Adhesion mechanism in a DOPA-deficient foot protein from green mussels

Hwang, Dong Soo,Zeng, Hongbo,Lu, Qingye,Israelachvili, Jacob,Waite, J. Herbert The Royal Society of Chemistry 2012 SOFT MATTER Vol.8 No.20

<P>The holdfast or byssus of Asian green mussels, <I>Perna viridis</I>, contains a foot protein, pvfp-1, that differs in two respects from all other known adhesive mussel foot proteins (mfp): (1) instead of the hallmark <SMALL>L</SMALL>-3,4-dihydroxyphenylalanine (DOPA) residues in mfp-1, for example, pvfp-1 contains C<SUP>2</SUP>-mannosyl-7-hydroxytryptophan (Man7OHTrp). (2) In addition, pvfp-1 chains are not monomeric like mfp-1 but trimerized by collagen and coiled-coil domains near the carboxy terminus after a typical domain of tandemly repeated decapeptides. Here, the contribution of these peculiarities to adhesion was examined using a surface forces apparatus (SFA). Unlike previously studied mfp-1s, pvfp-1 showed significant adhesion to mica and, in symmetric pvfp-1 films, substantial cohesive interactions were present at pH 5.5. The role of Man7OHTrp in adhesion is not clear, and a DOPA-like role for Man7OHTrp in metal complexation (<I>e.g.</I>, Cu<SUP>2+</SUP>, Fe<SUP>3+</SUP>) was not observed. Instead, cation–π interactions with low desolvation penalty between Man7OHTrp and lysyl side chains and conformational changes (raveling and unraveling of collagen helix and coiled-coil domains) are the best explanations for the strong adhesion between pvfp-1 monomolecular films. The strong adhesion mechanism induced by cation–π interactions and conformational changes in pvfp-1 provides new insights for the development of biomimetic underwater adhesives.</P> <P>Graphic Abstract</P><P>Molecular interactions of a DOPA-deficient foot protein from green mussels, pvfp-1, were measured using a surface forces apparatus (SFA). The strong adhesion mechanism induced by cation–π interactions and conformational changes in pvfp-1 provides new insights for the development of biomimetic underwater adhesives. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2sm25173f'> </P>

Adhesion Force of Chitosan: Effects of Acetylation, Contact Time, and Molecular Weight

Chanoong LIM,Dong Woog LEE,Jacob ISRAELACHVILI,Dong Soo HWANG 한국생물공학회 2015 한국생물공학회 학술대회 Vol.2015 No.10

Strong Adhesion and Cohesion of Chitosan in Aqueous Solutions

Lee, Dong Woog,Lim, Chanoong,Israelachvili, Jacob N.,Hwang, Dong Soo American Chemical Society 2013 Langmuir Vol.29 No.46

<P>Chitosan, a load-bearing biomacromolecule found in the exoskeletons of crustaceans and insects, is a promising biopolymer for the replacement of synthetic plastic compounds. Here, surface interactions mediated by chitosan in aqueous solutions, including the effects of pH and contact time, were investigated using a surface forces apparatus (SFA). Chitosan films showed an adhesion to mica for all tested pH ranges (3.0–8.5), achieving a maximum value at pH 3.0 after a contact time of 1 h (<I>W</I><SUB>ad</SUB> ∼ 6.4 mJ/m<SUP>2</SUP>). We also found weak or no cohesion between two opposing chitosan layers on mica in aqueous buffer until the critical contact time for maximum adhesion (chitosan–mica) was reached. Strong cohesion (<I>W</I><SUB>co</SUB> ∼ 8.5 mJ/m<SUP>2</SUP>) between the films was measured with increasing contact times up to 1 h at pH 3.0, which is equivalent to ∼60% of the strongest, previously reported, mussel underwater adhesion. Such time-dependent adhesion properties are most likely related to molecular or molecular group reorientations and interdigitations. At high pH (8.5), the solubility of chitosan changes drastically, causing the chitosan–chitosan (cohesion) interaction to be repulsive at all separation distances and contact times. The strong contact time and pH-dependent chitosan–chitosan cohesion and adhesion properties provide new insight into the development of chitosan-based load-bearing materials.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2013/langd5.2013.29.issue-46/la403124u/production/images/medium/la-2013-03124u_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la403124u'>ACS Electronic Supporting Info</A></P>

Adhesion of mussel foot proteins to different substrate surfaces

Lu, Qingye,Danner, Eric,Waite, J. Herbert,Israelachvili, Jacob N.,Zeng, Hongbo,Hwang, Dong Soo The Royal Society 2013 Journal of the Royal Society, Interface Vol.10 No.79

