Novel Photoactive Self-Assembled Monolayer for Immobilization and Cleavage of DNA (original) (raw)
Related papers
Fabrication of DNA monolayers on gold substrates and guiding of DNA with electric field
2003
We report electrically controlled selective coating of gold electrodes with mixed monolayers of oligonucleotides and alkanethiol passivation molecules. Gold nanoparticles are used as labels for visualization and voltage between the electrodes is applied for guiding the oligonucleotides. We discuss the efficiency of the guiding and monolayer preparation procedure.
ChemElectroChem, 2015
Mixed self-assembled monolayers composed of a fluorescently labeled DNA and a mercaptobutanol diluent immobilized on gold electrodes were characterized by electrochemical mea- surements coupled with in situ fluorescence microscopy. The reductive desorption of the self-assembled monolayers was monitored in real time through variations in the capacitance and fluorescence intensity. Desorption occurred in several steps, which was related to substrate crystallinity. Fluorescence microscopy revealed the presence of spatial heterogeneities in the form of highly fluorescent aggregates that remained at the electrode surface even after a reductive desorption step. This in situ electrofluorescence microscopy technique is useful to optimize the formation of the mixed layer to obtain a homoge- neous distribution of the probes, which thus improves the effi- ciency of the recognition process in the development of bio- sensors.
Control of DNA self-assembled monolayers surface coverage by electrochemical desorption
Journal of Electroanalytical Chemistry, 2007
In this report we present electrochemical studies of the immobilization of disulfide-modified single-stranded DNA (ssDNA) on gold. The effect of immobilization time on surface coverage was probed by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Additionally, linear sweep voltammetry was used to perform reductive electrochemical desorption of the ssDNA molecules, and the variations in surface coverage, charge transfer resistance (R ct ) and capacitance (C) with desorption cycles were monitored by EIS. The results show surface coverages greater than 0.9 for immobilization times of 15 hours or more. The coverage and R ct increased, while the C decreased for higher immobilization times. The opposite trend was observed for an increasing number of desorption cycles. These results suggest that a combination of variations in immobilization time and number of desorption cycles represents an alternative to optimize the density of immobilized DNA strands, which is desirable for the subsequent optimization of DNA hybridization and the development of DNA biosensors.
Controlled Reduction of Photobleaching in DNA Origami–Gold Nanoparticle Hybrids
Nano Letters, 2014
The amount of information obtainable from a fluorescence-based measurement is limited by photobleaching: Irreversible photochemical reactions either render the molecules nonfluorescent or shift their absorption and/or emission spectra outside the working range. Photobleaching is evidenced as a decrease of fluorescence intensity with time, or in the case of single molecule measurements, as an abrupt, single-step interruption of the fluorescence emission which determines the end of the experiment. Reducing photobleaching is central for improving fluorescence (functional) imaging, single molecule tracking and fluorescence based biosensors and assays. In this single molecule study, we use DNA self-assembly to produce hybrid nanostructures containing individual fluorophores and gold nanoparticles at a controlled separation distance of 8.5 nm. By changing the nanoparticles size we are able to systematically increase the mean number of photons emitted by the fluorophores before photobleaching.
DNA-Based Self-Assembly of Gold Nanostructures
Journal of Biomedical and Allied Research, 2020
Plasmonic assemblies of gold nanoparticles (AuNPs) triggered by DNA exhibited excellent biocompatibility and specific-targeting ability. Moreover, the integration of AuNPs and DNA allows the DNA scaffolds exhibit greater chemical stability and optical plasmonic properties. In this mini review, we summarized the development of DNA nanotechnology, especially DNA framework and DNA origami that were employed to fabricate two-dimensional and three-dimensional (3D) Au nanoassembled nanostructures.
