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Crystal structures, polymorphism, and phase transitions of five n-aklanethiols ( n-C n H2 n +1SH: CnSH), C18SH, C19SH, C22SH, C23SH, and C24HSH have been investigated by means of differential scanning calorimetry and X-ray diffraction. Normal alkanethiols with odd carbon number have only one crystalline form, the E2 form. While, n-alkanethiols with even carbon number have two low-temperature crystalline forms, the most stable E1 form and the meta-stable E1′ form. When even n-alkanethiols are crystallized from the solution (solution growth crystal: SGC), they crystallize into the E1 form. When they are cooled from the melt (melt growth crystal: MGC), on the other hand, the E1′ form appears. In all crystalline phases, two n-alkanethiol molecules are connected at SH end mutually by hydrogen bond resulting in forming a dimer in both forms. The SH groups and the CH3 groups are arranged on the respectively different layer surfaces resulting in the bilayer structure in the E1 form. In the E1′ form, on the other hand, although the molecules form dimers locally, the SH and methyl groups do not form the one layer surface, respectively, but are arranged disorderly. At temperature just below the melting point, characteristic high-temperature phase, the rotator phase, is observed in even n-alkanethiols as well as in n-alkane system. [ABSTRACT FROM AUTHOR]

In this study, thermosensitive liposomes (TSLs) encapsulating urinary excretable radiolabeled compounds were developed. We considered that the release of the radiolabeled compounds from the TSLs in the blood by heating the blood in peripheral tissues can achieve rapid clearance of radioactivity, resulting in improved imaging contrast. To demonstrate the hypothesis, classical TSLs mainly composed of 1,2-dipalmitoyl- sn -glycero-3-phosphocholine with a phase transition temperature of 41 °C were used. The optimal composition of TSLs was determined by an in vitro release test using [ 111 In]In-diethylenetriaminepentaacetic acid (DTPA)-encapsulated liposomes, which showed that the cholesterol content drastically changed the release characteristics of classical TSLs. In the biodistribution experiments, [ 111 In]In-DTPA was significantly released from the TSLs in the blood when the tails of mice were heated at 43 °C. The tumor-to-blood ratio of the heated group was three times higher than that of the nonheated group, and accumulation in normal tissues of the heated group was lower than that of the nonheated group. These results demonstrate the usefulness of the method using TSLs to encapsulate urinary excretable radiolabeled compounds for improving imaging contrast.

Gold nanorods (GNR) produce heat upon irradiation with near-infrared light, enabling a tumor-targeted photothermal therapy. In this study, we prepared GNR coated with sulfated hyaluronic acid (sHA) with a binding affinity for CD44 via electrostatic interactions to deliver GNR to tumors efficiently and stably, and evaluated their usefulness for photothermal therapy. Cationic GNR modified with trimethylammonium groups electrostatically interacted with native HA or sHA with varying degrees of sulfation to form complexes. While GNR/HA was unstable in saline, GNR/sHA maintained the absorbance peak in the near-infrared region, particularly for GNR/sHA with higher degrees of sulfation. GNR/sHA exhibited an intense photothermal effect upon irradiation with near-infrared light. Furthermore, in vitro and in vivo studies revealed that GNR coated with sHA containing approximately 1.2 sulfated groups per HA unit could accumulate in CD44-positive tumors via an HA-specific pathway. These findings indicate the effectiveness of GNR/sHA as a tumor-targeted photothermal therapeutic agent., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Acidic amino acid peptides have a high affinity for bone. Previously, we demonstrated that radiogallium complex-conjugated oligo-acidic amino acids possess promising properties as bone-seeking radiopharmaceuticals. Here, to elucidate the effect of stereoisomers of Glu in Glu-containing peptides [(Glu) 14 ] on their accumulation in the kidney, the biodistributions of [ 67 Ga]Ga- N , N '-bis-[2-hydroxy-5-(carboxyethyl)benzyl]ethylenediamine- N , N '-diacetic acid-conjugated (l-Glu) 14 ([ 67 Ga]Ga-HBED-CC-(l-Glu) 14 ), [ 67 Ga]Ga-HBED-CC-(d-Glu) 14 , [ 67 Ga]Ga-HBED-CC-(dl-Glu) 14 , and [ 67 Ga]Ga-HBED-CC-(d-Glu-l-Glu) 7 were compared. Although the accumulation of these compounds in the bone was comparable, their kidney accumulation and retention were strikingly different, with [ 67 Ga]Ga-HBED-CC-(d-Glu-l-Glu) 7 exhibiting the lowest level of kidney accumulation among these compounds. Repeated d- and l-peptides may be a useful method for reducing renal accumulation in some cases.

Purpose: A probe for targeted alpha therapy (TAT) using the RGD peptide (Ga-DOTA-K([ 211 At]APBA)-c(RGDfK) ([ 211 At]1)) with albumin-binding moiety (ABM) was recently developed. [ 211 At]1 highly accumulated in tumors and significantly inhibited tumor growth in U-87 MG tumor-bearing mice. However, high [ 211 At]1 retention in blood may cause critical adverse events, such as hematotoxicity. Therefore, we attempted to accelerate the blood clearance of [ 211 At]1 by competitively inhibiting the binding of [ 211 At]1 to albumin to modulate the pharmacokinetics of the former., Methods: To evaluate the effects of albumin-binding inhibitors in normal mice, sodium 4-(4-iodophenyl)butanoate at 2, 5, or 10 molar equivalents of blood albumin was administered at 1-h postinjection of [ 211 At]1. The biodistribution of [ 211 At]1, SPECT/CT imaging of [ 67 Ga]Ga-DOTA-K(IPBA)-c(RGDfK) ([ 67 Ga]2), and the therapeutic effects of [ 211 At]1 were compared with or without IPBA administration in U-87 MG tumor-bearing mice., Results: Blood radioactivity of [ 211 At]1 was decreased in a dose-dependent manner with IPBA in normal mice. In U-87 MG tumor-bearing mice, the blood radioactivity and accumulation in nontarget tissues of [ 211 At]1 were decreased by IPBA. Meanwhile, tumor [ 211 At]1 accumulation was not changed at 3-h postinjection of IPBA. In SPECT/CT imaging of [ 67 Ga]2, IPBA administration dramatically decreased radioactivity in nontarget tissues, and only tumor tissue was visualized. In therapeutic experiments, [ 211 At]1 with IPBA injected-group significantly inhibited tumor growth compared to the control group., Conclusion: IPBA administration (as an albumin-binding inhibitor) could modulate the pharmacokinetics and enhance the therapeutic effects of [ 211 At]1., (© 2024. The Author(s).)