<P> Mussel foot proteins (mfps) have been investigated as a source of inspiration for the design of underwater coatings and adhesives. Recent analysis of various mfps by a surface forces apparatus (SFA) revealed that mfp-1 functions as a coating, whereas mfp-3 and mfp-5 resemble adhesive primers on mica surfaces. To further refine and elaborate the surface properties of mfps, the force-distance profiles of the interactions between thin mfp (i.e. mfp-1, mfp-3 or mfp-5) films and four different surface chemistries, namely mica, silicon dioxide, polymethylmethacrylate and polystyrene, were measured by an SFA. The results indicate that the adhesion was exquisitely dependent on the mfp tested, the substrate surface chemistry and the contact time. Such studies are essential for understanding the adhesive versatility of mfps and related/similar adhesion proteins, and for translating this versatility into a new generation of coatings and (including <I>in vivo</I> ) adhesive materials. </P>

Versatile underwater adhesive with microarchitecture triggered by solvent exchange

이동욱,Qiang Zhao,B. Kollbe Ahn,Sungbaek Seo,Yair Kaufman,Jacob N. Israelachvili,J. Herbert Waite 한국고분자학회 2017 한국고분자학회 학술대회 연구논문 초록집 Vol.42 No.1

Versatile underwater adhesive with microarchitecture triggered by solvent exchange

DongWoog Lee(이동욱),Qiang Zhao,B. Kollbe Ahn,Sungbaek Seo,Yair Kaufman,Jacob N. Israelachvili,J. HerbertWaite 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

Simple-to-Apply Wetting Model to Predict Thermodynamically Stable and Metastable Contact Angles on Textured/Rough/Patterned Surfaces

Kaufman, Yair,Chen, Szu-Ying,Mishra, Himanshu,Schrader, Alex M.,Lee, Dong Woog,Das, Saurabh,Donaldson Jr., Stephen H.,Israelachvili, Jacob N. American Chemical Society 2017 The Journal of Physical Chemistry Part C Vol.121 No.10

<P>Rough/patterned/textured surfaces with nano/microcavities that broaden below the surface known as 're-entrants'-can be omniphobic (macroscopic contact angle greater than 90 for both water and oils). The existing theoretical models that explain the effects of texture on wetting are complex and do not provide a simple procedure for predicting the thermodynamically stable and metastable states and their corresponding contact angles (for example, wetting states that involve partially filled cavities). Here, we develop a simple-to-apply wetting model that allows for (1) predicting a priori the wetting state (partially or fully filled) of the cavities both under and outside the liquid droplet and the corresponding macroscopic contact angles on any type of textured surface; (2) determining the conditions under which metastable states exist; and (3) engineering specific nano/microtextures that yield any desired macroscopic contact angle, theta(v) for a given intrinsic contact angle theta(0). Subsequently, we experimentally demonstrate how one can use the model to predict the metastable and the thermodynamically stable contact angles on nondeformable textured surfaces consisting of arrays of axisymmetric cavities/protrusions. In this model, we do not consider the effects of gravitational forces, Laplace pressure of the droplet, line tension, droplet impact velocity, and quantitative aspects of contact angle hysteresis. Nonetheless, the model is suitable for accurately predicting the contact angles of macroscopic droplets (droplet volume similar to 1 mu L and base diameters <2 mm), which is of immense relevance in engineering. In the experimental section we also discuss the suitability of the model to be extended in order to include the effects of contact angle hysteresis on the macroscopic apparent contact angle on textured surfaces. Controlling these macroscopic contact angles, whether higher or lower than the intrinsic angle, theta(0), is desirable for many applications including nonwetting, self-cleaning, and antifouling surfaces and for completely wetting/spreading applications, such as creams, cosmetics, and lubricant fluids.</P>

Rates of cavity filling by liquids

Seo, Dongjin,Schrader, Alex M.,Chen, Szu-Ying,Kaufman, Yair,Cristiani, Thomas R.,Page, Steven H.,Koenig, Peter H.,Gizaw, Yonas,Lee, Dong Woog,Israelachvili, Jacob N. National Academy of Sciences 2018 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.115 No.32

