Search

High-resolution imaging of molecules intrinsically involved in malignancy and metastasis would be of great value for clinical detection and staging of tumors. We now report in vivo visualization of matrix metalloproteinase activities by MRI and fluorescence of dendrimeric nanoparticles coated with activatable cell penetrating peptides (ACPPs), labeled with Cy5, gadolinium, or both. Uptake of such nanoparticles in tumors is 4-to 15-fold higher than for unconjugated ACPPs. With fluorescent molecules, we are able to detect residual tumor and metastases as small as 200 gm, which can be resected under fluorescence guidance and analyzed histopathologically with fluorescence microscopy. We show that uptake via this mechanism is comparable to that of other near infrared protease sensors, with the added advantage that the approach is translatable to MRI. Once activated, the Gd-labeled nanoparticles deposit high levels (30-50 [micro]M) of Gd in tumor parenchyma with even higher amounts deposited in regions of infiltrative tumor, resulting in useful T1 contrast lasting several days after injection. These results should improve MRI-guided clinical staging, presurgical planning, and intraoperative fluorescence-guided surgery. The approach may be generalizable to deliver radiation-sensitizing and chemotherapeutic agents. Molecular navigation | dendrimeric nanoparticles | molecular amplification | targeted imaging agent | transgenic tumor model doi/10.1073/pnas.0910283107

The direct electrochemistry of laccase was promoted by Au nanoparticle (AuNP)-encapsulated dendrimers (Den), which was applied for the detection of catechin. To increase the electrical properties, AuNPs were captured in the interiors of the dendrimer (Den-AuNPs) as opposed to attachment at the periphery of dendrimer. To prepare Den-AuNPs, the Au(III) ions were first coordinated in the interior of dendrimer with nitrogen ligands and then reduced to form AuNPs. The size of AuNPs encapsulated within the interior of the dendrimer was determined to be 1.7 [+ or -] 0.4 nm. AuNPs-encapsulated dendrimers were then used to covalently immobilize laccase (PDATT/Den(AuNPs)/laccase) through the formation of amide bonds between carboxylic acid groups of the dendrimer and the amine groups of laccase. Each layer of the PDATT/Den(AuNPs)/laccase probe was characterized using CV, EIS, QCM, XPS, SEM, and TEM. The PDATT/Den(AuNPs)/laccase probe displayed a well-defined direct electron-transfer (DET) process of laccase. The quasi-reversible redox peak of the Cu redox center of the laccase molecule was observed at -0.03/ +0.13 V vs Ag/AgCl, and the electron-transfer rate constant was determined to be 1.28 [s.sup.-1]. A catechin biosensor based on the electrocatalytic process by direct electrochemistry of laccase was developed. The linear range and the detection limit in the catechin analysis were determined to be 0.1-10 and 0.05 [+ or -] 0.003 [micro]M, respectively. Interference effects from various phenolic and polyphenolic compounds were also studied, and the general applicability of the biosensor was evaluated by selective analysis of real samples of catechin.

The facile synthetic strategy of a series of novel pi-conjugated dendrimers (G0 and G1) based on 10,15-dihydro-5H-diindeno[1,2-a;1',2'-c]fluorene (truxene) in which the benzene cores are generated in situ from acetyl aromatics by the acid-promoted cyclotrimerizations is reported. The unique NMR behaviors, physical properties, and electroluminescence device applications are presented.

Two dendrimers based on a 1, 3, 5-trisubstituted benzenoid-type core, containing 9 and 21 viologen units in their branches and terminated with tetraarylmethane derivatives is presented. The host-guest interaction can be destroyed by addition of chloride ions, a procedure that permits eosin to escape from the dendrimer's interior in a controlled way and to regain its intense fluorescence.

The electroluminescent properties of polyamidoamine dendrimers containing pendant [Ru(bpy)(sub 3)](super +2) are investigated. Indium tin oxide (ITO) and gold electrodes were used to make devices and they were compared to devices made from [Ru(bpy)(sub 3)](super +2) films.

