title: Plasmon-enhanced two-photon-induced isomerization for highly-localized light-based actuation of inorganic/organic interfaces.
abstract: Two-photon initiated photo-isomerization of an azobenzene moiety adsorbed on silver nanoparticles (Ag NPs) is demonstrated. The azobenzene is linked to a materials-binding peptide that brings it into intimate contact with the Ag NP surface, producing a dramatic enhancement of its two-photon absorbance. An integrated modeling approach, combining advanced conformational sampling with Quantum Mechanics/Capacitance Molecular Mechanics and response theory, shows that charge transfer and image charges in the Ag NP generate local fields that enhance two-photon absorption of the cis isomer, but not the trans isomer, of adsorbed molecules. Moreover, dramatic local field enhancement is expected near the localized surface plasmon resonance (LSPR) wavelength, and the LSPR band of the Ag NPs overlaps the azobenzene absorbance that triggers cis to trans switching. As a result, the Ag NPs enable two-photon initiated cis to trans isomerization, but not trans to cis isomerization. Confocal anti-Stokes fluorescence imaging shows that this effect is not due to local heating, while the quadratic dependence of switching rate on laser intensity is consistent with a two-photon process. Highly localized two-photon initiated switching could allow local manipulation near the focal point of a laser within a 3D nanoparticle assembly, which cannot be achieved using linear optical processes.
authors.affiliation: Institute for Laser Photonics and Biophotonics, University at Buffalo (SUNY), Buffalo, NY 14260, USA. pnprasad@buffalo.edu.
authors.forename: Chang-Keun
authors.initials: CK
authors.lastname: Lim
authors.affiliation: Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Chemical and Biological Engineering, University at Buffalo (SUNY), Buffalo, NY 14260, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Li
authors.affiliation: Institute for Frontier Materials, Deakin University, Geelong, 3216 VIC, Australia.
authors.forename: Kurt L M
authors.initials: KL
authors.lastname: Drew
authors.affiliation: Institute for Frontier Materials, Deakin University, Geelong, 3216 VIC, Australia.
authors.forename: J Pablo
authors.initials: JP
authors.lastname: Palafox-Hernandez
authors.affiliation: Department of Chemistry, University of Miami. 1301 Memorial Drive, Coral Gables, Florida 33146, USA.
authors.forename: Zhenghua
authors.initials: Z
authors.lastname: Tang
authors.affiliation: Institute for Laser Photonics and Biophotonics, University at Buffalo (SUNY), Buffalo, NY 14260, USA. pnprasad@buffalo.edu.
authors.forename: Alexander
authors.initials: A
authors.lastname: Baev
authors.affiliation: Institute for Laser Photonics and Biophotonics, University at Buffalo (SUNY), Buffalo, NY 14260, USA. pnprasad@buffalo.edu.
authors.forename: Andrey N
authors.initials: AN
authors.lastname: Kuzmin
authors.affiliation: Department of Chemistry, University of Miami. 1301 Memorial Drive, Coral Gables, Florida 33146, USA.
authors.forename: Marc R
authors.initials: MR
authors.lastname: Knecht
authors.affiliation: Institute for Frontier Materials, Deakin University, Geelong, 3216 VIC, Australia.
authors.forename: Tiffany R
authors.initials: TR
authors.lastname: Walsh
authors.affiliation: Department of Chemical and Biological Engineering, University at Buffalo (SUNY), Buffalo, NY 14260, USA.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Swihart
authors.affiliation: Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Ågren
authors.affiliation: Institute for Laser Photonics and Biophotonics, University at Buffalo (SUNY), Buffalo, NY 14260, USA. pnprasad@buffalo.edu.
authors.forename: Paras N
authors.initials: PN
authors.lastname: Prasad