Properties and cellular uptake of photo-triggered mixed metallosurfactant vesicles intended for controlled CO delivery in gas therapy

The scientific relevance of carbon monoxide has increased since it was discovered that it is a gasotransmitter involved in several biological processes. This fact stimulated research to find a secure and targeted delivery and lead to the synthesis of CO-releasing molecules. In this paper we present a vesicular CO delivery system triggered by light composed of a synthetized metallosurfactant (TCOL10) with two long carbon chains and a molybdenum-carbonyl complex. We studied the characteristics of mixed TCOL10/phosphatidylcholine metallosomes of different sizes. Vesicles from 80 to 800 nm in diameter are mainly unilamellar, do not disaggregate upon dilution, in the dark are physically and chemically stable at 4 °C for at least one month, and exhibit a lag phase of about 4 days before they show a spontaneous CO release at 37 °C. Internalization of metallosomes by cells was studied as function of the incubation time, and vesicle concentration and size. Results show that large vesicles are more efficiently internalized than the smaller ones in terms of the percentage of cells that show TCOL10 and the amount of drug that they take up. On balance, TCOL10 metallosomes constitute a promising and viable approach for efficient delivery of CO to biological systems.

Design and applications of metallo-vesicular structures using inorganic-organic hybrids

In advanced biomedical diagnosis, various supramolecular assemblies based on inorganic-organic hybrids have found great interest as functional materials. These assemblies describe a new field of metallovesicles where the introduction of metal ions enables the chemical manipulation of assemblies in terms of their structural stability, redox activity, and pH stability. Additionally, they mimic the elaborative architecture of natural liposomal assemblies and exhibit hierarchical morphologies, and promise novel functions. With the constant developments in this field, various supramolecular assemblies such as MCsomes, Polymersomes, and Metallosomes, etc. came into existence. These hybrid assemblies have been utilized for several applications such as drug delivery, MRI contrasting, DNA delivery, and catalytic activity. The key advantage of these assemblies is their ability to deliver therapeutics to specific locations due to their biomimetic properties and release their contents at the desired time. Hence, they provide a valuable platform for the treatment of a variety of diseases. Through the present article, we intend to provide insights into the latest developments made in this field. This modularity underscores the tremendous promise of supramolecular assemblies as an emerging interdisciplinary research branch at the interface of chemistry and biological sciences.

Metallosurfactants Consisting of Amphiphilic Ligands and Transition Metals: Structure, Bonding, Reactivity, and Self-assembling Property

Metallosurfactants are emerging as a relatively new class of surfactants whose ligand moieties bind to various transition metals. Because transition metal centers are incorporated into the surfactant frameworks, they can form various self-assembled structures with metallic interfaces such as micelles, vesicles, and lyotropic liquid crystals. To reduce the lability of transition metal complexes under aqueous conditions, various amphiphilic ligands have been developed as surfactant frameworks. This review discusses some aspects of the design and chemical structures of amphiphilic ligands, as well as focus on various functions and types of chemical bonds present in metallosurfactants.

Metallosomes for biomedical applications by mixing molybdenum carbonyl metallosurfactants and phospholipids

New photo-CORM metallosomes with low cell toxicity were prepared from organometallic metallosurfactants and phospholipids.

Coding the Assembly of Polyoxotungstates with a Programmable Reaction System

Chemical transformations are normally conducted in batch or flow mode, thereby allowing the chemistry to be temporally or spatially controlled, but these approaches are not normally combined dynamically. However, the investigation of the underlying chemistry masked by the self-assembly processes that often occur in one-pot reactions and exploitation of the potential of complex chemical systems requires control in both time and space. Additionally, maintaining the intermediate constituents of a self-assembled system “off equilibrium” and utilizing them dynamically at specific time intervals provide access to building blocks that cannot coexist under one-pot conditions and ultimately to the formation of new clusters. Herein, we implement the concept of a programmable networked reaction system, allowing us to connect discrete “one-pot” reactions that produce the building block{W₁₁O₃₈} ≡ {W₁₁} under different conditions and control, in real time, the assembly of a series of polyoxometalate clusters {W₁₂O₄₂} ≡ {W₁₂}, {W₂₂O₇₄} ≡ {W₂₂} 1a, {W₃₄O₁₁₆} ≡ {W₃₄} 2a, and {W₃₆O₁₂₀} ≡ {W₃₆} 3a, using pH and ultraviolet–visible monitoring. The programmable networked reaction system reveals that is possible to assemble a range of different clusters using {W₁₁}-based building blocks, demonstrating the relationship between the clusters within the family of iso-polyoxotungstates, with the final structural motif being entirely dependent on the building block libraries generated in each separate reaction space within the network. In total, this approach led to the isolation of five distinct inorganic clusters using a “fixed” set of reagents and using a fully automated sequence code, rather than five entirely different reaction protocols. As such, this approach allows us to discover, record, and implement complex one-pot reaction syntheses in a more general way, increasing the yield and reproducibility and potentially giving access to nonspecialists.

