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Response of villin headpiece-capped gold nanoparticles to ultrafast laser heating


Hassan, Shabir; Schade, Marco; Shaw, Christopher P; Lévy, Raphaël; Hamm, Peter (2014). Response of villin headpiece-capped gold nanoparticles to ultrafast laser heating. Journal of Physical Chemistry B, 118(28):7954-7962.

Abstract

The integrity of a small model protein, the 36-residue villin headpiece HP36 attached to gold nanoparticles (AuNP) is examined and its response to laser excitation of the AuNPs is investigated. To that end, it is first verified by stationary IR and CD spectroscopy together with denaturation experiments that the folded structure of the protein is fully preserved when attached to the AuNP surface. It is then shown by time-resolved IR spectroscopy that the protein does not unfold even upon the highest pump fluences that lead to local temperature jumps in the order of 1000 K of the phonon system of the AuNPs, since that temperature jump persists for too short a time of a few nanoseconds only to be destructive. Judged from a blue shift of the amide I band, indicating destabilized or a few broken hydrogen bonds, the protein either swells, becomes more unstructured from the termini, and/or changes its degree of solvation. In any case, it recovers immediately after the excess energy dissipates into the bulk solvent. The process is entirely reversible for millions of laser shots without any indication of aggregation of the protein and/or the AuNPs and with only a minor fraction of broken protein-AuNP thiol-bonds. The work provides important cornerstones in designing laser pulse parameters for maximal heating with protein-capped AuNPs without destroying the capping layer.

Abstract

The integrity of a small model protein, the 36-residue villin headpiece HP36 attached to gold nanoparticles (AuNP) is examined and its response to laser excitation of the AuNPs is investigated. To that end, it is first verified by stationary IR and CD spectroscopy together with denaturation experiments that the folded structure of the protein is fully preserved when attached to the AuNP surface. It is then shown by time-resolved IR spectroscopy that the protein does not unfold even upon the highest pump fluences that lead to local temperature jumps in the order of 1000 K of the phonon system of the AuNPs, since that temperature jump persists for too short a time of a few nanoseconds only to be destructive. Judged from a blue shift of the amide I band, indicating destabilized or a few broken hydrogen bonds, the protein either swells, becomes more unstructured from the termini, and/or changes its degree of solvation. In any case, it recovers immediately after the excess energy dissipates into the bulk solvent. The process is entirely reversible for millions of laser shots without any indication of aggregation of the protein and/or the AuNPs and with only a minor fraction of broken protein-AuNP thiol-bonds. The work provides important cornerstones in designing laser pulse parameters for maximal heating with protein-capped AuNPs without destroying the capping layer.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:17 July 2014
Deposited On:09 Oct 2014 08:56
Last Modified:05 Apr 2016 18:24
Publisher:American Chemical Society
ISSN:1520-5207
Funders:European Research Council (ERC) Advanced Investigator Grant (DYNALLO) and in part by the Swiss National Science Foundation through the National Center of Competence and Research (NCCR) MUST
Publisher DOI:https://doi.org/10.1021/jp500845f
PubMed ID:24597838

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