Enhancing Two-photon Optical Properties of Nanomaterials for Biomedical Applications

Title: 
Enhancing Two-photon Optical Properties of Nanomaterials for Biomedical Applications

Schedule: 
Date: 15 November 2022 (Tuesday)
Time: Start from 5:30 PM (HKT)

Delivery: Face-to-face 
Venue: CYP P1

Speaker: 
Prof. Qing-Hua XU
Department of Chemistry, National University of Singapore

About the Speaker: 

Prof. 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 since 2011. His primary research interests focus on optical responses 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 ~240 peer-reviewed articles with total citations of ~15,800 times and H-index of 74 (Google scholar). 

Abstract: 
Two-photon excitation techniques have unique advantages such as 3-dimensional selectivity and deep penetration into biological tissues in biomedical applications compared to their one-photon counterparts. In this talk, I will present our recent efforts on development of nanomaterials with enhanced two-photon excitation properties and their applications. Two different strategies have been utilized in our approach. One is based on energy transfer from conjugated polymers that have large two-photon absorption cross sections as two-photon light harvesting materials. We have developed various schemes for two-photon sensing, imaging and photodynamic therapy, with efficiency improved by over 1000-fold.  Another approach is based on plasmon resonance enhancement. Noble metal nanoparticles are known to display unique properties of localized surface plasmon resonance, which could be utilized to enhance linear and nonlinear optical properties of external chromophores and metal nanoparticles themselves. We have developed various plasmon engineered nanocomposites with enhanced two-photon properties, explored their biological applications, and conducted single particle spectroscopy and ultrafast spectroscopy studies to understand the underlying enhancement mechanisms. We have further combined these two strategies to develop plasmon enhanced two-photon optical properties of conjugated polymer-based NPs for biomedical applications.

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