Rhenium disulfide (ReS2) with distinct physicochemical properties has shown promising potential in disease theranostics, such as drug delivery, computed tomography (CT), radiotherapy, and photothermal therapy (PTT). However, the synthesis and post-modification of ReS2 agents for different application scenarios are time- and energy-consuming, which seriously hinders the clinical translation of ReS2. Herein, we proposed three facile excipient strategies for different theranostic applications of ReS2 just through the flexible use of commercial ReS2 powder. Three excipients, including sodium alginate (ALG), xanthan gum (XG), and ultraviolet-cured resin (UCR), were used to prepare different dosage forms of commercial ReS2 powder, like hydrogel, suspension, and capsule, respectively. These dosage forms of ReS2 with distinct characteristics showed great potential for second near-infrared window PTT against tumours, gastric spectral CT imaging, and functional evaluation of the digestive tract in vivo. In addition, these ReS2 formulations exhibited good biocompatibility both in vitro and in vivo, showing a promising prospect for clinical transformation. More importantly, the facile excipient strategies for commercial agents pave a bridge to the development and wide bioapplication of many other theranostic biomaterials.

Recently, spectral computed tomography (CT) technology has received great interest in the field of radiology. Spectral CT imaging utilizes the distinct, energy-dependent X-ray absorption properties of substances in order to provide additional imaging information. Dual-energy CT and multi-energy CT (Spectral CT) are capable of constructing monochromatic energy images, material separation images, energy spectrum curves, constructing effective atomic number maps, and more. However, poor contrast, due to neighboring X-ray attenuation of organs and tissues, is still a challenge to spectral CT. Hence, contrast agents (CAs) are applied for better differentiation of a given region of interest (ROI). Currently, many different kinds of inorganic nanoparticulate CAs for spectral CT have been developed due to the limitations of clinical iodine (I)-based contrast media, leading to the conclusion that inorganic nanomedicine applied to spectral CT will be a powerful collaboration both in basic research and in clinics. In this review, the underlying principles and types of spectral CT techniques are discussed, and some evolving clinical diagnosis applications of spectral CT techniques are introduced. In particular, recent developments in inorganic CAs used for spectral CT are summarized. Finally, the challenges and future developments of inorganic nanomedicine in spectral CT are briefly discussed.

Spectral computed tomography (CT) imaging as a novel imaging technique shows promising prospects in the accurate diagnosis of various diseases. However, clinically iodinated contrast agents suffer from poor signal-to-noise ratio, and emerging heavy-metal-based CT contrast agents arouse great biosafety concern. Herein, we show the fabrication of rhenium sulfide (ReS₂) nanoparticles, a clinic radiotherapy sensitizer, as a biosafe spectral CT contrast agent for the gastrointestinal tract imaging and tumor theranostics in vivo by teaching old drugs new tricks. The ReS₂ nanoparticles were fabricated in a one-pot facile method at room temperature, and exhibited sub-10 nm size, favorable monodispersity, admirable aqueous solubility, and strong X-ray attenuation capability. More importantly, the proposed nanoparticles possess an outstanding spectral CT imaging ability and undoubted biosafety as a clinic therapeutic agent. Besides, the ReS₂ nanoparticles possess appealing photothermal performance due to their intense near-infrared absorption. The proposed nano-agent not only guarantees obvious contrast enhancement in gastrointestinal tract spectral CT imaging in vivo, but also allows effective CT imaging-guided tumor photothermal therapy. The proposed "teaching old drugs new tricks" strategy shortens the time and cuts the cost required for clinical application of nano-agents based on existing clinical toxicology testing and trial results, and lays down a low-cost, time-saving, and energy-saving method for the development of multifunctional nano-agents toward clinical applications.

The purpose of this study was to review the role of radioactive microparticles (1-100 μm) for the treatment of solid tumors and provide a comprehensive overview of the feasibility, safety, and efficacy.

A systematic search was performed in MEDLINE, EMBASE, and The Cochrane Library (January 2017) by combining synonyms for the determinants "tumor," "injection," and "radionuclide." Data on injection technique, toxicity, tumor response, and survival were collected.

The search yielded 7271 studies, and 37 were included for analysis. Twelve studies were performed in human patients and 25 animal studies. The studies were heterogeneous in patient population, tumors, follow-up time, and treatment characteristics. The direct intratumoral injection of radioactive microparticles resulted in a response rate of 71% in a variety of tumors and uncomplicated procedures with high cumulative doses of >19,000 Gy were reported.

The large variety of particles, techniques, and treated tumors in the studies provided an important insight into issues concerning efficacy, safety, particle and isotope choice, and other concepts for future research. Animal studies showed efficacy and a dose response. Most studies in humans concluded that intratumoral treatment with radioactive beta-emitting microparticles is relatively safe and effective. Conflicting evidence about safety and efficacy might be explained by the considerable variation in the treatment characteristics. Larger particles had a better retention which resulted in higher anti-tumor effect. Leakage seems to follow the path of least resistance depending on anatomical structures. Subsequently, a grid-like injection procedure with small volume depots is advised over a single large infusion. Controlled image-guided treatment is necessary because inadequate local delivery and inhomogeneous dose distribution result in reduced treatment efficacy and in potential complications.

