Radionuclide 131I labeled reduced graphene oxide for nuclear imaging guided combined radio- and photothermal therapy of cancer

Controllable Synthesis of Gold Nanorod/Conducting Polymer Core/Shell Hybrids Toward in Vitro and in Vivo near-Infrared Photothermal Therapy

Photothermal therapy (PTT) is a minimally invasive tumor treatment technology, and is regarded as a potential anticancer strategy because of its targeted destruction and low toxicity. Specifically, near-infrared light-induced PTT has attracted intriguing interest because of the high transparency of tissue, blood, and water. However, effective PTT generally requires the assistance of photothermal agents. Gold nanorods (GNRs) and conducting polymer are often used as photothermal materials because of their high absorption efficiency and photothermal conversion efficiency. Herein, we combined GNRs with poly( o-methoxyaniline) (POMA, a polyaniline derivative) to form GNRs/POMA core/shell hybrids through the surfactant-assisted chemical oxidative polymerization route and studied their photothermal conversion properties. The configuration of GNRs/POMA core/shell hybrids has been precisely controlled through adjusting the monomer concentration, and the relationship between morphology and absorption band of GNRs/POMA core/shell hybrids has been revealed. Finally, the in vitro and in vivo experiments were performed, and the results indicated that the GNRs/POMA core/shell hybrids with optimized absorbance at around 808 nm exhibited the best performance on photothermal therapy under 808 nm NIR laser irradiation.

Therapy of cervical cancer using 131I-labeled nanoparticles

Objective

To evaluate the effectiveness of two kinds of Arg-Gly-Asp (RGD)-targeted ¹³¹I-containing nanoliposomes for the treatment of cervical cancer in vitro and in vivo.

Methods

The nanoparticle liposomes designated RGD-¹³¹I-tyrosine peptide chain (TPC)-L and ¹³¹I-RGD-L were prepared. The emulsion solvent evaporation method was used to encapsulate the polypeptide into liposomes. The quantity of entrapped polypeptide was measured using UV spectrophotometry. The labeling rates, radiochemical purities, and total radioactivities were measured using paper chromatography. Cytotoxicity was assessed using the MTS assay and flow cytometry. Therapeutic efficacy was monitored using a mouse xenograft model of cervical cancer.

Results

The labeling efficiency, radiochemical purity, and specific radioactivity of RGD-¹³¹I-TPC-L were greater than those of ¹³¹I-RGD-L. The cytotoxicity test indicated that late apoptosis of cells treated with RGD-¹³¹I-TPC-L and ¹³¹I-RGD-L was higher than that of cells treated with Na¹³¹I. The therapeutic effect of RGD-¹³¹I-TPC-L was better than that of ³¹I-RGD-L in the mouse model.

Conclusions

The specific activity of liposome-encapsulated RGD-¹³¹I-TPC-L was higher than that of ¹³¹I-RGD-L, which labeled liposomes directly. Moreover, the RGD-¹³¹I-TPC-L liposomes were more effective for killing xenografted tumor cells.

Pd nanosheets with their surface coordinated by radioactive iodide as a high-performance theranostic nanoagent for orthotopic hepatocellular carcinoma imaging and cancer therapy

We report a pH-sensitive multifunctional theranostic platform with radiolabeled Pd nanosheets through a simple mixture of ultra-small Pd nanosheets and radioisotopes utilizing the specific adsorption of ¹³¹I and ¹²⁵I on their surfaces.

Radiolabeled nanoparticles (NPs), taking advantage of nanotechnology and nuclear medicine, have shown attractive potential for cancer diagnosis and therapy. However, the high background signal in the liver and long-term toxic effects of radioisotopes caused by the nonselective accumulation of radiolabeled nanoparticles in organs have become the major challenges. Here, we report a pH-sensitive multifunctional theranostic platform with radiolabeled Pd nanosheets through a simple mixture of ultra-small Pd nanosheets and radioisotopes utilizing the strong adsorption of ¹³¹I and ¹²⁵I on their surfaces (denoted as ¹³¹I–Pd–PEG or ¹²⁵I–Pd–PEG). Systematic studies reveal that the labeling efficiency is higher than 98% and the adsorption of radioiodine is more stable in an acidic environment. In vivo studies further validate the pH-dependent behavior of this platform and the enhanced retention of radioisotopes in tumors due to the acidic microenvironment. Single photon emission computed tomography (SPECT) images with zero background were successfully achieved in a subcutaneous 4T1 tumor model, an orthotopic LM3 tumor model, and even in a Mst1/2 double-knockout hepatoma model. Moreover, the application of radiolabeled Pd nanosheets for photoacoustic (PA) imaging, and combined photothermal and radiotherapy was also explored. Therefore, this study provides a simple and efficient strategy to solve the critical high background issue of radiolabeled nanoparticles and shows enormous potential for clinical applications.