The stepwise addition of monosaccharides to N-glycans attached to client proteins to generate a repertoire of mature proteins involves a concerted action of many glycosidases and glycosyltransferases. Here, we report that Golgi α-mannosidase II (GMII), a pivotal enzyme catalyzing the first step in the conversion of hybrid- to complex-type N-glycans, is activated by Zn 2+ supplied by the early secretory compartment-resident ZNT5-ZNT6 heterodimers (ZNT5-6) and ZNT7 homodimers (ZNT7). Loss of ZNT5-6 and ZNT7 function results in marked accumulation of hybrid-type and complex/hybrid glycans with concomitant reduction of complex- and high-mannose-type glycans. In cells lacking the ZNT5-6 and ZNT7 functions, the GMII activity is substantially decreased. In contrast, the activity of its homolog, lysosomal mannosidase (LAMAN), is not decreased. Moreover, we show that the growth of pancreatic cancer MIA PaCa-2 cells lacking ZNT5-6 and ZNT7 is significantly decreased in a nude mouse xenograft model. Our results indicate the integral roles of ZNT5-6 and ZNT7 in N-glycosylation and highlight their potential as novel target proteins for cancer therapy., Competing Interests: Conflict of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

We investigated the importance of the carboxy group density in bone affinity during the development of peptide-based bone-seeking radiopharmaceuticals and carriers. Oligo-γ-carboxy glutamic acid peptides [(Gla) n ] with higher carboxy group density than oligo-glutamic acid peptides [(Glu) n ] and oligo-aspartic acid peptides [(Asp) n ] were chosen. Using the radiogallium chelator N,N' -bis-[2-hydroxy-5-(carboxyethyl)benzyl]ethylenediamine- N,N' -diacetic acid (HBED-CC), we synthesized [ 67 Ga]Ga-HBED-CC-(Gla) n ( n = 1, 2, 5, 8, 11, or 14) with high yields. Hydroxyapatite-binding assays, biodistribution, and SPECT imaging showed higher affinity and bone accumulation for [ 67 Ga]Ga-HBED-CC-(Gla) n compared to [ 67 Ga]Ga-HBED-CC-(Glu) n . Notably, [ 67 Ga]Ga-HBED-CC-(Gla) 8 and [ 67 Ga]Ga-HBED-CC-(Gla) 11 exhibited superior bone accumulation and rapid blood clearance. SPECT/CT imaging with [ 67 Ga]Ga-HBED-CC-(Gla) 8 exclusively visualized the bone tissue. These findings support the potential use of [ 67 Ga]Ga-HBED-CC-(Gla) n as excellent bone-imaging PET probes, suggesting (Gla) n peptides are superior bone-seeking carriers.

Survivin is highly expressed in most human cancers, making it a promising target for cancer diagnosis and treatment. In this study, we developed peptide probes consisting of Bor 65-75 , a high-affinity survivin-binding peptide, and a survivin protein segment using peptide linkers as survivin-sensitive fluorescent probes (SSFPs). All conjugates were attached to 5(6)-carboxyfluorescein (FAM) at the C -terminal as a fluorophore and to 4((4(dimethylamino)phenyl)azo)benzoic acid (DABCYL) at the N -terminal as a quencher. Fluorescence (or Förster) resonance energy transfer (FRET) quenching via intramolecular binding of Bor 65-75 with survivin protein segment could be diminished by the approach of survivin to SSFPs, which dissociate Bor 65-75 from SSPF and increased the distance between FAM and DABCYL. A binding assay using recombinant human survivin protein (rSurvivin) demonstrated moderate to high affinity of SSFPs for survivin (dissociation constants ( K d ) = 121-1740 nM). Although the SSFPs (0.5 μM) had almost no fluorescence under baseline conditions, a dose-dependent increase in fluorescence intensity was observed in the presence of rSurvivin (0.1-2.0 μM). In particular, the proline-rich SSFP (SSFP5) showed the highest (2.7-fold) fluorescence induction at 2.0 μM survivin compared to the signals in the absence of survivin. Confocal fluorescence imaging demonstrated that SSFP5 exhibited clear fluorescence signals in survivin-positive MDA-MB-231 cells, whereas no marked fluorescence signals were observed in survivin-negative MCF-10A cells. Collectively, these results suggest that SSFPs can be used as survivin-specific FRET imaging probes., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Co-published by Nanjing University and American Chemical Society.)

Radiotheranostics utilizes a set of radioligands incorporating diagnostic or therapeutic radionuclides to achieve both diagnosis and therapy. Imaging probes using diagnostic radionuclides have been used for systemic cancer imaging. Integration of therapeutic radionuclides into the imaging probes serves as potent agents for radionuclide therapy. Among them, targeted alpha therapy (TAT) is a promising next-generation cancer therapy. The α-particles emitted by the radioligands used in TAT result in a high linear energy transfer over a short range, inducing substantial damage to nearby cells surrounding the binding site. Therefore, the key to successful cancer treatment with minimal side effects by TAT depends on the selective delivery of radioligands to their targets. Recently, TAT agents targeting biomolecules highly expressed in various cancer cells, such as sodium/iodide symporter, norepinephrine transporter, somatostatin receptor, α v β 3 integrin, prostate-specific membrane antigen, fibroblast-activation protein, and human epidermal growth factor receptor 2 have been developed and have made remarkable progress toward clinical application. In this review, we focus on two radionuclides, 225 Ac and 211 At, which are expected to have a wide range of applications in TAT. We also introduce recent fundamental and clinical studies of radiopharmaceuticals labeled with these radionuclides., (© 2024. The Author(s).)

