(7cd) Functional Materials Interfacing Chemistry and Biology

Zhang, W., Harvard University
Research Interests:

My research interests focus on fabricating various functional materials and exploring their applications in different fields. Primarily, I am interested in rationally designing and synthesizing molecules with different functionalities. Using chemical methods and microfluidic technology, I engineer these as-synthesized molecules to construct nanoscale, microscale and bulk materials, including carbon nanomaterials, silicon nanowires, stimuli-responsive microcapsules, porous materials and photonic crystals. Furthermore, I am also interested in applying these as-prepared materials to address both fundamental and practical issues in chemistry, biology and energy fields.

Research Experience:

My research has involved many fields of science and engineering. My formal research training started in Chemistry Departments at both Tsinghua University and Purdue University, in which I have studied organic synthesis, self-assembly, nanomaterials synthesis and biomedical applications of nanomaterials. After completing my PhD, I joined the School of Engineering at Harvard University working on microfluidics for producing functional materials, such as stimuli-responsive microcapsules for controlled release and bio-sensing applications.

Synthesis of Nanomaterials: With my chemistry background for molecular design and organic synthesis, I fabricated nanomaterials through rationally designing and synthesizing amphiphilic molecules with different functional groups, followed by investigating their self-assembly behavior, and finally using these self-assembled structures as templates and/or precursors to controllably prepare highly ordered mesoporous materials, ultrathin carbon nanofiber and pure single layer graphene. Besides nanomaterials fabrication, I also synthesized ionic liquids and incorporated them into 3D photonic crystal structure to develop chemical sensors with capability for naked-eye detection.

Bio-applications of Nanomaterials: My PhD research mainly focused on biomedical applications of nanomaterials. I used chemical vapor deposition methods to controllably prepare silicon nanowires (SiNWs) and graphene. By visualizing SiNWs with their intrinsic non-linear optical (NLO) signals, I investigated the impact of size and surface functionalities of SiNWs on their cellular binding and internalization. In addition, I demonstrated that graphene protects metals from corrosion in biological environment and reduces immune responses toward metallic devices. Moreover, I worked with a collaborator to develop a new NLO imaging method based on highly sensitive transient absorption to characterize graphene and graphene oxide in bulk and in biological systems.

Microfluidics for Functional Materials Production: As a postdoc in Prof. David Weitz’s group at Harvard University, I am engaged to produce novel functional materials using microfluidic processes. By using glass capillary microfluidic devices, I efficiently encapsulated a variety of enzymes and antibodies within microcapsules with different shell structures. These encapsulated bio-actives can be well maintained for long-term storage without losing their biological activities and can be controllably released upon applying osmotic pressure changes. This encapsulation technique shows great potential in protection and delivery of enzymes and antibodies. Additionally, I prepared biosensors by encapsulating quantum dots within microcapsules for glucose detection. This study opened the possibilities of developing implantable biosensors with high sensitivity. Besides microfluidics, I also developed a versatile strategy to fabricate 3D porous conductive collectors using various inorganic, organic and metallic substrates, as lithium battery anodes. I demonstrate the performance, such as battery life and efficiency, of lithium batteries with these anodes is as good as the best reported results in the literature.

Future Direction:

As a research faculty member, I would like to continue the philosophy of designing and fabricating novel functional materials based on chemistry and microfluidics to explore and solve challenges in chemistry and biology. I will contribute my efforts to prepare functional materials with hierarchical structures and novel properties to meet requirements for studying both fundamental and practical problems.

One interesting direction is to further explore biomedical applications of nanomaterials, particularly, graphene. Due to its biocompatibility, excellent mechanic and electric properties, graphene is an ideal candidate to study cellular biomechanics and differentiation behavior of neuron stem cells under an external electrical field.

I am also anticipated to fabricate “smart” microcapsules for specific release. In comparison to the release triggered by osmotic pressure, the release of encapsulated actives triggered by specific chemical or biological species can be precisely controlled. The specific release can be achieve by introducing functional groups into shell materials, which can degrade by adding specific additives. This precisely controlled specific release will have broad applications in both industry and biomedical fields.

Additionally, I am interested in fabricating novel chemical and biological sensors. Based on photonic crystals, I want to prepare sensitive sensors for detecting chemicals without using sophisticate instruments, which will have wide applications in chemistry and environmental detection. I also like to develop implantable biosensors using microfluidic approach.

In addition to the above directions, due to the interdisciplinary nature of my research work, I look forward to establishing a strong and active collaboration with fellow faculties in science and engineering to explore new opportunities at the interface of chemistry, biology and materials science.

