The Biological Side of Water-Soluble Arene Ruthenium Assemblies

Abstract

This review article covers the synthetic strategies, structural aspects, and host-guest properties of ruthenium metalla-assemblies, with a special focus on their use as drug delivery vectors. The two-dimensional metalla-rectangles show interesting host-guest possibilities but seem less appropriate for being used as drug carriers. On the other hand, metalla-prisms allow encapsulation and possible targeted release of bioactive molecules and consequently show some potential as drug delivery vectors. The reactivity of these metalla-prisms can be fine-tuned to allow a fine control of the guest’s release. The larger metalla-cubes can be used to stabilize the formation of G-quadruplex DNA and can be used to encapsulate and release photoactive molecules such as porphins. These metalla-assemblies demonstrate great prospective in photodynamic therapy.

Biomedically Relevant Self-Assembled Metallacycles and Metallacages

“…In addition to cisplatin and porphin, Cur (G14) is another anticancer drug that can be encapsulated. We prepared a host− guest complex comprising MOC 102 (Figure 5e) and cucurbituril [8] (CB [8]), 76 which acts as an aqueous carrier of Cur and delivers it to cancer cells. This work shows how a judicious combination of coordination-driven self-assembly and host−guest interactions can be utilized for hydrophobic drug delivery with improved efficacy.…”

“…Metal–organic complexes (MOCs) , are well-defined, discrete two-dimensional (2D) or three-dimensional (3D) molecular entities with suitable metal centers undergoing coordination-driven self-assembly with ligands containing multiple binding sites. , The inspiration for using MOCs in biological applications − originates from their characteristic properties, such as the ease of fine-tuning the dimensions of the complexes, the selection of metal ions with specific sizes, their coordination geometry, and the simple incorporation of essential functional groups through pre- or post-self-assembly − modifications (Scheme , top).…”

“…By using Pt, Pd, Ru, Rh, and Ir as the metal center (Scheme , bottom, left), Therrien, Stang, and Casini published recent work on MOC design for biochemical and biomedical applications (Scheme , bottom, middle). For example, 2D metalla­cycles such as triangles, rectangles, rhomboids, and hexagons can be formed by coordination between ligands and a metal acceptor for biomedical applications.…”

“…Biological studies involving MOCs have been widely conducted (Scheme , bottom, right), and the effects of the characteristic structural features of MOCs have been described . For example, Therrien and co-workers found that half-sandwich Ru complexes are essential functional units in treating many kinds of cancers. In contrast to Therrien’s work, our group has devoted much attention to Pt-containing MOCs and their in vivo study. ,− We introduced various functional units, such as TPPE, into MOCs, improving the precision of cell imaging and achieving “tissue-specific” aggregation and imaging .…”

The Role of the Second Coordination Sphere in the Biological Activity of Arene Ruthenium Metalla-Assemblies

“…For many years, we have been involved in the field of coordination-driven self-assembly, using piano-stool complexes (also called half-sandwich complexes) as building blocks, and especially arene ruthenium complexes as biological agents (Therrien and Furrer, 2014; Therrien, 2015). The piano-stool unit provides three coordination sites at 90° from each other for a strategic coordination of ligands on metals (Therrien, 2009), which allows the design of 2D and 3D entities (Cook et al, 2013; Singh et al, 2014; Therrien, 2018).…”