Radiotherapy-Sensitized Tumor Photothermal Ablation Using γ-Polyglutamic Acid Nanogels Loaded with Polypyrrole

Development of versatile nanoscale platforms for cancer diagnosis and therapy is of great importance for applications in translational medicine. In this work, we present the use of γ-polyglutamic acid (γ-PGA) nanogels (NGs) to load polypyrrole (PPy) for thermal/photoacoustic (PA) imaging and radiotherapy (RT)-sensitized tumor photothermal therapy (PTT). First, a double emulsion approach was used to prepare the cystamine dihydrochloride (Cys)-cross-linked γ-PGA NGs. Next, the cross-linked NGs served as a reactor to be filled with pyrrole monomers that were subjected to in situ oxidation polymerization in the existence of Fe(III) ions. The formed uniform PPy-loaded NGs having an average diameter of 38.9 ± 8.6 nm exhibited good water-dispersibility and colloid stability. The prominent near-infrared (NIR) absorbance feature due to the loaded PPy endowed the NGs with contrast enhancement in PA imaging. The hybrid NGs possessed excellent photothermal conversion efficiency (64.7%) and stability against laser irradiation, and could be adopted for PA imaging and PTT of cancerous cells and tumor xenografts. Importantly, we also explored the cooperative PTT and X-ray radiation-mediated RT for enhanced tumor therapy. We show that PTT of tumors can be more significantly sensitized by RT using the sequence of laser irradiation followed by X-ray radiation as compared to using the reverse sequence. Our study suggests a promising theranostic platform of hybrid NGs that may be potentially utilized for PA imaging and combination therapy of different types of tumors.

Iodine-131-labeled, transferrin-capped polypyrrole nanoparticles for tumor-targeted synergistic photothermal-radioisotope therapy

Combining different therapeutic functions within single tumor-targeted nanoscale delivery systems is promising to overcome the limitations of conventional cancer therapies. Herein, transferrin that recognizes transferrin receptors up-regulated on tumor cells is pre-labeled with iodine-131 (¹³¹I) and then utilized as the stabilizer in the fabrication of polypyrrole (PPy) nanoparticles. The obtained transferrin-capped PPy@Tf-¹³¹I nanoparticles could be used for tumor-targeted radioisotope therapy (RIT) and photothermal therapy (PTT), by employing beta-emission from ¹³¹I and the intrinsic high near-infrared (NIR) absorbance of PPy, respectively. Owing to the transferrin-mediated tumor targeting, PPy@Tf-¹³¹I nanoparticles exhibit obviously enhanced in vitro cancer cell binding and in vivo tumor uptake compared to its non-targeting counterpart. The combined RIT and PTT based on PPy@Tf-¹³¹I nanoparticles is then conducted, achieving a remarkable synergistic therapeutic effect. This work thus demonstrates a rather simple one-step approach to fabricate tumor-targeting nanoparticles based on protein-capped conjugated polymers, promising for combination cancer therapy with great efficacy and high safety.

Nano-graphene oxide-manganese dioxide nanocomposites for overcoming tumor hypoxia and enhancing cancer radioisotope therapy

While radiotherapy (RT) is commonly used in clinics for cancer treatment, the therapeutic efficiency is not satisfactory owing to the existence of the hypoxic tumor microenvironment which seriously affects the efficiency of RT. Herein, we design polyethylene glycol (PEG)-modified reduced nano-graphene oxide-manganese dioxide (rGO-MnO₂-PEG) nanocomposites to trigger oxygen generation from H₂O₂ to reduce the tumor hypoxic microenvironments. We use the radioisotope, ¹³¹I labeled rGO-MnO₂-PEG nanocomposites as therapeutic agents for in vivo tumor radioisotope therapy (RIT), achieving excellent tumor killing and further enhancing the therapeutic efficiency of RIT. More importantly, the dissolution of MnO₂ under acidic conditions and the redox process during the catalytic pathway of H₂O₂ decomposition in the cellular microenvironment direct to the production of an enormous amount of Mn²⁺ which has been used as a contrast agent for magnetic resonance imaging (MRI). Our proposed work provides a strategy to trigger oxygen formation via an internal stimulus to enhance imaging-guided RIT efficiency.

