Astatine-211 (²¹¹At) has emerged as a promising radionuclide for targeted alpha therapy of cancer by virtue of its favorable nuclear properties. However, the limited in vivo stability of ²¹¹At-labeled radiopharmaceuticals remains a major challenge. This review provides a comprehensive overview of the current strategies for ²¹¹At radiolabeling, including nucleophilic and electrophilic substitution reactions, as well as the recent advances in the development of novel bifunctional coupling agents and labeling approaches to enhance the stability of ²¹¹At-labeled compounds. The preclinical and clinical applications of ²¹¹At-labeled radiopharmaceuticals, including small molecules, peptides, and antibodies, are also discussed. Looking forward, the identification of new molecular targets, the optimization of ²¹¹At production and quality control methods, and the continued evaluation of ²¹¹At-labeled radiopharmaceuticals in preclinical and clinical settings will be the key to realizing the full potential of ²¹¹At-based targeted alpha therapy. With the growing interest and investment in this field, ²¹¹At-labeled radiopharmaceuticals are poised to play an increasingly important role in future cancer treatment.

Photothermal therapy (PTT), a rapidly advancing non-invasive cancer treatment modality, utilizes photothermal agents to convert light energy into thermal energy, enabling precise and localized destruction of cancer cells. Recent developments have focused on photothermal agents operating in the second near-infrared (NIR-II) biological window (1000–1350 nm), which offer enhanced tissue penetration depth and improved therapeutic precision for deep-seated tumors while minimizing collateral damage to healthy tissues. In this study, we developed a novel class of nitrogen-doped carbon dots (N-CDs) through a facile one-pot hydrothermal synthesis approach. The synthesized N-CDs demonstrate remarkable dual functionality, exhibiting both superior photothermal performance and fluorescence imaging capabilities within the NIR region, thereby enabling simultaneous tumor diagnosis and therapy. These N-CDs display exceptional biocompatibility and achieve impressive photothermal conversion efficiencies of 31.25% and 27.12% under 808 nm and 1060 nm laser irradiation, respectively, with corresponding temperature changes of 42.8 ℃ and 39.7 ℃ in vitro. Notably, the N-CDs exhibit a strong fluorescence emission peak at 660 nm, approaching the NIR-I window, which facilitates high-contrast bioimaging. In vivo studies confirmed the therapeutic efficacy of N-CDs, demonstrating cancer cell ablation under both 808 nm and 1060 nm laser irradiation, coupled with accurate tumor localization capabilities. The unique combination of intense fluorescence emission, exceptional photothermal conversion efficiency, and outstanding biocompatibility positions these N-CDs as a highly promising theranostic platform for integrated cancer diagnosis and treatment.

The potential value of multiplexed positron emission tomography (PET) tracers in mice with turpentine-induced inflammation was evaluated and compared with 2-[¹⁸F]fluoro-2-deoxy-D-glucose ([¹⁸F]FDG) for glucose metabolism imaging. These PET tracers included [¹⁸F]fluoromethylcholine ([¹⁸F]FCH) for choline metabolism imaging, (S-[¹¹C]methyl)-D-cysteine ([¹¹C]DMCYS) for amino acid metabolism imaging, [¹¹C]bis(zinc(II)-dipicolylamine) ([¹¹C]DPA-Zn²⁺) for apoptosis imaging, 2-(4-N-[¹¹C]-methylaminophenyl)-6-hydroxybenzothiazole ([¹¹C]PIB) for β amyloid binding imaging, and [¹⁸F]fluoride (¹⁸F⁻) for bone metabolism imaging. In mice with turpentine-induced inflammation mice, the biodistribution of all the tracers mentioned above at 5, 15, 30, 45, and 60 min postinjection was determined. Also, the time-course curves of the tracer uptake ratios for inflammatory thigh muscle (IM) to normal uninflammatory thigh muscle (NM), IM to blood (BL), IM to brain (BR), and IM to liver (LI) were acquired, respectively. Moreover, PET imaging with the tracers within 60 min postinjection on a clinical PET/CT scanner was also conducted. [¹⁸F]FDG and ¹⁸F⁻ showed relatively higher uptake ratios for IM to NM, IM to BL, IM to BR, and IM to LI than [¹⁸F]FCH, [¹¹C]DPA-Zn²⁺, [¹¹C]DMCYS and [¹¹C]PIB, which were highly consistent with the results delineated in PET images. The results demonstrate that ¹⁸F⁻ seems to be a potential PET tracer for inflammation imaging. [¹⁸F]FCH and [¹¹C]DMCYS, with lower accumulation in inflammatory tissue than [¹⁸F]FDG, are not good PET tracers for inflammation imaging. As a promising inflammatory tracer, the chemical structure of [¹¹C]DPA-Zn²⁺ needs to be further optimized.

