Micelle-like nanoparticles of block copolymer poly(ethylene oxide)-block-poly(methacrylic acid) incorporating fluorescently substituted metallacarboranes designed as HIV protease inhibitor interaction probes

Nanoparticle-based strategies to target HIV-infected cells

Antiretroviral drugs employed for the treatment of human immunodeficiency virus (HIV) infections have remained largely ineffective due to their poor bioavailability, numerous adverse effects, modest uptake in infected cells, undesirable drug-drug interactions, the necessity for long-term drug therapy, and lack of access to tissues and reservoirs. Nanotechnology-based interventions could serve to overcome several of these disadvantages and thereby improve the therapeutic efficacy of antiretrovirals while reducing the morbidity and mortality due to the disease. However, attempts to use nanocarriers for the delivery of anti-retroviral drugs have started gaining momentum only in the past decade. This review explores in-depth the various nanocarriers that have been employed for the treatment of HIV infections highlighting their merits and possible demerits.

Ex Vivo and In Vivo Evaluation of Dodecaborate-Based Clusters Encapsulated in Ferumoxytol Nanoparticles

Host-guest interactions represent a growing research area with recent work demonstrating the ability to chemically manipulate both host molecules as well as guest molecules to vary the type and strength of bonding. Much less is known about the interactions of the guest molecules and hybrid materials containing similar chemical features to typical macrocyclic hosts. This work uses in vitro and in vivo kinetic analyses to investigate the interaction of closo-dodecahydrododecaborate derivatives with ferumoxytol, an iron oxide nanoparticle with a carboxylated dextran coating. We find that several boron cluster derivatives can become encapsulated into ferumoxytol, and the lack of pH dependence in these interactions suggests that ion pairing, hydrophobic/hydrophilic interaction, and hydrogen bonding are not the driving force for encapsulation in this system. Biodistribution experiments in BALB/c mice show that this system is nontoxic at the reported dosage and demonstrate that encapsulation of dodecaborate-based clusters in ferumoxytol can alter the biodistribution of the guest molecules.

Preparing (Metalla)carboranes for Nanomedicine

"There's plenty of room at the bottom" (Richard Feynman, 1959): an invitation for (metalla)carboranes to enter the (new) field of nanomedicine. For two decades, the number of publications on boron cluster compounds designed for potential applications in medicine has been constantly increasing. Hundreds of compounds have been screened in vitro or in vivo for a variety of biological activities (chemotherapeutics, radiotherapeutics, antiviral, etc.), and some have shown rather promising potential for further development. However, until now, no boron cluster compounds have made it to the clinic, and even clinical trials have been very sparse. This review introduces a new perspective in the field of medicinal boron chemistry, namely that boron-based drugs should be regarded as nanomedicine platforms, due to their peculiar self-assembly behaviour in aqueous solutions, and treated as such. Examples for boron-based 12- and 11-vertex clusters and appropriate comparative studies from medicinal (in)organic chemistry and nanomedicine, highlighting similarities, differences and gaps in physicochemical and biological characterisation methods, are provided to encourage medicinal boron chemists to fill in the gaps between chemistry laboratory and real applications in living systems by employing bioanalytical and biophysical methods for characterising and controlling the aggregation behaviour of the clusters in solution.

Preparation of membrane-mimicking lamellar structures by molecular confinement of hybrid nanocomposites

Hybrid nanocomposites are multiphase systems with a wide range of applications. Some nanocomposites are water insoluble thereby preventing several applications. Thus, we prepared telechelic PEO with glucose molecules to form water-soluble lamellar nanostructures by co-assembly with metallacarborane. The lamellas formed by PEO/metallacarborane decorated by glucose molecules on the surface can serve as delivery agents for boron clusters and benzoxaboroles.

Cation-sensitive compartmentalization in metallacarborane containing polymer nanoparticles

The inner structure of hybrid nanoparticles based on metallacarborane complexation with diblock copolymer PEO–POX is sensitive to alkaline cations.

Preparation and evaluation of PCL–PEG–PCL polymeric nanoparticles for doxorubicin delivery against breast cancer

DOX-loaded polymeric NPs based on PCL–PEG–PCL triblock copolymers were successfully prepared and showed highly efficient targeting and accumulation in tumor via EPR effect. The prepared NPs would be a promising nanosized DDS for cancer therapy.

Compartmentalization in Hybrid Metallacarborane Nanoparticles Formed by Block Copolymers with Star-Like Architecture

One strategy to control the morphology of hybrid polymeric nanostructures is the proper selection of macromolecule architecture. We prepared metallacarborane-rich nanoparticles by interaction of double-hydrophilic block copolymers consisting of both poly(2-alkyl oxazolines) and poly(ethylene oxide) blocks with cobaltabisdicarbollide anion in physiological saline. The inner structure of the hybrid nanoparticles was studied by cryo-TEM, light scattering, SAXS, NMR, and ITC. Although the thermodynamics of diblock and star-like systems are almost identical, the macromolecular architecture has a great impact on the size and inner morphology of the nanoparticles. While hybrid nanoparticles formed by linear diblock copolymers are homogeneous, resembling gel-like nanospheres, the star-like shape of 4-arm block copolymers with PEO blocks in central parts of macromolecules leads to distinct compartmentalization. Because metallacarboranes are promising species in medicine, the studied nanoparticles are important for targeted drug delivery of boron cluster compounds.

Polymeric micelles based on poly(methacrylic acid) block-containing copolymers with different membrane destabilizing properties for cellular drug delivery

Poly(methacrylic acid)-b-poly(ethylene oxide) are double hydrophilic block copolymers, which are able to form micelles by complexation with a counter-polycation, such as poly-l-lysine. A study was carried out on the ability of the copolymers to interact with model membranes as a function of their molecular weights and as a function of pH. Different behaviors were observed: high molecular weight copolymers respect the membrane integrity, whereas low molecular weight copolymers with a well-chosen asymmetry degree can induce a membrane alteration. Hence by choosing the appropriate molecular weight, micelles with distinct membrane interaction behaviors can be obtained leading to different intracellular traffics with or without endosomal escape, making them interesting tools for cell engineering. Especially micelles constituted of low molecular weight copolymers could exhibit the endosomal escape property, which opens vast therapeutic applications. Moreover micelles possess a homogeneous nanometric size and show variable properties of disassembly at acidic pH, of stability in physiological conditions, and finally of cyto-tolerance.