Liu Y, Yong X, McFarlin IV G, Kuksenok O, Aizenberg J, Balazs AC. Designing a gel–fiber composite to extract nanoparticles from solution. Soft Matter. 2015;11 :8692-8700.Abstract

The extraction of nanoscopic particulates from flowing fluids is a vital step in filtration processes, as well as the fabrication of nanocomposites. Inspired by the ability of carnivorous plants to use hair-like filaments to entrap species, we use computational modeling to design a multi-component system that integrates compliant fibers and thermo-responsive gels to extract particles from the surrounding solution. In particular, hydrophobic fibers are embedded in a gel that exhibits a lower critical solution temperature (LCST). With an increase in temperature, the gel collapses to expose fibers that self assemble into bundles, which act as nanoscale ‘‘grippers’’ that bind the particles and draw them into the underlying gel. By varying the relative stiffness of the fibers, the fiber–particle interaction strength and the shear rate in the solution, we identify optimal parameters where the particles are effectively drawn from the solution and remain firmly bound within the gel layer. Hence, the system can be harnessed in purifying fluids and creating novel hybrid materials that integrate nanoparticles with polymer gels.

Wei Z, Schneider TM, Kim J, Kim H-J, Aizenberg J, Mahadevan L. Elastocapillary coalescence of plates and pillars. Proc. R. Soc. A. 2015;471 :20140593.Abstract

When a fluid-immersed array of supported plates or pillars is dried, evaporation leads to the formation of menisci on the tips of the plates or pillars that bring them together to form complex patterns. Building on prior experimental observations, we use a combination of theory and computation to understand the nature of this instability and its evolution in both the two- and three-dimensional setting of the problem. For the case of plates, we explicitly derive the interaction torques based on the relevant physical parameters associated with pillar deformation, contact-line pinning/depinning and fluid volume changes. A Bloch-wave analysis for our periodic mechanical system captures the window of volumes where the two-plate eigenvalue characterizes the onset of the coalescence instability. We then study the evolution of these binary clusters and their eventual elastic arrest using numerical simulations that account for evaporative dynamics coupled to capillary coalescence. This explains both the formation of hierarchical clusters and the sensitive dependence of the final structures on initial perturbations, as seen in our experiments. We then generalize our analysis to treat the problem of pillar collapse in three dimensions, where the fluid domain is completely connected and the interface is a minimal surface with the uniform mean curvature. Our theory and simulations capture the salient features of experimental observations in a range of different situations and may thus be useful in controlling the ensuing patterns.

Friedlander RS, Vogel N, Aizenberg J. Role of Flagella in Adhesion of Escherichia coli to Abiotic Surfaces. Langmuir. 2015;31 :6137-6144.Abstract

Understanding the interfacial activity of bacteria is of critical importance due to the huge economic and public health implications associated with surface fouling and biofilm formation. The complexity of the process and difficulties of predicting microbial adhesion to novel materials demand study of the properties of specific bacterial surface features and their potential contribution to surface attachment. Here, we examine flagella, cell appendages primarily studied for their cell motility function, to elucidate their potential role in the surface adhesion of Escherichia coli - a model organism and potential pathogen. We use self-assembled monolayers (SAMs) of thiol-bearing molecules on gold films to generate surfaces of varying hydrophobicity, and measure adhesion of purified flagella using quartz crystal microbalance. We show that flagella adhere more extensively and bind more tightly to hydrophobic SAMs than to hydrophilic ones, and we propose a two-step vs a single-step adhesion mechanism that accounts for the observed dissipation and frequency changes for the two types of surfaces, respectively. Subsequently, study of the adhesion of wild-type and flagella knockout cells confirms that flagella improve adhesion to hydrophobic substrates, whereas cells lacking flagella do not show preferred affinity to hydrophobic substrates. Together, these properties bring about an interesting ability of cells with flagella to stabilize emulsions of aqueous culture and dodecane, not observed for cells lacking flagella. This work contributes to our overall understanding of nonspecific bacterial adhesion and confirms that flagella, beyond motility, may play an important role in surface adhesion.