131I-Labeled Copper Sulfide-Loaded Microspheres to Treat Hepatic Tumors via Hepatic Artery Embolization

Purpose: Transcatheter hepatic artery embolization therapy is a minimally invasive alternative for treating inoperable liver cancer but recurrence is frequent. Multifunctional agents, however, offer an opportunity for tumor eradication. In this study, we were aim to synthesized poly (lactic-co-glycolic acid) (PLGA) microspheres encapsulating hollow CuS nanoparticles (HCuSNPs) and paclitaxel (PTX) that were then labeled with radioiodine-131 (¹³¹I) to produce ¹³¹I-HCuSNPs-MS-PTX. This compound combines the multi-theranostic properties of chemotherapy, radiotherapy and photothermal therapy. In addition, it can also be imaged with single photon emission computed tomography (SPECT) imaging and photoacoustic imaging. Methods: We investigated the value of therapeutic and imaging of ¹³¹I-HCuSNPs-MS-PTX in rats bearing Walker-256 tumor transplanted in the liver. After the intra-arterial (IA) injection of ¹³¹I-HCuSNPs-MS-PTX, ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) micro-positron emission tomography/computed tomography (micro-PET/CT) imaging was used to monitor the therapeutic effect. PET/CT findings were verified by immunohistochemical analysis. SPECT/CT and photoacoustic imaging were performed to demonstrate the distribution of ¹³¹I-HCuSNPs-MS-PTX in vivo. Results: We found that embolization therapy in combination with chemotherapy, radiotherapy and photothermal therapy offered by ¹³¹I-HCuSNPs-MS-PTX completely ablated the transplanted hepatic tumors at a relatively low dose. In comparison, embolization monotherapy or combination with one or two other therapies had less effective anti-tumor efficacy. The combination of SPECT/CT and photoacoustic imaging effectively confirmed microsphere delivery to the targeted tumors in vivo and guided the near-infrared laser irradiation. Conclusion: Our study suggests that there is a clinical theranostic potential for imaging-guided arterial embolization with ¹³¹I-HCuSNPs-MS-PTX for the treatment of liver tumors.

Analysis of iodinated quorum sensing peptides by LC-UV/ESI ion trap mass spectrometry

Five different quorum sensing peptides (QSP) were iodinated using different iodination techniques. These iodinated peptides were analyzed using a C₁₈ reversed phase HPLC system, applying a linear gradient of water and acetonitrile containing 0.1% (m/v) formic acid as mobile phase. Electrospray ionization (ESI) ion trap mass spectrometry was used for the identification of the modified peptides, while semi-quantification was performed using total ion current (TIC) spectra. Non-iodinated peptides and mono- and di-iodinated peptides (NIP, MIP and DIP respectively) were well separated and eluted in that order. Depending on the used iodination method, iodination yields varied from low (2%) to high (57%).

Intracellular Proteolytic Disassembly of Self-Quenched Near-Infrared Nanoparticles Turning Fluorescence on for Tumor-Targeted Imaging

The design of tumor-targeting, intracellular protease-activatable near-infrared fluorescence (NIRF) nanoprobes is broadly interesting but remains challenging. In this work, we report the rational design of a NIR probe Cys(StBu)-Lys(Biotin)-Lys-Lys(Cy5.5)-CBT (1) to facilely prepare the self-quenched nanoparticles 1-NPs for tumor-targeted imaging in vitro and in vivo. The biotinylated 1-NPs could be actively uptaken by biotin receptor-overexpressing tumor cells via receptor-mediated endocytosis. Upon intracellular proteolytic cleavage, 1-NPs were disassembled to yield the small molecular probe Lys(Cy5.5)-Luciferin-Lys(Biotin)-Lys-OH (1-D-cleaved), accompanied by fluorescence "Turn-On". With this NIRF "Turn-On" property, 1-NPs were successfully applied for tumor-targeted imaging. We envision that our nanoparticles could be applied for fluorescence-guided tumor surgery in the near future.

