Showing papers by "Vincent M. Rotello published in 2006"
TL;DR: It is demonstrated here the effective delivery of a dye payload into cells using 2-nm core gold nanoparticles, with release occurring via place exchange of glutathione onto the particle surface.
Abstract: We demonstrate here the effective delivery of a dye payload into cells using 2-nm core gold nanoparticles, with release occurring via place exchange of glutathione onto the particle surface. In vitro experiments demonstrate effective release of drug analogues upon addition of glutathione. Cell culture experiments show rapid uptake of nanoparticle and effective release of payload. The role of glutathione in the release process was demonstrated through improved payload release upon transient increase in glutathione levels achieved via introduction of glutathione ethyl ester into the cell.
781 citations
TL;DR: Photosensitive synthetic DNA carriers will provide new directions for gene delivery owing to the potential for versatile and facile chemical modifications and the modularity of the carrier–DNA complex.
Abstract: Gene therapy is one of the most promising prospects in biomedical and bioorganic realms. The success of gene therapy benefits mainly from having effective gene-delivery vectors for transporting plasmid DNA, small interfering RNA, or antisense oligonucleotides into target cells. The delivery of therapeutic nucleotides using nanomaterials such as polymeric micelles, dendrimers, nanorods, nanotubes, and nanoparticles is attracting increasing attention as a consequence of their unique dimensions and properties.Despite much progress, unpacking DNA inside target cells in a spatiotemporally controlled fashion is a major limiting factor in designing these artificial carriers. Although several intracellular release strategies have been employed, including low pH, high enzyme concentration, and redox materials inside the cells, the use of light as an external stimulus represents a unique siteand time-specific means of unloading DNA. As such, photosensitive synthetic DNA carriers will provide new directions for gene delivery owing to the potential for versatile and facile chemical modifications and the modularity of the carrier–DNA complex. As a highly orthogonal external stimulus, photochemical processes enjoy wide use in surface patterning, advanced materials, biochemistry, and drug-delivery systems. Light-regulated methods uniquely limit the resultant biological effects to the illuminated areas with temporal control. For example, biologically active molecules can be modified with photosensitive groups to be essentially bioinert; they can then be reactivated by photointervention. Such caged compounds have shown tremendous applications in chemical
288 citations
TL;DR: The present study indicates that functionalized gold particles can initiate VLP assembly by mimicking the electrostatic behavior of the nucleic acid component of the native virus.
Abstract: Self-assembly of regular protein surfaces around nanoparticle templates provides a new class of hybrid biomaterials with potential applications in medical imaging and in bioanalytical sensing. We report here the first example of efficiently self-assembled virus-like particles (VLPs) having a brome mosaic virus protein coat and a functionalized gold core. The present study indicates that functionalized gold particles can initiate VLP assembly by mimicking the electrostatic behavior of the nucleic acid component of the native virus. These VLP constructs are symmetric, with the protein stoichiometry and packaging properties indicating similarity to the icosahedral packing of the capsid. Moreover, a pH-induced swelling transition of the VLPs is observed, in direct analogy to the native virus.
227 citations
TL;DR: Several strategies for the incorporation of QDs into viral capsids were explored; those functionalized with poly(ethylene glycol) (PEG) can be self-assembled into viral particles with minimal release of photoreaction products and enhanced stability against prolonged irradiation.
Abstract: Incorporation of CdSe/ZnS semiconductor quantum dots (QDs) into viral particles provides a new paradigm for the design of intracellular microscopic probes and vectors. Several strategies for the incorporation of QDs into viral capsids were explored; those functionalized with poly(ethylene glycol) (PEG) can be self-assembled into viral particles with minimal release of photoreaction products and enhanced stability against prolonged irradiation.
214 citations
TL;DR: A new class of comb-shaped polymers for use as a proton conducting membrane is presented in this article, which combines the beneficial physical, chemical, and structural attributes of fluorinated Nafion-like materials with higher-temperature, polyaromatic-based polymer backbones.