<P>Understanding the fundamental wetting behavior of liquids on surfaces with pores or cavities provides insights into the wetting phenomena associated with rough or patterned surfaces, such as skin and fabrics, as well as the development of everyday products such as ointments and paints, and industrial applications such as enhanced oil recovery and pitting during chemical mechanical polishing. We have studied, both experimentally and theoretically, the dynamics of the transitions from the unfilled/partially filled (Cassie-Baxter) wetting state to the fully filled (Wenzel) wetting state on intrinsically hydrophilic surfaces (intrinsic water contact angle <90 degrees, where the Wenzel state is always the thermodynamically favorable state, while a temporary metastable Cassie-Baxter state can also exist) to determine the variables that control the rates of such transitions. We prepared silicon wafers with cylindrical cavities of different geometries and immersed them in bulk water. With bright-field and confocal fluorescence microscopy, we observed the details of, and the rates associated with, water penetration into the cavities from the bulk. We find that unconnected, reentrant cavities (i.e., cavities that open up below the surface) have the slowest cavity-filling rates, while connected or non-reentrant cavities undergo very rapid transitions. Using these unconnected, reentrant cavities, we identified the variables that affect cavity-filling rates: (i) the intrinsic contact angle, (ii) the concentration of dissolved air in the bulk water phase (i.e., aeration), (iii) the liquid volatility that determines the rate of capillary condensation inside the cavities, and (iv) the presence of surfactants.</P>

Contact Angle and Adhesion Dynamics and Hysteresis on Molecularly Smooth Chemically Homogeneous Surfaces

Chen, Szu-Ying,Kaufman, Yair,Schrader, Alex M.,Seo, Dongjin,Lee, Dong Woog,Page, Steven H.,Koenig, Peter H.,Isaacs, Sandra,Gizaw, Yonas,Israelachvili, Jacob N. American Chemical Society 2017 Langmuir Vol.33 No.38

<P>Measuring truly equilibrium adhesion energies or contact angles to obtain the thermodynamic values is experimentally difficult because it requires loading/unloading or advancing/receding boundaries to be measured at rates that can be slower than 1 nm/s. We have measured advancing-receding contact angles and loading-unloading adhesion energies for various systems and geometries involving molecularly smooth and chemically homogeneous surfaces moving at different but steady velocities in both directions, ±<I>V</I>, focusing on the thermodynamic limit of ±<I>V</I> → 0. We have used the Bell Theory (1978) to derive expressions for the dynamic (velocity-dependent) adhesion energies and contact angles suitable for both (i) dynamic adhesion measurements using the classic Johnson-Kendall-Roberts (JKR, 1971) theory of “contact mechanics” and (ii) dynamic contact angle hysteresis measurements of both rolling droplets and syringe-controlled (sessile) droplets on various surfaces. We present our results for systems that exhibited both steady and varying velocities from <I>V</I> ≈ 10 mm/s to 1 nm/s, where in all cases but one, the advancing (<I>V</I> > 0) and receding (<I>V</I> < 0) adhesion energies and/or contact angles converged toward the same theoretical (thermodynamic) values as <I>V</I> → 0. Our equations for the dynamic contact angles are similar to the classic equations of Blake & Haynes (1969) and fitted the experimental adhesion data equally well over the range of velocities studied, although with somewhat different fitting parameters for the characteristic molecular <I>length/dimension</I> or <I>area</I> and characteristic bond formation/rupture <I>lifetime</I> or <I>velocity</I>. Our theoretical and experimental methods and results unify previous kinetic theories of adhesion and contact angle hysteresis and offer new experimental methods for testing kinetic models in the thermodynamic, <I>quasi-static</I>, limit. Our analyses are limited to kinetic effects only, and we conclude that hydrodynamic, i.e., viscous, and inertial effects do not play a role at the interfacial velocities of our experiments, i.e., <I>V</I> < (1-10) mm/s (for water and hexadecane, but for viscous polymers it may be different), consistent with previously reported studies.</P> [FIG OMISSION]</BR>

Mussel-Inspired Anchoring of Polymer Loops That Provide Superior Surface Lubrication and Antifouling Properties

Kang, Taegon,Banquy, Xavier,Heo, Jinhwa,Lim, Chanoong,Lynd, Nathaniel A.,Lundberg, Pontus,Oh, Dongyeop X.,Lee, Han-Koo,Hong, Yong-Ki,Hwang, Dong Soo,Waite, John Herbert,Israelachvili, Jacob N.,Hawker, American Chemical Society 2016 ACS NANO Vol.10 No.1

<P>We describe robustly anchored triblock copolymers that adopt loop conformations on surfaces and endow them with unprecedented lubricating and antifouling properties. The triblocks have two end blocks with catechol-anchoring groups and a looping poly(ethylene oxide) (PEO) midblock. The loops mediate strong steric repulsion between two mica surfaces. When sheared at constant speeds of similar to 2.5 mu m/s, the surfaces exhibit an extremely low friction coefficient of similar to 0.002-0.004 without any signs of damage up to pressures of similar to 2-3 MPa that are close to most biological bearing systems. Moreover, the polymer loops enhance inhibition of cell adhesion and proliferation compared to polymers in the random coil or brush conformations. These results demonstrate that strongly anchored polymer loops are effective for high lubrication and low cell adhesion and represent a promising candidate for the development of specialized high-performance biomedical coatings.</P>