Purpose: We have developed probes for multiradionuclides radiotheranostics using RGD peptide ([ 67 Ga]Ga-DOTA-c[RGDf(4-I)K] ([ 67 Ga]1) and Ga-DOTA-[ 211 At]c[RGDf(4-At)K] ([ 211 At]2)) for clinical applications. The introduction of an albumin binding moiety (ABM), such as 4-(4-iodophenyl)-butyric acid (IPBA), that has high affinity with the blood albumin and prolongs the circulation half-life can improve the pharmacokinetics of drugs. To perform more effective targeted alpha therapy (TAT), we designed and synthesized Ga-DOTA-K([ 211 At]APBA)-c(RGDfK) ([ 211 At]5) with 4-(4-astatophenyl)-butyric acid (APBA), which has an astato group instead of an iodo group in IPBA. We evaluated whether APBA functions as ABM and [ 211 At]5 is effective for TAT. In addition, we prepared 67 Ga-labeled RGD peptide without ABM, [ 67 Ga]Ga-DOTA-K-c(RGDfK) ([ 67 Ga]3), and 125 I-labeled RGD peptide with ABM, Ga-DOTA-K([ 125 I]IPBA)-c(RGDfK) ([ 125 I]4), to compare with [ 211 At]5., Methods: Biodistribution experiments of [ 67 Ga]3 without ABM, [ 125 I]4 and [ 211 At]5 with ABM were conducted in normal mice and U-87 MG tumor-bearing mice. In addition, two doses of [ 211 At]5 (370 or 925 kBq) were administered to U-87 MG tumor-bearing mice to confirm the therapeutic effects., Results: The blood retention of [ 125 I]4 and [ 211 At]5 was remarkably increased compared to [ 67 Ga]3. Also, [ 125 I]4 and [ 211 At]5 showed similar biodistribution and significantly greater tumor accumulation and retention compared to [ 67 Ga]3. In addition, [ 211 At]5 inhibited tumor growth in a dose-dependent manner., Conclusion: The functionality of APBA as ABM like IPBA, and the usefulness of [ 211 At]5 as the radionuclide therapy agent for TAT was revealed., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Macrophage infiltration is a characteristic feature of atherosclerotic plaque progression. Since liposomes containing 1,2-distearoyl-sn-glycero-3-phosphoglycerol (DSPG) are efficiently phagocytosed by macrophages, we deduced that radiolabeled liposomes containing DSPG could potentially be used for nuclear imaging of vulnerable atherosclerotic plaques. Indium-111 ( 111 In)-labeled liposomes containing different ratios of DSPG were developed with a high labeling efficiency. 111 In-labeled liposomes with higher DSPG content showed higher uptake by macrophage-like RAW264 cells. A biodistribution study demonstrated rapid blood clearance and selective accumulation in the liver and spleen, especially in normal mice injected with 111 In-labeled liposomes with higher DSPG content. Accumulation in atherosclerotic plaques was evaluated using 111 In-labeled DSPG liposomes, which had the highest DSPG content among the studied liposomes. 111 In-labeled DSPG liposomes accumulated in the plaques and the radioactive regions were mostly consistent with the distribution of macrophages. The target-to-non-target ratio of 111 In-labeled DSPG liposomes was higher than that of 111 In-labeled control liposomes without DSPG. These results suggest that 111 In-labeled liposomes containing DSPG are useful for nuclear medical diagnosis of atherosclerotic plaques., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023. Published by Elsevier Inc.)

Introduction: Systemic amyloidosis is a rare disease caused by the deposition of amyloid fibrils in various organs. Amyloid-targeted radiopharmaceuticals have been developed and applied to diagnose systemic amyloidosis peripherally; however, high-contrast imaging has not been achieved because of the high background signals in normal organs. To overcome this problem, we designed an amyloid-targeted radioiodinated probe 1 with a metabolizable linkage (ester bond) to release of radiolabeled metabolites (m-iodohippuric acid) in normal organs that could be rapidly excreted in the urine., Methods: Compound 1 was synthesized by conjugating 2-(4-(methylamino)phenyl)benzo[d]thiazol-6-ol, an amyloid-targeting compound, with m-iodohippuric acid. [ 125 I]1 was synthesized via iododestannylation using a tributyltin precursor. Mouse models of amyloid A (AA) amyloidosis, a type of systemic amyloidosis, were prepared by administering amyloid-enhancing factor to mice and used for in vitro autoradiography using organ sections and in vivo evaluation., Results: [ 125 I]1 was obtained with a radiochemical yield of 59% and radiochemical purity of over 95%. An in vitro autoradiographic study demonstrated that [ 125 I]1 specifically binds to amyloid in the splenic tissue. Upon administration to normal mice, [ 125 I]1 was distributed to organs throughout the body, followed by the rapid excretion of radioactivity in the urine as m-[ 125 I]iodohippuric acid. Furthermore, ex vivo autoradiography showed that [ 125 I]1 bound to the amyloid formed around the follicles in the spleens of AA amyloidosis model mice., Conclusion: These results suggest that the interposition of a metabolizable linkage between an amyloid-targeting moiety and a radiolabeled hippuric acid would be useful in the design of radiopharmaceuticals for high-contrast imaging of systemic amyloidosis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Introduction: As sigma receptors are abundantly expressed on different types of cancer cells, several radiolabeled sigma receptor ligands have been developed for cancer imaging and therapy. Previously, we synthesized and evaluated radioiodinated aza-vesamicol derivatives, [ 125 I]pIC 3 NV, [ 125 I]mIC 2 N5V, and [ 125 I]mIC 3 N5V. They accumulated in tumors, and [ 125 I]mIC 2 N5V and [ 125 I]mIC 3 N5V showed higher tumor to non-target tissue ratios than [ 125 I]pIC 3 NV. Therefore, we synthesized and evaluated the corresponding 211 At-labeled compounds, [ 211 At]mAtC 2 N5V and [ 211 At]mAtC 3 N5V, for targeted alpha therapy (TAT)., Methods: [ 211 At]mAtC 2 N5V and [ 211 At]mAtC 3 N5V were prepared by the standard method of electrophilic astatodestannylation of the corresponding trimethylstannyl precursors. Cellular uptake experiments, and biodistribution experiments and therapeutic experiments in tumor-bearing mice were performed., Results: The radiochemical yields of [ 211 At]mAtC 2 N5V and [ 211 At]mAtC 3 N5V were 45.5 ± 14.4% and 56.9 ± 13.8%, respectively. After HPLC purification, their radiochemical purities were over 95%. [ 211 At]mAtC 2 N5V and [ 211 At]mAtC 3 N5V showed high uptake in DU-145 cells. They demonstrated high accumulation in tumors (6.9 ± 1.4%injected dose/g and 5.1 ± 1.4%injected dose/g at 1 h, respectively) and similar biodistribution tendencies compared with the corresponding 125 I-labeled compounds. A single injection of [ 211 At]mAtC 2 N5V (0.48 MBq) or [ 211 At]mAtC 3 N5V (0.48 MBq) significantly inhibited tumor growth., Conclusion: These results indicated that [ 211 At]mAtC 2 N5V and [ 211 At]mAtC 3 N5V could be potential candidates for TAT., Competing Interests: Declaration of competing interest The authors have declared that no conflict of interest., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Auger electrons (AEs) are very low-energy electrons emitted by radionuclides such as I-125 ( 125 I). This energy is deposited across a small distance (<0.5 μm), resulting in high linear energy transfer that is potent for causing lethal damage to cancer cells. Thus, AE-emitting radiotherapeutic agents have great potential for cancer treatment. In this study, thermosensitive liposomes (TSLs) encapsulating 125 I-labeled doxorubicin (DOX) derivatives were developed for Auger electron therapy, targeting the DNA of cancer cells. A radioiodinated DOX derivative [ 125 I] 5 highly accumulated in the nuclei of cancer cells and showed potent cytotoxicity against Colon 26 cancer cells by AEs. Subsequently, [ 125 I] 5 was loaded into the TSLs with high encapsulation efficiency. Potent release of [ 125 I] 5 from TSLs was achieved with heating, whereas a decreased release was observed without heating. Furthermore, TSLs encapsulating [ 125 I] 5 showed a high uptake in the nuclei at 42 °C for 1 h. We supposed that [ 125 I] 5 was released by heating at 42 °C and accumulated in the nuclei in the cells. These results suggest that the combination of TSLs encapsulating [ 125 I] 5 and hyperthermia is an effective cancer therapy.