Graphene Oxide/Ag Nanoparticles Cooperated with Simvastatin as a High Sensitive X-Ray Computed Tomography Imaging Agent for Diagnosis of Renal Dysfunctions

Graphene oxides (GO) are attracting much attention in the diagnosis and therapy of the subcutaneous tumor as a novel biomaterial, but its diagnosis to tissue dysfunction is yet to be found. Here, a novel application of GO for diagnosis of renal dysfunction via contrast-enhanced computed tomography (CT) is proposed. In order to serve as contrast-enhanced agent, Ag nanoparticles (AgNPs) are composited on the surface of GO to promote its X-ray absorption, and then simvastatin is coinjected for eliminating in vivo toxicity induced by AgNPs. It is found that GO/AgNPs can enhance the imaging of CT into the lung, liver, and kidney of mice for a long circulation time (≈24 h) and a safety profile in vivo in the presence of simvastatin. Interestingly, the lower dose of GO/AgNPs (≈0.5 mg per kg bw) shows an excellent performance for CT imaging of renal perfusion, and visually exhibits the right renal dysfunction in model mice. Hence, this work suggests that graphene nanoparticles will play a vital role for the future medical translational development including drug carrier, biosensing, and disease therapy.

Emerging Nanotechnology and Advanced Materials for Cancer Radiation Therapy

Radiation therapy (RT) including external beam radiotherapy (EBRT) and internal radioisotope therapy (RIT) has been widely used for clinical cancer treatment. However, owing to the low radiation absorption of tumors, high doses of ionizing radiations are often needed during RT, leading to severe damages to normal tissues adjacent to tumors. Meanwhile, the RT efficacies are limited by different mechanisms, among which the tumor hypoxia-associated radiation resistance is a well-known one, as there exists hypoxia inside most solid tumors while oxygen is essential to enhance radiation-induced DNA damages. With the development in nanotechnology, there have been great interests in using nanomedicine strategies to enhance radiation responses of tumors. Nanomaterials containing high-Z elements to absorb radiation rays (e.g. X-ray) can act as radio-sensitizers to deposit radiation energy within tumors and promote treatment efficacy. Nanoscale carriers are able to deliver therapeutic radioisotopes into tumors for internal RIT, or chemotherapeutic drugs for synergistically combined chemo-radiotherapy. As uncovered in recent studies, the tumor microenvironment could be modulated by various nanomedicine approaches to overcome hypoxia-associated radiation resistance. Herein, the authors will summarize the applications of nanomedicine for RT cancer treatment, and pay particular attention to the latest development of 'advanced materials' for enhanced cancer RT.

Positron emission tomography and nanotechnology: A dynamic duo for cancer theranostics

Development of novel imaging probes for cancer diagnosis is critical for early disease detection and management. The past two decades have witnessed a surge in the development and evolution of radiolabeled nanoparticles as a new frontier in personalized cancer nanomedicine. The dynamic synergism of positron emission tomography (PET) and nanotechnology combines the sensitivity and quantitative nature of PET with the multifunctionality and tunability of nanomaterials, which can help overcome certain key challenges in the field. In this review, we discuss the recent advances in radionanomedicine, exemplifying the ability to tailor the physicochemical properties of nanomaterials to achieve optimal in vivo pharmacokinetics and targeted molecular imaging in living subjects. Innovations in development of facile and robust radiolabeling strategies and biomedical applications of such radionanoprobes in cancer theranostics are highlighted. Imminent issues in clinical translation of radiolabeled nanomaterials are also discussed, with emphasis on multidisciplinary efforts needed to quickly move these promising agents from bench to bedside.

Black Phosphorus Nanosheet-Based Drug Delivery System for Synergistic Photodynamic/Photothermal/Chemotherapy of Cancer

A black phosphorus (BP)-based drug delivery system for synergistic photodynamic/photothermal/chemotherapy of cancer is constructed. As a 2D nanosheet, BP shows super high drug loading capacity and pH-/photoresponsive drug release. The intrinsic photothermal and photodynamic effects of BP enhance the antitumor activities. The synergistic photodynamic/photothermal/chemotherapy makes BP-based drug delivery system a multifunctional nanomedicine platform.

Recent advances in carbon based nanosystems for cancer theranostics

This review deals with four different types of carbon allotrope based nanosystems and summarizes the results of recent studies that are likely to have applications in cancer theranostics. We discuss the applications of these nanosystems for cancer imaging, drug delivery, hyperthermia, and PDT/TA/PA.

