(6fu) Sheikhi Laboratory for Sustainable Soft Matter and Active Interfaces

How can natural resources be engineered at the micro- and nanoscale to address the current limitations of synthetic, often hazardous materials? How may Nature inspire us with its sophisticated structure-property relationships to overcome everyday life challenges? These two key questions propel us to seek solutions for persistent bottlenecks in environment, water, healthcare, and food sectors by combining sustainability with the fundamentals of soft materials and interfaces. Our research focuses primarily on micro- and nanoengineering natural or semi-natural materials to develop advanced soft matter, including colloidal particles and macromolecules, as well as active interfaces with tailored structure-property relationships. We are particularly excited about the interdisciplinary research in the intersection between materials science, chemical engineering, environmental engineering, and bioengineering wherein biopolymers, such as cellulose and proteins as well abundant minerals play key roles in designing functional materials with unique properties. The overarching theme of our Lab is reflected in the following three platforms:

(1) Nanoengineered colloidal systems

Colloids, aggregates of molecules that form particles with a size between 1 nm-1 µm, distributed in a fluid, include dispersion, gels, foams, and emulsions. These materials are the main pillars of everyday life, contributing to a broad spectrum of applications and extraordinary phenomena. Our research endeavors to take control over the structure and properties of colloidal systems and ultimately use them for water treatment, environmental remediation, biosensing, energy storage, and smart foods. To this end, our effort is geared towards harnessing the potential of cellulose, the most abundant biopolymer in the world, by nanoengineering the building blocks of trees. We will develop a library of nanocelluloses with tailored physical and surface properties, providing stable colloidal dispersion (e.g., in extreme ionic strengths and biofluids), multifunctional hydrogels, ultralight aerogels, and robust films. Parallel efforts will be devoted to taking advantage of structural heterogeneity of nanoclays in developing adaptive nanocomposites.

Selected publications:

• Sheikhi, A. Kakkar, and T.G.M. van de Ven. Nanoengineering colloidal and polymeric celluloses for threshold scale inhibition: towards universal biomass-based crystal modification. Materials Horizons, 5:248-255. 2018.⁺Featured on the inside back cover.
• Sheikhi and T.G.M. van de Ven. Colloidal starch and cellulose nanocrystals unite to improve the mechanical properties of paper: From enhanced coatings to reinforced nanocomposites. ACS Applied Nano Materials, 1:1841-1852. 2018.
• Sheikhi, S. Afewerki, R. Oklu, A.K. Gaharwar, and A. Khademhosseini. Effect of ionic strength on shear-thinning nanoclay-polymer composite hydrogels. Biomaterials Science, Accepted. 2018.⁺Featured on the outside back cover.
• Sheikhi, H. Yang, P.J. Carreau, and T.G.M. van de Ven. Colloidal nanotoolbox for molecularly regulated polymerization: chemorheology over 6 decades of viscoelasticity. Materials Horizons, 4:1165-1170. 2017.
• Sheikhi and T.G.M. van de Ven. Squishy nanotraps: hybrid cellulose nanocrystal-zirconium metallogels for controlled trapping of biomacromolecules. Chemical Communications, 53:8747-8750. 2017.
• Sheikhi and T.G.M. van de Ven. Colloidal aspects of Janus-like hairy cellulose nanocrystalloids. Invited Review Article to the Special Issue on Nanocelluloses. Current Opinion in Colloid & Interface Science, 29:21-31. 2017.

(2) Biomimicry for sustainable material design

Nature has mastered on-demand, highly engineered responsive architectures to minimize the material demand while maximizing the performance and functionality. We build on this invaluable lesson by carefully exploring natural systems and mimicking their structures. We have two main approaches here: (i) taking advantage of naturally-derived nanomaterials to design hybrid systems with inherited inspiration from all-natural systems, and (ii) achieving biomimicry through gaining a precise control over the molecular architecture of designer dendritic macromolecules, which are typically highly symmetric and monodisperse. These compounds enable elucidating the role of functional groups as well as, often neglected, structural backbones in designing biomimetic materials. We envision that understanding these principles may have direct implications in developing advanced materials and devices for water technology and biomedical applications.

