Stability of Gold Nanoparticle-Bound DNA toward Biological, Physical, and Chemical Agents (original) (raw)
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DNA-binding by Functionalized Gold Nanoparticles: Mechanism and Structural Requirements
Chemical Biology <html_ent glyph="@amp;" ascii="&"/> Drug Design, 2006
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.
Langmuir, 2011
Gold nanoparticles functionalized with thiol-modified DNA have been widely used in making various nanostructures, colorimetric biosensors, and drug delivery vehicles. Over the past 15 years, significant progress has been made to improve the stability of such functionalized nanoparticles. The stability of the gold-thiol bond in this system, however, has not been studied in a systematic manner. Most information on the gold-thiol bond was obtained from the study of self-assembled monolayers (SAMs). In this study, we employed two fluorophore-labeled and thiol-modified DNAs. The long-term stability of the thiol-gold bond as a function of time, salt, temperature, pH, and organic solvent has been studied. We found that the bond spontaneously dissociated under all tested conditions. The dissociation was favored at high salt, high pH, high temperature and little DNA degradation was observed in our system. Most organic solvents showed a moderate protection effect on the gold-thiol bond. The stability of the gold-thiol bond in the DNA system was also compared with that in SAMs. While there are many similarities, we also observed opposite trends for the salt and ethanol effect. This study suggests that the purified DNA-functionalized gold nanoparticles should be freshly prepared and used in a day or two. Long term storage should be carried out at relatively low temperature in low salt and slight acidic buffers.
Packed DNA Denatures on Gold Nanoparticles
The Journal of Physical Chemistry B, 2010
Toward the construction of double stranded DNA-based biosensors, packing of thiolated double-stranded DNA adsorbed on gold nanoparticles was observed to induce DNA denaturation. The denaturation was investigated as a function of DNA density, nanoparticle surface area, and DNA length. Direct correlation was found between DNA surface coverage and the denaturation. Denaturation occurred only at high densities of adsorbed DNA and was dependent on DNA length and therefore stability, providing guidelines for controlled adsorption of dsDNA on GNPs. Our results invoke a model in which the formation of a thiol-gold bond competes with the free energy associated with the denaturation of two DNA strands. Denaturation vacates space for additional molecules to bind through a thiol-gold bond.
Gold nanoparticles have attracted strong biomedical interest for drug delivery due to their low toxic nature, surface plasmon resonance and capability of increasing the stability of the payload. However, gene transfection represents another important biological application. Considering that cellular barriers keep enclosed their secret to deliver genes using nanoparticles, an important step can be achieved by studying the functionalization of nanoparticles with DNA. In the present contribution the synthesis of nanoparticles consisting of a gold core coated with one or more layers of amino acid (l-lysine), and cationic polyelectrolytes (poly-ethyleneimine and poly-l-lysine) is reported. All nanoparticles were subjected to dynamic light scattering, electrophoretic mobility measurements, UV-vis optical spectrophotometry analysis and transmission electron microscopy imaging. In addition, the adsorption of DNA plasmid (pSGS) with linear and supercoiled configurations was studied for those gold nanoparticles under the most suitable surface modifications. Preliminary results showed that the gold nanoparticles functionalized with poly-ethyleneimine and poly-l-lysine, respectively, and bound to linear DNA configurations, present in absolute value a higher electrophoretic mobility irrespective of the pH of the media, compared to the supercoiled and nicked configuration. The findings from this study suggest that poly-ethyleneimine and poly-l-lysine functionalized gold nanoparticles are biocompatible and may be promising in the chemical design and future optimization of nanostructures for biomedical applications such as gene and drug delivery.
Site-Specific Attachment of Gold Nanoparticles to DNA Templates
MRS Proceedings, 2000
DNA was used as a scaffold for the binding of gold nanoparticles using a standard chemical technique. A DNA template was designed with amino-modified thymines located every 3.7 nm, which would allow the attachment of the carboxylic acid functionalized gold nanoparticles. The gold particles were covalently bound to the amino groups on the DNA using standard 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) chemistry in the presence of a competitor to block excess gold binding sites. The products were analyzed by transmission electron microscopy (TEM) and atomic force microscopy (AFM).
Inhibition of DNA Transcription Using Cationic Mixed Monolayer Protected Gold Clusters
Journal of the American Chemical Society, 2001
Efficient recognition of DNA is a prerequisite for the development of biological effectors, including transcription and translation regulators, transfection vectors, and DNA sensors. To provide an effective scaffold for multivalent interactions with DNA, we have fabricated mixed monolayer protected gold clusters (MMPCs) functionalized with tetraalkylammonium ligands that can interact with the DNA backbone via charge complementarity. Binding studies indicate that the MMPCs and DNA form a charge-neutralized, nonaggregated assembly. The interactions controlling these assemblies are highly efficient, completely inhibiting transcription by T7 RNA polymerase in vitro.