131I-labeled and DOX-loaded multifunctional nanoliposomes for radiotherapy and chemotherapy in brain gliomas

The codelivery of different therapeutics is a promising option because of its synergetic effects of drugs. In this study, a new combination therapy that used the doxorubicin-loaded and ¹³¹I-labeled nanoliposomes (¹³¹I-DOX-NL) was proposed to delay tumor growth of gliomas, which are characterized by significant mortality and morbidity. ¹³¹I-DOX-NL was constructed based on bovine serum albumin (BSA)-tailor made hydrophobic maleimide-functionalized poly(ε-caprolactone) (PCL) (Fig. 1) and was evaluated by cellular viability in vitro and by U87 xenograft models in vivo. Compared with using ¹³¹I-NL or DOX-NL alone, our experimental results show that ¹³¹I-DOX-NL exhibits similar high cellular uptake but enhanced efficacy to cure gliomas because of its codelivery of ¹³¹I and DOX. In the U87 mouse tumor models, the combination therapy resulted in higher survival rates of mice and smaller tumor sizes than monotherapy did alone. In conclusion, multifunctional nanoliposome ¹³¹I-DOX-NL is a good candidate for the codelivery of ¹³¹I-mediated radiotherapy and DOX-mediated chemotherapy due to its ability to inhibit U87 cell proliferation and tumor growth. ¹³¹I-DOX-NL can be used as a promising effective therapy for malignant gliomas and deserves further investigation.

Synthetic nanoparticles for delivery of radioisotopes and radiosensitizers in cancer therapy

Radiotherapy has been, and will continue to be, a critical modality to treat cancer. Since the discovery of radiation-induced cytotoxicity in the late 19th century, both external and internal radiation sources have provided tremendous benefits to extend the life of cancer patients. Despite the dramatic improvement of radiation techniques, however, one challenge persists to limit the anti-tumor efficacy of radiotherapy, which is to maximize the deposited dose in tumor while sparing the rest of the healthy vital organs. Nanomedicine has stepped into the spotlight of cancer diagnosis and therapy during the past decades. Nanoparticles can potentiate radiotherapy by specifically delivering radionuclides or radiosensitizers into tumors, therefore enhancing the efficacy while alleviating the toxicity of radiotherapy. This paper reviews recent advances in synthetic nanoparticles for radiotherapy and radiosensitization, with a focus on the enhancement of in vivo anti-tumor activities. We also provide a brief discussion on radiation-associated toxicities as this is an area that, up to date, has been largely missing in the literature and should be closely examined in future studies involving nanoparticle-mediated radiosensitization.

Enhanced Radiosensitization of Gold Nanospikes via Hyperthermia in Combined Cancer Radiation and Photothermal Therapy

Metallic nanostructures as excellent candidates for nanosensitizers have shown enormous potentials in cancer radiotherapy and photothermal therapy. Clinically, a relatively low and safe radiation dose is highly desired to avoid damage to normal tissues. Therefore, the synergistic effect of the low-dosed X-ray radiation and other therapeutic approaches (or so-called "combined therapeutic strategy") is needed. Herein, we have synthesized hollow and spike-like gold nanostructures by a facile galvanic replacement reaction. Such gold nanospikes (GNSs) with low cytotoxicity exhibited high photothermal conversion efficiency (η = 50.3%) and had excellent photostability under cyclic near-infrared (NIR) laser irradiations. We have demonstrated that these GNSs can be successfully used for in vitro and in vivo X-ray radiation therapy and NIR photothermal therapy. For the in vitro study, colony formation assay clearly demonstrated that GNS-mediated photothermal therapy and X-ray radiotherapy reduced the cell survival fraction to 89% and 51%, respectively. In contrast, the cell survival fraction of the combined radio- and photothermal treatment decreased to 33%. The synergistic cancer treatment performance was attributable to the effect of hyperthermia, which efficiently enhanced the radiosensitizing effect of hypoxic cancer cells that were resistant to ionizing radiation. The sensitization enhancement ratio (SER) of GNSs alone was calculated to be about 1.38, which increased to 1.63 when the GNS treatment was combined with the NIR irradiation, confirming that GNSs are effective radiation sensitizers to enhance X-ray radiation effect through hyperpyrexia. In vivo tumor growth study indicated that the tumor growth inhibition (TGI) in the synergistically treated group reached 92.2%, which was much higher than that of the group treated with the GNS-enhanced X-ray radiation (TGI = 29.8%) or the group treated with the GNS-mediated photothermal therapy (TGI = 70.5%). This research provides a new method to employ GNSs as multifunctional nanosensitizers for synergistic NIR photothermal and X-ray radiation therapy in vitro and in vivo.

