Theranostics with multifunctional magnetic gold nanoshells: photothermal therapy and t2* magnetic resonance imaging

Dual-imaging nanoparticles based on surface-modified magnetic nanoparticles and biodegradable photoluminescent polymers

Theranostic nanoparticles, which combine diagnostic and therapeutic capabilities, have gained significant interest in disease management. We previously developed dual-imaging enabled cancer-targeting nanoparticles (DICT-NPs) composed of a biodegradable photoluminescent polymer (BPLP) and iron oxide-based superparamagnetic nanoparticles (MNPs). While DICT-NPs demonstrated cytocompatibility, magnetic targeting, and imaging capabilities, their fluorescence was inconsistent due to quenching by the MNP core and inefficient BPLP grafting. To address these limitations, we modified the MNP surface with silane, hydroxyapatite, or silane-coupled azide coatings before conjugating with BPLP. The resulting surface-modified DICT-NPs (mDICT-NPs) ranged in size from 200-350 nm and were cyto-compatible with human dermal fibroblasts and normal human prostate epithelial cells. Surface modifications and BPLP conjugation did not affect the superparamagnetic properties of the nanoparticles but enhanced fluorescence by ∼50% compared to the original DICT-NPs. Hydroxyapatite-modified DICT-NPs exhibited significant improvements, including sustained drug release of Paclitaxel and Docetaxel (71% and 68%, respectively, over 21 days), dose-dependent tumor cell uptake in melanoma, thyroid, and prostate cancer cells (with the highest uptake exceeding 60% at 500 μg/mL), and a reduction in cancer cell viability (less than 50% viability in TT thyroid cancer and KAT-4 cancer cell lines). These advancements represent a significant step in overcoming the fluorescence quenching issues associated with iron oxide-based magneto-fluorescent theranostic nanoparticle platforms, enhancing both their imaging and therapeutic potential in cancer treatment.

Review on macromolecule-based magnetic theranostic agents for biomedical applications: Targeted therapy and diagnostic imaging

Clinical diagnostics and biological research are advanced by magnetic theranostic, which uses macromolecule-based magnetic theranostic agents for targeted therapy and diagnostic imaging. Within this review, the interaction of magnetic nanoparticles (MNPs) with biological macromolecules will be covered. The exciting potential of macromolecule-based magnetic theranostic agents to be used as a tool in drug delivery, photothermally therapy (PTT), gene therapy, hyperthermia therapy and photodynamic therapy (PDT) will be discussed. Innovative imaging technique: magnetic resonance imaging (MRI), magnetic particle imaging (MPI), fluorescence scanning, and photoacoustic scanning are revolutionizing biological diagnosis by potentially overcoming historical limitations. This review will cover the challenge of fabricating of macromolecule-based magnetic theranostic agents as a promising platform for theranostic that can combine therapies with diagnostics at subcellular level. Additionally, it looks at several chemical pathways leading to the process for generating MNPs, including the co-precipitation, the sol-gel, the hydrothermal synthesis, the polyol route, and the microemulsion technique. Eventually, the demands and prospects for magnetic theranostic are discussed, focusing on the requirement of further investigation to improve MNP structure towards biocompatible material and translation of these promising theranostic agents into clinical applications.

Iron Oxide Nanoparticles: Parameters for Optimized Photoconversion Efficiency in Synergistic Cancer Treatment

Photothermal therapy (PTT) can overcome cancer treatment resistance by enhancing the cell membrane permeability, facilitating drug accumulation, and promoting drug release within the tumor tissue. Iron oxide nanoparticles (IONPs) have emerged as effective agents for PTT due to their unique properties and biocompatibility. Approved for the treatment of anemia, as MRI contrast agents, and as magnetic hyperthermia mediators, IONPs also offer excellent light-to-heat conversion and can be manipulated using external magnetic fields for targeted accumulation in specific tissue. Optimizing parameters such as the laser wavelength, power density, shape, size, iron oxidation state, functionalization, and concentration is crucial for IONPs' effectiveness. In addition to PTT, IONPs enhance other cancer treatment modalities. They improve tumor oxygenation, enhancing the efficacy of radiotherapy and photodynamic therapy. IONPs can also trigger ferroptosis, a programmed cell death pathway mediated by iron-dependent lipid peroxidation. Their magneto-mechanical effect allows them to exert a mechanical force on cancer cells to destroy tumors, minimizing the damage to healthy tissue. This review outlines strategies for the management of the photothermal performance and PTT efficiency with iron oxide nanoparticles, as well as synergies with other cancer therapies.

Green synthesis of iron nanoparticles: Sources and multifarious biotechnological applications

Green synthesis of iron nanoparticles is a highly fascinating research area and has gained importance due to reliable, sustainable and ecofriendly protocol for synthesizing nanoparticles, along with the easy availability of plant materials and their pharmacological significance. As an alternate to physical and chemical synthesis, the biological materials, like microorganisms and plants are considered to be less costly and environment-friendly. Iron nanoparticles with diverse morphology and size have been synthesized using biological extracts. Microbial (bacteria, fungi, algae etc.) and plant extracts have been employed in green synthesis of iron nanoparticles due to the presence of various metabolites and biomolecules. Physical and biochemical properties of biologically synthesized iron nanoparticles are superior to that are synthesized using physical and chemical agents. Iron nanoparticles have magnetic property with thermal and electrical conductivity. Iron nanoparticles below a certain size (generally 10-20 nm), can exhibit a unique form of magnetism called superparamagnetism. They are non-toxic and highly dispersible with targeted delivery, which are suitable for efficient drug delivery to the target. Green synthesized iron nanoparticles have been explored for multifarious biotechnological applications. These iron nanoparticles exhibited antimicrobial and anticancerous properties. Iron nanoparticles adversely affect the cell viability, division and metabolic activity. Iron nanoparticles have been used in the purification and immobilization of various enzymes/proteins. Iron nanoparticles have shown potential in bioremediation of various organic and inorganic pollutants. This review describes various biological sources used in the green synthesis of iron nanoparticles and their potential applications in biotechnology, diagnostics and mitigation of environmental pollutants.

Nanoscale Au@SiO2-drug/VEGF as an in vivo probe for osteosarcoma diagnosis and therapy

Osteosarcoma is a common primary bone malignancy, with a 5-year survival rate of only 20–30% in patients undergoing surgical treatment. Thus, it is important to identify novel methods for diagnosing and treating osteosarcoma, which was the aim of the present study. Vascular endothelial growth factor (VEGF) was used as the tumor-targeting protein to synthesize a multifunctional core-shell nanostructure, Au@SiO₂-drug/VEGF, in which the drug can be indocyanine green (ICG; as an optical tracer) or doxorubicin (DOX; as a chemotherapeutic agent). With VEGF as the osteosarcoma-targeting protein, Au exhibited optimal photothermal transformation performance, while SiO₂ served as the carrier for the drug. Au@SiO₂-ICG/VEGF nanoparticles (NPs) were evaluated for imaging and for the monitoring of drug accumulation in a tumor region in mice. Once the optimal drug accumulation was achieved, combined treatment of osteosarcoma (chemotherapy and photothermal therapy) was assessed. In the perioperative period associated with minimal invasive embolization of osteosarcoma, photothermal therapy and chemotherapy were applied for osteosarcoma diagnosis using Au@SiO₂-DOX/VEGF NPs. Taken together, the results of the present study provide a promising strategy for tumor detection prior to surgical treatment to improve the survival outcome of patients with osteosarcoma.

