Nanofabrication of helical peptide-shelled dendrimers

Chain length effects of oligo(l-lysine)-shelled dendrimers on interaction with DNA

The interaction of novel oligo(L-lysine)-shelled dendrimers (G3-PLL) with DNA was studied by means of circular dichroism spectroscopy, dynamic light scattering, and melting behavior of double-stranded DNA. G3-PLLs having various oligo(L-lysine) (PLL) segment (n = 5-40) were successfully synthesized by graft-polymerization of L-lysine NCA initiated with amino groups at the 3rd-generation poly(amidoamine) dendrimer surface. The ionization property of the newly prepared G3-PLLs were first examined. The evaluated pK(a) values (8.3-8.5) for G3-PLLs were found to be significantly lower than those (9.2-9.4) for the corresponding linear PLLs, probably due to alignment of PLL segments on the three-dimensional core surface. The binding experiments of G3-PLLs to DNA showed that double-stranded DNAs were fairly strongly bound to G3-PLLs primarily through electrostatic interactions. In addition, G3-PLLs served as a DNA cross-linker. A longer PLL-containing G3-PLL was found to interact with DNA more effectively than a shorter one.

Preparation of helical peptide monolayer-coated gold nanoparticles

We describe herein the preparation of polypeptide (poly(gamma-benzyl-L-glutamate)) monolayer-covered gold nanoparticles (PBLG(n)SS-Au). Two types of PBLG(n)SS having PBLG segment length n=20 and 50 were synthesized and successfully attached to the gold nanoparticle surface using the Brust-Schiffern method. The mean sizes of PBLG(n)SS-Au particles and their gold cluster cores in CHCl3, which were evaluated by means of dynamic light scattering and TEM, respectively, demonstrated that the gold cluster surfaces were covered with PBLG monolayers, and their conformation was found to be mainly in alpha-helix on the basis of FT-IR spectroscopy.

Biological applications of dendrimers

In the past year, significant advances have been made in the synthesis and study of glycodendrimers and peptide dendrimers. Application of these dendrimers to the study of carbohydrate-protein and protein-protein interactions has facilitated the understanding of these processes. In addition, dendrimers show great promise as DNA- and drug-delivery systems.