Optical activation of neurons requires genetic manipulation or the use of chemical photoactivators with undesirable side effects.As a solution to these disadvantages,here,we demonstrate optically evoked neuronal activ...Optical activation of neurons requires genetic manipulation or the use of chemical photoactivators with undesirable side effects.As a solution to these disadvantages,here,we demonstrate optically evoked neuronal activity in mouse cortical neurons in acute slices and in vivo by nonlinear excitation of gold nanoparticles.In addition,we use this approach to stimulate individual epitheliomuscular cells and evoke body contractions in Hydra vulgaris.To achieve this,we use a low-power pulsed near-infrared excitation at the double-wavelength of the plasmon resonance of gold nanoparticles,which enables optical sectioning and allows for high spatial precision and large penetration depth.The effect is explained by second-harmonic Mie scattering,demonstrating light absorption by a second-order nonlinear process,which enables photothermal stimulation of the cells.Our approach also minimizes photodamage,demonstrating a major advancement towards precise and harmless photoactivation for neuroscience and human therapeutics.展开更多
Increasing temperature is known to quench the excitonic emission of bulk silicon,which is due to thermally induced dissociation of excitons.Here,we demonstrate that the effect of temperature on the excitonic emission ...Increasing temperature is known to quench the excitonic emission of bulk silicon,which is due to thermally induced dissociation of excitons.Here,we demonstrate that the effect of temperature on the excitonic emission is reversed for quantumconfined silicon nanocrystals.Using laser-induced heating of silicon nanocrystals embedded in SiO2,we achieved a more than threefold(4300%)increase in the radiative(photon)emission rate.We theoretically modeled the observed enhancement in terms of the thermally stimulated effect,taking into account the massive phonon production under intense illumination.These results elucidate one more important advantage of silicon nanostructures,illustrating that their optical properties can be influenced by temperature.They also provide an important insight into the mechanisms of energy conversion and dissipation in ensembles of silicon nanocrystals in solid matrices.In practice,the radiative rate enhancement under strong continuous wave optical pumping is relevant for the possible application of silicon nanocrystals for spectral conversion layers in concentrator photovoltaics.展开更多
基金supported by The Raymond&Beverly Sackler Center,NIMH(R01MH101218)the Howard Hughes International Student Research Fellowshipsupported in part by the U.S.Army Research Office under contract number W911NF-12-1-0594(MURI).
文摘Optical activation of neurons requires genetic manipulation or the use of chemical photoactivators with undesirable side effects.As a solution to these disadvantages,here,we demonstrate optically evoked neuronal activity in mouse cortical neurons in acute slices and in vivo by nonlinear excitation of gold nanoparticles.In addition,we use this approach to stimulate individual epitheliomuscular cells and evoke body contractions in Hydra vulgaris.To achieve this,we use a low-power pulsed near-infrared excitation at the double-wavelength of the plasmon resonance of gold nanoparticles,which enables optical sectioning and allows for high spatial precision and large penetration depth.The effect is explained by second-harmonic Mie scattering,demonstrating light absorption by a second-order nonlinear process,which enables photothermal stimulation of the cells.Our approach also minimizes photodamage,demonstrating a major advancement towards precise and harmless photoactivation for neuroscience and human therapeutics.
基金supported by the Dutch Technology Foundation STW,which is part of the Netherlands Organisation for Scientific Research(NWO)funded by the Ministry of Economic Affairs+1 种基金support within the framework of the Czech-German collaborative project,16-09745J(DFT-GACR)supported by the Russian Science Foundation,Grant No.14-12-01067。
文摘Increasing temperature is known to quench the excitonic emission of bulk silicon,which is due to thermally induced dissociation of excitons.Here,we demonstrate that the effect of temperature on the excitonic emission is reversed for quantumconfined silicon nanocrystals.Using laser-induced heating of silicon nanocrystals embedded in SiO2,we achieved a more than threefold(4300%)increase in the radiative(photon)emission rate.We theoretically modeled the observed enhancement in terms of the thermally stimulated effect,taking into account the massive phonon production under intense illumination.These results elucidate one more important advantage of silicon nanostructures,illustrating that their optical properties can be influenced by temperature.They also provide an important insight into the mechanisms of energy conversion and dissipation in ensembles of silicon nanocrystals in solid matrices.In practice,the radiative rate enhancement under strong continuous wave optical pumping is relevant for the possible application of silicon nanocrystals for spectral conversion layers in concentrator photovoltaics.
