Solid Peptide Nanoparticles – Structural Characterization and Quantification of Cargo Encapsulation

✍ Scribed by Christian Dittrich; Wolfgang Meier

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 478 KB
• Volume: 10
• Category: Article
• ISSN: 1616-5187
• DOI: 10.1002/mabi.201000221

✦ Synopsis

Abstract

CD3ac, an uncharged and strongly hydrophobic 10 amino acid peptide (Ac‐LK(Ac)‐LK(Ac)‐LK(Ac)‐LW‐DL‐LW‐DL‐LW‐DL‐LW‐NH2) was synthesized and purified. The peptide readily dissolves in ethanol and – upon solvent exchange to water – assembles into solid spherical particles with diameters of around 500 nm and low size‐polydispersity. CD3ac self‐assembles in a convenient one‐step‐process in the absence of a templating two‐phase solvent system or any other templating agents. Circular dichroism reveals a gramicidin‐like secondary structure, which can be attributed to the presence of D‐leucine, whereas LCD3ac, a peptide of identical constitution yet composed entirely of L‐amino acids precipitates amorphously. The unacetylated derivative of LCD3ac (LCD3) displays α‐helical character in circular dichroism. During the process of bead formation, CD3ac can take up and enrich water‐soluble and – insoluble cargo compounds, which is exemplified by the encapsulation of rose bengal (RB) and 5‐carboxy‐fluorescein (CF), two xanthene derivatives. We confirmed their presence in CD3ac beads by confocal fluorescence microscopy and quantified the encapsulation efficiency by absorption measurements of dissolved RB‐containing peptide bead suspensions. Loaded CD3ac beads consist of up to 40 mol‐% RB, which corresponds to a logarithmic partition coefficient of 2.95. To the best of our knowledge CD3ac is the first peptide synthesized by Fmoc chemistry which forms solid particles in the nano‐ and micrometer size range and holds promise for drug delivery applications.

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