Our previous studies revealed that the PLGA-based particulate systems loaded with cucurbitacin showed limited anti-melanoma efficiency in xenograft animal models after intratumoral injection, which was due to the undesirable initial burst release and the leakage of the particulate carriers from the injection site through the pinhole. In this paper, two categories of in situ-forming implants (ISFIs) for intratumoral injection, PLGA ISFIs and SAIB ISFIs, were systemically evaluated for their potentials for on solid tumor treatment via intratumoral injection. The in vitro drug release profiles of these two ISFIs were different due to the different sol-gel transition properties. The pharmacodynamics results revealed that SAIB ISFIs displayed obvious therapeutic efficiencies to melanoma, and multi-points injection of SASIB ISFIs displayed better efficiency than single-point injection. The different sol-gel transition properties and mechanism for PLGA ISFIs and SAIB ISFIs affected both the drug release and strongly impacted the pharmacokinetic parameters and pharmacodynamic effectiveness. Also, the adhesive property of SAIB to the local tissue could extend the retention and inhibit the leakage of the SAIB ISFIs, thus enhanced the anticancer effectiveness. Comparison of the various intratumoral injection systems, appropriate drug release profiles (lower initial burst and steady release) and good retention (minimum leakage from the injection site) would benefit to the antitumor effects of the intratumoral depots.

Many radiopharmaceuticals have been studied as radiation synovectomy agents. In this study, we developed a new potential agent for radiation synovectomy: poly(lactic acid)-histidine (PLA-his) microspheres radiolabelled with [188Re(CO)3(H2O)3]+.

The reaction conditions for the chelation of [188Re(CO)3(H2O)3]+ and the radiolabelling of PLA microspheres were optimized and the stabilities for both steps tested in vitro.

The chelation efficiency of [188Re(CO)3(H2O)3]+ reached 93.12 +/- 1.82% with >95% radiochemical purity once the colloidal and free 188Re were removed by a small Sep-Pak column (Plus QMA). More than 90% of radioactivity stayed in the [188Re(CO)3(H2O)3]+ form over 5 h. The radiolabelling efficiency of PLA-his microspheres with [188Re(CO)3(H2O)3]+ was above 92%. After 3 days incubation at 37 degrees C in calf serum, more than 80% of the radioactivity was still bound to the microspheres.

Such microspheres are potentially useful as a radiation synovectomy agent for the treatment of chronically inflamed arthritic joints. Furthermore, they might be valuable in cancer brachytherapy.

While breast cancer is still increasing in frequency, new diagnostic procedures are now available to challenge existing procedures and to make diagnosis of breast cancer more accurate and reliable. Mammography remains the standard investigation to reveal disease in an asymptomatic population: it can also be used to diagnose breast cancer in symptomatic patients (e.g. those with palpable breast lumps) and for guiding fine needle aspiration (FNA). Because the majority of breast lumps are benign, the challenge is to distinguish benign from malignant lesions without the use of invasive methods and this has attracted nuclear medicine physicians and medical oncologists to investigate the role of scintigraphic procedures to identify which patients require FNA. This review attempts to shed light on the various scintigraphic methods available which are of potential practical use in the assessment of malignant breast disease as well as looking at the possible role of nuclear medicine in the treatment of advanced disease.

For homogeneous delivery of beta radiation to skin cancer, we developed a simple method for preparing (188) Re-labeled nitrocellulose paper. The homogeneity and stability of the labeled paper were investigated. Absorbed dose estimates were calculated using the Monte-Carlo method. A 74-MBq (188) Re-labeled paper with 1-cm diameter delivered 147.2 Gy up to 1-mm depth after 2-h irradiation. Animal experiments on tumor-bearing mice showed that 50 Gy is an adequate dose for treating skin cancer. Tumors disappeared 7 days after irradiation in all the groups irradiated by 50 or 100 Gy. The (188) Re-labeled paper provided a convenient, economical, effective, and non-invasive method of treating skin cancer.

Hepatocellular carcinoma (HCC) is one of the most common malignancies in China. Direct intratumoral injection of nonremovable radioactive material has been widely studied because it could deliver high doses of radiation to target sites and minimize radiation leakage to non-target organs or tissues. Thirty nude mice bearing SMMC 7721 human liver carcinoma were used for the biodistribution study after intratumoral injection of [(188)Re]rhenium sulfide suspension or sodium [(188)Re]perrhenate solution. Another 30 tumor-bearing mice were divided into six groups, four groups of which were treated with a 0.1 ml [(188)Re]rhenium sulfide suspension at doses of 3.7, 7.4, 18.5, 29.6 MBq by a single intratumoral injection. For control studies, to study the tumor inhibiting ratio, the remaining two groups were injected with nonradioactive rhenium sulfide suspension and Hanks' balanced salt solution, respectively. The injections were repeated 6 days later. The retention percentages of radioactivity (%ID) in tumors injected with [(188)Re]rhenium sulfide suspension were 90.96+/-6.63%, 86.09+/-22.58% and 87.62+/-13.97% at 1, 24 and 48 h, respectively. Tumor inhibition ratios are as high as 89% when the outer space of tumor (0.5-0.6 cm from center) received about 507.6 Gy doses. Intratumoral injection of [(188)Re]rhenium sulfide suspension results in high tumor retention indicating this approach has strong potential for the treatment of hepatic carcinoma.