The Waterloo Institute for Nanotechnology (WIN) is pleased to present a WIN Seminar talk by Professor Qing-Hua Xu from theDepartment of Department of Chemistry, National University of Singapore.
Plasmon Enhanced Optical Properties and Their Biomedical Applications
Abstract
Noble metal nanoparticles (NPs) have been known to display unique localized surface plasmon resonance (LSPR) property, which could be utilized to significantly enhance optical responses of metal NPs themselves and nearby chromophores, such as Surface enhanced Raman scattering (SERS), metal enhanced fluorescence and Plasmon enhanced nonlinear optical (NLO) responses.
In this talk, I will present our group’s efforts on various Plasmon enhanced optical properties and their applications. I will focus on aggregation induced two-photon photoluminescence of metal NPs and aggregation induced emission (AIE) of chromophore conjugated metal NPs. Our group found an interesting phenomenon that two-photon photoluminescence of metal NPs were significantly enhanced upon formation of aggregates, up to >800-fold in the colloid solution and several orders of magnitude on single particle level. This phenomenon has been demonstrated to be universal for Plasmonic metal NPs, which has been further utilized to develop various two-photon-excitation based biomedical applications. We have also employed ultrafast spectroscopy and single particle spectroscopy to understand the underlying enhancement mechanisms. Taking advantages of giant local electric amplification of plasmon coupled nanostructures, we have developed a new type of AIE based on aggregation of metal-chromophore conjugates. The working principle of this new AIE scheme is based on aggregation induced plasmon coupling of metal NPs that help to enhance the excitation efficiency and emission quantum yield at the same time. We have further developed photosensitizer conjugated gold NPs that display significantly enhanced fluorescence, singlet oxygen generation and photothermal response, which allow applications for multimodal imaging and synergistic photothermal and photodynamic cancer therapy below the skin tolerance threshold.
Biography
Qing-Hua
Xu
received
his
B.S.
from
Zhejiang
University
(1993),
M.S.
from
Peking
University
(1996)
and
University
of
Chicago
(1997),
and
Ph.D.
from
UC
Berkeley
(2001).
He
conducted
the
postdoctoral
research
at
Stanford
University
(2001-2002)
and
UC
Santa
Barbara
(2002-2005).
He
joined
NUS
Chemistry
in
2005
and
became
a
tenured
Associate
Professor
in
2011. His
primary
research
interests
focus
on
optical
properties
and
dynamical
processes
of
novel
low-dimensional
materials
as
well
as
their
applications
in
biomedicine,
optoelectronics,
energy,
and
environmental
areas.
His
research
spans
a
broad
range
from
materials
preparation
to
practical
applications
as
well
as
fundamental
studies
by
using
single
particle
spectroscopy
and
femtosecond
time-resolved
spectroscopy
and
microscopy. So
far
he
has
published
~230
peer
reviewed
articles
with
citations
of
>14,000
times
and
H-index
of
71
(Google
scholar).
He
was
selected
as
top
2%
of
the
most-cited
scientists
in
the
world
for
both
year
2020
and
2021
(ranked
by
Stanford
University).
Registration is required. If you have any questions or issues registering, please contact win-office@uwaterloo.ca