Transformation of graphene oxide by chlorination and chloramination: Implications for environmental transport and fate

The rapidly increasing and widespread use of graphene oxide (GO) calls for immediate attention on the environmental fate of this material. To date, very little is known about the environmental transformation of GO. This study explored the changes of physicochemical properties of GO from chlorination and chloramination, which simulated the reactions occurring in water and wastewater treatment systems. Significant changes of GO surface O-functionalities occurred and scrolling of graphene sheets (those of very large sizes) were observed upon the treatments. Chloroform, a byproduct from chlorination was also detected, indicating the ring-opening on the edge of GO nanosheets. The changes of GO surface O-functionalities were attributable to the oxidation of quinone groups of GO by chlorine or chloramine. The scrolling of large-sized GO sheets may be attributable to the destruction of benzene rings at the edge of the GO. The results of membrane filtration experiments and column transport experiments indicated that chlorination and chloramination enhanced the mobility and transport of GO, likely by increasing the colloidal stability and inhibiting the agglomeration of GO nanosheets. The findings of this study further underline the significant implications of GO transformation on the fate and transport of this new nanomaterial.

Synergistic thermoradiotherapy based on PEGylated Cu3BiS3 ternary semiconductor nanorods with strong absorption in the second near-infrared window

In this work, we report a successful synthesis of copper bismuth sulfide nanorods (NRs) with broad and strong photoabsorption ranging from ultraviolet (UV) to near-infrared (NIR) wavelengths, which can be used as a 1064 nm-laser-driven photothermal agent with the photothermal conversion efficiency of 40.7%, noticeably higher than most of the reported PTT agents working in NIR-II window. The as-prepared PEGylated Cu₃BiS₃ NRs were used as photoacoustic imaging (PAI) and CT imaging agents due to their strong NIR absorption and large X-ray attenuation coefficient of bismuth. We are the first to demonstrate that a small quantity of PEGylated Cu₃BiS₃ NRs in tumors can concentrate radiation energy and trigger mild PTT under NIR-II irradiation and thus, these particles could be used as a novel, synergistic thermoradiotheraputic agent that enhances the efficacy of radiotherapy.

Stimuli responsive drug delivery systems based on nano-graphene for cancer therapy

Nano-graphene as a class of two-dimensional sp² carbon nanomaterial has attracted tremendous attentions in various fields in the past decade. Utilizing its unique physical and chemical properties, nano-graphene has also shown great promises in the area of biomedicine, for application in biosensing, imaging and therapy. In particular, with all atoms exposed on its surface, nano-graphene exhibits ultra-high surface area available for efficient binding/loading of various biomolecules of interests, and has been widely used as multifunctional nano-carriers for drug and gene delivery. In this review article, we will summarize the recent advances in the development of nano-graphene as stimuli-responsive nano-carriers for drug delivery, as well as the applications of these smart systems for cancer therapy.

MoS2 Quantum Dot@Polyaniline Inorganic-Organic Nanohybrids for in Vivo Dual-Modal Imaging Guided Synergistic Photothermal/Radiation Therapy

In this study, we introduce a versatile nanomaterial based on MoS2 quantum dot@polyaniline (MoS2@PANI) inorganic-organic nanohybrids, which exhibit good potential to not only enhance photoaccoustic (PA) imaging/X-ray computed tomography (CT) signal but also perform efficient radiotherapy (RT)/photothermal therapy (PTT) of cancer. Upon the intravenous injection of MoS2@PANI hybrid nanoparticles, the in vivo tumor could be precisely positioned and thoroughly eliminated under the PA/CT image-guided combination therapy of PTT/RT. This versatile nanohybrid could show good potential to facilitate simultaneously dual-modal imaging and synergetic PTT/RT to realize better anticancer efficiency.

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.

A Donor-Acceptor Conjugated Polymer with Alternating Isoindigo Derivative and Bithiophene Units for Near-Infrared Modulated Cancer Thermo-Chemotherapy

