing mice compared to the solubilized sorafenib solution (oral or i.v. administration) group (P < 0.05). In the MRI test, the T1 relaxivity value of TPTN was 17.300 mM(-1) s(-1) which was 3.6 times higher than Magnevist® (r1 = 4.8 mM(-1) s(-1)). As a positive contrast agent, TPTN exhibited higher resolution and longer imaging time (more than 90 min) in the MRI diagnosis of tumor-bearing mice compared to Magnevist® (more than 60 min). Furthermore, histological examination of TBN (blank TPTN, without sorafenib loaded) showed no visible tissue toxicity compared to normal saline. Thus, TPTN possessed dual-loading drugs and imaging agents, active targeting and pH-triggered drug release properties in one platform with good biocompatibility. All of these results indicated that TPTN was a promising theranostic carrier which could be a platform for the development of novel multifunctional theranostic agents.

Passive versus active tumor targeting using RGD- and NGR-modified polymeric nanomedicines

Enhanced permeability and retention (EPR) and the (over-) expression of angiogenesis-related surface receptors are key features of tumor blood vessels. As a consequence, EPR-mediated passive and Arg-Gly-Asp (RGD) and Asn-Gly-Arg (NGR) based active tumor targeting have received considerable attention in the last couple of years. Using several different in vivo and ex vivo optical imaging techniques, we here visualized and quantified the benefit of RGD- and NGR-based vascular vs EPR-mediated passive tumor targeting. This was done using ∼ 10 nm sized polymeric nanocarriers, which were either labeled with DY-676 (peptide-modified polymers) or with DY-750 (peptide-free polymers). Upon coinjection into mice bearing both highly leaky CT26 and poorly leaky BxPC3 tumors, it was found that vascular targeting did work, resulting in rapid and efficient early binding to tumor blood vessels, but that over time, passive targeting was significantly more efficient, leading to higher overall levels and to more efficient retention within tumors. Although this situation might be different for larger carrier materials, these insights indicate that caution should be taken not to overestimate the potential of active over passive tumor targeting.

Doxorubicin and Fe3O4 loaded albumin nanoparticles with folic acid modified dextran surface for tumor diagnosis and therapy

Doxorubicin loaded albumin nanoparticles with folic acid receptor-targeted and magnetically-guided functions significantly improve tumor therapy and MRI.

Multifunctional upconversion mesoporous silica nanostructures for dual modal imaging and in vivo drug delivery

Incorporating the agents for magnetic resonance imaging (MRI), optical imaging, and therapy in one nanostructured matrix to construct multifunctional nanomedical platform has attracted great attention for simultaneous diagnostic and therapeutic applications. In this work, a facile methodology is developed to construct a multifunctional anticancer drug nanocarrier by combining the special advantages of upconversion nanoparticles and mesoporous silica. β-NaYF4 :Yb(3+) , Er(3+) @β-NaGdF4 :Yb(3+) is chosen as it can provide the dual modality of upconversion luminescence and MRI. Then mesoporous silica is directly coated onto the upconversion nanoparticles to form discrete, monodisperse, highly uniform, and core-shell structured nanospheres (labeled as UCNPs@mSiO2 ), which are subsequently functionalized with hydrophilic polymer poly(ethylene glycol) (PEG) to improve the colloidal stability and biocompatibility. The obtained multifunctional nanocomposites can be used as an anticancer drug delivery carrier and applied for imaging. The anticancer drug doxorubicin (DOX) is absorbed into UCNPs@mSiO2 -PEG nanospheres and released in a pH-sensitive pattern. In vitro cell cytotoxicity tests on cancer cells verify that the DOX-loaded UCNPs@mSiO2 -PEG has comparable cytotoxicity with free DOX at the same concentration of DOX. In addition, the T1 -weighted MRI that measures in aqueous solutions reveals that the contrast brightening increases with the concentration of Gd(3+) component. Upconversion luminescence images of UCNPs@mSiO2 -PEG uptaken by cells show green emission under 980 nm infrared laser excitation. Finally, the nanocomposites show low systematic toxicity and high in vivo antitumor therapy efficacy. These findings highlight the fascinating features of upconversion-mesoporous nanocomposites as multimodality imaging contrast agents and nanocarrier for drug molecules.

Rational design for multifunctional non-liposomal lipid-based nanocarriers for cancer management: theory to practice

Nanomedicines have gained more and more attention in cancer therapy thanks to their ability to enhance the tumour accumulation and the intracellular uptake of drugs while reducing their inactivation and toxicity. In parallel, nanocarriers have been successfully employed as diagnostic tools increasing imaging resolution holding great promises both in preclinical research and in clinical settings. Lipid-based nanocarriers are a class of biocompatible and biodegradable vehicles that provide advanced delivery of therapeutic and imaging agents, improving pharmacokinetic profile and safety. One of most promising engineering challenges is the design of innovative and versatile multifunctional targeted nanotechnologies for cancer treatment and diagnosis. This review aims to highlight rational approaches to design multifunctional non liposomal lipid-based nanocarriers providing an update of literature in this field.

