Vibrational Energy Transport through a Capping Layer of Appropriately Designed Peptide Helices over Gold Nanoparticles

Schade, Marco; Moretto, Alessandro; Donaldson, Paul M.; Toniolo, Claudio; Hamm, Peter

doi:10.1021/nl101580w

Cited by 33 publications

(59 citation statements)

References 31 publications

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“…In our experiments, we observe essentially the same transport mechanism independent from the heating source [19][20][21][22]. One may therefore conclude that vibrational energy is not fed into the peptide chain in a mode-specific manner but is already randomized to a certain extent so that this condition is met reasonably well.…”

Section: Resultssupporting

confidence: 74%

“…To gain a microscopic understanding of vibrational energy transport phenomena on this sort of length and time scales, we have recently introduced a new experimental concept, which we applied to short 3 10 -helical peptides: vibrational excess energy is deposited at one position of the peptide by various kinds of local heating mechanisms, i.e., the ultrafast electronic relaxation of an azobenzene-moiety [19,20], vibrational relaxation of C−D modes [21], or the relaxation of the plasmon resonance in gold nanoparticles [22]. The subsequent flow of vibrational energy through the helix is detected with subpicosecond time resolution by employing vibrational probes at various distances from the heating source as local thermometers.…”

Section: Introductionmentioning

confidence: 99%

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Transition from IVR limited vibrational energy transport to bulk heat transport

Schade

Hamm

2012

Chemical Physics

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In a previous paper (J. Chem. Phys. 131, 044511 (2009)), it has been shown that on ultrashort length and time scales, the speed of vibrational energy transport along a molecular chain is limited by intrasite vibrational relaxation rather than the actual inter site propagation. However, since intrasite vibrational relaxation is length independent, the inter site propagation rate is expected to become ratelimiting at some length scale, where propagation approaches the bulk limit. In the present paper, we investigate the transition between both regimes. The response of different types of modes may be very different at early times, depending on how much they contribute directly to energy transport. Surprisingly though, when averaging the energy content over all vibrational modes of the various chain sites, the complexity of the intrasite vibrational relaxation process is completely hidden so that energy transport on the nanoscale can be described by an effective propagation rate, that equals the bulk value, even at short times. Transition from IVR limited vibrational energy transport to bulk heat transport Marco Schade and Peter HammPhysikalisch-Chemisches Institut, Universität Zürich, Winterthurerstr. 190, Switzerland Abstract: In a previous paper (J. Chem. Phys. 131, 044511 (2009)), it has been shown that on ultrashort length and time scales, the speed of vibrational energy transport along a molecular chain is limited by intrasite vibrational relaxation rather than the actual inter site propagation. However, since intrasite vibrational relaxation is length independent, the inter site propagation rate is expected to become rate-limiting at some length scale, where propagation approaches the bulk limit. In the present paper, we investigate the transition between both regimes. The response of different types of modes may be very different at early times, depending on how much they contribute directly to energy transport. Surprisingly though, when averaging the energy content over all vibrational modes of the various chain sites, the complexity of the intrasite vibrational relaxation process is completely hidden so that energy transport on the nanoscale can be described by an effective propagation rate, that equals the bulk value, even at short times.

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Section: Resultssupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Transition from IVR limited vibrational energy transport to bulk heat transport

Schade

Hamm

2012

Chemical Physics

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“…The hindered rotational motion of the CO molecule, which is not covalently bound, results in a very sensitive response of its IR lineshape to temperature [16,17]. Compared to previous work [10][11][12][13][14], where we have used anharmonic frequency shifts of protein backbone C=O modes as a signature of local temperature, the mechanism of this thermometer is more direct and better understood.…”

Section: Discussionmentioning

confidence: 99%

Temperature Dependence of the Heat Diffusivity of Proteins

et al. 2011

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In a combined experimental-theoretical study, we investigated the transport of vibrational energy from the surrounding solvent into the interior of a heme protein, the sperm whale myoglobin double mutant L29W-S108L, and its dependence on temperature from 20 to 70 K. The hindered libration of a CO molecule that is not covalently bound to any part of the protein but is trapped in one of its binding pockets (the Xe4 pocket) was used as the local thermometer. Energy was deposited into the solvent by IR excitation. Experimentally, the energy transfer rate increased from (30 ps)−1 at 20 K to (8 ps)−1 at 70 K. This temperature trend is opposite to what is expected, assuming that the mechanism of heat transport is similar to that in glasses. In order to elucidate the mechanism and its temperature dependence, nonequilibrium molecular dynamics (MD) simulations were performed, which, however, predicted an essentially temperature-independent rate of vibrational energy flow. We tentatively conclude that the MD potentials overestimate the coupling between the protein and the CO molecule, which appears to be the rate-limiting step in the real system at low temperatures. Assuming that this coupling is anharmonic in nature, the observed temperature trend can readily be explained. In a combined experimental-theoretical study, we investigated the transport of vibrational energy from the surrounding solvent into the interior of a heme-protein, the sperm whale myoglobin double mutant L29W-S108L, in dependence of temperature from 20 K to 70 K. The hindered libration of a CO molecule that is not covalently bound to any part of the protein but is trapped in one of its binding pockets (the Xe4 pocket), was used as "local thermometer". Energy was deposited into the solvent by IR excitation. Experimentally, the energy transfer rate increased from (30 ps) −1 at 20 K to (8 ps) −1 at 70 K. This temperature trend is opposite to what is expected, assuming the mechanism of heat transport is similar to that in glasses. In order to elucidate the mechanism and its temperature dependence, non-equilibrium molecular dynamics (MD) simulations were performed, which, however, predicted an essentially temperature independent rate of vibrational energy flow. We tentatively conclude that the MD potentials overestimate the coupling between the protein and the CO molecule, which appears to be the rate limiting step in the real system at low temperatures. Assuming that this coupling is anharmonic in nature, the observed temperature trend can readily be explained.

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“…To this end, we covalently attach a local heater to a peptide or a protein, and use certain vibrational modes as local thermometers at various distances from the heater so we can observe the transport through a protein in unprecedented detail. We have tested various heaters (an ultrafast photochemical reaction after UV pumping, [26] direct IR excitation of vibrational modes, [27] or through the plasmon resonance of gold-nano particles [28] ), all revealing very similar heat transport times, suggesting that vibrational energy is randomized fairly quickly.…”

Section: Energy Transport In Macromoleculesmentioning

confidence: 99%