Unambiguous spectroscopic evidence of strong cooperative enhancement of two-photon absorption (TPA) in a series of dendritic macromolecules is presented. The results show that enhancement is facilitated by the quasi-planar structure, which allows direct interbranch conjugation throughout the molecule.

The photophysical characteristics of light-harvesting dendrimer thin films are studied by photoluminescence near-field scanning optical microscopy (PL NSOM). It is found that the films exhibit pronounced nanoscopic domains and become more homogeneous.

Byline: Antonio de Padua (1), J.A. de MirandaaNeto (1), Isaac M. Xavier (2), Fernando Moraes (1) Abstract: In this work, we propose a geometrical model for the study of conformational properties of a starburst dendrimer with the topology of a truncated Bethe lattice. A convenient embedding of the Bethe lattice in the hyperbolic plane is used to study the architecture of the dendrimer. As results, we find an upper bound for the molecular size and the density profile. Author Affiliation: (1) Departamento de Fisica, Universidade Federal de Pernambuco, 50670a901, Recife, PE, Brazil (2) Departamento de Estatistica, Universidade Federal de Pernambuco, 50670a901, Recife, PE, Brazil Article History: Registration Date: 11/09/2004

College students are tasked to synthesize and characterize dendrimer-encapsulated copper nanoparticles in a two-part laboratory experiment. This experiment increases their understanding of Bronsted-Lowry and Lewis acid-base chemistry, pH, and kinetics.

The analysis of the patterns formed on mica substrates by evaporating small droplets of pentanol containing three different but closely related poly(amidoamine) PAMAM dendrimer molecules dispersed in solution is presented. The morphology of condensed molecule-based ring patterns formed by evaporation of microdroplets on surfaces is used as a fingerprint to identify solute molecule surface chemistry and concentration and function as a sensor for a variety of biochemical events.

A description of the ionic core-shell dendrimers with an octacationic core applied as noncovalent supports for homogenous catalysts is presented. The investigation of the structural aspects and the nature of the metallodendritic assemblies reveal that the dendritic supports and arylpalladium complexes are strongly associated in solution to give unimolecular assemblies due to their nanoscopic size.

The formation of the tubular objects with coiled ribbons from the self-assembly of conjugated rod building blocks in a rigid-flexible macrocyclic molecule in aqueous solution is reported. The energy balance between repulsive interactions among the adjacent flexible chains and pi-pi stacking interactions is the primary driving force responsible for the tubular structure with a coiled ribbon.

Results of a femtosecond fluorescence upconversion study of the C3-symmetrical disk molecular TAB (1a) and the subgroup molecule DAC (2a) are presented. The results show that 1a and 2a exhibit excited-state intramolecular double proton transfer (ESIDPT) with a typical time of approximately 200-300 fs in 1a, ESIDPT takes place for the molecule in the aggregated as well as the nonaggregated state.

The nonlinear optical and time-resolved properties of a series of phenylazomethine--porphyrin dendrimers are reported. Measurements were carried out with the basic building-block molecules and time-resolved measurements suggested efficient intramolecular vibrational energy redistributions in the system.

The properties of a dendrimer with hydrophobic and hydrophilic substituents on an orthogonal plane is synthesized and studied. The resulting polymer contains one of the substituents in its concave interior and the other at the convex surface and the design promotes micelle-like behavior in polar solvent and inverted micelle arrangement in non-polar solvent.

The results of structural studies of poly (benzyl phenyl ether) dendrimers (PBPE dendrimers) are presented using classical molecular dynamics simulations. The results can be correlated with observed with photophysical properties of dendrimers in related systems containing donor/acceptor pairs.

A combined biosynthetic route toward a new class of cylindrical dendrimers with predictable size, shape and solubility is developed. The dendronized protein polymer (DPP) materials self-assemble into highly ordered liquid crystalline (LC) phases with ordering length-scales (a,d) controlled by the dimensions of the DPP molecules.