1. Research Summary Hanwei Liu
I worked as an undergraduate researcher in Prof. Ting Xu’s group from May 2014 to
October 2014 on a project designing polymer-supported metal-organic frameworks (MOFs)
for the selective adsorption of CO2. My tasks included (i) synthesizing new ligands for MOFs
and characterizing these ligands using NMR and UV-Vis spectroscopies, (ii) synthesizing
MOF nanoparticles, (iii) characterizing the quality of MOF nanoparticles by transmission
electron microscopy (TEM), and (iv) synthesizing polymers supports for MOF nanoparticles.
In the end, several polymer-supported MOF materials were isolated; however, their CO2
adsorption efficiency and selectivity did not meet our expectations.
Since February 2015, I have been working as an undergraduate researcher in the
group of Prof. Matthew Francis, who specializes in chemical biology. I am working on a
project of preparing protein-rotaxane bioconjugates using the Michael addition of maleimides
and cysteines. Rotaxanes are mechanically interlocked structures that can act as “molecular
machines” by changing conformation in response to stimuli such as light, pH, or temperature.
Our goal is to allosterically regulate protein function by actuating these bioconjugated
molecular machines, for example, to turn an enzyme “on” or “off”. I independently came up
with an idea of using polypeptide-capped rotaxanes to react with proteins, which solved our
problems of low water solubility and brought more insight on how to effectively combine
artificial molecular machines with biological molecules to achieve novel functions. We have
now developed a high-yield method of bioconjugating rotaxanes to proteins, and
characterized these bioconjugates by mass spectrometry, NMR spectroscopy, and gel
electrophoresis. We are currently writing on a communication on this project’s initial results.1
Figure 1. Stoppering general scheme, the third model pseudorotaxane is designed by Hanwei Liu.
From May 2015 to August 2015, I worked as a research assistant in medicinal
chemistry at Plexxicon Inc., where I specialized in designing and synthesizing kinase
inhibitors as potent anti-cancer drugs. I prepared two promising macrolactones through an
optimized thirteen-step synthetic route. These drug candidates possessed at least ten-fold
greater selectivity compared to the original drug from which they were inspired. I
characterized the macrolactones using liquid chromatography, mass spectrometry, and NMR
spectroscopy. The results of this project were presented at Plexxikon Inc.’s monthly meeting.
1. Bruns, C.; Liu, H.; Francis, M. B. Near-Quantitative Bioconjugation of Rotaxanes. In
Preparation.