Kinetic model studies on the chemical ligation of oligonucleotides via hydrazone formation

Targeted amplification of delivery to cell surface receptors by dendrimer self-assembly

Nanometer-scale architectures assembled on cell surface receptors from smaller macromolecular constituents generated a large amplification of fluorescence. A targeted dendrimer was synthesized from a cystamine-core G4 PAMAM dendrimer, and contained an anti-BrE3 monoclonal antibody as the targeting group, several fluorophores and an average of 12 aldehyde moieties as complementary bio-orthogonal reactive sites for the covalent assembly. A cargo dendrimer, derived from a PAMAM G4 dendrimer, contained several fluorophores as the cargo for delivery and five hydrazine moieties as complimentary bio-orthogonal reactive sites. The system is designed to be flexible and allow for facile incorporation of a variety of targeting ligands.

Solid-phase supports for oligonucleotide synthesis

This unit attempts to provide a reasonably complete inventory of over 280 solid supports available to oligonucleotide chemists for preparation of natural and 3'-modified oligonucleotides. Emphasis is placed on non-nucleosidic solid supports. The relationship between the structural features of linkers and their behavior in oligonucleotide synthesis and deprotection is discussed wherever the relevant observations are available.

Preparation of catalytically active, covalent α-polylysine-enzyme conjugates via UV/vis-quantifiable bis-aryl hydrazone bond formation

Covalent UV/vis-quantifiable bis-aryl hydrazone bond formation was investigated for the preparation of conjugates between α-poly-d-lysine (PDL) and either α-chymotrypsin (α-CT) or horseradish peroxidase (HRP). PDL and the enzymes were first modified via free amino groups with the linking reagents succinimidyl 6-hydrazinonicotinate acetone hydrazone (S-HyNic, at pH 7.6) and succinimidyl 4-formylbenzoate (S-4FB, at pH 7.2), respectively. The modified PDL and enzymes were then conjugated at pH 4.7, whereby polymer chains carrying several enzymes were obtained. Kinetics of the bis-aryl hydrazone bond formation was investigated spectrophotometrically at 354 nm. Retention of the enzymatic activity after conjugate formation was confirmed by using the substrates N-succinimidyl-l-Ala-l-Ala-l-Pro-l-Phe-p-nitroanilide (for α-CT) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS, for HRP). Thus, not only a mild and efficient preparation and convenient quantification of a conjugate between the polycationic α-polylysine and enzymes could be shown, but also the complete preservation of the enzymatic activity.