Selected publications:

• Sheikhi, A. Kakkar, and T.G.M. van de Ven. Biomimetic scale-resistant polymer nanocomposites: Towards universal additive-free scale inhibition. Journal of Materials Chemistry A, 6:10189-10195. 2018.
• Sheikhi, A. Kakkar, and T.G.M. van de Ven. A leaf out of Nature’s book: hairy nanocelluloses for bioinspired mineralization. Crystal Growth & Design, 16:46274634. 2016.
• Sheikhi, S.L. Mejlsoe, N. Li, E. Bomal, T.G.M. van de Ven, and A. Kakkar. Biomimetic dendrimers for mineralization: Rare fibrous amorphous calcium carbonate (ACC) and branch-and-bud ACC-vaterite polymorphs. Submitted. 2018.

(3) Microfluidic-enabled biomaterials

Reducing the scale of common “bulk” soft materials, such as hydrogels may open a new horizon for next-generation biomaterials with exceptional properties that would otherwise be implausible to achieve. An example is hydrogel scaffolds for three-dimensional biological cell culture that have interdependent porosity and stiffness, imposing inevitable limitations when highly stiff substrates with large pores are demanded. We are interested in revisiting biomaterial design by breaking down bulk platforms into modular compartments and rebuild them in a bottom-up approach. We aim at building biomaterials, such as polysaccharide- and protein-based hydrogels, using annealable microparticles, produced in common microfluidic platforms, e.g., a flow focusing device. Directed self-assembly of these soft building blocks will provide microporous scaffolds, which may enable engineering spatiotemporal cell-cell and cell-matrix interactions for a variety of applications, including organoid development for drug evaluation and screening.

Selected publications:

• Sheikhi, J. de Rutte, R. Haghniaz, O. Akouissi, M. Rasti, K. Suthiwanich, H. Mary, D. di Carlo, and A. Khademhosseini. Annealable gelatin methacryloyl microbeads: A versatile microenvironment with orthogonal stiffness and porosity. To be submitted. 2018.

Teaching Interests:

Amir Sheikhi has long been passionately involved in active teaching, initiated from numerous Teaching Assistantships in the undergraduate core courses as well as the specialized graduate-level curriculum of Chemical Engineering, encompassing Chemical Manufacturing Processes (Freshman), Fluid Mechanics (Sophomore), Heat and Mass Transfer (Sophomore), Kinetics and Chemical Reactions Engineering (Junior), Process Simulation and Modeling (Senior), Process Control (Senior), Material Surfaces: A Biomimetic Approach (Senior/Graduate), and Biochemical Engineering (Senior). In addition, he has developed and instructed lectures in Advanced Computer-Aided Process Simulation (Senior/Graduate), Advanced Materials (Graduate), and Colloid Chemistry (Graduate). Amir believes that the quality of undergraduate teaching directly shapes the next-generation scientists, and pursues three main goals in undergraduate teaching: (i) to facilitate active learning in which students are highly engaged in the process of learning through cognitive-affective-sensory domains within the Bloom's taxonomy, (ii) to bridge the gap between undergraduate coursework and graduate research by integrating real-life and laboratory experiences in the lectures, and (iii) to develop new, highly multidisciplinary curricula for extending the vision of young scholars beyond their major degree, eternalizing a built-in “curiosity”. Amir has also been active and passionate about chemical education, hands-on demonstrations, and academic life advising.

Selected publications:

• Sheikhi, N. Boonsukha, O. Akouissi, S.-K. Hu, J. Hayashi, and A. Khademhosseini. Assembling an affordable miniature microscope (mini-microscope). Submitted to the Journal of Chemical Education. 2018.
• Sheikhi, Learning to be more than my publications: Thriving in academic life through a silence of publications, Submitted to Science, 2018.
• Sheikhi, H. Yang, Md. N. Alam, T.G.M. van de Ven. Highly stable, functional hairy nanoparticles and biopolymers from wood fibers: Towards sustainable nanotechnology. Journal of Visualized Experiments, 113:e54133. 2016.