Teaching Interests:

Teaching is a very important part in academia, since teaching is not only transferring knowledge, but also a process of learning and inspiring. I am always eager to involve myself in teaching. My teaching experience came from teaching in classes as a teaching-assistant, and mentoring undergraduate and graduate students in the lab. During my PhD study at Purdue University, I was repeatedly chose by my department to teach several courses including both lectures and laboratory for students from Chemistry and Chemical Engineering Departments. My duties included lecturing undergrads, experiment demo, holding office hours, preparing course materials and exams. In addition, I mentored undergraduate students as a part of their undergraduate thesis, and one of these undergraduates received the undergraduate research award and graduated in Purdue Chemistry Honors Program with the Highest Distinction. I have also been mentoring about 10 undergraduate and graduate students to conduct research programs in my labs at both Purdue University and Harvard University.

With my education and research background, I am well prepared to teach a broad range of courses in chemistry, chemical engineering and materials science at both undergraduate and graduate. I also envision instructing and encouraging students and postdocs to deliberate about questions and to conduct independent research studies in my lab.

Selected Peer-Reviewed Publications:

-24 peer-reviewed journal articles (12 first-authored or corresponding-authored papers), 2 patents, 1 book chapter († co-first author, * Corresponding author).

W. Zhang†, L. Qu†, H. Pei, Z. Wu, J. Didier, D. Ingber, D. Weitz, Asymmetric Swelling and Rupture of Inhomogeneous Microcapsules for Biologics Release. (In Preparation).

H. Zhao, R. Ding, X. Zhao, Y. Li, L. Qu, H. Pei, L. Yildirimer, Z. Wu, W. Zhang*, Graphene-based Nanomaterials for Drug/Gene Delivery, Bioimaging and Tissue Engineering. Drug Discov. Today, Accepted, (Invited Review).

W. Zhang†, A. Abbaspourrad†, D. Chen, E. Campbell, H. Zhao, Y. Li, Q. Li, D. Weitz, Osmotic Pressure Triggered Rapid Release of Encapsulated Enzymes with Enhanced Activity. Adv. Funct. Mater., In print, (Featured as inside front cover).

Y. Li†, W. Zhang†, et al., Rapid Assembly of Large Scale Transparent Circuit Arrays Using PDMS Nanofilm Shaped Coffee Ring. Adv. Funct. Mater., 2017, 27, 1606045.

X. Xie†, W. Zhang†, A. Abbaspourrad†, et al., Microfluidic Fabrication of Colloidal Nanomaterials-Encapsulated Microcapsules for Biomolecular sensing. Nano Lett., 2017, 17, 2015-2020.

J. Li†, W. Zhang†, et al., Highly sensitive transient absorption imaging of graphene and graphene oxide in living cells and circulating blood. Sci. Rep., 2015, 5, 12394.

W. Zhang, S. Lee, et al., Use of graphene as protection film in Biological Environments. Sci. Rep., 2014, 4, 4097.

W. Zhang, L. Tong, C. Yang, Cellular Binding and Internalization of Functionalized Silicon Nanowires. Nano Lett., 2012, 12, 1002-1006.

W. Zhang, J. Cui, et al., A strategy of Producing Pure-Layer Graphene Sheets Based on a Confined Self-Assembly Approach. Angew. Chem., 2009, 121, 5978-5982.

  • Selected as Hot Paper by Angewandte Chemie
  • Reported by C&EN, Latest News, “Graphene Via Self-Assembly”. July 8 (2009)
  • Reported by Nature China, Research Highlight, “Material chemistry: Casting graphene”, DOI:10.1038/nchina.2009.147, July 22 (2009)
  • Reported by NPG Asia Materials, Research Highlight, “Graphene: Confined approach”, DOI:10.1038/asiamat.2009.22, October 27 (2009)

W. Zhang, J. Cui, et al., Pyrrole containing ionic liquid as tecton for construction of ordered mesoporous silica with aligned polypyrrole nanowires in channels. J. Mater. Chem., 2009, 19, 3962-3970.

W. Zhang, J. Cui, et al., Confined Self-Assembly Approach to Produce Ultrathin Carbon Nanofibers. Langmuir, 2009, 25, 8235-8239.

W. Zhang, Y. Li, et al., Electrochemical Polymerization of Imidazolum-Ionic Liquids Bearing a Pyrrole Moiety. J. Polym. Sci. A: Polym. Chem., 2008, 46, 4151-4161.