The aim of this study was to compare the properties and feasibility of the glucose analog, 2-18F-fluoro-2-deoxy-D-glucose (18F-FDG), three short 18F-labeled carboxylic acids, 18F-fluoroacetate (18F-FAC), 2-18F-fluoropropionic acid (18F-FPA) and 4-(18F)fluorobenzoic acid (18F-FBA), for differentiating tumors from inflammation. Biodistributions of 18F-FAC, 18F-FPA and 18F-FBA were determined on normal Kunming mice, and positron emission tomography (PET) imaging with these tracers were performed on the separate tumor-bearing mice model and inflammation mice model in comparison with 18F-FDG. Biodistribution results showed that 18F-FAC and 18F-FPA had similar biodistribution profiles and the slow radioactivity clearance from most tissues excluding the in vivo defluorination of 18F-FAC, and 18F-FBA demonstrated a lower uptake and fast clearance in most tissues. PET imaging with 18F-FDG, 18F-FAC and 18F-FPA revealed the high uptake in both tumor and inflammatory lesions. The ratios of tumor-to-inflammation were 1.63 ± 0.28 for 18F-FDG, 1.20 ± 0.38 for 18F-FAC, and 1.41 ± 0.33 for 18F-FPA at 60 min postinjection, respectively. While clear tumor images with high contrast between tumor and inflammation lesion were observed in 18F-FBA/PET with the highest ratio of tumor-to-inflammation (1.98 ± 0.15). Our data demonstrated 18F-FBA is a promising PET probe to distinguish tumor from inflammation. But the further modification of 18F-FBA structure is required to improve its pharmacokinetics.

Fully automated synthesis of 11C–labeled 2β-carbomethoxy-3β-(4-fluorophenyl)tropane (11C CFT) as a dopamine transporter positron emission tomography (PET) tracer is performed with Sep-Pak purification, which cannot separate 11C CFT from nor-β-CFT and will result in the residual precursor nor-β-CFT in the final 11C CFT injection. The aim of this study is to estimate the influence of the residual precursor nor-β-CFT in the 11C CFT injection on the Parkinson disease (PD) diagnosis results. Automated synthesis of 11C CFT was performed using the different chemical amounts (0.10, 0.20, 0.25, and 0.30 mg) of nor-β-CFT with Sep-Pak purification. According to the given different amounts of nor-β-CFT in the radiosynthesis, clinically suspected 25 PD patients were randomly divided into the following 4 groups: 0.10 mg, 0.20 mg, 0.25 mg, and 0.30 mg, which had 5, 9, 5, and 6 cases, respectively. A normal control group with 0.10 mg of nor-β-CFT included 2 volunteers. After the brain PET images of the subjects were acquired, the regions of interests of striatum and cerebellum were drawn, and the standard uptake values of these regions were calculated. Finally, comparing the 18F FDG PET and clinical diagnosis, the coincidence rates of 11C CFT PET imaging for PD patients were determined. Given 0.25 mg of the precursor nor-β-CFT, high radiochemical yield (59.4%) and high radiochemical purity of 11C CFT were obtained using Sep-Pak purification within a short synthesis time. The 11C CFT standard uptake value ratios of striatum to cerebellum had no statistically significant difference (P > 0.05) between the 4 suspected PD groups. However, there was statistically significant difference (P Conclusions A simple, rapid, and efficient automated synthesis of 11C CFT using 0.25 mg of nor-β-CFT with Sep-Pak purification is afforded, providing enough radioactivity for PD PET imaging routinely. The residual nor-β-CFT in the 11C CFT injection is not inhibit 11C CFT binding to dopamine transporter, and also has no influence on PET diagnosis results of PD.