(7cc) Three-Dimensional Responsive Soft Micro/Nano-Structures for Biomedical and Electronic Applications

Three-dimensional responsive soft micro/nano-structures for biomedical and electronic applications
Weinan Xu, David H. Gracias
Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA

Responsive soft micro/nanostructures have attracted much attention in recent years due to their abilities to adapt and respond to external stimuli, and promising applications in biosensing, drug delivery, self-healing materials and flexible electronics. To further improve the performance of the 3D responsive structures, one promising way is to use novel and smart materials as the building blocks. In this work, novel polymers with branched architecture and multi-responsive properties were used to fabricate hierarchical microcapsules, which have the ability to simultaneously encapsulate multiple types of cargo molecules, and release them in a programmable manner triggered by external stimuli. On the other hand, for the fabrication of 3D bioelectronics, 2D nanomaterials including graphene and transition metal dichalcogenides, were utilized as the major components. The 2D materials were folded into well-defined 3D geometries by combining surface functionalization and top-down fabrication. Such 3D graphene microstructures have the ability to encapsulate biological samples such as live cells, which enables highly sensitive 3D analysis, mapping and sensing. To sum up, responsive 3D soft micro/nano-structures were built with novel and smart components, which leads to hierarchical internal structures and superior performance compared with traditional ones, such ultra-thin, flexible, and biocompatible 3D structures provide a new platform for bioelectronics, biosensing and drug delivery.

Related publications:

[18] Xu, W.; Qin, Z.; Chen, C.; Kwag, H. R.; Ma, Q.; Sarkar, A.; Buehler, M. J.; Gracias, D. H. Ultra-thin thermo-responsive self-folding 3D graphene. Science Advances 2017, In revision.
[17] Erwin, A. J.; Xu, W.; He, H.; Matyjaszewski, K.; Tsukruk, V. V. Linear and Star Poly(ionic liquid) Assemblies: Surface Monolayers and Multilayers. Langmuir 2017, 33, 3187-3199.
[16] Korolovych, F. V.; Ledin, P. A.; Stryutsky, A.; Shevchenko, V. V.; Sobko, O.; Xu, W.; Bulavin, L. A.; Tsukruk, V. V. Assembly of Amphiphilic Hyperbranched Polymeric Ionic Liquids in Aqueous Media at Different pH and Ionic Strength. Macromolecules 2016, 49, 8697–8710.
[15] Xu, W.; Ledin, P. A.; Iatridi, Z.; Tsitsilianis, C.; Tsukruk, V. V. Multicompartmental Microcapsules with Orthogonal Programmable Two-way Sequencing of Hydrophobic and Hydrophilic Cargo Release. Angew. Chem. 2016, 55, 4908-4913.
[14] Xu, W.; Steinschulte, A. A.; Plamper, F. A.; Korolovych, V. F.; Tsukruk, V. V. Hierarchical Assembly of Star Polymer Polymersomes into Responsive Multicompartmental Microcapsules. Chem. Mater. 2016, 28, 975–985.
[13] Xiong, R.; Hu, K.; Grant, A. M.; Ma, R.; Xu, W.; Lu, C.; Zhang, X.; Tsukruk, V. V. Ultrarobust Transparent Cellulose Nanocrystal-Graphene Membranes with High Electrical Conductivity. Adv. Mater. 2016, 28, 1501-1509.
[12] Ledin, P. A.; Xu, W.; Friscourt, F.; Boons, G.; Tsukruk, V. V. Branched Polyhedral Oligomeric Silsesquioxane Nanoparticles Prepared via Strain-Promoted 1,3-Dipolar Cycloadditions. Langmuir. 2015, 31, 8146-8155.
[11] Xu, W.; Ledin, P. A.; Shevchenko, V. V.; Tsukruk, V. V. Architecture, Assembly, and Emerging Applications of Branched Functional Polyelectrolytes and Poly(ionic liquids). ACS Appl. Mater. Interfaces 2015, 7, 12570-12596.
[10] Xu, W.; Ledin, P. A.; Iatridi, Z.; Tsitsilianis, C.; Tsukruk, V. V. Multi-Responsive Star-Graft Quarterpolymer Monolayers. Macromolecules 2015, 48, 3344-3353.
[9] Steinschulte, A. A.; Xu, W.; Draber, F.; Hebbeker, P.; Jung, A.; Bogdanovski, D.; Schneider, S.; Tsukruk, V. V.; Plamper, F. A. Interface-Enforced Complexation between Copolymer Blocks. Soft Matter 2015, 11, 3559-3565.
[8] Xu, W.; Ledin, P. A.; Plamper, F. A.; Synatschke, C. V.; Müller, A. H.; Tsukruk, V. V. Multiresponsive Microcapsules Based on Multilayer Assembly of Star Polyelectrolytes. Macromolecules 2014, 47, 7858-7868.
[7] Ledin, P. A.; Tkachenko, I. M.; Xu, W.; Choi, I.; Shevchenko, V. V.; Tsukruk, V. V. Star-Shaped Molecules with Polyhedral Oligomeric Silsesquioxane Core and Azobenzene Dye Arms. Langmuir 2014, 30, 8856-8865.
[6] Xu, W.; Choi, I.; Plamper, F. A.; Synatschke, C. V.; Müller, A. H.; Melnichenko, Y. B.; Tsukruk, V. V. Thermo-Induced Limited Aggregation of Responsive Star Polyelectrolytes. Macromolecules 2014, 47, 2112-2121.
[5] Ren, H.; Kulkarni, D. D.; Kodiyath, R.; Xu, W.; Choi, I.; Tsukruk, V. V. Competitive Adsorption of Dopamine and Rhodamine 6G on the Surface of Graphene Oxide. ACS Appl. Mater. Interfaces 2014, 6, 2459–2470.
[4] Choi, I.; Kulkarni, D. D.; Xu, W.; Tsitsilianis, C.; Tsukruk, V. V. Star Polymer Unimicelles on Graphene Oxide Flakes. Langmuir 2013, 29, 9761-9769.
[3] Xu, W.; Choi, I.; Plamper, F. A.; Synatschke, C. V.; Müller, A. H.; Tsukruk, V. V. Nondestructive Light-Initiated Tuning of Layer -by-Layer Microcapsule Permeability. ACS Nano 2013, 7, 598-613.
[2] Choi, I.; Malak, S. T.; Xu, W.; Heller, W. T.; Tsitsilianis, C.; Tsukruk, V. V. Multicompartmental Microcapsules from Star Copolymer Micelles. Macromolecules 2013, 46, 1425-1436.
[1] Xu, W.; Qin, Z.; Yu, H.; Liu, Y.; Liu, N.; Zhou, Z.; Chen, L. Cellulose nanocrystals as organic nanofillers for transparent polycarbonate films. J. Nanopart. Res. 2013, 15, 1-8.