Shastri A, McGregor LM, Liu Y, Harris V, Nan H, Mujica M, Vasquez Y, Bhattacharya A, Ma Y, Aizenberg M, et al. An aptamer-functionalized chemomechanically modulated biomolecule catch-and-release system. Nature Chemistry. 2015;7 :447-454. Shastri_NatChem2015.pdf
Vogel N, Utech S, England GT, Shirman T, Phillips KR, Koay N, Burgess IB, Kolle M, Weitz DA, and Aizenberg J. Color from hierarchy: Diverse optical properties of micron-sized spherical colloidal assemblies. Proc. Nat. Acad. Sci. 2015. PNAS_Photonic_Balls.pdf
Schaffner M, England G, Kolle M, Aizenberg J, and Vogel N. Combining Bottom-Up Self-Assembly with Top-Down Microfabrication to Create Hierarchical Inverse Opals with High Structural Order. Small. 2015. Schaffner_et_al-2015-Small.pdf
Cui J, Daniel D, Grinthal A, Lin K, Aizenberg J. Dynamic polymer systems with self-regulated secretion for the control of surface properties and material healing. Nature Materials. 2015;14 (8) :790-795. NatMat2015_Cui_et_al.pdf
Kaplan CN, Wu N, Madres S, Aizenberg J, Mahadevan L. Dynamics of evaporative colloidal patterning. Physics of Fluids. 2015;27 :092105. kaplan2015.dynamics_of_evaporative_colloidal_patterning.pdf
Li L, Kolle S, Weaver JC, Ortiz C, Aizenberg J, Kolle M. A highly conspicuous mineralized composite photonic architecture in the translucent shell of the blue-rayed limpet. Nature Communications. 2015;6. Li2015.NatComm..pdf
Hou X, Hu Y, Grinthal A, Khan M, Aizenberg J. Liquid-based gating mechanism with tunable multiphase selectivity and antifouling behaviour. Nature. 2015;519 :70-73. Hou2015.nature.pdf
MacCallum N, Howell C, Kim P, Sun D, Friedlander R, Ranisau J, Ahanotu O, Lin JJ, Vena A, Hatton B, et al. Liquid-Infused Silicone As a Biofouling-Free Medical Material. ACS Biomater. Sci. Eng. 2015;1 :43-51. MacCallum2015.ACSBiomaterials.pdf
Li L, Connors MJ, Kolle M, England GT, Speiser DI, Xiao X, Aizenberg J, Ortiz C. Multifunctionality of chiton biomineralized armor with an integrated visual system. Science. 2015;350 (6263) :952-956. Science2015.Li.pdf
Monn MA, Weaver JC, Zhang T, Aizenberg J, Kesari H. New functional insights into the internal architecture of the laminated anchor spicules of Euplectella aspergillum. Proc. Nat. Acad. Sci. 2015;112 (16) :4976-4981. PNAS2015_sponge_spicules.pdf
Howell C, Vu TL, Johnson CP, Hou X, Ahanotu O, Alvarenga J, Leslie DC, Uzun O, Waterhouse A, Kim P, et al. Stability of Surface-Immobilized Lubricant Interfaces under Flow. Chem. Mater. 2015;27 (5) :1792-1800. Howell_ChemMat2015.pdf
Tesler AB, Kim P, Kolle S, Howell C, Ahanotu O, Aizenberg J. Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel. Nature Communications. 2015;6 :8649.
Aizenberg J. Slippery Liquid-Infused Porous Surfaces. The Journal of Ocean Technology. 2014;9 (4) :113-114.Abstract

Marine biofouling, the process of accumulation of microorganisms, plants, algae and animals on submerged surfaces, is an age-old problem associated with any maritime activity affecting commercial and recreational shipping activities, naval operations, aquaculture facilities and marine renewable energy structures alike. The adverse effects of marine biofouling include the increase of drag on ship hulls, damage to ships and maritime equipment such as corrosion, the spread of diseases in aquaculture and the distribution of invasive species causing extensive damage to coastal ecosystems and the benefits derived from them. An estimated global annual total of $60 billion in fuel cost alone can be saved by the application of marine antifouling coatings, making the treatment of marine biofouling a necessity not an option.

England G, Kolle M, Kim P, Khan M, Munoz P, Mazur E, and Aizenberg J. Bioinspired micrograting arrays mimicking the reverse color diffraction elements evolved by the butterfly Pierella luna. Proc. Nat. Acad. Sci. 2014;111 (44) :15630–15634. PNAS-2014-England-1412240111.pdf
Leslie DC, Waterhouse A, Berthet JB, Valentin TM, Watters AL, Jain A, Kim P, Hatton BD, Nedder A, Donovan K, et al. A bioinspired omniphobic surface coating on medical devices prevents thrombosis and biofouling. Nature Biotechnology. 2014. NatBiotech2014.Leslie_et_al.pdf
Hashmi B, Zarzar LD, Mammoto T, Jiang A, Aizenberg J, Ingber DE. Developmentally-Inspired Shrink-Wrap Polymers for Mechanical Induction of Tissue Differentiation. Adv. Mater. 2014. AdvMat2013.Zarzar.pdf
Phillips KR, Vogel N, Burgess IB, Perry CC, Aizenberg J. Directional Wetting in Anisotropic Inverse Opals. Langmuir. 2014. Langmuir2014.Phillips.Directional_wetting_in_anisotropic_inverse_opals.pdf