Abstract: A new class of comb-shaped polymers for use as a proton conducting membrane is presented. The polymer is designed to combine the beneficial physical, chemical, and structural attributes of fluorinated Nafion-like materials with higher-temperature, polyaromatic-based polymer backbones. The comb-shaped polymer unites a rigid, polyaromatic, hydrophobic backbone with lengthy hydrophilic polymer side chains; this combination affords direct control over the polymer nanostructure within the membrane and results in distinct microphase separation between the opposing domains. The microphase separation serves to compartmentalize water into the hydrophilic polymer side chain domains, resulting in effective membrane water management and excellent proton conductivities.
170 citations
TL;DR: The MMPC‐bound DNA was found to show enhanced cleavage upon exposure to chemically induced radicals, which may indicate that bound DNA is bent and wrapped on the surface of the cationic MMPC.
Abstract: Positively charged trimethylammonium-modified mixed monolayer protected clusters (MMPCs) interact with DNA by complementary electrostatic binding, serving as efficient DNA delivery systems. The stability of gold nanoparticle-bound DNA toward biological, physical, and chemical agents is investigated. The MMPC-bound DNA is efficiently protected from DNAse I digestion and experiences nicking/cleavage-induced morphology changes with higher concentrations of DNAse I. Significant protection of MMPC-bound DNA was also observed in a physical sonication assay. However, the MMPC-bound DNA was found to show enhanced cleavage upon exposure to chemically induced radicals. The latter may indicate that bound DNA is bent and wrapped on the surface of the cationic MMPC.
160 citations
TL;DR: This review highlights recent advances in nanoparticle-biomacromolecule interactions, focusing on two key areas: the modulation of structure and function of biomacromolescules through engineered interactions with nanoparticle surfaces and the use of biomACromolecules as building blocks for nanostructured materials.
Abstract: Monolayer-protected nanoparticles feature tunable size, surface functionality and core material, providing scaffolds for targeting biomacromolecules. This review highlights recent advances in nanoparticle-biomacromolecule interactions, focusing on two key areas: (1) The modulation of structure and function of biomacromolecules through engineered interactions with nanoparticle surfaces; (2) The use of biomacromolecules as building blocks for nanostructured materials.
129 citations
TL;DR: Kinetic studies reveal that the substrate specificity of ChT-nanoparticle complexes increases by approximately 3-fold for the cationic substrate but decreases by 95% for the anionic substrate as compared with that of free ChT, providing enhanced substrate selectivity.
Abstract: Amino-acid-functionalized gold clusters modulate the catalytic behavior of alpha-chymotrypsin (ChT) toward cationic, neutral, and anionic substrates. Kinetic studies reveal that the substrate specificity (k(cat)/K(M)) of ChT-nanoparticle complexes increases by approximately 3-fold for the cationic substrate but decreases by 95% for the anionic substrate as compared with that of free ChT, providing enhanced substrate selectivity. Concurrently, the catalytic constants (k(cat)) of ChT show slight augmentation for the cationic substrate and significant attenuation for the anionic substrate in the presence of amino-acid-functionalized nanoparticles. The amino acid monolayer on the nanoparticle is proposed to control both the capture of substrate by the active site and release of product through electrostatic interactions, leading to the observed substrate specificities and catalytic constants.
125 citations
TL;DR: This two-component orthogonal surface modification was accomplished in a self-sorting, single-step fashion, providing a versatile tool for the rapid and efficient creation of complex materials.
Abstract: We demonstrate the patterning of silica substrates with thymine (Thy-PS) and positively charged N-methylpyridinium (PVMP) polymers using photolithography and the subsequent orthogonal modification ...
91 citations
TL;DR: The efficiency of DNA‐binding was determined, demonstrating in a fivefold modulation in binding a 37‐mer DNA strand, and the affinity of the nanoparticle for the DNA can be regulated by external agents, though stability of the complex is observed at relatively high ionic strengths.
Abstract: A family of nanoparticles featuring surfaces of varying hydrophobicity was synthesized. The efficiency of DNA-binding was determined, demonstrating in a fivefold modulation in binding a 37-mer DNA strand. Nanoparticle-binding causes a reversible conformational change in the DNA structure, as demonstrated by circular dichroism and fluorescence experiments. Furthermore, the affinity of the nanoparticle for the DNA can be regulated by external agents, though stability of the complex is observed at relatively high ionic strengths.