2,2,6,6-Tetramethylpiperidin-N-oxyl (TEMPO)-type nitroxides are susceptible to bioreduction, leading to a loss of radical properties. Although it has been reported that the steric and electronic environments around the N-O moiety of nitroxides affect the reduction, how the relative configuration of nitroxide derivatives alters it is unclear. In this study, we investigated the effect of diastereomers on the radical properties of C2- and C4-disubstituted TEMPO-type nitroxides. We succeeded in isolating the diastereomers of the studied nitroxides for the first time. In addition, we compared the reactivities of nitroxide derivatives with different substituents at the C2 and C4 positions toward ascorbate reduction. We found that the bulky substituents at both C2 and C4 and the electronic effect of C4 affected the reduction of the isomers. C2- and C4-disubstituted nitroxides were administered to mice for electron spin resonance imaging to assess bioreduction in the brain. Similar to the reactivity to reduction in vitro, a difference in the bioreduction of diastereomers was observed in brain tissues. Our research strongly indicates that bioreduction can be controlled by changing the relative configuration, which can be used in the design of nitroxide derivatives for biological applications., Competing Interests: Declaration of competing interests None., (Copyright © 2022 Elsevier Inc. All rights reserved.)

A boron neutron capture therapy (BNCT) system, using boron-10-introduced agents coupled with companion diagnostics, is anticipated as a promising cancer theranostic. Thus, this study aimed to synthesize and evaluate a probe closo -dodecaborate-(Ga-DOTA)-c(RGDfK) ( 16 ) [Ga = gallium, DOTA =1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, and c(RGDfK) = cyclo(arginine-glycine-aspartate-d-phenylalanine-lysine] containing closo -dodecaborate ([B 12 H 12 ] 2- ) as a boron cluster, a [ 67 Ga]Ga-DOTA derivative for nuclear medicine imaging, and an RGD peptide for tumor targeting. Moreover, we prepared a radioiodinated probe [ 125 I] 17 in which I-125 is introduced into a closo -dodecaborate moiety of 16 . [ 67 Ga] 16 and [ 125 I] 17 showed high stability and high uptake in cancer cells in vitro . Biodistribution experiments in tumor-bearing mice revealed similar biodistribution patterns between [ 67 Ga] 16 and [ 125 I] 17 , such as a high uptake in the tumor and a low uptake in other non-target tissues. Meanwhile, [ 125 I] 17 exhibited higher accumulation in most tissues, including the tumor, than [ 67 Ga] 16 , probably because of higher albumin binding. The higher the [ 125 I] 17 accumulation in the tumor, the more desirable it is for BNCT, with the possibility that the iodo- closo -dodecaborate site may work as an albumin binder.

Survivin is overexpressed in most cancer cells but is rarely expressed in normal adult tissues. It is associated with poor prognosis and resistance to radiation therapy and chemotherapy. In this study, we designed and synthesized borealin-derived small peptides (Bor peptides) to function as survivin-targeting agents for the diagnosis and treatment of cancers. These peptides exhibited binding affinities for recombinant human survivin ( K d = 49.6-193 nM), with Bor 65-75 showing the highest affinity ( K d = 49.6 nM). Fluorescence images of fluorescein isothiocyanate-labeled Bor 65-75 showed its co-localization with survivin expression in the human pancreatic cancer cell line, MIA PaCa-2. In the WST-1 assay, cell penetrable nona-d-arginine-conjugated Bor 65-75 (r9-Bor 65-75 ) inhibited the growth of MIA PaCa-2 cells and MDA-MB-231 cells (89 and 88% inhibition at 10 μM, respectively), whereas it had almost no effect on the human mammary epithelial cell line, MCF-10A, that inherently does not have high survivin expression. Flow cytometry with annexin V and propidium iodide staining revealed that r9-Bor 65-75 induced apoptosis in MIA PaCa-2 cells in a dose-dependent manner. An increase in cleaved poly ADP-ribose polymerase protein expression was observed in MIA PaCa-2 cells exposed to r9-Bor 65-75 by western blotting, suggesting that r9-Bor 65-75 inhibits cell proliferation by inducing apoptosis. In vivo , r9-Bor 65-75 significantly suppressed tumor growth in MIA PaCa-2 xenograft mice, without any marked weight loss. Hence, Bor peptides are promising candidates for the development of cancer imaging and anticancer agents targeting survivin.