Optimization of the GSH-Mediated Formation of Mesoporous Silica-Coated Gold Nanoclusters for NIR Light-Triggered Photothermal Applications

Cancer light-triggered hyperthermia mediated by nanomaterials aims to eliminate cancer cells by inducing localized temperature increases to values superior to 42 °C, upon irradiation with a laser. Among the different nanomaterials with photothermal capacity, the gold-based nanoparticles have been widely studied due to their structural plasticity and advantageous physicochemical properties. Herein, a novel and straightforward methodology was developed to produce gold nanoclusters coated with mesoporous silica (AuMSS), using glutathione (GSH) to mediate the formation of the gold clusters. The obtained results revealed that GSH is capable of triggering and control the aggregation of gold nanospheres, which enhanced the absorption of radiation in the NIR region of the spectra. Moreover, the produced AuMSS nanoclusters mediated a maximum temperature increase of 20 °C and were able to encapsulate a drug model (acridine orange). In addition, these AuMSS nanoclusters were also biocompatible with both healthy (fibroblasts) and carcinogenic (cervical cancer) cells, at a maximum tested concentration of 200 μg/mL. Nevertheless, the AuMSS nanoclusters’ NIR light-triggered heat generation successfully reduced the viability of cervical cancer cells by about 80%. This confirms the potential of the AuMSS nanoclusters to be applied in cancer therapy, namely as theragnostic agents.

Superparamagnetic Nanoparticles with Efficient Near-Infrared Photothermal Effect at the Second Biological Window

Superparamagnetic nanoparticles (iron oxide nanoparticles-IONs) are suitable for hyperthermia after irradiating with radiofrequency radiation. Concerning the suitability for laser ablation, IONs present a low molar absorption coefficient in the near-infrared region close to 800 nm. For this reason, they are combined with other photothermal agents into a hybrid composite. Here, we show that IONs absorb and convert into heat the infrared radiation characteristic of the so-called second-biological window (1000-1350 nm) and, in consequence, they can be used for thermal ablation in such wavelengths. To the known excellent water solubility, colloidal stability and biocompatibility exhibited by IONs, an outstanding photothermal performance must be added. For instance, a temperature increase of 36 °C was obtained after irradiating at 8.7 W cm^-2 for 10 min a suspension of IONs at iron concentration of 255 mg L^-1. The photothermal conversion efficiency was ~72%. Furthermore, IONs showed high thermogenic stability during the whole process of heating/cooling. To sum up, while the use of IONs in the first bio-window (700-950 nm) presents some concerns, they appear to be good photothermal agents in the second biological window.

Understanding Nanoparticle Toxicity to Direct a Safe-by-Design Approach in Cancer Nanomedicine

Nanomedicine is a rapidly growing field that uses nanomaterials for the diagnosis, treatment and prevention of various diseases, including cancer. Various biocompatible nanoplatforms with diversified capabilities for tumor targeting, imaging, and therapy have materialized to yield individualized therapy. However, due to their unique properties brought about by their small size, safety concerns have emerged as their physicochemical properties can lead to altered pharmacokinetics, with the potential to cross biological barriers. In addition, the intrinsic toxicity of some of the inorganic materials (i.e., heavy metals) and their ability to accumulate and persist in the human body has been a challenge to their translation. Successful clinical translation of these nanoparticles is heavily dependent on their stability, circulation time, access and bioavailability to disease sites, and their safety profile. This review covers preclinical and clinical inorganic-nanoparticle based nanomaterial utilized for cancer imaging and therapeutics. A special emphasis is put on the rational design to develop non-toxic/safe inorganic nanoparticle constructs to increase their viability as translatable nanomedicine for cancer therapies.

siRNA Conjugated Nanoparticles-A Next Generation Strategy to Treat Lung Cancer

Despite major progress in both therapeutic and diagnostic techniques, lung cancer is still considered the leading cause of cancer mortality in the world due to the ineffectiveness of the classical treatments used nowadays. Luckily, the discovery of small interfering RNA (siRNA) planted hope in the hearts of scientists and patients worldwide as a new breakthrough in the world of oncology and a robust tool for finally curing cancer. However, the valuable siRNA must be protected and preserved to ensure the effectiveness of this gene therapy, thus nanoparticles are gaining more attention than previous years as the optimal carriers for this fragile molecule. siRNA-loaded nanoparticles are being extensively investigated to find the appropriate formulation, combination, and delivery route with one objective in mind—successfully overcoming all possible limitations shown in clinical studies and making full use of this novel technique to become the next generation treatment to wipe out many chronic diseases, including cancer. In this review, the benefits of using siRNA and nanoparticles in lung cancer treatment will be globally reviewed before discussing why and how nanoparticles and siRNA can be combined to achieve an efficient treatment of lung cancer for prospective clinical applications.

Gold nanostructures as cancer theranostic probe: promises and hurdles

Gold nanostructures (GNSts) have emerged as substitute for conventional contrast agents in imaging techniques and therapeutic probes due to their tunable surface plasmon resonance and optical properties in near-infrared region. Thus GNSts provide platform for the amalgamation of diagnosis and treatment (theranostics) into a single molecule for a more precise treatment. Hence, the article talks about the application of GNSts in imaging techniques and provide a holistic view on differently shaped GNSts in cancer theranostics. However, with promises GNSts also face various hurdles for their use as theranostic probe which are primarily associated with toxicity. Finally, the article attempts to discuss the challenges faced by GNSts and the way ahead that need to be traversed to place them in nanomedicine.

Synthetic Methodologies to Gold Nanoshells: An Overview

Gold nanostructures that can be synthetically articulated to adapt diverse morphologies, offer a versatile platform and tunable properties for applications in a variety of areas, including biomedicine and diagnostics. Among several conformational architectures, gold nanoshells provide a highly advantageous combination of properties that can be fine-tuned in designing single or multi-purpose nanomaterials, especially for applications in biology. One of the important parameters for evaluating the efficacy of gold nano-architectures is their reproducible synthesis and surface functionalization with desired moieties. A variety of methods now exist that allow fabrication and chemical manipulation of their structure and resulting properties. This review article provides an overview and a discussion of synthetic methodologies to a diverse range of gold nanoshells, and a brief summary of surface functionalization and characterization methods employed to evaluate their overall composition.

