Solid-Phase Synthesis of Peptide-Conjugated Perylene Diimide Bolaamphiphile and Its Application in Photodynamic Therapy.

Here, we describe a rapid and efficient synthetic method of peptide-conjugated perylene diimide (P-PDI) using solid-phase peptide synthesis (SPPS). Due to severe insolubility of perylene dianhydride (PDA) as a starting material of perylene diimide (PDI), PDA was initially conjugated with amino acids to obtain soluble PDI derivatives. Target peptides were synthesized on a 2-chlorotrityl chloride resin using the SPPS method and then conjugated with the amino acid-appended PDI. Various conditions such as loading levels, reaction times and solvents were optimized for introducing the peptides to both sides of the amino acid-appended PDI. The final P-PDI was obtained with a maximum yield of 80% in 12 h. Its singlet oxygen-derived phototoxicity on cells was confirmed, which could be applicable to photodynamic therapy.

Tailoring a Tyrosine-Rich Peptide into Size- and Thickness-Controllable Nanofilms.

Self-assembled nanostructures of tyrosine-rich peptides have a number of potential applications such as biocatalysts, organic conducting films, and ion-selective membranes. In modulating a self-assembly process of peptides, the interfacial force is an important factor for kinetic control. Here, we present the formation of large-sized and thickness-controllable nanofilms from the YYACAYY peptide sequence (Tyr-C7mer peptide) using Langmuir-Blodgett and Langmuir-Schaefer deposition methods. The Tyr-C7mer peptide showed typical surfactant-like properties, which were demonstrated via the isotherm test (surface pressure-area) by spreading the Tyr-C7mer peptide solution onto an air/water interface. Uniform and flat peptide nanofilms were successfully fabricated and characterized. The redox activity of densely packed tyrosine moieties on the peptide nanofilm was also evaluated by assembling silver nanoparticles on the nanofilm without requiring any additives.