Prostate cancer frequently metastasizes to the bone. Because patients with bone metastases suffer from skeletal-related events, the diagnosis and treatment of bone metastases in the early stage are important. In this study, to improve the sensitivity of detecting bone metastases in patients with prostate cancer, we designed, synthesized, and evaluated a multifunctional radiotracer, [ 67 Ga]Ga-D 11 -PSMA-617 ([ 67 Ga]3), with an undeca-aspartic acid as a bone-seeking moiety between [ 67 Ga]Ga-DOTA and a prostate-specific membrane antigen (PSMA) ligand based on the lysine-urea-glutamate motif. [ 67 Ga]3 showed a high affinity for hydroxyapatite and high uptake in PSMA-positive LNCaP cells. Moreover, in biodistribution experiments using tumor-bearing mice, [ 67 Ga]3 exhibited high accumulation in the bone and PSMA-positive tumor although the accumulation of [ 67 Ga]3 in the PSMA-positive tumor was lower than that of [ 67 Ga]Ga-PSMA-617. This study provides valuable information for developing radiotheranostic probes combining multiple carriers with different mechanisms., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Nitroxides are known to undergo oxidation, reduction, and radical scavenging reactions due to their stable radicals. Nitroxides have a wide range of applications due to their reactivities, including radical detecting probes and catalysts. Because nitroxides are easily reduced by ascorbate, a reducing agent, in biological applications, it is critical to control their reactivity to use them as a probe to trace the target reaction. On the other hand, the phenyl group, which is present in many functional organic molecules, is useful for controlling the electronic and steric effects. However, there has been few systematic studies on the substituent effects of TEMPO-type nitroxides with phenyl rings in the vicinity of a radical (α-position). In this study, we synthesized three nitroxides with a phenyl group at the α-position of a TEMPO-type nitroxide and tested their redox properties. The results showed that the reduction reactivity and redox potential differed depending on the position of the phenyl group, implying that the phenyl group one carbon away from the α-carbon of the N-O moiety increases the degree of steric hindrance. This finding is expected to be the basis for the development of functional nitroxides.

Radioiodinated porphyrin derivatives and the corresponding nonradioactive iodine introduced compounds, [ 125 I]I-TPP OH ([ 125 I]3), [ 125 I]I-l-tyrosine-TPP ([ 125 I]9), I-TPP OH (3), and I-l-tyrosine-TPP (9) were designed, synthesized, and evaluated by in vitro and in vivo experiments. In cytotoxicity assays, 3 and 9 exhibited significant cytotoxicity under light conditions but did not show significant cytotoxicity without light irradiation. Biodistribution experiments with [ 125 I]3 and [ 125 I]9 showed similar distribution patterns with high retention in tumors. In photodynamic therapeutic (PDT) experiments, 3 and 9 at a dose of 13.6 μmol kg -1 weight with 50 W single light irradiation onto the tumor area significantly inhibited tumor growth. These results indicate that the iodinated porphyrin derivatives [ 123/nat I]3 and [ 123/nat I]9 are promising cancer theranostic agents., Competing Interests: There is no conflict of interest to declare., (This journal is © The Royal Society of Chemistry.)

Cisplatin (CDDP) has been widely used for chemotherapy. However, it has several unfavorable side effects due to its low tumor selectivity. In this study, we designed, synthesized, and evaluated Pt(IV)-[c(RGDyK)] 2 (9), in which two molecules of an RGD peptide are introduced as a carrier molecule to cancer into oxoplatin, a Pt(IV) prodrug of CDDP, to enhance cancer selectivity. Furthermore, we prepared and evaluated Pt(IV)-[c(RGDyK)]{[ 125 I]c[RGDy(3-I)K]} ([ 125 I]10) for a preliminary step of nuclear medicine imaging and theranostics. Compound 9 inhibited cell growth in the cell viability assay and, [ 125 I]10 was highly accumulated in tumor tissues (1 h: 3.53 ± 0.53 %ID/g) in the biodistribution study. These results indicate that implementing RGD peptides into oxoplatin enabled tumor-specific accumulation, and combining [ 123/124 I]10 and 9 for diagnostic imaging and therapy could be useful for cancer theranostics., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Liposomes are highly biocompatible drug carriers in drug delivery systems (DDSs). Preferential accumulation of liposomes and acceleration of drug release at target tumor sites are essential for effective cancer therapy using liposomal formulations; however, conventional liposomes are unsuitable for on-demand drug release. We have previously reported that drug release can be accelerated via a bio-orthogonal inverse electron demand Diels-Alder (IEDDA) reaction between amphiphilic tetrazine (Tz)-containing liposomes and norbornene (NB) derivatives in vitro . In this study, we prepared HSTz-liposomes composed of hydrogenated soybean phosphatidylcholine (HSPC) and Tz compound (2-hexadecyl- N -(6-(6-(pyridin-2-yl)-1,2,4,5-tetrazin-3-yl)pyridin-3-yl)octadecanamide) with particle sizes of 60-80 nm and ζ-potentials of -5 to 0 mV. Similar to our previous report, the addition of 5-norbornene-2-carboxylic acid (NBCOOH) to HSTz-liposomes accelerated drug release from the liposomes in vitro . In the biodistribution study using colon26 tumor-bearing mice, the radiolabeled HSTz-liposomes were accumulated and retained in the tumor at 6-48 h post-injection, whereas the radioactivity in the blood almost disappeared at 48 h. Therefore, the timing of the injection of NBCOOH was selected to be 48 h after the injection of the HSTz-liposome to avoid the IEDDA reaction in the bloodstream. We investigated the in vivo drug release by evaluating the intratumoral localization of doxorubicin (DOX) encapsulated in HSTz-liposomes labeled with fluorescent lipids. In the tumors treated with HSTz-liposomes and NBCOOH, DOX was more widely dispersed in the tumor compared with fluorescent lipid, suggesting that the release of encapsulated drugs (DOX) from HSTz-liposomes was enhanced in the tumor tissue via the bio-orthogonal IEDDA reaction. Furthermore, the combination of DOX-encapsulated HSTz-liposomes with NBCOOH significantly suppressed tumor growth compared to conventional DOX-encapsulated liposomes. In conclusion, the bio-orthogonal IEDDA reactions in the liposomal membrane enabled the acceleration of drug release from HSTz-liposomes in vivo , suggesting a promising strategy for effective cancer therapy.

