Peptide-driven charge-transfer organogels built from synergetic hydrogen bonding and pyrene–naphthalenediimide donor–acceptor interactions

\u3cp\u3eThe 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 \u3csup\u3e1\u3c/sup\u3eH 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.\u3c/p\u3

Cholesterol modification of an anticancer drug for efficient incorporation into a supramolecular hydrogel system

\u3cp\u3eTreatment 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-PEG\u3csub\u3e24\u3c/sub\u3e-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.\u3c/p\u3