Applied Organometallic Chemistry, 2019
Binding DNA on nanoparticles was pursued to form nanoplatform for formation of non-viral gene system. Carboxyl derivatized gold-aryl nanoparticles can bind with biodegradable cationic polyelectrolytes such as polydiallyldimethylammonium chloride (PDADMAC). In our study, we used gold-aryl nanoparticles (AuNPs) treated with PDADMAC to form conjugates with non-thiol or non-disulfide modified oligonucleotide DNA. Both AuNPs-DNA and PDADMAC-AuNPs-DNA biomaterials were characterized using UV-Vis, dynamic light scattering (DLS), atomic force microscopy (AFM), transmission electron microscopy (TEM) and agarose gel electrophoresis. UV-Vis showed a red shift in the plasmon peak as compared with unconjugated AuNPs. DLS measurements also showed difference in the size of AuNPs-DNA and PDADMAC-AuNPs-DNA. AFM and TEM results showed proper conjugation of DNA with AuNPs. Gel electrophoresis proved the presence of interaction between PDADMAC-AuNPs and negatively charged DNA. The binding of DNA in the described bioconjugate enhanced its protection against nuclease degradation and prolonged its presence in the digestive environment of DNase-I. From the results we expect that these biomaterials can be used in nanomedicine with emphasis on non-viral gene system.
Double-shell gold nanoparticle-based DNA-carriers with poly-l-lysine binding surface
Biomaterials, 2011
In view of the prospective applications of polyamine coatings in functional gold nanoparticles for use as carriers in gene delivery systems, in tissue repair and as bactericidal and virucidal non-toxic vehicle, we have investigated the interactions of poly-L-lysine (PLL) with gold nanoparticles (AuNP). Since direct binding of PLL to AuNP is not strong at neutral pH, we have focused on PLL interactions with carboxylated self-assembled monolayers (SAM) on AuNP, such as the citrate-capped AuNP. The double-shell nanoparticles AuNP@Cit/PLL thus produced do not contain any toxic thiols. We have observed strong electrostatic interactions between polycationic chains of PLL and AuNP@Cit in weakly acidic to weakly alkaline solutions (pH 5e9), as evidenced by the bathochromic shift of the local surface plasmon (SP) band and strong increase in resonance elastic light scattering (RELS) intensity. The stoichiometry of interactions evaluated on the basis of RELS data indicates on a hyper-Langmuirian type of interactions with stoichiometric coefficient n ¼ 1.35 (PLL : AuNP@Cit). From the RELS titration data, a shift of the deprotonation constant for the bound PLL has been determined (pK a ¼ 11.6 for the bound PLL vs. 10.48 for the free PLL). The deprotonation of PLL leads to AuNP aggregate disassembly, evidenced by sharp RELS decline and hypsochromic shift of SP band. We have found that under these conditions, a residual aggregation due to the interparticle interactions between b-sheets of PLL overcoat become predominant.
Langmuir, 2012
The last 16 years have witnessed the landmark development of polyvalent thiolated DNA-functionalized gold nanoparticles (AuNP's) possessing striking properties within the emerging field of nanobiotechnology. Many novel properties of this hybrid nanomaterial are attributed to the dense DNA shell. However, the question of whether nonthiolated polyvalent DNA−AuNP could be fabricated with a high DNA density and properties similar to those of its thiolated counterpart has not been explored in detail. Herein, we report that by simply tuning the pH of the DNA−AuNP mixture an ultrahigh capacity of nonthiolated DNA can be conjugated to AuNP's in a few minutes, resulting in polyvalent DNA−AuNP conjugates with cooperative melting behavior, a typical property of polyvalent thiolated DNA-functionalized AuNP's. With this method, large AuNP's (e.g., 50 nm) can be functionalized to achieve the colorimetric detection of sub-nanometer DNA. Furthermore, this fast, stable DNA loading was employed to separate AuNP's of different sizes. We propose that a large fraction of the attached DNAs are adsorbed via one or a few terminal bases to afford the high loading capacity and the ability to hybridize with the complementary DNA. This discovery not only offers a time-and cost-effective way to functionalize AuNP's with a high density of nonthiolated DNA but also provides new insights into the fundamental understanding of how DNA strands with different sequences interact with AuNP's.