Liquid-Liquid and Liquid-Solid Interfacial Nanoarchitectonics

Nanoscale science is becoming increasingly important and prominent, and further development will necessitate integration with other material chemistries. In other words, it involves the construction of a methodology to build up materials based on nanoscale knowledge. This is also the beginning of the concept of post-nanotechnology. This role belongs to nanoarchitectonics, which has been rapidly developing in recent years. However, the scope of application of nanoarchitectonics is wide, and it is somewhat difficult to compile everything. Therefore, this review article will introduce the concepts of liquid and interface, which are the keywords for the organization of functional material systems in biological systems. The target interfaces are liquid-liquid interface, liquid-solid interface, and so on. Recent examples are summarized under the categories of molecular assembly, metal-organic framework and covalent organic framework, and living cell. In addition, the latest research on the liquid interfacial nanoarchitectonics of organic semiconductor film is also discussed. The final conclusive section summarizes these features and discusses the necessary components for the development of liquid interfacial nanoarchitectonics.

Navigating through the coordination preferences of heavy alkaline earth metals: Laying the foundations for 223Ra- and 131/135mBa-based targeted alpha therapy and theranostics of cancer

The clinical success of [223Ra]RaCl2 (Xofigo®) for the palliative treatment of bone metastases in patients with prostate cancer has highlighted the therapeutic potential of α-particle emission. Expanding the applicability of radium-223 in Targeted Alpha Therapy of non-osseous tumors is followed up with significant interest, as it holds the potential to unveil novel treatment options in the comprehensive management of cancer. Moreover, the use of barium radionuclides, like barium-131 and -135m, is still unfamiliar in nuclear medicine applications, although they can be considered as radium-223 surrogates for imaging purposes. Enabling these applications requires the establishment of chelators able to form stable complexes with radium and barium radionuclides. Until now, only a limited number of ligands have been suggested and these molecules have been primarily inspired by existing structures known for their ability to complex large metal cations. However, a systematic inspection of chelators specifically tailored to Ra2+ and Ba2+ has yet to be conducted. This work delves into a comprehensive investigation of a series of small organic ligands, aiming to unveil the coordination preferences of both radium-223 and barium-131/135m. Electronic binding energies of both metal cations to each ligand were theoretically computed via Density Functional Theory calculations (COSMO-ZORA-PBE-D3/TZ2P), while thermodynamic stability constants were experimentally determined for Ba2+-ligand complexes by potentiometry, NMR and UV-Vis spectroscopies. The outcomes revealed malonate, 2-hydroxypyridine 1-oxide and picolinate as the most favorable building blocks to design multidentate chelators. These findings serve as foundation guidelines, propelling the development of cutting-edge radium-223- and barium-131/135m-based radiopharmaceuticals for Targeted Alpha Therapy and theranostics of cancer.

Confined Space Nanoarchitectonics for Dynamic Functions and Molecular Machines

Nanotechnology has advanced the techniques for elucidating phenomena at the atomic, molecular, and nano-level. As a post nanotechnology concept, nanoarchitectonics has emerged to create functional materials from unit structures. Consider the material function when nanoarchitectonics enables the design of materials whose internal structure is controlled at the nanometer level. Material function is determined by two elements. These are the functional unit that forms the core of the function and the environment (matrix) that surrounds it. This review paper discusses the nanoarchitectonics of confined space, which is a field for controlling functional materials and molecular machines. The first few sections introduce some of the various dynamic functions in confined spaces, considering molecular space, materials space, and biospace. In the latter two sections, examples of research on the behavior of molecular machines, such as molecular motors, in confined spaces are discussed. In particular, surface space and internal nanospace are taken up as typical examples of confined space. What these examples show is that not only the central functional unit, but also the surrounding spatial configuration is necessary for higher functional expression. Nanoarchitectonics will play important roles in the architecture of such a total system.

Advancing Chelation Strategies for Large Metal Ions for Nuclear Medicine Applications

Nuclear medicine leverages radioisotopes of a wide range of elements, a significant portion of which are metals, for the diagnosis and treatment of disease. To optimally use radioisotopes of the metal ions, or radiometals, for these applications, a chelator that efficiently forms thermodynamically and kinetically stable complexes with them is required. The chelator also needs to attach to a biological targeting vector that locates pathological tissues. Numerous chelators suitable for small radiometals have been established to date, but chelators that work well for large radiometals are significantly less common. In this Account, we describe recent progress by us and others in the advancement of ligands for large radiometal chelation with emerging applications in nuclear medicine.First, we discuss and analyze the coordination chemistry of the chelator macropa, a macrocyclic ligand that contains the 18-crown-6 backbone and two picolinate pendent arms, with large metal ions in the context of nuclear medicine. This ligand is known for its unusual reverse size selectivity, the preference for binding large over small metal ions. The radiolabeling properties of macropa with large radiometals ²²⁵Ac³⁺, ^132/135La³⁺, ¹³¹Ba²⁺, ²²³Ra²⁺, ²¹³Bi³⁺, and related in vivo investigations are described. The development of macropa derivatives containing different pendent donors or rigidifying groups in the macrocyclic core is also briefly reviewed.Next, efforts to transform macropa into a radiopharmaceutical agent via covalent conjugation to biological targeting vectors are summarized. In this discussion, two types of bifunctional analogues of macropa reported in the literature, macropa-NCS and mcp-click, are presented. Their implementation in different radiopharmaceutical agents is discussed. Bioconjugates containing macropa attached to small-molecule targeting vectors or macromolecular antibodies are presented. The in vitro and in vivo evaluations of these constructs are also discussed.Lastly, chelators with dual size selectivity are described. This class of ligands exhibits good affinities for both large and small metal ions. This property is valuable for nuclear medicine applications that require the simultaneous chelation of both large and small radiometals with complementary therapeutic and diagnostic properties. Recently, we reported an 18-membered macrocyclic ligand called macrodipa that attains this selectivity pattern. This chelator, its second-generation analogue py-macrodipa, and their applications for chelating the medicinally relevant large ¹³⁵La³⁺, ²²⁵Ac³⁺, ²¹³Bi³⁺, and small ⁴⁴Sc³⁺ ions are also presented. Studies with these radiometals show that py-macrodipa can effectively radiolabel and stably retain both large and small radiometals. Overall, this Account makes the case for innovative ligand design approaches for novel emerging radiometal ions with unusual coordination chemistry properties.