Iron Oxide Nanoparticles in Photothermal Therapy

Photothermal therapy is a kind of therapy based on increasing the temperature of tumoral cells above 42 °C. To this aim, cells must be illuminated with a laser, and the energy of the radiation is transformed in heat. Usually, the employed radiation belongs to the near-infrared radiation range. At this range, the absorption and scattering of the radiation by the body is minimal. Thus, tissues are almost transparent. To improve the efficacy and selectivity of the energy-to-heat transduction, a light-absorbing material, the photothermal agent, must be introduced into the tumor. At present, a vast array of compounds are available as photothermal agents. Among the substances used as photothermal agents, gold-based compounds are one of the most employed. However, the undefined toxicity of this metal hinders their clinical investigations in the long run. Magnetic nanoparticles are a good alternative for use as a photothermal agent in the treatment of tumors. Such nanoparticles, especially those formed by iron oxides, can be used in combination with other substances or used themselves as photothermal agents. The combination of magnetic nanoparticles with other photothermal agents adds more capabilities to the therapeutic system: the nanoparticles can be directed magnetically to the site of interest (the tumor) and their distribution in tumors and other organs can be imaged. When used alone, magnetic nanoparticles present, in theory, an important limitation: their molar absorption coefficient in the near infrared region is low. The controlled clustering of the nanoparticles can solve this drawback. In such conditions, the absorption of the indicated radiation is higher and the conversion of energy in heat is more efficient than in individual nanoparticles. On the other hand, it can be designed as a therapeutic system, in which the heat generated by magnetic nanoparticles after irradiation with infrared light can release a drug attached to the nanoparticles in a controlled manner. This form of targeted drug delivery seems to be a promising tool of chemo-phototherapy. Finally, the heating efficiency of iron oxide nanoparticles can be increased if the infrared radiation is combined with an alternating magnetic field.

Magnetic resonance and photoacoustic imaging of brain tumor mediated by mesenchymal stem cell labeled with multifunctional nanoparticle introduced via carotid artery injection

OBJECTIVE

To evaluate the feasibility of visualizing bone marrow-derived human mesenchymal stem cells (MSCs) labeled with a gold-coated magnetic resonance (MR)-active multifunctional nanoparticle and injected via the carotid artery for assessing the extent of MSC homing in glioma-bearing mice.

MATERIALS AND METHODS

Nanoparticles containing superparamagnetic iron oxide coated with gold (SPIO@Au) with a diameter of ∼82 nm and maximum absorbance in the near infrared region were synthesized. Bone marrow-derived MSCs conjugated with green fluorescent protein (GFP) were successfully labeled with SPIO@Au at 4 μg ml^-1 and injected via the internal carotid artery in six mice bearing orthotopic U87 tumors. Unlabeled MSCs were used as a control. The ability of SPIO@Au-loaded MSCs to be imaged using MR and photoacoustic (PA) imaging at t = 0 h, 2 h, 24 h, and 72 h was assessed using a 7 T Bruker Biospec experimental MR scanner and a Vevo LAZR PA imaging system with a 5 ns laser as the excitation source. Histological analysis of the brain tissue was performed 72 h after MSC injection using GFP fluorescence, Prussian blue staining, and hematoxylin-and-eosin staining.

RESULTS

MSCs labeled with SPIO@Au at 4 μg ml^-1 did not exhibit cell death or any adverse effects on differentiation or migration. The PA signal in tumors injected with SPIO@Au-loaded MSCs was clearly more enhanced post-injection, as compared with the tumors injected with unlabeled MSCs at t = 72 h. Using the same mice, T2-weighted MR imaging results taken before injection and at t = 2 h, 24 h, and 72 h were consistent with the PA imaging results, showing significant hypointensity of the tumor in the presence of SPIO@Au-loaded MSCs. Histological analysis also showed co-localization of GFP fluorescence and iron, thereby confirming that SPIO@Au-labeled MSCs continue to carry their nanoparticle payloads even at 72 h after injection.

CONCLUSIONS

Our results demonstrated the feasibility of tracking carotid artery-injected SPIO@Au-labeled MSCs in vivo via MR and PA imaging.

Non-invasive monitoring of branched Au nanoparticle-mediated photothermal ablation

Nanoparticle-mediated photothermal therapy for treatment of different types of tumors has attracted tremendous attention in recent years. One major factor that drives this therapy is the ability to carefully control and prevent inadvertent damage to local tissues, while focusing therapeutic heating to specific regions of the tumor tissues. To this end, it is critical to generate efficient heating in the targeted tumors while monitoring the extent and distribution of heating. In our study, we demonstrated the photothermal heating properties of our synthesized branched Au nanoparticles (b-AuNPs) using non-invasive MR thermometry (MRT) techniques to assess its effects both in vitro and in vivo. 75 nm b-AuNPs were synthesized; these b-AuNPs demonstrated strong near infrared (NIR) absorption and high heat transducing efficiency. Proton resonance frequency MRT approaches for monitoring b-AuNPs mediated heating were validated using in vitro agar phantoms and further evaluated during in vivo animal model tumor ablation studies. In vitro phantom studies demonstrated a strong linear correlation between MRT and reference-standard thermocouple measurements of b-AuNPs-mediated heating upon NIR laser irradiation; temperatures increased with both an increase in laser power and increased exposure duration. Localized photothermal heating in regions containing the b-AuNPs was confirmed through MRT generated temperature maps acquired serially at increasing depths during both phantom and in vivo studies. Our results suggested that b-AuNPs exposed to NIR radiation produced highly efficient localized heating that can be accurately monitored dynamically using non-invasive MRT measurements. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2352-2359, 2017.

Gold-coated magnetic nanoparticle as a nanotheranostic agent for magnetic resonance imaging and photothermal therapy of cancer

Because of their great scientific and technological potentials, iron oxide nanoparticles (IONPs) have been the focus of extensive investigations in biomedicine over the past decade. Additionally, the surface plasmon resonance effect of gold nanoparticles (AuNPs) makes them a good candidate for photothermal therapy applications. The unique properties of both IONPs (magnetic) and AuNPs (surface plasmon resonance) may lead to the development of a multi-modal nanoplatform to be used as a magnetic resonance imaging (MRI) contrast agent and as a nanoheater for photothermal therapy. Herein, core-shell gold-coated IONPs (Au@IONPs) were synthesized and investigated as an MRI contrast agent and as a light-responsive agent for cancer photothermal therapy.The synthesized Au@IONPs were characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential analysis. The transverse relaxivity (r ₂) of the Au@IONPs was measured using a 3-T clinical MRI scanner. Through a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the cytotoxicity of the Au@IONs was examined on a KB cell line, derived from the epidermal carcinoma of a human mouth. Moreover, the photothermal effects of Au@IONPs in the presence of a laser beam (λ = 808 nm; 6.3 W/cm²; 5 min) were studied.The results show that the Au@IONPs are spherical with a hydrodynamic size of 33 nm. A transverse relaxivity of 95 mM^-1 S^-1 was measured for the synthesized Au@IONPs. It is evident from the MTT results that no significant cytotoxicity in KB cells occurs with Au@IONPs. Additionally, no significant cell damage induced by the laser is observed. Following the photothermal treatment using Au@IONPs, approximately 70% cell death is achieved. It is found that cell lethality depended strongly on incubation period and the Au@IONP concentration.The data highlight the potential of Au@IONPs as a dual-function MRI contrast agent and photosensitizer for cancer photothermal therapy.

