Cholesterol Modification of an Anticancer Drug for Efficient Incorporation into a Supramolecular Hydrogel System.

Treatment of cancer in the peritoneal cavity may be improved with macroscale drug delivery systems that offer control over intraperitoneal concentration of chemotherapeutic agents. Currently, suitable drug carriers to facilitate a sustained release of small hydrophilic drugs such as mitomycin C are lacking. For this purpose, a pH-responsive supramolecular hydrogel based on ureido-pyrimidinone (UPy) chemistry is utilized here. In order to provide a sustained release profile, a lipophilicity-increasing cholesterol conjugation strategy is proposed that enhances affinity between the modified drug (mitomycin-PEG24 -cholesterol, MPC) and the hydrophobic compartments in the UPy gel. Additional advantages of cholesterol conjugation include improved chemical stability and potency of mitomycin C. In vitro the tunability of the system to obtain optimal effective concentrations over time is demonstrated with a combinatorial treatment of mitomycin C and MPC in one UPy hydrogel delivery system.

Peptide-Driven Charge-Transfer Organogels Built from Synergetic Hydrogen Bonding and Pyrene-Naphthalenediimide Donor-Acceptor Interactions.

The peptide-driven formation of charge transfer (CT) supramolecular gels featuring both directional hydrogen-bonding and donor-acceptor (D-A) complexation is reported. Our design consists of the coassembly of two dipeptide-chromophore conjugates, namely diphenylalanine (FF) dipeptide conveniently functionalized at the N-terminus with either a pyrene (Py-1, donor) or naphthalene diimide (NDI-1, acceptor). UV/Vis spectroscopy confirmed the formation of CT complexes. FTIR and 1 H NMR spectroscopy studies underlined the pivotal role of hydrogen bonding in the gelation process, and electronic paramagnetic resonance (EPR) measurements unraveled the advantage of preorganized CT supramolecular architectures for charge transport over solutions containing non-coassembled D and A molecular systems.

Elucidation of the Cellular Uptake Mechanisms of Polycationic HYDRAmers.

Dendrimers and dendrons appeared to potentially fulfill the requirements for being good and well-defined carriers in drug and gene delivery applications. We recently demonstrated that polycationic adamantane-based dendrons called HYDRAmers are easily internalized by both phagocytic and nonphagocytic cells in vitro. The aim of the present study was to investigate which of the different pathways of cellular internalization is involved in the cellular uptake of the first and second generation ammonium and guanidinium HYDRAmers. For this purpose, we have evaluated the internalization of fluorescently labeled HYDRAmers in both phagocytic murine macrophages and nonphagocytic human cervix epithelioid carcinoma cells in the presence of different well-known active uptake inhibitors. Our data revealed that the first and second generation HYDRAmers are internalized via different endocytic pathways based on the cellular type and on the type of functional groups present at the periphery of the dendrons. In particular, it was registered that the first generations were mainly internalized by clathrin-mediated endocytosis and macropinocytosis while the cellular internalization of the second generations was less affected by the inhibitory conditions of the endocytic pathways. These results suggest the possibility of addressing dendrimers toward specific subcellular compartments by tuning their structure properties and, in particular, the functional groups at their periphery.

Multifunctional adamantane derivatives as new scaffolds for the multipresentation of bioactive peptides.

The remarkable structural and chemical properties of adamantane afford attractive opportunities to design various adamantane-based scaffolds for biomedical applications. A wide range of mono-functionalized adamantane compounds have already been investigated and reviewed, mostly as anti-viral agents. The four bridgehead positions of adamantane provide many possibilities to design poly-functional derivatives, and the recent conception of adamantane building blocks with multiple substituents has shown promising applications in several domains. In this review, we provide a detailed description of the different ways to synthesize multifunctional derivatives starting from adamantane molecule as the main core. We will then describe the interesting biological activity of the diverse multivalent scaffolds, focusing in particular on peptide-based systems. The results reported here will certainly encourage the development of novel adamantane-based structures for biological purposes.

Adamantane-based dendrons for trimerization of the therapeutic P140 peptide.

Dendrons constituted of an adamantane core, a focal point and three arms, were synthetized starting from a multifunctional adamantane derivative. Maleimido groups at the periphery of the scaffold were used to covalently attach the peptide called P140, a therapeutic phosphopeptide controlling disease activity in systemic lupus, both in mice and patients. Biotinylation of the trimers at the focal point was performed using click chemistry and the conjugates were studied in terms of solubility, binding affinity to its receptor, the HSPA8/HSC70 chaperone protein, effect on HSPA8 folding property and in vivo activity. The results showed that the trimerization of P140 peptide does not trigger aggregation or steric hindrances during the interaction with HSPA8 protein. Compared to the monomeric cognate peptide, the trivalent P140 peptide displayed the same capacity, in vitro, to down-regulate HSPA8 activity and, in vivo in MRL/lpr lupus-prone mice, to reduce abnormal blood hypercellularity. The control trimer synthesized with the same scaffold and a scrambled sequence of P140 showed no effect in vivo. This work reveals that adamantane-based scaffolds with a well-defined spatial conformation are promising trivalent systems for molecular recognition and for biomedical applications.

Polycationic adamantane-based dendrons of different generations display high cellular uptake without triggering cytotoxicity.

Dendrons used as synthetic carriers are promising nanostructures for biomedical applications. Some polycationic dendritic systems, such as the commercially available polyethylenimine (PEI), have the ability to deliver genetic material into cells. Nevertheless, polycationic vectors are often associated with potential cellular toxicity, which prevents their use in clinical development. In this context, our research focused on the design and synthesis of a novel type of polycationic dendrons that are able to penetrate into cells without triggering cytotoxic effects. We synthesized first- and second-generation polycationic adamantane-based dendrons via a combined protection/deprotection strategy starting from different adamantane scaffolds. The linker between the adamantane cores is constituted of short ethylene glycol chains, and the periphery consists of ammonium and guanidinium groups. None of these dendritic structures, which we previously called HYDRAmers, displayed significant cytotoxicity effects on two different cell lines (RAW 264.7 and HeLa). Conjugation of the fluorescent probe cyanine 5 at their focal point via click chemistry permitted the evaluation of their cellular internalization. All of the dendrons penetrated through the membrane with efficient cellular uptake depending of the dendron generation and the nature of the peripheral groups. These results suggest that the polycationic HYDRAmers are potentially interesting as new vectors in biomedical applications, including gene and drug delivery.