Inchworm-type PNA-PEG conjugate regulates gene expression based on single nucleotide recognition.

In order to detect single nucleotide mutations and suppress gene expression, we synthesized an artificial nucleic acid, an inchworm-type PNA-PEG conjugate (i-PPc), that possessed a chemical structure in which 8 residues of peptide nucleic acid (PNA) were linked to both ends of a polyethylene glycol molecule. I-PPc_T7FM, which forms a complementary strand with the T7 promoter region of luciferase-expressing mRNA, failed to suppress the amount of luciferase produced via gene expression. However, 10 µM of i-PPc_ATGFM, targeting the start codon of luciferase (Luc+), suppressed approximately 85% of Luc+ production compared to that of the control in the cell-free protein synthesis system. Moreover, i-PPc_ATGMM (i-PPc_ATGFM with a single base mutation) only suppressed the amount of luciferase produced by approximately 15%, and such suppression of luciferase expression has not been achieved with block-type PPc or PNA oligos. The thermodynamic parameters suggested that the difference in stability of each PNA segment of the i-PPc contributed to single nucleotide recognition. These results indicate that the i-PPc could be used in antisense therapy to target single nucleotide polymorphisms (SNP).

The design of polymer microcarrier surfaces for enhanced cell growth.

A variety of neutral and cationic polymers based on polyamino acids were prepared and investigated as microcarriers for cell attachment and growth. Among neutral polymer particles including the alkylated poly(gamma-methyl L-glutamate) (PG) particles, in which the hydrophobicity changes as a function of the length of the alkyl groups, and hydroxy terminal PG particles, the PG particle with the longest alkyl chain (PG-C12) demonstrated the highest cell attachment rate and highest rate of cell growth. Moreover, the introduction of hydroxyl groups (PG-OH) led to a deterioration of cell growth. Cell growth on cationic particles having primary amino groups was drastically dependent upon the anion exchange capacity (AEC). A higher AEC for aminated PG microcarriers inhibited cell growth. In contrast, a higher AEC for cross-linked poly( epsilon -lysine) (PL) microcarriers facilitated cell growth. Cell growth on cationic particles clearly showed a good correlation with the pK(a,app) of the microcarriers, but not with their AEC. The particles with low and high pK(a) values possessed toxically acidic and basic pH microenvironments near the surface, respectively. These microenvironments had cytotoxic effects. On the other hand, no correlation between attachment rate constants and high cell growth was observed. The aminated particles, in which pK(a) were controlled at neutral pH, and PG-C12 produced obviously higher cell growth than did a commercially available microcarrier.

Stabilization of enhanced chirality from pyrene-containing l-glutamide lipid in methyl methacrylate by photo-induced polymerization.

Enhanced CD spectra based on chirally-oriented structures of pyrene-containing L-glutamic acid-derived lipid were observed in polymerizable monomers and CD strength was maintained after photo-induced polymerization of the monomer solvents.

Evaluation of Aß fibrillization inhibitory effect by a PEG-peptide conjugate based on an Aß peptide fragment with intramolecular FRET.

A PEG-peptide conjugate based on an amyloid ß peptide fragment was synthesized. The formed amyloid protofibril-like aggregates induced intramolecular FRET. It proved to be useful as a bioprobe to evaluate the inhibitory effect of organic molecules toward amyloid fibrillization.

Novel self-assembling organogelators by combination of a double chain-alkylated L-glutamide and a polymeric head group.

This communication introduces a new class of self-assembling organogelators composed of a double chain-alkylated L-glutamide with a polymeric head group.