Synthesis and Properties of Magnetic-Optical Core-Shell Nanoparticles

Due to their high integrity, facile surface chemistry, excellent stability, and dual properties from the core and shell materials, magnetic-plasmonic core-shell nanoparticles are of great interest across a number of science, engineering and biomedical disciplines. They are promising for applications in a broad range of areas including catalysis, energy conversion, biological separation, medical imaging, disease detection and treatment. The technological applications have driven the need for high quality nanoparticles with well controlled magnetic and optical properties. Tremendous progress has been made during past few decades in synthesizing and characterizing magnetic-plasmonic core-shell nanoparticles, mainly iron oxide-gold core-shell nanoparticles. This review introduces various approaches for the synthesis of spherical and anisotropic magnetic-plasmonic core-shell nanoparticles focusing on iron oxide-gold core-shell nanoparticles. Growth mechanisms are discussed to provide understanding of the key factors controlling shape-controlled synthesis. Magnetic and optical properties are summarized from both computational and experimental studies.

Biomedical Applications of Multifunctional Gold-Based Nanocomposites

Active application of gold nanoparticles for various diagnostic and therapeutic purposes started in recent decades due to the emergence of new data on their unique optical and physicochemical properties. In addition to colloidal gold conjugates, growth in the number of publications devoted to the synthesis and application of multifunctional nanocomposites has occurred in recent years. This review considers the application in biomedicine of multifunctional nanoparticles that can be produced in three different ways. The first method involves design of composite nanostructures with various components intended for either diagnostic or therapeutic functions. The second approach uses new bioconjugation techniques that allow functionalization of gold nanoparticles with various molecules, thus combining diagnostic and therapeutic functions in one medical procedure. Finally, the third method for production of multifunctional nanoparticles combines the first two approaches, in which a composite nanoparticle is additionally functionalized by molecules having different properties.

Multifunctional gold-based nanocomposites for theranostics

Although Au-particle potential in nanobiotechnology has been recognized for the last 15 years, new insights into the unique properties of multifunctional nanostructures have just recently started to emerge. Multifunctional gold-based nanocomposites combine multiple modalities to improve the efficacy of the therapeutic and diagnostic treatment of cancer and other socially significant diseases. This review is focused on multifunctional gold-based theranostic nanocomposites, which can be fabricated by three main routes. The first route is to create composite (or hybrid) nanoparticles, whose components enable diagnostic and therapeutic functions. The second route is based on smart bioconjugation techniques to functionalize gold nanoparticles with a set of different molecules, enabling them to perform targeting, diagnostic, and therapeutic functions in a single treatment procedure. Finally, the third route for multifunctionalized composite nanoparticles is a combination of the first two and involves additional functionalization of hybrid nanoparticles with several molecules possessing different theranostic modalities. This last class of multifunctionalized composites also includes fluorescent atomic clusters with multiple functionalities.

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.

Recent advances in different modal imaging-guided photothermal therapy

Photothermal therapy (PTT) has recently attracted considerable attention owing to its controllable treatment process, high tumour eradication efficiency and minimal side effects on non-cancer cells. PTT can melt cancerous cells by localising tissue hyperthermia induced by internalised therapeutic agents with a high photothermal conversion efficiency under external laser irradiation. Numerous in vitro and in vivo studies have shown the significant potential of PTT to treat tumours in future practical applications. Unfortunately, the lack of visualisation towards agent delivery and internalisation, as well as imaging-guided comprehensive evaluation of therapeutic outcome, limits its further application. Developments in combined photothermal therapeutic nanoplatforms guided by different imaging modalities have compensated for the major drawback of PTT alone, proving PTT to be a promising technique in biomedical applications. In this review, we introduce recent developments in different imaging modalities including single-modal, dual-modal, triple-modal and even multi-modal imaging-guided PTT, together with imaging-guided multi-functional theranostic nanoplatforms.

Size- and Shape-Controlled Synthesis and Properties of Magnetic-Plasmonic Core-Shell Nanoparticles

Magnetic-plasmonic core-shell nanomaterials offer a wide range of applications across science, engineering and biomedical disciplines. However, the ability to synthesize and understand magnetic-plasmonic core-shell nanoparticles with tunable sizes and shapes remains very limited. This work reports experimental and computational studies on the synthesis and properties of iron oxide-gold core-shell nanoparticles of three different shapes (sphere, popcorn and star) with controllable sizes (70 to 250 nm). The nanoparticles were synthesized via a seed-mediated growth method in which newly formed gold atoms were added onto gold-seeded iron oxide octahedrons to form gold shell. The evolution of the shell into different shapes was found to occur after the coalescence of gold seeds, which was achieved by controlling the amount of additive (silver nitrate) and reducing agent (ascorbic acid) in the growth solution. First principles calculation, together with experimental results, elucidated the intimate roles of thermodynamic and kinetic parameters in the shape-controlled synthesis. Both discrete dipole approximation calculation and experimental results showed that the nanopopcorns and nanostars exhibited red-shifted plasmon resonance compared with the nanospheres, with the nanostars giving multispectral feature. This research has made a great step further in manipulating and understanding magnetic-plasmonic hybrid nanostructures and will make important impact in many different fields.

Nanotechnology: Future of Oncotherapy

Recent advances in nanotechnology have established its importance in several areas including medicine. The myriad of applications in oncology range from detection and diagnosis to drug delivery and treatment. Although nanotechnology has attracted a lot of attention, the practical application of nanotechnology to clinical cancer care is still in its infancy. This review summarizes the role that nanotechnology has played in improving cancer therapy, its potential for affecting all aspects of cancer care, and the challenges that must be overcome to realize its full promise.

The Combination of Laser Therapy and Metal Nanoparticles in Cancer Treatment Originated From Epithelial Tissues: A Literature Review

Several methods have been employed for cancer treatment including surgery, chemotherapy and radiation therapy. Today, recent advances in medical science and development of new technologies, have led to the introduction of new methods such as hormone therapy, Photodynamic therapy (PDT), treatments using nanoparticles and eventually combinations of lasers and nanoparticles. The unique features of LASERs such as photo-thermal properties and the particular characteristics of nanoparticles, given their extremely small size, may provide an interesting combined therapeutic effect. The purpose of this study was to review the simultaneous application of lasers and metal nanoparticles for the treatment of cancers with epithelial origin. A comprehensive search in electronic sources including PubMed, Google Scholar and Science Direct was carried out between 2000 and 2013. Among the initial 400 articles, 250 articles applied nanoparticles and lasers in combination, in which more than 50 articles covered the treatment of cancer with epithelial origin. In the future, the combination of laser and nanoparticles may be used as a new or an alternative method for cancer therapy or diagnosis. Obviously, to exclude the effect of laser's wavelength and nanoparticle's properties more animal studies and clinical trials are required as a lack of perfect studies.