Conjugated polymers containing alternating donor/acceptor units have strong and sharp absorbance peaks in near-infrared (NIR) region, which could be suitable for photothermal therapy. However, these polymers as photothermal transducers are rarely reported because of their water insolubility, which limits their applications for cancer therapy. Herein, we report the donor-acceptor conjugated polymer PBIBDF-BT with alternating isoindigo derivative (BIBDF) and bithiophene (BT) units as a novel photothermal transducer, which exhibited strong near-infrared (NIR) absorbance due to its low band gap (1.52 eV). To stabilize the conjugated polymer physiological environments, we utilized an amphiphilic copolymer, poly(ethylene glycol)-block-poly(hexyl ethylene phosphate) (mPEG-b-PHEP), to stabilize PBIBDF-BT-based nanoparticles (PBIBDF-BT@NPPPE) through a single emulsion method. The obtained nanoparticles PBIBDF-BT@NPPPE showed great stability in physiological environments and excellent photostability. Moreover, the PBIBDF-BT@NPPPE exhibited high photothermal conversion efficiency, reaching 46.7%, which is relatively high compared with those of commonly used materials for photothermal therapy. Accordingly, in vivo and in vitro experiments demonstrated that PBIBDF-BT@NPPPE exhibits efficient photothermal anticancer efficacy. More importantly, PBIBDF-BT@NPPPE could simultaneously encapsulate other types of therapeutic agents though hydrophobic interactions with the PHEP core and achieve NIR-triggered intracellular drug release and a synergistic combination therapy of thermo-chemotherapy for the treatment of cancer.

Rhenium-188 Labeled Tungsten Disulfide Nanoflakes for Self-Sensitized, Near-Infrared Enhanced Radioisotope Therapy

Radioisotope therapy (RIT), in which radioactive agents are administered or implanted into the body to irradiate tumors from the inside, is a clinically adopted cancer treatment method but still needs improvement to enhance its performances. Herein, it is found that polyethylene glycol (PEG) modified tungsten disulfide (WS2 ) nanoflakes can be easily labeled by (188) Re, a widely used radioisotope for RIT, upon simple mixing. Like other high-Z elements acting as radiosensitizers, tungsten in the obtained (188) Re-WS2 -PEG would be able to absorb ionization radiation generated from (188) Re, enabling ''self-sensitization'' to enhance the efficacy of RIT as demonstrated in carefully designed in vitro experiments of this study. In the meanwhile, the strong NIR absorbance of WS2 -PEG could be utilized for NIR light-induced photothermal therapy (PTT), which if applied on tumors would be able to greatly relieve their hypoxia state and help to overcome hypoxia-associated radioresistance of tumors. Therefore, with (188) Re-WS2 -PEG as a multifunctional agent, which shows efficient passive tumor homing after intravenous injection, in vivo self-sensitized, NIR-enhanced RIT cancer treatment is realized, achieving excellent tumor killing efficacy in a mouse tumor model. This work presents a new concept of applying nanotechnology in RIT, by delivering radioisotopes into tumors, self-sensitizing the irradiation-induced cell damage, and modulating the tumor hypoxia state to further enhance the therapeutic outcomes.

Long circulating reduced graphene oxide-iron oxide nanoparticles for efficient tumor targeting and multimodality imaging

Polyethylene glycol (PEG) surface modification is one of the most widely used approaches to improve the solubility of inorganic nanoparticles, prevent their aggregation and prolong their in vivo blood circulation half-life. Herein, we developed double-PEGylated biocompatible reduced graphene oxide nanosheets anchored with iron oxide nanoparticles (RGO-IONP-(1st)PEG-(2nd)PEG). The nanoconjugates exhibited a prolonged blood circulation half-life (∼27.7 h) and remarkable tumor accumulation (>11 %ID g(-1)) via an enhanced permeability and retention (EPR) effect. Due to the strong near-infrared absorbance and superparamagnetism of RGO-IONP-(1st)PEG-(2nd)PEG, multimodality imaging combining positron emission tomography (PET) imaging with magnetic resonance imaging (MRI) and photoacoustic (PA) imaging was successfully achieved. The promising results suggest the great potential of these nanoconjugates for multi-dimensional and more accurate tumor diagnosis and therapy in the future.

Multifunctional Inorganic Nanoparticles: Recent Progress in Thermal Therapy and Imaging

Nanotechnology has enabled the development of many alternative anti-cancer approaches, such as thermal therapies, which cause minimal damage to healthy cells. Current challenges in cancer treatment are the identification of the diseased area and its efficient treatment without generating many side effects. Image-guided therapies can be a useful tool to diagnose and treat the diseased tissue and they offer therapy and imaging using a single nanostructure. The present review mainly focuses on recent advances in the field of thermal therapy and imaging integrated with multifunctional inorganic nanoparticles. The main heating sources for heat-induced therapies are the surface plasmon resonance (SPR) in the near infrared region and alternating magnetic fields (AMFs). The different families of inorganic nanoparticles employed for SPR- and AMF-based thermal therapies and imaging are described. Furthermore, inorganic nanomaterials developed for multimodal therapies with different and multi-imaging modalities are presented in detail. Finally, relevant clinical perspectives and the future scope of inorganic nanoparticles in image-guided therapies are discussed.