81 citations
TL;DR: It is demonstrated that MALDI-MS can detect peptide concentrations as low as 500 pM from 250-microL solutions using these nanoparticle scaffolds as extraction and concentration agents.
Abstract: Cationic and anionic nanoparticles selectively target peptides with low and high isoelectric points, respectively. Additionally, their high surface area-to-volume ratios make these nanoparticles (∼2-nm core diameter) very efficient extraction and concentration agents. Upon extraction, the peptide-bound nanoparticles can be analyzed by MALDI-MS to provide highly sensitive detection of the targeted peptides. We demonstrate that MALDI-MS can detect peptide concentrations as low as 500 pM from 250-μL solutions using these nanoparticle scaffolds as extraction and concentration agents.
TL;DR: The use of magnetic nanoparticles in biological applications is hampered by the lack of versatile methods to transfer them into aqueous solutions as discussed by the authors. But this method is not suitable for a wide range of applications.
Abstract: The use of magnetic nanoparticles in biological applications is hampered by the lack of versatile methods to transfer them into aqueous solutions. Monolayer exchange using anionic octa(tetramethylammonium)−polyhedral oligomeric silsesquioxane provides individual particles that are soluble in aqueous environments and possess excellent stability in biologically relevant pH ranges and salt concentrations. In addition, this surface exchange reaction proved to be general in nature, allowing facile functionalization of a variety of magnetic nanoparticles.
TL;DR: Functionalized gold nanoparticles bind selectively to cytochrome c or cy tochrome c peroxidase and inhibit enzyme turnover.
TL;DR: Place exchange reactions were studied using dye displacement: subtle changes in ligand structure greatly affected both the rate of displacement and the stability of the monolayer.
TL;DR: Gold nanoparticles stabilize chymotrypsin (ChT) against denaturation at the air-water interface through catenation and preferential localization of the nanoparticles at the water interface with concomitant decrease in interfacial energy.
Abstract: Gold nanoparticles stabilize chymotrypsin (ChT) against denaturation at the air–water interface through catenation and preferential localization of the nanoparticles at the air–water interface with concomitant decrease in interfacial energy.
TL;DR: Cytochrome c adsorbed to anionic nanoparticles is selectively proteolyzed by trypsin, providing a mechanism for the catalytic degradation of proteins.
TL;DR: A gold nanoparticle functionalized with substrates for α-chymotrypsin was fabricated to afford an enzyme modulator that exhibited enzyme-specific activation coupled with general inhibition of other proteases.
TL;DR: It was found that placing stereocenters in both recognition units resulted in a strong bisignated profile and enhancement of complex stability, indicative of cooperative self-assembly.
Abstract: Complementary diaminopyridine (DAP) and flavin derivatives self-assemble into discrete helically stacked tetrads in hydrocarbon solvents. The self-assembled structure was demonstrated through induced circular dichroism using DAPs with chiral side-chains and flavin with achiral side-chains. Flavin derivatives with chiral side-chains were synthesized; cooperativity in the self-assembly was established through circular dichroism (CD) profiles and melting curves. It was found that placing stereocenters in both recognition units resulted in a strong bisignated profile and enhancement of complex stability, indicative of cooperative self-assembly.
TL;DR: In this paper, the authors describe the utilization of hydrogenbonds for modular self-assembly of nano-sized building blocks into two or three-dimensional aggregates and the precise control over their structural parameters and morphologies.
Abstract: Materials with nanoscale dimensions display electronic, photonic, and magnetic properties differentfrom those observed by their respective bulk materials. This article describes the utilization of hydrogenbonds for modular self-assembly of nano-sized building blocks into two or three-dimensional aggregates andthe precise control over their structural parameters and morphologies. We will depict recent investigationson the synthesis and assembly of polymer and nanoparticle-based composite materials both in solution phaseand on solid substrates. The advantages, potential applications, and current challenges associated withthis “bottom up” assembly approach will also be discussed.