Diffusion-Weighted Magnetic Resonance Imaging for Therapy Response Monitoring and Early Treatment Prediction of Photothermal Therapy

Photothermal therapy (PTT) as a relatively new cancer treatment method has attracted worldwide attention. Previous research on PTT has focused on its therapy efficiency and selectivity. The early prognosis of PTT, which is pivotal for the assessment of the treatment and the therapy stratification, however, has been rarely studied. In the present study, we investigated diffusion-weighted magnetic resonance imaging (DW-MRI) as a tool for therapy monitoring and early prognosis of PTT. To this end, we injected PEGylated graphene oxide (GO-PEG) or iron oxide deposited graphene oxide (GO-IONP-PEG) to 4T1 tumor models and irradiated the tumors at different drug-light intervals to induce PTT. For GO-IONP-PEG injected animals, we also included therapy arms where an external magnetic field was applied to the tumors to improve the delivery of the nanoparticle transducers. DW-MRI was performed at different time points after PTT and the tumor apparent diffusion coefficients (ADCs) were analyzed and compared. Our studies show that photothermal agents, magnetic guidance, and drug-light intervals can all affect PTT treatment efficacy. Impressively, ADC value changes at early time points after PTT (less than 48 h) were found to be well-correlated with tumor growth suppression that was apparent days or weeks later. The changes were most sensitive to conditions that can extend the survival for more than 4 weeks, in which cases the 48 h ADC values were increased by more than 80%. These studies demonstrate for the first time that DW-MRI can be an accurate prognosis tool for PTT, suggesting an important role it can play in the future PTT evaluation and clinical translation of the modality.

Photothermal cancer therapy by gold-ferrite nanocomposite and near-infrared laser in animal model

Surface plasmon resonance effect of gold nanostructures makes them good candidates for photothermal therapy (PTT) application. Herein, gold-ferrite nanocomposite (GFNC) was synthesized and characterized as a photothermal agent in PTT. The aim of this study was to investigate the effect of GFNC upon laser irradiation on treatment of cancer in mice bearing melanoma cancer. Thirty mice received 1.5 × 10(6) B16/F10 cells subcutaneously. After 1 week, the mice bearing solid tumor were divided into four groups: control group (without any treatment), laser group (received laser irradiation without GFNC injection), GFNC group (only received intratumorally GFNC), and GFNC + laser group (received intratumorally GFNC upon laser irradiation). In GFNC + laser group, 200 μL of fluid, 1.3 × 10(-7) mol L(-1) gold nanoparticles, was injected intratumorally and immediately the site of tumor was exposed to continuous wave diode laser beam (808 nm, 1.6 W cm(-2)) for 15 min. All mice but four were euthanized 24 h after treatment to compare the necrotic surface area histologically by using measuring graticule. Statistical analyses revealed significant differences in necrosis extent for GFNC + laser group, compared to other groups. Four subjects (control group and GFNC + laser group, two mice each) were kept for longitudinal study. Histological analyses and tumor volume measurements of the four subjects indicated that tumor in GFNC + laser group was controlled appropriately. It was concluded that combining an 808-nm laser at a power density of 1.6 W cm(-2) with GFNC has a destruction effect in melanoma cancer cells in an animal model.

In vivo delivery, pharmacokinetics, biodistribution and toxicity of iron oxide nanoparticles

Iron oxide nanoparticles (IONPs) have been extensively used during the last two decades, either as effective bio-imaging contrast agents or as carriers of biomolecules such as drugs, nucleic acids and peptides for controlled delivery to specific organs and tissues. Most of these novel applications require elaborate tuning of the physiochemical and surface properties of the IONPs. As new IONPs designs are envisioned, synergistic consideration of the body's innate biological barriers against the administered nanoparticles and the short and long-term side effects of the IONPs become even more essential. There are several important criteria (e.g. size and size-distribution, charge, coating molecules, and plasma protein adsorption) that can be effectively tuned to control the in vivo pharmacokinetics and biodistribution of the IONPs. This paper reviews these crucial parameters, in light of biological barriers in the body, and the latest IONPs design strategies used to overcome them. A careful review of the long-term biodistribution and side effects of the IONPs in relation to nanoparticle design is also given. While the discussions presented in this review are specific to IONPs, some of the information can be readily applied to other nanoparticle systems, such as gold, silver, silica, calcium phosphates and various polymers.

Single agent nanoparticle for radiotherapy and radio-photothermal therapy in anaplastic thyroid cancer

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human malignancies. The aggressive behavior of ATC and its resistance to traditional treatment limit the efficacy of radiotherapy, chemotherapy, and surgery. The purpose of this study is aimed at enhancing the therapeutic efficacy of radiotherapy (RT) combined with photothermal therapy (PTT) in murine orthotopic model of ATC, based on our developed single radioactive copper sulfide (CuS) nanoparticle platform. We prepare a new dual-modality therapy for ATC consisting of a single-compartment nanoplatform, polyethylene glycol-coated [(64)Cu]CuS NPs, in which the radiotherapeutic property of (64)Cu is combined with the plasmonic properties of CuS NPs. Mice with Hth83 ATC were treated with PEG-[(64)Cu]CuS NPs and/or near infrared laser. Antitumor effects were assessed by tumor growth and animal survival. We found that in mice bearing orthotopic human Hth83 ATC tumors, micro-PET/CT imaging and biodistribution studies showed that about 50% of the injected dose of PEG-[(64)Cu]CuS NPs was retained in tumor 48 h after intratumoral injection. Human absorbed doses were calculated from biodistribution data. In antitumor experiments, tumor growth was delayed by PEG-[(64)Cu]CuS NP-mediated RT, PTT, and combined RT/PTT, with combined RT/PTT being most effective. In addition, combined RT/PTT significantly prolonged the survival of Hth83 tumor-bearing mice compared to no treatment, laser treatment alone, or NP treatment alone without producing acute toxic effects. These findings indicate that this single-compartment multifunctional NPs platform merits further development as a novel therapeutic agent for ATC.

Au-nanomaterials as a superior choice for near-infrared photothermal therapy

Photothermal therapy (PPT) is a platform to fight cancer by using multiplexed interactive plasmonic nanomaterials as probes in combination with the excellent therapeutic performance of near-infrared (NIR) light. With recent rapid developments in optics and nanotechnology, plasmonic materials have potential in cancer diagnosis and treatment, but there are some concerns regarding their clinical use. The primary concerns include the design of plasmonic nanomaterials which are taken up by the tissues, perform their function and then clear out from the body. Gold nanoparticles (Au NPs) can be developed in different morphologies and functionalized to assist the photothermal therapy in a way that they have clinical value. This review outlines the diverse Au morphologies, their distinctive characteristics, concerns and limitations to provide an idea of the requirements in the field of NIR-based therapeutics.

A promising road with challenges: where are gold nanoparticles in translational research?

