Dendrimer Platform Research Articles

Dendrimer-Mediated Formation of Multicomponent Nanospheres

Silica encapsulation of nanoparticles has had important applications in areas as diverse as catalyst support in heterogeneous processes to controlled drug release. Current methods of production often require stringent conditions which can lead to degradation of the encapsulated material. Recently, we have developed a dendrimer-driven biomimetic approach to nanoparticle silica formation that occurs at ambient conditions. Extending this chemistry, PAMAM dendrimers have been utilized successfully as both a host for Au0 nanoparticle synthesis and an active agent for silica condensation. The resulting product yields mesoporous silica nanospheres of 80-nm diameter supporting randomly distributed gold nanoparticles. Alternately, the positively charged surface of the dendrimers may be used to form an electrostatic precursor complex with low ratios of negatively charged CdSe/ZnS core shell semiconductor nanoparticles (AMP dots) that condense silica, trapping the AMP dots within 200-nm diameter silica nanospheres. These separate routes to the formation of silica nanocomposites demonstrate the potential versatility of the dendrimer platform for materials synthesis.

In Vitro Targeting of Synthesized Antibody-Conjugated Dendrimer Nanoparticles

This study reports the synthesis and in vitro biological properties of dendrimer-antibody conjugates. The polyamidoamine dendrimer platform was conjugated to fluorescein isothiocyanate as a means to analyze cell binding and internalization. Two different antibodies, 60bca and J591, which bind to CD14 and prostate-specific membrane antigen (PSMA), respectively, were used as model targeting molecules. The binding of the antibody-conjugated dendrimers to antigen-expressing cells was evaluated by flow cytometry, confocal microscopy, and a new two-photon-based optical fiber fluorescence detection system. The conjugates specifically bound to the antigen-expressing cells in a time- and dose-dependent fashion, with affinity similar to that of the free antibody. Confocal microscopic analysis suggested at least some cellular internalization of the dendrimer conjugate. Dendrimer-antibody conjugates are a suitable platform for targeted molecule delivery into antigen-expressing cells.

Dendritic Supramolecular Assembly with Multiple Ru(II) Tris(bipyridine) Units at the Periphery: Synthesis, Spectroscopic, and Electrochemical Study

A supramolecular assembly with eight peripheral ruthenium(II) tris(bipyridine), [Ru(bpy)3]2+, units covalently linked to a carbosilane dendrimer platform has been synthesized. 1H NMR and MALDI-TOF mass spectrometry confirm the target structure. Spectroscopic and electrochemical studies disclose that the identical [Ru(bpy)3]2+ units in this system interact neither in the ground state nor in the excited state. In acetonitrile solutions of identical molar concentration of [Ru(bpy)3]2+ units, both the dendrimer and reference monomeric [Ru(bpy)2(4-octoxy-2,2‘-bipyridine)]2+ exhibit identical absorption and emission spectra. Cyclic voltammetry reveals that the dendrimer and monomer possess the same redox potentials of the metal-centered oxidation process [Ru(bpy)3]2+/3+ and the first ligand-centered reduction process [Ru(bpy)3]1+/2+. The abnormal redox peaks of the [Ru(bpy)3]0/1+ and [Ru(bpy)3]1-/0 transitions of the dendrimer are attributed to the accumulation of neutral dendrimer on the electrode. A prelimina...