Background: Zinc homeostasis is essential for human health and is regulated by several zinc transporters including ZIP and ZnT. ZIP4 is expressed in the small intestine and is important for zinc absorption from the diet. We investigated in the present study the effects of Panax ginseng ( P. ginseng ) extract on modulating Zip4 expression and cellular zinc levels in mouse Hepa cells., Methods: Hepa cells were transfected with a luciferase reporter plasmid that contains metal-responsive elements, incubated with P. ginseng extract, and luciferase activity was measured. Using 65 ZnCl 2 , zinc uptake in P. ginseng -treated cells was measured. The expression of Zip4 mRNA and protein in Hepa cells was also investigated. Finally, using a luciferase reporter assay system, the effects of several ginsenosides were monitored., Results: The luciferase activity in cells incubated with P. ginseng extract was significantly higher than that of control cells cultured in normal medium. Hepa cells treated with P. ginseng extract exhibited higher zinc uptake. P. ginseng extract induced Zip4 mRNA expression, which resulted in an enhancement of Zip4 protein expression. Furthermore, some ginsenosides, such as ginsenoside Rc and Re, enhanced luciferase activity driven by intracellular zinc levels., Conclusion: P. ginseng extract induced Zip4 expression at the mRNA and protein level and resulted in higher zinc uptake in Hepa cells. Some ginsenosides facilitated zinc influx. On the basis of these results, we suggest a novel effect of P. ginseng on Zip4-mediated zinc influx, which may provide a new strategy for preventing zinc deficiency., Competing Interests: The authors declare that no competing interests., (© 2021 The Korean Society of Ginseng. Publishing services by Elsevier B.V.)

Introduction: Systemic amyloidosis is a group of diseases characterized by the deposition of amyloid protein in multiple organs throughout the body and causing their dysfunction. As amyloid deposition is observed at an early phase and is highly specific to systemic amyloidosis, noninvasive detection of amyloid is considered useful for the early diagnosis of systemic amyloidosis. In this study, we designed and synthesized a novel radiolabeled amyloid imaging probe, sodium (E)-4-amino-3-((4-(6-iodobenzothiazol-2-yl)phenyl)diazenyl)naphthalene-1-sulfonate (1), which combines two amyloid-binding compounds, thioflavin-T and Congo-red, and evaluated its effectiveness in diagnosing amyloidosis., Methods: A tributyltin precursor was synthesized through a 5-step reaction from 2-amino-6-bromobenzothiazole, and [ 125 I]1 was synthesized by an iododestannylation reaction with a tributyltin precursor. Mouse models of amyloid A (AA) amyloidosis, a type of systemic amyloidosis, were prepared by intraperitoneal injection of amyloid-enhancing factor into mice. An in vitro autoradiographic study was performed using spleen sections from normal mice and AA amyloidosis mice. Furthermore, [ 125 I]1 was intravenously injected into mice, and its distribution was evaluated. Finally, an ex vivo autoradiographic study was performed using AA amyloidosis mice., Results: [ 125 I]1 was obtained with a radiochemical yield of 66% and a radiochemical purity of over 95%. In vitro autoradiography revealed specific binding of [ 125 I]1 to thioflavin-S-stained regions in the spleen. Normal mice showed relatively rapid clearance of [ 125 I]1 from the organs, whereas radioactivity was retained in the spleen, where amyloid deposition was observed in model mice. Furthermore, ex vivo autoradiography showed a heterogeneous distribution of [ 125 I]1, which was co-localized with thioflavin-S-stained regions in the spleen of model mice., Conclusion: These results indicate the potential of radioiodinated 1 as a nuclear imaging probe for diagnosing AA amyloidosis., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The aim of this study was to establish a drug delivery system (DDS) for marked therapy of tumors using a thermoresponsive polymer, polyoxazoline (POZ). The effectiveness of the following was investigated: (i) the delivery of gold nanorods (GNRs) to tumor tissues, (ii) heat production of GNR upon irradiation with near-infrared (NIR) light, and (iii) high accumulation of an intravenously injected radiolabeled POZ as a drug carrier in tumors by sensing heat produced by GNRs. When the GNR solution was irradiated with NIR light (808 nm), the solution temperature was increased both in a GNR-concentration-dependent manner and in a light-dose-dependent manner. POZ, with a lower critical solution temperature of 38 °C, was aggregated depending on the heat produced by the GNR irradiated by NIR light. When it was intratumorally pre-injected into colon26-tumor-bearing mice, followed by NIR light irradiation (GNR+/Light+ group), the tumor surface temperature increased to approximately 42 °C within 5 min. Fifteen minutes after irradiation with NIR light, indium-111 ( 111 In)-labeled POZ was intravenously injected into tumor-bearing mice, and the radioactivity distribution was evaluated. The accumulation of POZ in the tumor was significantly (approximately 4-fold) higher than that in the control groups (GNR+/without NIR light irradiation (Light-), without injection of GNR (GNR-)/Light+, and GNR-/Light- groups). Furthermore, an in vivo confocal fluorescence microscopy study, using fluorescence-labeled POZ, revealed that uptake of POZ by the tumor could be attributed to the heat produced by GNR. In conclusion, we successfully established a novel DDS in which POZ could be efficiently delivered into tumors by using the heat produced by GNR irradiated with NIR light.