Self-Assembly of DNA Functionalized Gold Nanoparticles at the Liquid-Vapor Interface
Advanced Materials Interfaces, 2016
Surface sensitive synchrotron X-ray scattering and spectroscopy are used to monitor and characterize the spontaneous formation of 2D Gibbs monolayers of thiolated single-stranded DNA-functionalized gold nanoparticles (ssDNA-AuNPs) at the vapor-solution interface by manipulating salt concentrations. Grazing incidence small-angle X-ray scattering and X-ray reflectivity show that the noncomplementary ssDNA-AuNPs dispersed in aqueous solution spontaneously accumulate at the vapor-liquid interface in the form of a single layer by increasing MgCl2 or CaCl2 concentrations. Furthermore, the monoparticle layer undergoes a transformation from short-to long-range (hexagonal) order above a threshold salt-concentration. Using various salts at similar ionic strength to those of MgCl2 or CaCl2 such as, NaCl or LaCl3, it is found that surface adsorbed NPs lack any order. X-ray fluorescence near total reflection of the same samples provides direct evidence of interfacial gold and more importantly a significant surface enrichment of the cations. Quantitative analysis reveals that divalent cations screen the charge of ssDNA, and that the hydrophobic hexyl-thiol group, commonly used to functionalize the ssDNA (for capping the AuNPs), is likely the driving force for the accumulation of the NPs at the interface.
Selective DNA-Mediated Assembly of Gold Nanoparticles on Electroded Substrates
Langmuir, 2008
Motivated by the technological possibilities of electronics and sensors based on gold nanoparticles (Au NPs), we investigate the selective assembly of such NPs on electrodes via DNA hybridization. Protocols are demonstrated for maximizing selectivity and coverage using 15mers as the active binding agents. Detailed studies of the dependences on time, ionic strength, and temperature are used to understand the underlying mechanisms and their limits. Under optimized conditions, coverage of Au NPs on Au electrodes patterned on silicon dioxide (SiO 2 ) substrates was found to be ∼25-35%. In all cases, Au NPs functionalized with non-complementary DNA show no attachment and essentially no nonspecific adsorption is observed by any Au NPs on the SiO 2 surfaces of the patterned substrates. DNA-guided assembly of multilayers of NPs was also demonstrated and, as expected, found to further increase the coverage, with three deposition cycles resulting in a surface coverage of approximately 60%.
Controlled Confinement of DNA at the Nanoscale: Nanofabrication and Surface Bio-Functionalization
Methods in Molecular Biology, 2011
Nanopatterned arrays of biomolecules are a powerful tool to address fundamental issues in many areas of biology. DNA nanoarrays, in particular, are of interest in the study of DNA-protein interactions and for biodiagnostic investigations. In this context, achieving a highly specific nanoscale assembly of oligonucleotides at surfaces is critical. In this chapter, we describe a method to control the immobilization of DNA on nanopatterned surfaces; the nanofabrication and the bio-functionalization involved in the process will be discussed.
Enzymatic Disassembly of DNA–Gold Nanostructures
Small, 2007
The current success of interdisciplinary research in nanoscience is generating great expectations for the emergence of new technologies. It is widely believed that significant advances in electronics, information technology, sensor development, catalysis, and biomedical sciences will arise from gaining precise control over the manipulation of nanometersized objects. The interactions that govern the behavior of matter on this scale are predominantly chemical in nature. Therefore, the development of new chemical tools for the controlled assembly and manipulation of nanostructures is of great interest. An important step has been the development of so-called programmed assembly, where connectivity between building blocks is predetermined by specific recognition between biomolecular or synthetic connectors. For instance, excellent specificity and control over the binding process can be achieved by exploiting DNA base-pair recognition for the attachment of DNA-modified nanoparticles to each other by hybridization with complementary linker strands. Using this approach, originally developed by Alivisatos and Mirkin and co-workers, it is possible to design particles that will selectively bind to other particles of a particular type or to designated sites on surfaces. There are well-established biomolecular methods for DNA manipulation, based on the use of DNA-processing enzymes (restriction endonucleases and ligases), to cleave and rejoin double-stranded DNA with impressive site specificity. Using a combination of these enzymes and thiol-modified DNA attached to gold nanoparticles, we have recently dem-onstrated hierarchical and temporal control of assembly of DNA-modified gold nanoparticles. In particular, restriction endonucleases can be used to reveal reactive DNA ends on DNA-modified particles, which may then be converted to permanent links with high specificity between particles (and between particles and surfaces) using DNA ligase. In this Communication we report our recent progress in using DNA-processing enzymes for the specific cleavage of preassembled DNA-modified gold nanostructures. Yun et al. have suggested this possibility using dimers of DNA-modified gold nanoparticles, based on a statistical analysis of transmission electron microscopy (TEM) images before and after the enzymatic reaction step. We now demonstrate, using a number of complementary techniques, that aggregates of gold nanoparticles linked to each other by double-stranded DNA can be efficiently cleaved and redispersed by restriction enzymes.