A polymeric fastener can easily functionalize liposome surfaces with gadolinium for enhanced magnetic resonance imaging

Common methods of loading magnetic resonance imaging (MRI) contrast agents into nanoparticles often suffer from challenges related to particle formation, complex chemical modification/purification steps, and reduced contrast efficiency. This study presents a simple, yet advanced process to address these issues by loading gadolinium, an MRI contrast agent, exclusively on a liposome surface using a polymeric fastener. The fastener, so named for its ability to physically link the two functional components together, consisted of chitosan substituted with diethylenetriaminepentaacetic acid (DTPA) to chelate gadolinium, as well as octadecyl chains to stabilize the modified chitosan on the liposome surface. The assembly strategy, mimicking the mechanisms by which viruses and proteins naturally anchor to a cell, provided greater T1 relaxivity than liposomes loaded with gadolinium in both the interior and outer leaflet. Gadolinium-coated liposomes were ultimately evaluated in vivo using murine ischemia models to highlight the diagnostic capability of the system. Taken together, this process decouples particle assembly and functionalization and, therefore, has considerable potential to enhance imaging quality while alleviating many of the difficulties associated with multifunctional particle fabrication.

Hyaluronic acid derivative-coated nanohybrid liposomes for cancer imaging and drug delivery

Nanohybrid liposomes coated with amphiphilic hyaluronic acid-ceramide (HACE) was fabricated for targeted delivery of anticancer drug and in vivo cancer imaging. Nanohybrid liposomes including doxorubicin (DOX) and Magnevist, a contrast agent for magnetic resonance (MR) imaging, with 120-130nm mean diameter and a narrow size distribution were developed. DOX release from the developed formulation was improved at acidic pH (pH5.5 and 6.8) versus physiological pH (pH7.4). Cytotoxicity induced by the blank plain liposome was reduced by coating the outer surface of the nanohybrid liposome with HACE. Cellular uptake of DOX from the nanohybrid liposome was enhanced by HA and CD44 receptor interaction, versus the plain liposome. In vivo contrast-enhancing effects revealed that the nanohybrid liposome can be used as a tumor targeting MR imaging probe for cancer diagnosis. In a pharmacokinetic study in rats, in vivo clearance of DOX was decreased in the order DOX solution, plain liposome (F2), and nanohybrid liposome (F3), indicating prolonged circulation of the drug in the blood stream and improved therapeutic efficacy of the nanohybrid liposome (F3). Based on these findings, the nanohybrid liposomal system may be a useful candidate for real-time cancer diagnosis and therapy.

Synthesis of polymer-lipid nanoparticles for image-guided delivery of dual modality therapy

For advanced treatment of diseases such as cancer, multicomponent, multifunctional nanoparticles hold great promise. In the current study we report the synthesis of a complex nanoparticle (NP) system with dual drug loading as well as diagnostic properties. To that aim we present a methodology where chemically modified poly(lactic-co-glycolic) acid (PLGA) polymer is formulated into a polymer-lipid NP that contains a cytotoxic drug doxorubicin (DOX) in the polymeric core and an anti-angiogenic drug sorafenib (SRF) in the lipidic corona. The NP core also contains gold nanocrystals (AuNCs) for imaging purposes and cyclodextrin molecules to maximize the DOX encapsulation in the NP core. In addition, a near-infrared (NIR) Cy7 dye was incorporated in the coating. To fabricate the NP we used a microfluidics-based technique that offers unique NP synthesis conditions, which allowed for encapsulation and fine-tuning of optimal ratios of all the NP components. NP phantoms could be visualized with computed tomography (CT) and near-infrared (NIR) fluorescence imaging. We observed timed release of the encapsulated drugs, with fast release of the corona drug SRF and delayed release of a core drug DOX. In tumor bearing mice intravenously administered NPs were found to accumulate at the tumor site by fluorescence imaging.

Multimodal iron oxide nanoparticles for hybrid biomedical imaging

Iron oxide core nanoparticles are attractive imaging agents because their material properties allow the tuning of pharmacokinetics as well as the attachment of multiple moieties to their surface. In addition to affinity ligands, these include fluorochromes and radioisotopes for detection with optical and nuclear imaging. As the iron oxide core can be detected by MRI, options for combining imaging modalities are manifold. Already, preclinical imaging strategies have combined noninvasive imaging with higher resolution techniques, such as intravital microscopy, to gain unprecedented insight into steady-state biology and disease. Going forward, hybrid iron oxide nanoparticles will help to merge modalities, creating a synergy that will enable imaging in basic research and, potentially, also in the clinic.