Research Interests:

Stimuli-responsive polymers, 2D nanomaterials, 3D micro- and nano-fabrication, Additive manufacturing, Drug delivery

Postdoctoral Fellow, Department of Chemical & Biomolecular Engineering, Johns Hopkins University. Jan. 2016-Present

Ph.D. in Materials Science and Engineering, Aug. 2011 – Dec. 2015, Georgia Institute of Technology, Atlanta, GA, USA

B.S. in Polymer Science and Engineering, Sept. 2007 – Jul. 2011, Donghua University, Shanghai, China

My PhD research is focused on stimuli-responsive polymers, and their assembly into well-defined micro- and nano-structures, for smart coating, self-healing materials, and drug delivery applications. My postdoc work is focused on the fabrication of 3D micro- and nano-structures from atomically thin 2D materials, including graphene, BN, and TMDs, with applications in miniaturized 3D electronic devices, biosensing and bioelectronics.

For my future work as an independent researcher, I will focus on combining the structural flexibility and easy processability of polymeric materials, with the superior electrical, optical and catalytic properties of 2D nanomaterials. And it is distinct from traditional polymer nanocomposite research which simply mixing polymers with nanomaterials. In the first place, functional and responsive polymers will be attached to 2D nanomaterials mostly through non-covalent interaction, including electrostatic attraction, hydrophobic interaction, π - π interaction and host-guest interaction, which enables the precise control of the structures in a molecular and nanosale level. After the functionalization with responsive polymers, the 2D nanomaterials will be used to fabricate smart and intelligent devices, such as transistors or sensors. The changes in external conditions induce the structural changes of the functionalized nanomaterials, which will lead to the actuation and detection of the devices. On the other hand, engineering the interface between responsive polymers and 2D nanomaterials in a layer-by-layer way will lead to high-performance membranes, which have promising applications in ion and gas separation, water purification and ion conducting membranes for batteries.

Teaching Interests:

Introduction to Materials Science

Introduction to Polymer Materials

Polymer Physics

Polymer Chemistry

Polymer Characterization

Micro- and Nano-fabrication

I believe teaching is as important, if not more important than research in any university including research universities, because the ultimate goal of college and graduate education is to transform the students into all-round developed talents with expertise in certain fields, so that they can contribute to the advancement of our society in various ways. To this purpose, teaching is the most direct and effective approach. The materials science and engineering major is one which closely related to our real life, and can have significant influence in our way of thinking and view of the world, that’s the main reason that I am very enthusiastic about teaching class in the materials science and engineering field.

My main objective of teaching is to provide the students with a more scientific and deeper view of the objects around us and the world, during the same time, the students develop strong ability of critical thinking and self-learning. Moreover, the students can also use the knowledge from materials science to make inventions for the future, for example, the concept of smart clothes, which have large number of miniaturized flexible electronic devices embedded in them, and can communicate with our body, is an excellent showcase of advanced materials science. I will adopt active teaching and teaching as scholarship methods in my class, such as small-group discussions, group presentations and frequent assessments, to make my teaching more effective and inclusive.