Measurement of the zeta potential of planar surfaces with a rotating disk

Lameiras, Fernando Soares; Souza, Aldalberto Leles de; Melo, Valéria Alves Rodrigues de; Nunes, Eduardo H.M.; Braga, Ivan Dionizio

doi:10.1590/s1516-14392008000200018

Cited by 46 publications

(29 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, when the PCDME gels are in contact with the glass surface that is negatively charged in water, 38 the positively charged quaternary ammonium moiety may have attractive interaction with glass surface, especially when we take consider the weak acidic nature of the carboxylate moiety. If the ionic attraction between the gel and the glass exist, it should be shielded at high ionic strength.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Lameiras et al showed that lowering the pH of the solution pushes the ζ potential of glass toward zero ( Figure 6a). 38 The electrostatic interaction between gel and glass surface can be approximated as the product of their surface potential ψ gel ψ glass . Using the ζ potential of glass from literature as ψ glass and the measured ψ gel of PCDME hydrogel, Figure 6b shows the correlation between ψ gel ψ glass and frictional stress as a function of pH.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Sliding Friction of Zwitterionic Hydrogel and Its Electrostatic Origin

et al. 2014

View full text Add to dashboard Cite

Polyzwitterionic materials, which have both cationic and anionic groups in each repeating unit of polymer, show excellent antibiofouling properties. In this study, the surface friction of carboxybetaine type zwitterionic hydrogels, poly(N-(carboxymethyl)-N,N-dimethyl-2-(methacryloyloxy)-ethanaminium, inner salt) (PCDME), against glass substrates were investigated in aqueous solutions. The friction measurement was performed using a rheometer with parallel plate geometry and the sliding interface was monitored during the measurement. The frictional stress on glass was high in water and it showed weak dependence on pressure as long as the two sliding surfaces were in complete contact. The results performed in solutions with varied ionic strength revealed that the high friction on glass substrates has an electrostatic origin. The electrostatic potential measurement revealed that the PCDME gels have an isoelectric point at pH 8.5. Since the glass substrates carrying negative charges in pure water, the gel and the glass have electrostatic attraction in water. Study on the effect of pH has shown that below pH 8.5, attraction between the positively charged gels and negatively charged glass gives high friction, while above pH 8.5, the electrical double layer repulsion between two negatively charged surfaces gives low friction. From these results, it is concluded that although the PCDME gels behave like neutral gels in the bulk properties, their surface properties sensitively change with pH and ionic strength of the medium. ■ INTRODUCTIONPolyzwitterionic materials, which have both cationic and anionic groups in each repeating unit of polymer, are drawing great attention as biomaterials due to their excellent antibiofouling properties and biocompatibility. 1−10 The antibiofouling materials that prevent the attachment of bioorganisms in wet environment are in a great demand for advanced technologies. Recently a tough double network (DN) hydrogel has been developed by using poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) as the first network and a carboxybetaine type zwitterion poly(N-(carboxymethyl)-N,Ndimethyl-2-(methacryloyloxy)ethanaminium, inner salt) (PCDME) as the second network. 11 Comparing to the conventional double network (DN) hydrogels that use neutral polyacrylamide or poly(dimethyl acrylamide) as the second network, 12 the DN hydrogel using the zwitterionic polymer as the second network exhibits excellent antibiofouling properties in addition to high mechanical strength and toughness. 11 This promises a great potential of the zwitterion-based hydrogels as better candidate for bioapplication, for example, as coating materials of low-friction biomedical devices and implants. Understanding the surface frictional properties of the zwitterion hydrogels is indispensable for these potential applications.As the water-swollen hydrogels have many common features to that of internal organs in our body, the sliding friction of hydrogels in aqueous solution has recently been drawing great scientific attention. 13−24...

show abstract

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Sliding Friction of Zwitterionic Hydrogel and Its Electrostatic Origin

et al. 2014

View full text Add to dashboard Cite

show abstract

“…When the pH of the solution is significantly above the pI of the substrate, the characteristic zones of ionic enrichment and depletion are observed upstream and downstream of the nanochannel, respectively. The glass substrates, used in this report for the production of the microfluidic devices, have a pI near 2.1 [41]. Second, co-ion (Alexa fluor 430) Fig.…”

Section: Characterization Of Junctionmentioning

confidence: 89%

“…The double layer thickness is dependent on both the pH and the concentration of the electrolyte solution used. As the pH increases, increased deprotonation of the acidic silanol groups increases the z-potential and double layer thickness [41].…”

Section: Characterization Of Junctionmentioning

confidence: 99%

Analyte transport past a nanofluidic intermediate electrode junction in a microfluidic device