Here we describe a programmable networked reaction system connecting reactors that produce the building block{W₁₁O₃₈} ≡ {W₁₁} under different conditions and control the assembly of a series of polyoxometalate clusters {W₁₂O₄₂} ≡ {W₁₂}, {W₂₂O₇₄} ≡ {W₂₂} 1a, {W₃₄O₁₁₆} ≡ {W₃₄} 2a, and {W₃₆O₁₂₀} ≡ {W₃₆} 3a, using pH and ultraviolet−visible monitoring. This approach led to the isolation of five clusters using a fully automated sequence code, rather than five entirely different reaction protocols.

Low-toxicity metallosomes for biomedical applications by self-assembly of organometallic metallosurfactants and phospholipids

New photo-CORM metallosomes prepared by a straightforward method from organometallic metallosurfactants and phospholipids show a drastic diminution of cell toxicity.

Fabrication of metalosomes (metal containing cationic liposomes) using single chain surfactants as a precursor via formation of inorganic organic hybrids

This work reveals a methodology to modify a single chain surfactant to fabricate a liposome-like assembly by controlling the stoichiometry by virtue of a metallic counter ion. It is a noteworthy advancement in the area of self-assembled molecular structures.

Hierarchical Self-Assembly of Luminescent Tartrate-Bridged Chiral Binuclear Tb(III) Complexes in Ethanol

A new family of supramolecular metalloamphiphiles carrying two metal centers is developed. They are formed by bridging two coordinatively unsaturated lipophilic Tb³⁺ complexes (TbL⁺) with chiral dicarboxylate anions. The formation of bridging coordination bonds is confirmed using UV spectroscopy, induced circular dichroism (ICD), increased luminescence intensity of TbL⁺, and electrospray ionization mass spectrometry (ESIMS) analysis. These supramolecular metalloamphiphiles hierarchically self-assemble in ethanol to give luminescent nanospheres, as observed using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The two hydroxyl groups introduced in the bridging ligands of [TbL]₂(d-/l-tartrate) significantly promote self-assembly by increasing coherent forces via intermolecular hydrogen bonding. The observed self-assembly in ethanol also merits mention because such polar alcoholic media have been unfavorable for conventional molecular self-assemblies. The present approach offers a new molecular design strategy for composable metalloamphiphiles.

Aggregation and surface behavior of aqueous solutions of cis-bis(1,3-diaminopropane)bis(dodecylamine)cobalt(iii) nitrate. A double-chained metallosurfactant

Metallosurfactants or amphiphilic metal complexes are emerging as a new class of material with a range of properties inherent to both metal complexes and surfactants.

Iron-Carbonyl Aqueous Vesicles (MCsomes) by Hydration of [Fe(CO){CO(CH2)5CH3}(Cp)(PPh3)] (FpC6): Highly Integrated Colloids with Aggregation-Induced Self-Enhanced IR Absorption (AI-SEIRA)

Self-assembly of hydrophobic molecules into aqueous colloids contradicts common chemical intuition, but has been achieved through hydration of [Fe(CO){CO(CH2)5CH3}(Cp)(PPh3)] (FpC6). FpC6 has no surface activity, no NMR signals in D2O and no critical aggregation concentration (CAC) in H2O. The molecule, however, contains both acyl and terminal CO groups that are prone to being hydrated. By adding water to a solution in THF, self-assembly of FpC6 can be initiated through water-carbonyl interactions (WCIs) with the highly polarized acyl CO groups. This aggregation subsequently enhances the hydration of the acyl CO groups and also induces the WCI of otherwise unhydrated terminal CO groups. The resultant metal-carbonyl aggregates have been proved to be bilayer vesicles with iron complexes exposed towards water and alkyl chains forming inner walls (MCsomes). These MCsomes show high structure integration upon dilution due to the hydrophobic nature of the building blocks. The highly polarized CO groups on the surface of the MCsomes result in a negative zeta potential (-65 mV) and create a local electric field, which significantly enhances the IR absorption of CO groups by more than 100-fold. This is the first discovery of aggregation-induced self-enhanced IR absorption (AI-SRIRA) without the assistant of external dielectric substrates. Highly integrated MCsomes are, therefore, promising as a novel group of materials, for example, for IR-based sensing and imaging.

End Group Functionalization of PFpP Macromolecules Via Fp Migration Insertion Reactions

PFpP macromolecules, synthesized via migration insertion polymerization of CpFe(CO)2 (CH2)3 PPh2 (FpP), exhibit reactive Fp end groups for further migration insertion reactions in the presence of phosphines. A number of alkyl diphenylphosphines with varied alkyl length, Ph2PCn (n = 6, 10, 18), have been prepared for the reaction, resulting in PFpP-PPh2Cn (n = 6, 10, 18) amphiphiles. The phosphines with longer alkyl chains impose steric hindrance for the reaction and therefore require longer reaction times and excess phosphines relative to PFpP.