Nanoenabled technology holds great potential for health issues and biological research. Among the numerous inorganic nanoparticles that are available today, gold nanoparticles are fully developed as therapeutic and diagnostic agents both in vitro and in vivo due to their physicochemical properties. Owing to this, substantial work has been conducted in terms of developing biosensors for noninvasive and targeted tumor diagnosis and treatment. Some studies have even expanded into clinical trials. This article focuses on the fundamentals and synthesis of gold nanoparticles, as well as the latest, most promising applications in cancer research, such as molecular diagnostics, immunosensors, surface-enhanced Raman spectroscopy and bioimaging. Challenges to their further translational development are also discussed.

Cancer theranostics with gold nanoshells

Gold nanoshells (AuNSs) present a vivid example of integrating nanoscience in order to solve a biomedical problem. AuNSs exhibit tunable surface plasmon resonance, which can be tuned to the near-infrared region in order to realize optimal tissue penetration. The highly efficient light-to-heat transformation by AuNSs during laser irradiation causes thermal damage to the tumor without damaging healthy organs. Transient nanobubbles can form around AuNSs during laser treatment and induce mechanical stress specifically in tumor cells. AuNSs also serve as a versatile platform for the delivery of various diagnostic and therapeutic agents. In this article, we describe the physicochemical properties of AuNSs in the context of their design, preparation and application in cancer theranostics. Ultimately, we look beyond the current research on AuNSs and discussed future challenges to their successful translation into clinical use.

Encapsulated Fe3O4 /Ag complexed cores in hollow gold nanoshells for enhanced theranostic magnetic resonance imaging and photothermal therapy

Designed and fabrication of a novel magnetic hollow gold nanoshell complexes that incorporates iron oxide nanoparticles in the hollow interior. The combined effect of the smaller IONPs improved the overall magnetic properties of the design and MRI contrast capability. The overall complex could be synthesized in the range of 60-80 nm in diameter while still having a plasmonic peak in the near infrared region.

The surprising in vivo instability of near-IR-absorbing hollow Au-Ag nanoshells

Photothermal ablation based on resonant illumination of near-infrared-absorbing noble metal nanoparticles that have accumulated in tumors is a highly promising cancer therapy, currently in multiple clinical trials. A crucial aspect of this therapy is the nanoparticle size for optimal tumor uptake. A class of nanoparticles known as hollow Au (or Au-Ag) nanoshells (HGNS) is appealing because near-IR resonances are achievable in this system with diameters less than 100 nm. However, in this study, we report a surprising finding that in vivo HGNS are unstable, fragmenting with the Au and the remnants of the sacrificial Ag core accumulating differently in various organs. We synthesized 43, 62, and 82 nm diameter HGNS through a galvanic replacement reaction, with nanoparticles of all sizes showing virtually identical NIR resonances at ∼800 nm. A theoretical model indicated that alloying, residual Ag in the nanoparticle core, nanoparticle porosity, and surface defects all contribute to the presence of the plasmon resonance at the observed wavelength, with the major contributing factor being the residual Ag. While PEG functionalization resulted in stable nanoparticles under laser irradiation in solution, an anomalous, strongly element-specific biodistribution observed in tumor-bearing mice suggests that an avid fragmentation of all three sizes of nanoparticles occurred in vivo. Stability studies across a wide range of pH environments and in serum confirmed HGNS fragmentation. These results show that NIR resonant HGNS contain residual Ag, which does not stay contained within the HGNS in vivo. This demonstrates the importance of tracking both materials of a galvanic replacement nanoparticle in biodistribution studies and of performing thorough nanoparticle stability studies prior to any intended in vivo trial application.

Assessment of rat antigen-induced arthritis and its suppression during glucocorticoid therapy by use of hemicyanine dye probes with different molecular weight in near-infrared fluorescence optical imaging

PURPOSE

Arthritic joints are ideal disease entities to be assessed via optical imaging. Here, we investigated the selective accumulation behavior of two differently sized hemicyanine optical probes in arthritic joints and its modification during glucocorticoid therapy in the course of inflammation.

MATERIALS AND METHODS

The well-standardized preclinical antigen-induced arthritis (AIA) model in rats was used. The animals were divided into 3 groups: arthritic, arthritic and dexamethasone-treated, and immunized only. After intravenous coinjection of DY-752 (size, 800 Da) and DY-682-(rat) IgG (size, 150 kDa) probes, spectrally unmixed near-infrared fluorescence images were acquired and analyzed semiquantitatively. Probe organ distribution, joint swelling, blood cell counts, joint vessel density, and histological scoring of arthritis were determined.

RESULTS

The local joint accumulation kinetics of the DY-752 probe differed from the DY-682-IgG one. In the course of AIA, probe signaling in arthritic joints was similar between each other. Joint swelling and histological scoring were in accordance with signaling. Dexamethasone treatment of rats with AIA significantly reduced both the near-infrared fluorescence signals and severity of arthritis but did not change the joint vascular density or the uptake of the probes by phagocytes. A differential biodistribution of both probes was encountered, but such an accumulation was prevented by dexamethasone treatment.

CONCLUSIONS

Near-infrared fluorescence signaling in the course of AIA closely reflects the pathophysiological events of the arthritic joint and the effects of therapy independently of the molecular size of the probe. The results show the suitability of our hemicyanine probes for imaging of arthritis.

Emerging advances in nanomedicine with engineered gold nanostructures

Gold nanostructures possess unique characteristics that enable their use as contrast agents, as therapeutic entities, and as scaffolds to adhere functional molecules, therapeutic cargo, and targeting ligands. Due to their ease of synthesis, straightforward surface functionalization, and non-toxicity, gold nanostructures have emerged as powerful nanoagents for cancer detection and treatment. This comprehensive review summarizes the progress made in nanomedicine with gold nanostructures (1) as probes for various bioimaging techniques including dark-field, one-photon and two-photon fluorescence, photothermal optical coherence tomography, photoacoustic tomography, positron emission tomography, and surface-enhanced Raman scattering based imaging, (2) as therapeutic components for photothermal therapy, gene and drug delivery, and radiofrequency ablation, and (3) as a theranostic platform to simultaneously achieve both cancer detection and treatment. Distinct from other published reviews, this article also discusses the recent advances of gold nanostructures as contrast agents and therapeutic actuators for inflammatory diseases including atherosclerotic plaque and arthritis. For each of the topics discussed above, the fundamental principles and progress made in the past five years are discussed. The review concludes with a detailed future outlook discussing the challenges in using gold nanostructures, cellular trafficking, and translational considerations that are imperative for rapid clinical viability of plasmonic nanostructures, as well as the significance of emerging technologies such as Fano resonant gold nanostructures in nanomedicine.

Research perspectives: gold nanoparticles in cancer theranostics

High recurrence rates after surgical resection remain a formidable challenge in many cancers. Although chemo- and/or radiotherapy are often applied following surgery to prevent tumor relapse, these treatments are generally accompanied by serious side effects and challenges in their delivery that limit their effectiveness. Gold nanoparticles (AuNPs), which possess unique physicochemical properties, have the potential to enhance the efficacy of these conventional treatment modalities. In this review, we briefly describe the current state of AuNP research in the area of cancer theranostics. Recent studies have investigated AuNPs' use as photothermal converters, drug carriers, radiosensitizers, and imaging probes in a wide range of applications for cancer diagnosis and therapy. AuNPs have promise in minimally invasive thermal ablation therapy, diagnostic imaging, intraoperative tumor margin delineation, and multimodal anticancer therapy. The successful translation of AuNPs into the clinic will have significant impact on the care of cancer patients using image-guided, minimally invasive approaches.

