Gold Nanoparticles as a Colorimetric Sensor for Protein Conformational Changes

Chah, Soonwoo; Hammond, Michelle; Zare, Richard N.

doi:10.1016/j.chembiol.2005.01.013

Cited by 254 publications

(185 citation statements)

References 27 publications

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“…5,27 Regarding the structure of aggregated YCc-AuNP, it can be hypothesized that the protein is in a more open conformation in relation to its HCc-AuNP counterpart, creating a thicker spherical crown around the AuNP. Another hypothesis is that as the pH is lowered, HCc detaches from the AuNP allowing for smaller interparticle distances as reflected in the positions of the SPR upon aggregation.…”

Section: Discussionmentioning

confidence: 99%

“…21 Color change of the solution can then be induced by AuNP aggregation, a phenomenon that has been advantageously utilized in specific DNA sequence detection for biomedical applications, 3,22,23 in determination of enzymatic activity, [24][25][26] or as a probe for protein conformational changes. 5,27 Cytochrome c (Cyt c) is a low molecular mass protein (ca. 12 kDa) containing a heme group.…”

Section: Introductionmentioning

confidence: 99%

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Probing Surface Properties of Cytochrome c at Au Bionanoconjugates

et al. 2008

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Bionanoconjugates were created with cytochrome c from horse heart (HCc) or yeast (YCc) and citrate-stabilized gold nanoparticles (AuNPs). Evidence for the formation of stable HCc-AuNP and YCc-AuNP bionanoconjugates came from a 5 nm red-shift of the surface plasmon resonance band of the AuNPs, increase of the -potential, and direct visualization by atomic force microscopy. Langmuir isotherm fittings of -potential data indicated that higher enthalpy changes are involved in the formation of the HCc-AuNP than in YCc-AuNP. UV-vis and circular dichroism studies of pH-induced aggregation of the bionanoconjugates revealed distinct protonation patterns with an aggregation pH of 8.8 and 6.2 for YCc-AuNP and HCc-AuNP, respectively. No appreciable changes were observed in the secondary structure of HCc in HCc-AuNP. In contrast, YCc in YCc-AuNP presented a decrease in R-helix content upon AuNP binding and an increase in -sheet content upon pH-induced aggregation. Data discussion is based on the distinct binding modes of both proteins to the AuNPs via a covalent bond (Cys 102) for YCc and via electrostatic interaction for HCc.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Probing Surface Properties of Cytochrome c at Au Bionanoconjugates

et al. 2008

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“…It has been reported that the analysis of the overall characteristics of the plasmon band can be exploited to elucidate phenomena occurring at nanoparticle interface, including bioconjugation and molecular recognition [10,36]. Accordingly, three factors can be invoked as possible causes of the plasmon band shift and/or broadening detected in the absorption spectra of Az+AuNP solutions: (a) aggregation of nanoparticles upon bioconjugation, (b) electronic communication between the Az redox center and the gold nanoparticle, and (c) changes in local dielectric environments.…”

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confidence: 99%

Optical investigation of the electron transfer protein azurin–gold nanoparticle system

Delfino

Cannistraro

2009

Biophysical Chemistry

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To cite this version:Ines Delfino, Salvatore Cannistraro.Optical investigation of the electron transfer protein azurin -gold nanoparticle system. Biophysical Chemistry, Elsevier, 2008, 139 (1), pp. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. delfino@unitus.it A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT ABSTRACTThe hybrid system obtained by conjugating the protein azurin, which is a very stable and well-described The fluorescence quenching of azurin bound molecules is explained by an energy transfer from protein to metal surface and it is discussed in terms of the involvement of the Az electron transfer route in the interaction of the protein with the nanoparticle.

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“…This method has two distinct advantages, where one is that the stabilizing citrate can be readily replaced allowing for easy functionalization of the particle and the other one is that biomolecules can be used for functionalization since the synthesis is performed in an aqueous medium. 26,123 Unmodified particles prepared by this route are sensitive to changes in ionic strength and pH of the surrounding media but also towards organic contaminants which can cause irreversible aggregation. 124 All gold nanoparticles used in this thesis are produced via citrate reduction of HAuCl 4 , although using different protocols.…”

Section: Gold Nanoparticle Synthesismentioning

confidence: 99%

Polypeptide functionalized gold nanoparticles for bioanalytical applications

Selegård¹

2014

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Detection strategies that allow for simple, rapid, cost efficient and sensitive monitoring of proteins and their interactions with biomolecules are of great importance in drug development and diagnostics. This thesis describes the development of bioanalytical applications based on the tunable self-assembly of gold nanoparticles functionalized with a de novo designed polypeptide. Strategies for protein affinity sensing and for detection of several fundamentally important biological processes have been investigated, including Zn 2+ -mediated coordination between polypeptides and low molecular weight chelants and protease and phosphatase activity.A Zn 2+ responsive synthetic polypeptide designed to fold into a helix-loop-helix motif and dimerize into a four-helix bundle has been used to control the stability and self-assembly of gold nanoparticles. This polypeptide has a high negative net charge at neutral pH as a consequence of its many glutamic acid residues, efficiently preventing folding and dimerization due to charge repulsion. Zn 2+ coordination provides a means to trigger folding and dimerization at neutral pH. The polypeptide can be readily attached to gold nanoparticles via a cysteine residue in the loop region, retaining its folding properties and responsiveness to Zn 2+ . The polypeptide functionalized gold nanoparticles display excellent colloidal stability but aggregate reversibly after addition of millimolar concentrations of Zn 2+ . Aggregates are dense with a defined interparticle distance corresponding to the size of the four-helix bundle, resulting in a distinct red shift of the localized surface plasmon resonance band.Three completely different strategies for colorimetric biosensing have been developed, all being based on the same responsive hybrid nanomaterial. In the first strategy a synthetic receptor was co-immobilized on the gold nanoparticles together with the Zn 2+ responsive polypeptide. Protein analyte binding to the receptor could be detected as this interaction sterically prevented aggregation induced by Zn 2+ . In the second strategy the reduction in colloidal stability caused by specific proteolytic cleavage of the immobilized polypeptide was exploited to monitor the enzymatic activity. The third strategy utilized the sensitivity of the system to small variations in Zn 2+ concentration. The presence of low molecular weight chelants was found to influence the mode of aggregation, both by sequestering Zn 2+ and through the formation of ternary complexes involving the polypeptides, which prevented dimerization and thus aggregation. This approach was further developed into a generic concept for phosphatase detection exploiting the different affinity of enzyme substrates and reaction products for Zn 2+ . VThe flexibility of the different detection schemes enables detection of a large number of analytes by exploiting the tunable stability of the nanoparticles and the possibilities to effectively decouple the recognition event and the nanoparticle stability modulation. VI POPULÄRVET...

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Gold Nanoparticles as a Colorimetric Sensor for Protein Conformational Changes

Cited by 254 publications

References 27 publications

Probing Surface Properties of Cytochrome c at Au Bionanoconjugates

Probing Surface Properties of Cytochrome c at Au Bionanoconjugates

Optical investigation of the electron transfer protein azurin–gold nanoparticle system

Polypeptide functionalized gold nanoparticles for bioanalytical applications

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