2010

View full text Add to dashboard Cite

A glass microfluidic device is presented in which a microchannel is split into two regions with different electric fields by a nanochannel intermediate electrode junction formed by dielectric breakdown. The objective is to sink current through the nanochannel junction without sample loss or broadening of the band as it passes the junction. This type of performance is desired in many microfluidic applications, including the coupling of microchannel/CE with ESI-MS, electrochemical detection, and electric field gradient focusing. The voltage offsets in this study are suitable for microchannel/CE-ESI-MS. Imaging of the transport of model anions and cations through the junction indicates that the junction exhibits nanofluidic behavior and the mean depth of the nanochannel is estimated to be approximately 105 nm. The ion permselectivity of the nanochannel induces concentration polarization and enriched and depleted concentration polarization zones form on opposite sides of the nanochannel, altering the current and electric field distributions along the main microchannel. Anion transport efficiency past the junction was high, 96.0%, and varied little over the pH range of 4.0-8.0. In contrast, cation transport is much lower, and decreases from 72 to 11% from pH 4.0 to 8.0. Band broadening increases with increasing pH less than 70% over the pH range of 4.0-8.0. It is anticipated that this characterization will aid in the understanding and optimization of such junctions made from permselective membranes and porous glass.

show abstract

“…[24] Thus, we can assemble the oppositely charged PE hydrogels, biological tissues, and glass using PA gel as adhesive layers ( Figure 2B). These results indicate that PA hydrogel can serve as an adhesive for reversible gluing of charged surfaces by forming the dynamic ion bond formation.…”

mentioning

confidence: 99%

Self‐Adjustable Adhesion of Polyampholyte Hydrogels

et al. 2015

View full text Add to dashboard Cite

Biological surfaces are very complex in nature. They have wide distribution in molecular species; including positive and negative charges, polar and non-polar groups. [1] A material to show adhesion to such biological surfaces should have the capability of creating enough adhesive interacting sites with these species in wet environment. [2] Conventional hydrogels usually have poor adhesion to biological surfaces. [3] This is because the adhesion in wet environment is usually based on the Columbic interaction that strongly depends on the charge combinations. [3,4] Many of the biological surfaces and hydrogels have net negative surface charge [5] and they are repulsive in water. Developing adhesives that possess the ability of quick, strong, and reversible adhesion to hydrogels and biological tissues regardless their net charge identity will substantially promote the application of hydrogels in biomedical applications. Several research groups have tried to develop different adhesive hydrogels based on surface modification, [6] mechanical interlocking, [7] making composites, [8] supramolecular recognition, [9] and nano-particles. [10,11] But these approaches have limitations in practical applications, such as lengthy and complicated way of processing, lack of water resistivity and universality, inability in non-residual removal, etc. [12] The clue to develop adhesives working for hydrogels and biological tissues hides in nature.Bacteria cells, ubiquitous in environment, can attach with almost any surfaces including human tissues, regardless the diversity in the surface chemistry. The self-adjustable capability of the extracellular polymeric matrix (EPM) of bacteria cells has made this possible. [13,14] EPM can provide sufficient interacting sites for adsorption of species at interface in response to substrates mechanical and chemical properties through re-distribution of their charged groups. [15] Inspired from nature, we intend to find out a self-adjustable hydrogel adhesive for adhesion to hydrogels and tissues. A self-adjustable surface is such a surface which can offer its species for the formation of attractive interaction depending on substrate charges through dynamic reorganization process. A possible design for achieving such a self-adjustable 3 adhesive is a hydrogel composed of both positively and negatively charged monomers.Presence of both charges in the hydrogel is expected to create attractive interacting sites with any charged surfaces regardless of their charge identity to facilitate adsorption. But this seems to be tricky, because incorporation of both type charges in the same hydrogel sometime encounters strong self-ionic association, which will made it impossible for the formation of bonds with other species residing in different surfaces or in some cases imbalance in component inside hydrogel offers a strong net charge over the surface, [16] which will prevent their non-specific adhesion property. We can overcome this problem by choosing a neutral (charge balanced) polyampholyte (PA) hydrogel th...

show abstract

Measurement of the zeta potential of planar surfaces with a rotating disk

Cited by 46 publications

References 6 publications

Sliding Friction of Zwitterionic Hydrogel and Its Electrostatic Origin

Sliding Friction of Zwitterionic Hydrogel and Its Electrostatic Origin

Analyte transport past a nanofluidic intermediate electrode junction in a microfluidic device

Self‐Adjustable Adhesion of Polyampholyte Hydrogels

Contact Info

Product

Resources

About