In vitro and in vivo mapping of drug release after laser ablation thermal therapy with doxorubicin-loaded hollow gold nanoshells using fluorescence and photoacoustic imaging

Doxorubicin-loaded hollow gold nanoshells (Dox@PEG-HAuNS) increase the efficacy of photothermal ablation (PTA) not only by mediating efficient PTA but also through chemotherapy, and therefore have potential utility for local anticancer therapy. However, in vivo real-time monitoring of Dox release and temperature achieved during the laser ablation technique has not been previously demonstrated before. In this study, we used fluorescence optical imaging to map the release of Dox from Dox@PEG-HAuNS and photoacoustic imaging to monitor the tumor temperature achieved during near-infrared laser-induced photothermal heating in vitro and in vivo. In vitro, treatment with a 3-W laser was sufficient to initiate the release of Dox from Dox@PEG-HAuNS (1:3:1 wt/wt, 1.32 × 10(12)particles/mL). Laser powers of 3 and 6W achieved ablative temperatures of more than 50°C. In 4T1 tumor-bearing nude mice that received intratumoral or intravenous injections of Dox@PEG-HAuNS, fluorescence optical imaging (emission wavelength = 600 nm, excitation wavelength = 500 nm) revealed that the fluorescence intensity in surface laser-treated tumors 24h after treatment was significantly higher than that in untreated tumors (p = 0.015 for intratumoral, p = 0.008 for intravenous). Similar results were obtained using an interstitial laser to irradiate tumors following the intravenous injection of Dox@PEG-HAuNS (p = 0.002 at t = 24h). Photoacoustic imaging (acquisition wavelength = 800 nm) revealed that laser treatment caused a substantial increase in tumor temperature, from 37 °C to ablative temperatures of more than 50 °C. Ex vivo analysis revealed that the fluorescence intensity of laser-treated tumors was twice as high as that of untreated tumors (p = 0.009). Histological analysis confirmed that intratumoral injection of Dox@PEG-HAuNS and laser treatment caused significantly more tumor necrosis compared to tumors that were not treated with laser (p<0.001). On the basis of these findings, we conclude that fluorescence optical imaging and photoacoustic imaging are promising approaches to assessing Dox release and monitoring temperature, respectively, after Dox@PEG-HAuNS-mediated thermal ablation therapy.

A historical overview of magnetic resonance imaging, focusing on technological innovations

Magnetic resonance imaging (MRI) has now been used clinically for more than 30 years. Today, MRI serves as the primary diagnostic modality for many clinical problems. In this article, historical developments in the field of MRI will be discussed with a focus on technological innovations. Topics include the initial discoveries in nuclear magnetic resonance that allowed for the advent of MRI as well as the development of whole-body, high field strength, and open MRI systems. Dedicated imaging coils, basic pulse sequences, contrast-enhanced, and functional imaging techniques will also be discussed in a historical context. This article describes important technological innovations in the field of MRI, together with their clinical applicability today, providing critical insights into future developments.

Mesoporous silica nanoparticles for the design of smart delivery nanodevices

Mesoporous silica nanoparticles (MSNPs) are receiving growing attention by the scientific community for their groundbreaking potential in nanomedicine. It is possible to load huge amounts of cargo into the mesopore voids and capping the pore entrances with different nanogates. Different internal or external stimuli can provoke the nanocap removal and trigger the departure of the cargo, which permits the design of stimuli-responsive drug delivery nanodevices. It is also feasible to combine the multifunctionality of MSNPs with the wide range of applications of magnetic nanoparticles (mNPs), giving rise to advanced smart nanosystems whose features and functionality can be tailored attending to specific clinical needs. This review describes the possible combinations of MSNPs, stimuli-responsive nanocaps and mNPs and the current scientific challenges aimed at accelerating the progression from bench to bedside.

Nanotheranostics--a review of recent publications

Theranostics is referred to as a treatment strategy that combines therapeutics with diagnostics, aiming to monitor the response to treatment and increase drug efficacy and safety, which would be a key part of personalized medicine and require considerable advances in predictive medicine. Theranostics associates with both a diagnosis that tests patients for possible reactions to taking new medication and targeted drug delivery based on the test results. Emerging nanotechnology provides a great deal of opportunity to design and develop such combination agents, permitting the delivery of therapeutics and concurrently allowing the detection modality to be used not only before or after but also throughout the entire treatment regimen. The introduction of nanotheranostics into routine health care has still a long way to go, since evaluations on cytotoxicity, genotoxicity, and immunotoxicity of prospective nanotheranostics, demonstration of cost-effectiveness, and availability of appropriate accessible testing systems are still required. An extensive review, from a chemistry point of view, of the recent development of nanotheranostics and its in vitro and in vivo applications are herein presented.

Challenges to effective cancer nanotheranostics

Advances in nanotechnology for oncology will arise from an increased understanding of the interaction between nanomaterials and biological systems; refinement of multifunctional nanocomposites for applications such as simultaneous imaging and therapy (theranostics); and harnessing of the unique physicochemical properties arising from nanoscale effects which distinguish them from small-molecular-weight molecules in the detection and destruction of cancer cells with high selectivity and efficiency. The major challenges in successful clinical translation of tumor specific nanoparticle delivery include overcoming various biological barriers and demonstrating enhanced therapeutic efficacy over the current standard of care in the clinic. For many nanoparticle mediated theranostic applications, image guidance can play a crucial role not only in exploiting the cancer specific imaging capabilities of these novel particles, but in planning, targeting, monitoring and verifying treatment delivery, thus enhancing the safety and efficacy of these emerging procedures.

Gold nanoparticles in theranostic oncology: current state-of-the-art

INTRODUCTION

In recent years, extensive multidisciplinary investigations have been carried out in the area of cancer nanotechnology. Gold nanoparticles (GNPs) have emerged as promising carrier for delivery of various pay-loads into their target. In view of their unique physicochemical and optical properties, GNPs have been exploited for multimodality imaging, tumor targeting, and as transporter of various therapeutics. Additionally, GNPs have been used as photothermal therapeutics against cancer.

AREAS COVERED

This review will focus on recent progress in the field of gold nanomaterials in cancer therapy and diagnosis. Moreover, concern about the toxicity of gold nanomaterials is addressed.

EXPERT OPINION

GNPs present versatile scaffolds for efficient delivery of cancer chemotherapeutics. Tuneable chemistry of the GNPs contributes to their ever increasing use in oncology research. The promises of a functional cancer therapy using GNPs have been extensively demonstrated, although the materials are still in their infancy stage and not surfaced to meet clinical standards.

