Yip Wai Tak

  • Studentship in 1989 at University of Hong Kong

One of my research projects focuses on understanding guest-host interactions inside heterogeneous sol-gel silica. Sol-gel silica is a form of porous glass in which a wide variety of guest molecules can be trapped inside to fabricate sensor devices. By examining interactions between an encapsulated guest molecule and its silica sol-gel host, our goal is to gain control on the mobility of a guest molecule. This is a critical issue for biosensor performance since minimizing the loss in conformational flexibility of an encapsulated enzyme should help the enzyme to retain its catalytic activity and deliver better sensor performance. We employ single-molecule spectroscopy to monitor the effect of local environment on the photophysics of an encapsulated fluorescent probe, through which the guest-host interactions can be examined.
Another research focus of my program is to develop high optical density materials for efficient solar energy harvesting. In order to construct material with high optical density, solar energy absorbing dyes have to be closely packed. Unfortunately, as the distance between adjacent dyes become shorter, exciton annihilation becomes increasingly efficient, thereby affecting the solar energy harvesting ability of an optical material. To suppress exciton annihilation, we employ cucurbit[7]uril (CB7) as a molecular host to encapsulate the solar energy absorbing dyes. In this design, CB7 serves as a barrier to block both physical and electronic interactions between adjacent dyes. The ability of CB7 to suppress exciton annihilation is examined through a wide variety of fluorescence techniques including single-molecule spectroscopy.