Radio-graphene in Theranostic Perspectives

Owing to its unique physicochemical properties such as high surface area, notable biocompatibility, robust mechanical strength, high thermal conductivity, and ease of functionalization, 2D-layered graphene has received tremendous attention as a futuristic nanomaterial and its-associated research has been rapidly evolving in a variety of fields. With the remarkable advances of graphene especially in the biomedical realm, in vivo evaluation techniques to examine in vivo behavior of graphene are largely demanded under the hope of clinical translation. Many different types of drugs such as the antisense oligomer and chemotherapeutics require optimal delivery conveyor and graphene is now recognized as a suitable candidate due to its simple and high drug loading property. Termed as 'radio-graphene', radioisotope-labeled graphene approach was recently harnessed in the realm of biomedicine including cancer diagnosis and therapy, contributing to the acquisition of in vivo information for targeted drug delivery. In this review, we highlight current examples for bioapplication of radiolabeled graphene with brief perspectives on future strategies in its extensive bio- or clinical applications.

Tungsten Sulfide Quantum Dots as Multifunctional Nanotheranostics for In Vivo Dual-Modal Image-Guided Photothermal/Radiotherapy Synergistic Therapy

Designing a multifunctional nanomedicine for integration of precise diagnosis and effective treatment of tumors is desirable but remains a great challenge. Here, we report a multifunctional nanomedicine based on WS2 quantum dots (QDs), which was prepared by a facile and "green" method through physical grinding and ultrasonication. The as-obtained WS2 QDs with small size (3 nm) possess not only significant X-ray computed tomography (CT)/photoaccoustic (PA) imaging signal enhancement but also remarkable photothermal therapy (PTT)/radiotherapy (RT) synergistic effect for tumor treatment. With CT/PA imaging and the synergistic effect between PTT and RT, the tumor could be accurately positioned and thoroughly eradicated in vivo after intravenous injection of WS2 QDs. Moreover, hematoxylin and eosin staining, blood hematology, and biochemistry analysis revealed no noticeable toxicity of WS2 QDs in vitro and in vivo, which confirmed that WS2 QDs possess good biocompatibility. This multifunctional nanoparticle could play an important role in facilitating simultaneously multimodal imaging and synergistic therapy between PTT and RT to achieve better therapeutic efficacy.

Green fabricated reduced graphene oxide: evaluation of its application as nano-carrier for pH-sensitive drug delivery

A green and mild approach for the preparation of reduced graphene oxide (rGO) was proposed by using riboflavin-5'-phosphate sodium salt dihydrate as a reducing reagent and stabilizer without any other reagent. The fabricated nano-rGO was systematically evaluated for its application as nano-carrier for pH-sensitive drug delivery. The hemolytic toxicity test indicated the as-prepared nano-rGO had negligible hemolytic activity, which demonstrating its safety in drug delivery system. Doxorubicin hydrochloride (DOX) as a model drug was successfully attached onto the surface of nano-rGO via strong π-π stacking interaction. Compared with common carriers, the obtained DOX-loaded nano-rGO nanohybrid exhibited characteristics of high drug loading content, good stability, pH-sensitive and sustainable release of drugs. Cytotoxicity assay results suggested such nanohybrid exhibited effective cytotoxicity to MCF-7 and A549 cells by nonspecific endocytosis mechanism. Therefore, the present green fabricated rGO could be a good candidate as an ideal nano-carrier for drug delivery and controlled release.

Nanoscale theranostics for physical stimulus-responsive cancer therapies

Physical stimulus-responsive therapies often employing multifunctional theranostic agents responsive to external physical stimuli such as light, magnetic field, ultra-sound, radiofrequency, X-ray, etc., have been widely explored as novel cancer therapy strategies, showing encouraging results in many pre-clinical animal experiments. Unlike conventional cancer chemotherapy which often accompanies with severe toxic side effects, physical stimulus-responsive agents usually are non-toxic by themselves and would destruct cancer cells only under specific external stimuli, and thus could offer greatly reduced toxicity and enhanced treatment specificity. In addition, physical stimulus-responsive therapies can also be combined with other traditional therapeutics to achieve synergistic anti-tumor effects via a variety of mechanisms. In this review, we will summarize the latest progress in the development of physical stimulus-responsive therapies, and discuss the important roles of nanoscale theranostic agents involved in those non-conventional therapeutic strategies.