TL;DR: The synthesis of flavin-stoppered hydrogen bonded [2]rotaxanes 1 and 2 is reported, and the electrochemically controllable properties of these systems in solution and for derivative 2, as an electropolymerized thin film are reported.
TL;DR: In this article, random polystyrene-based diblock copolymers with strongly interacting hydrogen-bonding units, diaminotriazine (triaz) functionality, on one of the blocks were used to assemble complementary thymine functionalized gold nanoparticles (Thy−Au) into micellar aggregates.
Abstract: Random polystyrene-based diblock copolymers with strongly interacting hydrogen-bonding units, diaminotriazine (triaz) functionality, on one of the blocks (PS/S-triaz) were used to assemble complementary thymine (Thy)-functionalized gold nanoparticles (Thy−Au) into micellar aggregates. The role of each of these blocks on the aggregate size was investigated by synthesizing two different series of diblock copolymers: in the first series unfunctionalized block (polystyrene block) length was kept constant and the recognition element functionalized block (triaz block) length increased; in the second series, triaz block length was kept constant and polystyrene block length increased. The size of these self-assembled aggregates was determined in solution by using dynamic light scattering and in thin films by using transmission electron microscopy and small-angle X-ray scattering.
TL;DR: Mixed monolayer protected gold nanoparticles have been fabricated incorporating 1,5-dialkyloxynaphthalene moieties that are capable of forming complexes with the tetracationic cyclophane cyclobis(paraquat-p-phenylene); electrochemical reduction of thecyclophane or the addition of tetrathiafulvalene results in disassembly of the complexes.
TL;DR: In this article, the application of electrochemistry to detect and modulate hydrogen bonding interactions between a phenanthrenequinone-functionalized self-assembled monolayer and a phenyl-urea terminated dendrimer was reported.
TL;DR: This work has used mixed monolayer protected gold clusters (MMPCs) to provide flavoenzyme model systems with a high affinity and ability to modulate cofactor reduction potential.
TL;DR: In this article, the synthesis of a dithienylpyrrole-stoppered rotaxane and its subsequent electrochemical polymerisation onto a platinum working electrode surface was reported.
Journal Article•
TL;DR: In this paper, a review highlights recent advances in nanoparticle-biomacromolecule interactions, focusing on two key areas: (1) modulation of structure and function of biomACromolecules through engineered interactions with nanoparticle surfaces, and (2) the use of biomacromolescules as building blocks for nanostructured materials.
Abstract: Monolayer-protected nanoparticles feature tunable size, surface functionality and core material, providing scaffolds for targeting biomacromolecules. This review highlights recent advances in nanoparticle-biomacromolecule interactions, focusing on two key areas: (1) The modulation of structure and function of biomacromolecules through engineered interactions with nanoparticle surfaces: (2) The use of biomacromolecules as building blocks for nanostructured materials.
Posted Content•
TL;DR: In this paper, the authors demonstrate a straightforward assembly approach in which metallic colloidal spheres serve as the electrodes, and demonstrate an altogether new approach to inexpensive and large-scale fabrication of electronic devices such as transistors with nanometer-scale features.
Abstract: The spontaneous assembly of particles in suspension provides a strategy for inexpensive fabrication of devices with nanometer-scale control, such as single-electron transistors for memory or logic applications. A scaleable and robust method to form electrodes with the required nanometer-scale spacing, however, remains a major challenge. Here, we demonstrate a straightforward assembly approach in which metallic colloidal spheres serve as the electrodes. The devices are formed by assembly in suspension followed by deposition onto a patterned substrate. The key to this approach is that the inter-electrode (inter-sphere) spacing is spontaneously set to allow tunneling contact with a single layer of nanoparticles. The measured current exhibits the Coulomb blockade owing to the small size and large electrostatic charging energy of the nanoparticles. We show that the device resistance can be tuned by means of a gate electrode. Our results demonstrate an altogether new approach to inexpensive and large-scale fabrication of electronic devices such as transistors with nanometer-scale features.
24 Aug 2006