Effective photothermal chemotherapy using doxorubicin-loaded gold nanospheres that target EphB4 receptors in tumors

Photothermal ablation (PTA) is an emerging technique that uses near-infrared (NIR) laser light-generated heat to destroy tumor cells. However, complete tumor eradication by PTA therapy alone is difficult because heterogeneous heat distribution can lead to sublethal thermal dose in some areas of the tumor. Successful PTA therapy requires selective delivery of photothermal conducting nanoparticles to mediate effective PTA of tumor cells, and the ability to combine PTA with other therapy modalities. Here, we synthesized multifunctional doxorubicin (DOX)-loaded hollow gold nanospheres (DOX@HAuNS) that target EphB4, a member of the Eph family of receptor tyrosine kinases overexpressed on the cell membrane of multiple tumors and angiogenic blood vessels. Increased uptake of targeted nanoparticles T-DOX@HAuNS was observed in three EphB4-positive tumors both in vitro and in vivo. In vivo release of DOX from DOX@HAuNS, triggered by NIR laser, was confirmed by dual-radiotracer technique. Treatment with T-DOX@HAuNS followed by NIR laser irradiation resulted in significantly decreased tumor growth when compared with treatments with nontargeted DOX@HAuNS plus laser or HAuNS plus laser. The tumors in 6 of the 8 mice treated with T-DOX@HAuNS plus laser regressed completely with only residual scar tissue by 22 days following injection, and none of the treatment groups experienced a loss in body weight. Together, our findings show that concerted chemo-photothermal therapy with a single nanodevice capable of mediating simultaneous PTA and local drug release may have promise as a new anticancer therapy.

Systematic review: the applications of nanotechnology in gastroenterology

BACKGROUND

Over the past 30 years, nanotechnology has evolved dramatically. It has captured the interest of variety of fields from computing and electronics to biology and medicine. Recent discoveries have made invaluable changes to future prospects in nanomedicine; and introduced the concept of theranostics. This term offers a patient specific 'two in one' modality that comprises of diagnostic and therapeutic tools. Not only nanotechnology has shown great impact on improvements in drug delivery and imaging techniques, but also there have been several ground-breaking discoveries in regenerative medicine.

AIM

Gastroenterology invites multidisciplinary approach owing to high complexity of gastrointestinal (GI) system; it includes physicians, surgeons, radiologists, pharmacologists and many more. In this article, we concentrate on current developments in nano-gastroenterology.

METHODS

Literature search was performed using Web of Science and Pubmed search engines with terms--nanotechnology, nanomedicine and gastroenterology. Article search was concentrated on developments since 2005.

RESULTS

We have described original and innovative approaches in gastrointestinal drug delivery, inflammatory disease and cancer-target treatments. Here, we have reviewed advances in GI imaging using nanoparticles as fluorescent contrast, and their potential for site-specific targeting. This review has also depicted various approaches and novel discoveries in GI regenerative medicine using nanomaterials for scaffold designs and induced pluripotent stem cells as cell source.

CONCLUSIONS

Developments in nanotechnology have opened new range of possibilities to help our patients. This includes novel drug delivery vehicles, diagnostic tools for early and targeted disease detection and nanocomposite materials for tissue constructs to overcome cosmetic or physical disabilities.

Theranostic nanoplatforms for simultaneous cancer imaging and therapy: current approaches and future perspectives

Theranostics is a concept which refers to the integration of imaging and therapy. As an evolving new field, it is related to but different from traditional imaging and therapeutics. It embraces multiple techniques to arrive at a comprehensive diagnostic, in vivo molecular images and an individualized treatment regimen. More recently, there is a trend of tangling these efforts with emerging materials and nanotechnologies, in an attempt to develop novel platforms and methodologies to tackle practical issues in clinics. In this article, topics of rationally designed nanoparticles for the simultaneous imaging and therapy of cancer will be discussed. Several exemplary nanoparticle platforms such as polymeric nanoparticles, gold nanomaterials, carbon nanotubes, magnetic nanoparticles and silica nanoparticles will be elaborated on and future challenges of nanoparticle-based systems will be discussed.

Cancer theranostics with near-infrared light-activatable multimodal nanoparticles

Nanomaterials that interact with light provide a unique opportunity for applications in biophotonic nanomedicine. Image-guided therapies could be designed based on multifunctional nanoparticles (NPs). Such NPs have a strong and tunable surface plasmon resonance absorption in the near-infrared region and can be detected using multiple imaging modalities (magnetic resonance imaging, nuclear imaging, and photoacoustic imaging). These novel nanostructures, once introduced, are expected to home in on solid tumors either via a passive targeting mechanism (i.e., the enhanced permeability and retention effect) or via an active targeting mechanism facilitated by ligands bound to their surfaces. Once the NPs reach their target tissue, their activity can then be turned on using an external stimulus. For example, photothermal conducting NPs primarily act by converting light energy into heat. As a result, the temperature in the treatment volume is elevated above the thermal damage threshold, which kills the cells. This process, termed photothermal ablation therapy (PTA), is effective, but it is also unlikely to kill all tumor cells when used alone. In addition to PTA, photothermal conducting NPs can also efficiently trigger the release of drugs and activate RNA interference. A multimodal approach, which permits simultaneous PTA therapy, chemotherapy, and therapeutic RNA interference, has the potential to completely eradicate residual diseased cells. In this Account, we provide an up-to-date review of the synthesis and characterization, functionalization, and in vitro and in vivo evaluation of NIR lightactivatable multifunctional nanostructures used for imaging and therapy. We emphasize research on hollow gold nanospheres, magnetic core-shell gold nanoshells, and semiconductor copper monosulfide NPs. We discuss three types of novel drug delivery systems in which hollow gold nanospheres are used to mediate controlled drug release.

Image-guided prostate cancer therapy using aptamer-functionalized thermally cross-linked superparamagnetic iron oxide nanoparticles

CG-rich duplex containing prostate-specific membrane antigen (PSMA) aptamer-conjugated thermally cross-linked superparamagnetic iron oxide nanoparticles (TCL-SPIONs) is reported as prostate cancer-specific nanotheranostic agents. These agents are capable of prostate tumor detection in vivo by magnetic resonance imaging (MRI) and selective delivery of drugs to the tumor tissue, simultaneously. The prepared PSMA-functionalized TCL-SPION via a hybridization method (Apt-hybr-TCL-SPION) exhibited preferential binding towards target prostate-cancer cells (LNCaP, PSMA+) in both in vitro and in vivo when analyzed by T(2) -weighted MRI. After Dox molecules were loaded onto the Apt-hybr-TCL-SPION through the intercalation of Dox to the CG-rich duplex containing PSMA aptamer as well as electrostatic interaction between the Dox-and-polymer coating layer of the nanoparticles, the resulting Dox@Apt-hybr-TCL-SPION showed selective drug-delivery efficacy in the LNCaP xenograft mouse model. These results suggest that Dox@Apt-hybr-TCL-SPION has potential for use as novel prostate cancer-specific nanotheranostics.