Background: The application of gold nanorods (GNRs) in photothermal therapy is a promising avenue for cancer treatment. The aim of this study was to develop a GNR-based targeted photothermal therapy for melanoma., Methods: We utilized the electrostatic interaction between cationic GNRs and an anionic polymer chondroitin sulfate A (CSA), which has an affinity for binding to melanoma cells, to construct an anionic binary GNR-CSA complex (GNR-CS) at an optimal theoretical charge ratio of the trimethylammonium groups of GNR: carboxyl and sulfate groups of CSA = 1:2.5. The cytotoxicity to normal cells and erythrocyte agglutination activity of GNR-CS were evaluated. After the cellular uptake of GNR-CS by melanoma cells (B16-F10) was investigated, the photothermal performance of GNR-CS against B16-F10 cells was evaluated in vitro., Results: The particle size and zeta potential of GNR-CS were approximately 35 nm and -20 mV, respectively. GNR-CS showed little cytotoxicity to normal cells and low erythrocyte agglutination activity, indicating good biocompatibility. Compared with negatively-charged GNR, GNR-CS was highly taken up by B16-F10 cells even if it was negatively charged. Cellular uptake was significantly suppressed upon treatment with excess CSA, suggesting the involvement of a CSA-specific uptake pathway. Furthermore, irradiation of the GNR-CS solution with near-infrared (NIR) light increased its temperature in light-intensity and GNR-concentration dependent manners. GNR-CS exhibited significant and GNR-dose dependent cytotoxicity in melanoma cells in combination with NIR light irradiation., Conclusion: GNRs coated with CSA have the potential as a medicine in targeted photothermal therapy for melanoma., (Copyright © 2021 Elsevier B.V. All rights reserved.)

It is well known that lipid carbon radicals (lipid radicals) are the origin of lipid peroxidation and are involved in various diseases such as cancer. Therefore, the in vivo detection of lipid radicals would be expected to lead to early diagnosis of these diseases. However, there are no methods for measuring lipid radicals in vivo. Nitroxides are known to be highly reactive with lipid radicals, but they tend to be reduced in vivo. Focusing on the excellent detection sensitivity of nuclear medical imaging, we have developed a radioiodinated nitroxide derivative with resistance to bioreduction for the in vivo detection of lipid radicals. The desired compound was obtained successfully and was highly stable against bioreduction while maintaining high reactivity toward lipid radicals. The I-125 labeling was efficacious with radiochemical yields of 84-87% and radiochemical purities of >99%. A cellular uptake assay showed that the radioiodinated compound was significantly taken up by cells under lipid radical-producing conditions compared to that in the absence of lipid radical production. A biodistribution study indicated that the radioiodinated compound accumulated more in organs where lipid peroxidation was promoted than the methoxyamine derivative, which lost reactivity to lipid radicals. These results indicated that the developed probe became trapped in cells or organs by reacting with lipid radicals. Thus, the radioiodinated nitroxide is a candidate probe for in vivo detection of lipid radicals., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Melanoma is a highly malignant skin cancer that frequently metastasizes to the lung, bone, and brain at an early phase. Therefore, noninvasive detection of metastasized melanoma could be beneficial to determine suitable therapeutic strategies. We previously reported a biocompatible ternary anionic complex composed of plasmid DNA (pDNA), polyethyleneimine (PEI), and γ-polyglutamic acid (γ-PGA) based on an electrostatic interaction, which was highly taken up by melanoma cells (B16-F10), even if it was negatively charged. Here, we developed a radiolabeled γ-PGA complex by using indium-111 ( 111 In)-labeled polyamidoamine dendrimer (4th generation; G4) instead of pDNA and iodine-125 ( 125 I)-labeled PEI instead of native PEI, and evaluated its effectiveness as a melanoma-targeted imaging probe. This ternary complex was synthesized at a theoretical charge ratio; carboxyl groups of 111 In-diethylenetriaminepentaacetic acid (DTPA)-G4 : amino groups of 125 I-PEI : carboxyl groups of γ-PGA was 1 : 8 : 16, and the size and zeta potential were approximately 29 nm and -33 mV, respectively. This complex was taken up by B16-F10 cells with time. Furthermore, a biodistribution study, using normal mice, demonstrated its accumulation in the liver, spleen, and lung, where macrophage cells are abundant. Almost the same level of radioactivity derived from both 111 In and 125 I was observed in these organs at an early phase after probe injection. Compared with the normal mice, significantly higher lung-to-blood ratios of radioactivity were observed in the B16-F10-lung metastatic cancer model. In conclusion, the radiolabeled γ-PGA complex would hold potentialities for nuclear medical imaging of lung metastatic melanoma.

Bio-orthogonal inverse electron demand Diels-Alder (IEDDA) reactions between liposomes containing a tetrazine-based (Tz) compound and 2-norbornene (2-NB) could be a novel trigger for accelerating drug release from the liposomes via temporary membrane destabilization, as shown in our previous report. Herein, we evaluated the in vitro drug release using NB derivatives with carboxyl groups [5-norbornene-2-carboxylic acid (NBCOOH) and 5-norbornene-2,3-dicarboxylic acid (NB(COOH) 2 )] to investigate the effects of substituents at the NB backbone on the drug release rate. First, POTz-liposome composed of a Tz compound (2-hexadecyl- N -(6-(6-(pyridin-2-yl)-1,2,4,5-tetrazin-3-yl)pyridin-3-yl)octadecanamide) and 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphatidylcholine (POPC) were prepared. The mass spectrometry analysis revealed the binding of NB derivatives to the Tz compound via the IEDDA reaction after the POTz-liposome reacted with the NB derivatives. Indium-111-labeled diethylenetriaminepentaacetic acid ( 111 In-DTPA) was encapsulated inside the liposomes, and the drug release rate was quantified by measuring radioactivity. At 24 h after incubation with 2-NB, NBCOOH, and NB(COOH) 2 , the release rates of 111 In-DTPA from POTz-liposome were 21.0, 80.8, and 23.3%, respectively, which were significantly higher than those of POTz-liposome that was not treated with NB derivatives (4.2%), indicating the involvement of the IEDDA reaction for prompting drug release. Additionally, a thermodynamic evaluation using Langmuir monolayers was conducted to explore the mechanism of the accelerated drug release. An increase in membrane fluidity and a reduction in intermolecular repulsion between POPC and the Tz compound were observed after the reaction with NB derivatives, especially for NBCOOH. Thus, the IEDDA reaction in the liposomal membrane could be a potent trigger for accelerating the release of encapsulated drugs by regulating membrane fluidity and intermolecular repulsion in the liposomal membrane.

Thus far, no accurate measurement technology has been developed to detect lipid alkyl radicals (lipid radicals), which cause lipid peroxidation. Therefore, we aimed to develop a nuclear medical imaging probe that can be taken up in the lipophilic site in cells such as biological membranes, by reacting specifically with the lipid radicals generated there. We designed and synthesized 4-(4-[ 125 I]iodobenzamido)-2,2,6,6-tetramethylpiperidine-1-oxyl, which shows high reactivity to lipid radicals with a high radiochemical yield and purity. Intracellular retention was found to increase significantly when lipid radicals were produced., Competing Interests: The authors declare no competing financial interest., (Copyright © 2019 American Chemical Society.)

Tetrazine irreversibly reacts with dienophiles, and its derivatives find wide applications in the fields of biochemistry and biophysics. We have synthesized an amphiphilic tetrazine derivative (2-hexadecyl-N-(6-(6-(pyridin-2-yl)-1,2,4,5-tetrazine-3-yl)pyridin-3-yl)octadecanamide; 1), which has a hydrophilic tetrazine structure and hydrophobic alkyl chains. Liposomes composed of compound 1 and 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) (PTz-liposome) were prepared. In search of a new drug delivery system (DDS), we investigated the viability of inverse electron-demand Diels-Alder, a reaction between tetrazine and 2-norbornene, on the surface of the liposomes to change membrane fluidity and promote spatial and temporal controlled release of the encapsulated drugs. Compound 1 was synthesized with a yield of 71%. MS analysis after incubation of 2-norbornene with PTz-liposome revealed the binding of 2-norbornene to tetrazine. Indium-111-labeled diethylenetriaminepentaacetic acid ( 111 In-DTPA) was encapsulated inside PTz-liposome to evaluate the leakage of free 111 In-DTPA from the liposomes quantitatively. After 24 h of adding 2-norbornene, the release percentage for PTz-liposome was significantly higher than that for the control liposome (without tetrazine structure). Furthermore, the membrane fluidity of the PTz-liposome was increased by adding 2-norbornene. These results suggested that the combination of dienophile and liposome containing a newly synthesized tetrazine derivative can be used as a controlled release DDS carrier., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Many zinc (Zn) complexes have been developed as promising oral antidiabetic agents. In vitro assays using adipocytes have demonstrated that the coordination structures of Zn complexes affect the uptake of Zn into cells and have insulinomimetic activities, for which moderate stability of Zn complexes is vital. The complexation of Zn plays a major role improving its bioavailability. However, investigation of the speciation changes of Zn complexes after oral administration is lacking. A dual radiolabeling approach was applied in order to investigate the speciation of bis(5-chloro-7-iodo-8-quinolinolato)zinc complex [Zn(Cq) 2 ], which exhibits the antidiabetic activity in diabetic mice. In the present study, 65 Zn- and 131 I-labeled [Zn(Cq) 2 ] were synthesized, and their biodistribution were analyzed after an oral administration using both invasive conventional assays and noninvasive gamma-ray emission imaging (GREI), a novel nuclear medicine imaging modality that enables analysis of multiple radionuclides simultaneously. The GREI experiments visualized the behavior of 65 Zn and [ 131 I]Cq from the stomach to large intestine and through the small intestine; most of the administered Zn was transported together with clioquinol (5-chloro-7-iodo-8-quinolinol) (Cq). Higher accumulation of 65 Zn for [Zn(Cq) 2 ] than ZnCl 2 suggests that the Zn associated with Cq was highly absorbed by the intestinal tract. In particular, the molar ratio of administered iodine to Zn decreased during the distribution processes, indicating the dissociation of most [Zn(Cq) 2 ] complexes. In conclusion, the present study successfully evaluated the speciation changes of orally administered [Zn(Cq) 2 ] using the dual radiolabeling method.

Various types of zinc (Zn) complexes have been developed as promising antidiabetic agents in recent years. However, the pharmacological action of Zn complex is not elucidated because the biodistribution of the complex in a living organism has not been studied. Nuclear medicine imaging is superior technology for the noninvasive analysis of the temporal distribution of drug candidates in living organisms. Gamma-ray emission imaging (GREI), which was developed by our laboratory as a novel molecular imaging modality, was adopted to visualize various γ-ray-emitting radionuclides that are not detected by conventional imaging techniques such as positron emission tomography and single-photon emission computed tomography. Therefore, we applied GREI to a biodistribution assay of Zn complexes. In the present study, 65 Zn was produced in the nat Cu(p,n) reaction in an azimuthal varying field cyclotron for the GREI experiment. The distribution was then noninvasively visualized using GREI after the intravenous administration of a 65 Zn-labeled di(1-oxy-2-pyridinethiolato)zinc [Zn(opt) 2 ], ZnCl 2 , and di(l-histidinato)zinc. The GREI images were validated using conventional invasive assays. This novel study showed that GREI is a powerful tool for the biodistribution analysis of antidiabetic Zn complexes in a living organism. In addition, accumulation of 65 Zn in the cardiac blood pool was observed for [Zn(opt) 2 ], which exhibits potent antidiabetic activity. These results suggest that the slow elimination of Zn from the blood is correlated to the antidiabetic activity of [Zn(opt) 2 ].

The increasing prevalence of diabetes mellitus (DM) worldwide has underscored the urgency of developing an efficient therapeutic agent. Recently, Zn complexes have been attracting attention due to their antidiabetic activity. In this study, we designed and synthesized a new Zn complex, Zn-3,4-heptanedione-bis(N (4)-methylthiosemicarbazonato) (Zn-HTSM), characterized its physicochemical properties, and examined its antidiabetic activity in KK-A(y) type 2 DM model mice. It was demonstrated that Zn-HTSM has adequate lipophilicity for the cellular permeability, shows potent hypoglycemic activity, and improves glucose intolerance in KK-A(y) mice. We also analyzed the levels of serum adipokines after continuous oral administration of Zn-HTSM. The level of serum leptin of KK-A(y) mice is significantly reduced by the treatment of Zn-HTSM. Nevertheless, the levels of serum insulin and adiponectin were not improved. These data suggested that the Zn-HTSM acts on the leptin metabolism. Our present studies indicate that Zn-HTSM is a candidate oral antidiabetic agent for the treatment of type 2 DM.